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1、OperabilityStrategy ReportDecember 2022NavigationText Links Click highlighted orange text to navigate to an external link.Or to jump to another section of the documentExpand content Rollover or click the plus symbol to expand or enlarge contentMore information Rollover or click the info symbol for m
2、ore informationButtons Access additional information by hovering on the rectangular buttons positioned beneath many of our chartsReturn to contentsFrom here you can navigate to any part of the publicationPage navigation explainedBack a pageForward a pageTo help you find the information you need quic
3、kly and easily we have published the report as an interactive document.Download the PDF in Acrobat Reader to view all interactivity.ButtonContentsDecarbonisation 04ESO Publications 06Executive Summary 08Reliable Network Summary 12Balancing the System Summary 16How to get involved 19Zero Carbon Opera
4、bility 20Reliable Network 25Stability 28Voltage 35Thermal 44Restoration 53Balancing the System 59Frequency 63Within-Day Flexibility 76Adequacy 86DecarbonisationOperability Strategy Report/Decarbonisation/05Operability Strategy Report/Decarbonisation/05DecarbonisationWhat do we mean by decarbonisatio
5、n?Decarbonising the electricity power system in GB is critical to meeting the governments ambitions on the way to net zero.A sustainable energy system is something we are committed to enabling through all of our work.As the ESO,in our role of powering Britain,we want to ensure that we are ready to d
6、ecarbonise the power system and this poses some challenges which,with industry,we intend to overcome.Here we explain what we mean by decarbonisation of the electricity system.We have then used these terms throughout the report.Decarbonisation of the electricity system is leading to changes in four k
7、ey areas:Less dispatchable generation More asynchronous generation More variable sources of generation Generation moving to different areasLess dispatchable generation refers to the closure of traditional synchronous generators like coal and gas.These provided firm,flexible power and system services
8、 like voltage and stability.They were also typically used for restoration services.More asynchronous generation refers to the increase in generators connected by inverter-based technologies,such as wind,solar and battery storage.These types of generators are less flexible than traditional synchronou
9、s generators and generally do not provide system services.More variable sources of generation refers to the increase in generators which are more dependent on an input to generate,like sunshine or wind,and are more prone to variability in energy output due to input variability.Generation moving to d
10、ifferent areas refers to new generation locating at network extremities and further away from demand centres such as offshore,in Scotland and in South West England.It also refers to the increase in generation on the distribution networks.Less dispatchable generationMore variable sources of generatio
11、nMore asynchronous generationGeneration moving to different areasESO PublicationsOperational&Investment relatedMarkets related ESO Strategy relatedETYSNOAFESMRBtGRIIO-2 BP2OSR/SOFOperability Strategy Report/ESO Publications/07Operability Strategy Report/ESO Publications/07Markets Roadmap Our ambitio
12、n is to design market arrangements that facilitate security of supply at the lowest sustainable cost for customers,while enabling the transition to net zero.Our annual Markets Roadmap sets out our development and design principles for how we will shape future market arrangements.We focus on the futu
13、re trends and investigate the interactions between ESO and wider industry markets.Bridging the Gap to Net Zero We look at the key messages from our Future Energy Scenarios to understand what needs to be done to bridge the gap between today and 2050.ESO PublicationsExecutive SummaryOperability Strate
14、gy Report/Executive Summary/09Operability Strategy Report/Executive Summary/09Our annual Operability Strategy Report explains the challenges we face in operating a rapidly changing electricity system and describes what capabilities we need to resolve these challenges and enable a zero carbon electri
15、city system in 2035.We continue to work closely with our stakeholders to look across systems,markets,policy,technology and innovation as we develop and deliver solutions in response to these challenges.Collaboration and co-creation are at the heart of everything we do and throughout this report,we s
16、ignpost where to look for more information.The how to get involved section of this report also highlights opportunities for industry engagement as we continue to tackle the future challenges in an ever-changing system.As with previous reports,there is a close interaction between the Markets Roadmap
17、and the Operability Strategy Report.These two documents complement one another with the Operability Strategy Report defining our operational requirements and future system needs,while the Markets Roadmap explains how our markets are evolving to meet these future needs in the most efficient way.Execu
18、tive SummaryOperability Strategy Report/Executive Summary/10Operability Strategy Report/Executive Summary/10ContextDecarbonisation,decentralisation and digitalisation are driving significant change across the electricity network,impacting how we operate the system now and into the future.These chall
19、enges are set against a backdrop of significant other industry change such as the Distribution Network Owner to Distribution System Operator transition and the growth of Distributed Energy Resources(DER)and interconnection.It is our role to support the energy transition,while making sure we can cont
20、inue to operate the system in a way that delivers the biggest benefits to consumers.Across the workstreams in this report we have delivered,and are delivering,innovative systems,products and services.These will transform how we operate Great Britains electricity system,and mean we are ready to opera
21、te a zero carbon network in 2025.But it doesnt stop there,the system will continue to evolve as we strive towards net zero.This means a fundamental change in how our system is operated integrating newer technologies right across the system from large scale off-shore wind,to domestic scale solar pane
22、ls,to increased demand side participation.We recognise the critical nature of our work to ensure safety and reliability,to lower consumer bills,reduce environmental damage and increase overall societal benefits and we are committed to collaborating with industry to unlock this value.Executive Summar
23、yOperability Strategy Report/Executive Summary/11Operability Strategy Report/Executive Summary/11Executive SummaryReport structure and key messagesPrevious editions of this report have considered the operability challenges in 5 security workstreams:Frequency,Stability,Voltage,Restoration and Thermal
24、.This year we have added two more:Within-day Flexibility and Adequacy.These new sections reflect the changing nature of the future system challenges we face.Across these seven workstreams we explain the future operability challenges,the capabilities and requirements we need,as well as the next big o
25、perational challenges on the horizon.For faster reading,a summary of our key messages in each chapter is provided here.To aid the reader,we have restructured the report and grouped the challenges into two themes:1.Reliable network This section focuses on system requirements that are locational by na
26、ture.These are Stability,Thermal,Voltage and Restoration.For each of these challenges,we resolve the requirement based on the physical needs of the power system and represent the sole customer of such services.2.Balancing the systemThis section focuses on the system energy balance.These are Frequenc
27、y,Within-day Flexibility and Adequacy.All of these areas ensure energy balance but over different timescales.They are national in scope and do not currently have a locational component.Within this area,both the market and the Electricity System Operator(ESO)have incentives to resolving the challenge
28、s.Operability Strategy Report/Executive Summary/12Operability Strategy Report/Executive Summary/12Reliable Network SummaryStabilityStability has traditionally been supplied as an inherent by-product of synchronous generation.More asynchronous generation continues to drive a decline in this inherent
29、stability of the system,with a gradual reduction in system inertia.We currently meet any requirement(after market dispatch)by synchronising gas and biomass generators.This has both an economic and carbon impact so we need to find and procure alternative sources of stability to support our net zero a
30、mbition.By 2025 the minimum inertia that we can operate at will be 102GVAs.This assumes we need to secure against a largest loss of 1800MW and keeping the Rate of Change of Frequency(RoCoF)within 0.5Hz/s.We currently operate at a minimum of 140GVAs and so are starting the process to reduce our opera
31、tional limits to meet our zero carbon targets.This will be achieved through the Frequency Risk and Control Report(FRCR)reducing minimum inertia is the focus of the 2023 report.Operationally we could meet our requirement to maintain system inertia at 102GVAs based on the current system conditions(mai
32、nly by synchronising plant),however we acknowledge that this is not the most economic,nor efficient approach.Future procurement of stability services will be to reduce operational costs,rather than for system security reasons.In addition to declining inertia,we are also starting to observe challenge
33、s with low short circuit levels as less dispatchable generation is replaced by more asynchronous generation.We are currently reviewing our policy for managing low short circuit levels.We are working closely with industry and international Transmission System Operators(TSOs)to understand the differen
34、t options for measuring and maintaining system strength,including defining the different obligations industry parties should aim to maintain.At present,our studies suggest that we have sufficient short circuit level on the system until 2029 and we are working on solutions for optimal procurement of
35、this service for future years.Any future procurement will take learnings from the ongoing policy work to understand and agree the best approach for calculating and managing low short circuit levels.We are also working towards enhancing the use of Electro Magnetic Transient(EMT)studies to provide det
36、ailed system studies.This will further support our ability to manage the emerging operability system stability challenges.Grid forming technology will be a significant,contributing factor to future stability of the system.This enables inverter-based technology to provide similar characteristics to t
37、raditional synchronous generation.This will be key to effectively managing a net zero power system.Whilst the non-mandatory Grid Code specification provides guidance on minimum requirements for enhancing asynchronous plant,we anticipate that future market arrangements will form the basis of where gr
38、id forming technology could be procured by the ESO.Operability Strategy Report/Executive Summary/13Operability Strategy Report/Executive Summary/13Reliable Network SummaryVoltageVoltage is influenced by,and managed through,the injection and absorption of reactive power.We must maintain voltage level
39、s across the transmission network within the Security and Quality of Supply Standards to ensure safety and reliability of the network.Voltage management continues to be challenging as reactive power demand on distribution networks continues to decrease and power flows across the transmission network
40、 reduce.These system changes are driving an increasing need to absorb reactive power on the transmission system.Less dispatchable generation is reducing available reactive power capacity in the right regions.In many regions,we are synchronising generation out of merit to access their reactive power
41、capacity.This increases balancing costs.Our voltage screening report 2022 has again highlighted numerous areas where reactive capacity is reducing or voltage management costs are increasing.There is a need in both the short and medium term to increase available reactive capacity in the right locatio
42、ns and reduce consumer costs.Reactive utilisation costs increased by nearly 200%in 2021/22 compared to 2020/21.This was mostly driven by the impact of wholesale gas prices on the default price paid to reactive power providers,but reactive utilisation still increased by 20%.In addition,more reactive
43、power capacity is needed to meet requirements in 2025 and beyond,otherwise this could increase operational costs significantly as we synchronise generation for voltage support.This would also negatively impact our ability to meet our zero carbon operation in 2025 ambition.We have worked with Nationa
44、l Grid Electricity Transmission to further refine the reactive needs for England and Wales in 2025 and are exploring options to deliver the best value for the consumer.We are now assessing requirements beyond 2025 and will provide an update to industry in mid-late 2023.Looking forward the message wi
45、thin our voltage screening reports and system studies is clear.We need to reduce our reliance on fossil fuel generators and increase access to more reactive capability in the right locations.We will need to manage high volts during low demand without removing more network assets,secure the system fo
46、r faults causing low volts during peak demand,and mitigate more dynamic voltage levels during interconnector flow changes.Operability Strategy Report/Executive Summary/14Operability Strategy Report/Executive Summary/14Reliable Network SummaryThermalWe manage the flow of electricity across the high v
47、oltage transmission system from where it is generated to where it is consumed.The transmission network has a limited capacity to transport this energy.We must manage the power flows to prevent network assets becoming overloaded and loss of supply to areas of the network.We are at the forefront of pl
48、anning a network fit for the future through the Electricity Ten Year Statement and Network Options Assessment.Where the network does not have enough capacity,we mostly manage network constraints by constraining generation.We are mindful of the impact these actions have from both a carbon and cost pe
49、rspective and are proactively focused on seeking innovative solutions to manage these constraints.We are developing further commercial intertrip schemes and have worked with the TOs to deliver innovative ways of increasing constraint boundaries on the existing network.We are also working with Ofgem
50、to accelerate delivery of strategic network investment ahead of 2030.Our ambition is to operate a zero carbon network in 2035 and enable net zero by 2050.This requires significant investment in the transmission network to transfer power from renewable generation to new and changing sources of demand
51、.In July 2022 we published our first Holistic Network Design(HND)alongside a refreshed Network Options Assessment.Together they recommend 94 asset investments to deliver a network which can accommodate the Governments ambition of 50GW offshore wind by 2030.The Future Energy Scenarios(FES)indicate th
52、e need for a demand side strategy to avoid wasting renewable energy.We need to incentivise new demand to connect where there is excess generation.This can help effectively alleviate constraint costs.To achieve this goal,we are working on two innovation projects to demonstrate how green hydrogen can
53、support constraint management and develop a probabilistic model which quantifies the risk of energy flow congestion.FES also indicates that we will be a net exporter of electricity by 2030.With much of our interconnection being in the South East,we will need to manage the increase in power flows in
54、the region and avoid the high cost actions on interconnectors seen in July 2022.We have argued in our Net Zero Market Reform programme that nodal pricing,which reveals the value of electricity at high locational and temporal granularity,could be beneficial to enable market participants to mitigate t
55、hermal constraints,particularly in operational timescales.The Department for Business,Energy&Industrial Strategy(BEIS)are also considering nodal pricing as one of several options to improve locational signals in its Review of Electricity Market Arrangements(REMA).We think long term,this solution cou
56、ld support with addressing thermal constraints and will reduce the need for additional network build.We are introducing a local constraint market in early 2023 to address high constraint costs between Scotland and England.This will help to inform our thinking on local markets.NET ZEROCARBONOperabili
57、ty Strategy Report/Executive Summary/15Operability Strategy Report/Executive Summary/15Reliable Network SummaryRestorationIn the unlikely event that the electricity system fails,and the lights go out,we have a robust plan to restore power to the country as quickly as possible.Historically,the electr
58、icity system has been dependent on large,dispatchable generation to provide restoration services.Less dispatchable generation means that we need to ensure restoration services can be provided by a range of users in the future.The enormous growth in Distributed Energy Resources(DER)presents an opport
59、unity to develop a radically different approach to system restoration.Greater diversity in the provision of restoration will improve resilience and increase competition leading to reductions in both cost and carbon emissions.Future diversity of service providers will also create operational challeng
60、es due to the complexities of managing a system with more variable sources of generation as well as a variety of providers.We need to ensure that engineering solutions,organisational coordination and commercial and regulatory frameworks can all work together to ensure resilience and flexibility in t
61、he operation of the network.The Grid Code has always required that we have the capability to restore the system,but has had limited detail as to what that meant.In April 2021 this changed when BEIS announced their intention to strengthen the existing regulatory framework by introducing a new Electri
62、city System Restoration Standard(ESRS).The ESRS requires that we can restore 100%of GB electricity demand within 5 days,with 60%of regional demand having been restored within 24 hours.These requirements should be implemented by December 2026.We have worked with industry to enable DER to provide rest
63、oration services through our Distributed Restart innovation project.The three-year project has been extended towards the end of 2022,to enable the completion of the power engineering live trials.We will take learnings from the project to manage future challenges,in order to implement the requirement
64、s of the ESRS directed by BEIS and Ofgem in 2021.The technical,organisational and commercial challenges that we need to resolve are being addressed through GC0156 and specific workgroups have been set up to focus on each area(such as markets,funding,regulatory frameworks and modelling tools).Looking
65、 forward and the future challenges will be to integrate the growing offshore networks into our restoration solutions.The System Operator-Transmission Owner Code(STC)does not currently recognise offshore networks as contributing to Restoration so this will need to be considered as part of the Offshor
66、e Network Design and HND work.Operability Strategy Report/Executive Summary/16Operability Strategy Report/Executive Summary/16Balancing the System SummaryFrequencyFalling inertia levels,increasing largest loss size and high RoCoF levels are driving many of the current and future frequency challenges
67、.In addition,supply and demand are becoming increasingly variable.This is making system frequency more volatile and unpredictable.The introduction of FRCR last year was a paradigm shift in how we manage frequency as it introduced a probabilistic approach that increases end consumer benefit compared
68、to the previous deterministic approach.We are tackling these challenges through our new suite of reserve and response services.Dynamic Containment,Dynamic Regulation and Dynamic Moderation are all live on the system.Looking forward,several new reserve services will be launched.Quick Reserve will be
69、used to recover frequency back towards 50Hz,mainly during normal operating conditions Slow Reserve will replace Short Term Operating Reserve(STOR)which will recover frequency to+/-0.2Hz within 15 minutes Balancing Reserve will provide flexibility in real-time to ensure balance between supply and dem
70、andThese reserve services will be launched soon through our response and reserve reform programme.The size of our frequency requirements are dictated by the inertia levels on the system and the size of both generation and demand losses.These requirements may change and are heavily impacted by how th
71、e system evolves.The following table sets out our 2025 requirement and assumes the inertia provided by the market falls as low as 102GVA.s:Frequency serviceSystem needRequiredDynamic Regulation and Dynamic ModerationRegulate steady-state frequency within the statutory limits of+/-0.5Hz up to 300MW e
72、achDynamic Containment Contain the frequency for events within standardsup to 1,400MW Quick ReserveRecover frequency back towards 50Hz,mainly during normal operating conditionsup to 1,400MW Slow ReserveRestore frequency to the operational range(+/-0.2Hz)within 15 minutesup to 1,400MW Balancing Reser
73、veFlexibility in real-time to ensure balance between supply and demandup to 2500MWWe have identified a gap within our new suite of services due to the ending of monthly procurements of dynamic Firm Frequency Response(FFR)and secondary static response.A future service is being designed to recover fre
74、quency to+/-0.5Hz within 60 seconds following large scale losses.We have been working through options to meet this need and a new service provisionally called Static Recovery has been identified.Greater locational fluctuations in frequency may occur due to lower inertia and increased largest loss si
75、ze.Were investigating any potential requirement and solutions to help develop our future frequency strategy.This potentially could lead to a requirement for regional frequency products.CO2Operability Strategy Report/Executive Summary/17Operability Strategy Report/Executive Summary/17Balancing the Sy
76、stem SummaryWithin-day flexibilityWithin-day flexibility is a new dimension of operability that has been added into the Operability Strategy Report this year.The operability challenge we are highlighting is how to manage daily peaks and troughs of supply demand lasting a few hours.We have defined Wi
77、thin-day flexibility as the ability to move demand(and supply from storage)within a 24-hour period.This flexibility will be used to ensure energy balance between more variable sources of generation and inflexible demand.These timing driven imbalances will grow rapidly over the next 10 years with inc
78、reasing volumes of renewable generation and electrified demand.The system will need the ability to shift demand through time because without it,there will be an increased need to curtail renewable generation and an increased reliance on dispatchable generation,which will increase costs and emissions
79、.In addition,the ability to adjust demand and network flows will help with our other operability requirements.The capacity of Within-day flexibility is currently small but will grow rapidly over the next 10 years.FES shows that by 2030,the system is expected to have 25-45GW of Within-day flexibility
80、 mainly from smart charging of electric vehicles,vehicle-to-grid,smart electric heat,smart domestic appliances and battery storage with duration of a few hours.This growth in Within-day flexibility will be driven by changes in market arrangements such as the introduction of market wide half hourly s
81、ettlement that will increase consumers exposure to time of use signals.Operability Strategy Report/Executive Summary/18Operability Strategy Report/Executive Summary/18Balancing the System SummaryAdequacy Adequacy measures whether there are sufficient available resources to meet electricity demand th
82、roughout the year.In Great Britain,this has traditionally meant having sufficient margins when demand is highest in winter.We commissioned AFRY to undertake a long-term adequacy study to assess the risks to security of supply in a fully decarbonised power system and the resources needed to ensure ad
83、equacy in the 2030s.The study examines four different potential portfolios of resources utilising different combinations of nuclear,CCS,hydrogen power generation and batteries.The purpose is not to identify a definitive pathway,or resource mix,for GB;but rather to explore the range and mix of option
84、s that could ensure adequacy,the implications of them and some of the trade-offs that might be required.This is a first step towards understanding the scale of the challenge facing GB.The full report is available on our website and the key findings are:There is no trade-off between adequacy and meet
85、ing net zero but we need to bring forward investment in clean,reliable technologies.Understanding risks due to weather patterns will become increasingly important to ensure adequacy in a fully decarbonised system with high levels of weather-dependent generation.New modelling approaches and metrics w
86、ill be required to assess risks to adequacy in a fully decarbonised power system.It will become more important to consider adequacy in the context of developing the right markets,the right networks and future operability challenges to be confident that adequacy is ensured in a cost-effective way.The
87、re are also operability impacts to consider.Whilst there are many different pathways that can provide similar levels of adequacy,there are significant differences in their operability impact throughout the year.For example,a resource mix with high levels of renewables combined with significant level
88、s of less flexible generation,will have a much higher level of surplus energy and renewable generation curtailment.While this poses little operational risk to security of supply,the need for curtailment could increase operational costs substantially.Operability Strategy Report/Executive Summary/19Op
89、erability Strategy Report/Executive Summary/19How to get involvedWe want to work with you!Our strategy is ambitions and transformative.It is vital for making sure we can continue to operate a safe,secure and reliable electricity system,and deliver against our zero carbon by 2025 ambition while maxim
90、ising benefits for the consumer and your input and support is critical.Throughout the main body of our report,you will find links to specific opportunities to get involved in all key areas of our work.We would also welcome to your comments and feedback on our overall approach to our operability chal
91、lenges or any specific feedback on the report content.Please get in touch by emailing us at System Operability Framework publication plan The System Operability Framework(SOF)takes a holistic view of the changing energy landscape to assess the future operation of Great Britains electricity networks.
92、The SOF combines insight from the Future Energy Scenarios with a programme of technical assessments to identify medium-term and long-term requirements for operability.The table below details the publications planned over the next few months.Please visit the SOF webpage for details of past and presen
93、t publications.ReportsOverviewWhen to expectPower Quality in Electrical Transmission NetworkPower quality is critical to the performance of equipment connected to the electricity network.There is direct correlation between power quality and system strength.The stronger the system strength,the easier
94、 it is to manage the power quality to the relevant standards.As more asynchronous generation connects to the system,the system strength continues to decline.This report will provide an outlook of the changes in the power quality of the electricity network.Mar 2023System StrengthHow to effectively ma
95、nage system strength of the GB system with a future high penetration of inverter-based resources(IBR)is important for stable operation of the system.This report shares our thinking about how system strength should be defined and managed in an IBR dominated system.May 2023Management and Mitigation of
96、 Oscillations on the GB Transmission SystemSince oscillations were observed on the SSEN-T transmission system in August 2021,detailed investigations have been taking place reviewing:Network analysis to understand the drivers of the oscillations.Assessment of indicators to be used as a screening tech
97、nique to determine areas at greater risk of oscillatory events;and Application of system monitoring tools to give greater visibility of eventsThis report will share findings and insights from our investigations.Aug 2023GB Grid Forming Development Grid Forming is widely recognised as a promising tech
98、nology for global net zero energy transitions.This report introduces the GB Grid Forming strategic developments that will help address existing or potential operability challenges on the GB system.In particular it will look at the interaction with the decline of system inertia and the reduction in s
99、ystem fault levels.Nov 2023Zero Carbon OperabilityOperability Strategy Report/Zero Carbon Operability/21Operability Strategy Report/Zero Carbon Operability/21Great Britain is one of the fastest decarbonising electricity systems in the world and as the system operator we have an ambition to be able t
100、o operate the network the network using 100%zero carbon electricity by 2025.To do this we are pushing forward innovative,world first approaches to transform how the power system operates.We are delivering frequency services that are fit for operating a zero carbon network where system frequency will
101、,at times,be more variable.Our stability and voltage pathfinders reduce our reliance on dispatchable generation for critical transmission system services.We can already maintain our system restoration capability without warming or running fossil fuelled generation.Across all our workstreams,we will
102、be ready to meet our 2025 zero carbon ambition.These innovative approaches and the plans we have put in place across each operability workstream,mean that by 2025,there could feasibly be periods where we will be able to operate a zero carbon system if the transmission generation scheduled by the mar
103、ket is zero carbon.Initially this maybe for a few settlement periods throughout the year,but these periods will grow as our capability to operate a zero carbon system expands and the market provides more zero carbon dispatch solutions.This could potentially happen in a manner similar to the phasing
104、out of coal,where we initially observed rare zero coal settlement periods.Within a few years after coal began to come off the system,these periods started to become the new normal.We assess progress against our ambition by measuring the proportion of zero carbon transmission connected generation tha
105、t the system can accommodate before and after our actions.Zero carbon generation includes hydropower,nuclear,solar,wind and pumped storage technologies.We share this progress through the Zero Carbon Operability(ZCO)indicator:This year our ability to operate a zero carbon network has increased.We saw
106、 an increase to a new zero carbon generation maximum of 87%on 5th January 2022 after our operational interventions(shown in the chart).During these periods,we synchronised six carbon units for system reasons(voltage and minimum inertia).However the need for these additional carbon units will be remo
107、ved for settlement periods such as these,through our on-going voltage and stability work.This means that by 2025 we will have the ability to operate a zero carbon network,reducing our reliance on carbon generation for ancillary services and also reducing operational costs.Please see following the es
108、sential activity that we have already completed and what is left to do to achieve our ambition.(Zero carbon transmission connected generation)(Total transmission connected generation)ZCO(%)=100Zero Carbon Operability0%10%20%30%40%50%60%70%80%90%100%01-Jan06-Jan11-Jan16-Jan22-Jan27-Jan01-Feb07-Feb12-
109、Feb17-Feb23-Feb28-Feb05-Mar11-Mar16-Mar28-MarZCO provided by marketFinal ZCO(after ESO interventions)January highest final ZCO:87.1%5 Jan,SP5February highest final ZCO:85.3%27 Feb,SP23March highest final ZCO:85.0%22 Mar,SP5Q4 ZCO detail by Settlement PeriodOperability Strategy Report/Zero Carbon Ope
110、rability/22Operability Strategy Report/Zero Carbon Operability/22Zero Carbon Operability20022202320242025FrequencyDCDynamic and fast acting response product to manage larger losses at lower inertia levelsDMDynamic response to better manage large changes in intermittent generation at lower
111、 inertia levelsDRDynamic response to better manage pre-fault frequency at lower inertia levelsReformed MarketsMarket reform across all response and reserve products to facilitate new zero carbon operationStabilityALOMCPRemoves the risk of DER activation at lower inertia levelsPhase 112.5GVAs of iner
112、tiaPhase 26.5GVAs of inertia and 11.5GVA SCL for ScotlandPhase 317GVAs of inertia and 12.7GVA SCL for E&WFRCREnables the enhancements from the Frequency provisions to change how we operate the system at lower inertiaInertia monitoringImplementing first of its kind inertia monitoring tools,providing
113、instantaneous,real time dataVoltageMerseyReduce the reliance on a single CCGT for voltage in one areaPenninesExpand the learning to cover a larger area and reduce reliance on a number of unitsE&WCover the whole of E&W to ensure no reliance on machines to manage voltageEfficiencyIncreased access to e
114、xisting capability through changes to codes and developments with the Transmission ownersThermalEfficiencyFive point plan and Constraint Management Pathfinders to increase zero carbon capabilitiesRestorationESRS ServicesEnsured that all ESRS services are in place and do not require units to be warme
115、d to provide the serviceActivity essential for 2025 zero carbon operationLooking back at the journey from setting our zero carbon ambition in 2019 to develop the capability to operate zero carbon in 2025,the following are the key activities which have made operating at zero carbon possible.020040060
116、08001,0001,2001,400222528349525558679828588919497100MWRankBiomassCCGTCoalOCGTOtherOperability Strategy Report/Zero Carbon Operability/23Operability Strategy Report/Zero Carbon Operability/23ZCO is highest when it is windy with significant contributions from nuclear,p
117、umped storage and hydro.It will be reduced by our actions to alleviate system constraints such as when we constrain zero carbon generation from the system and add on fossil fuelled generation such as gas or biomass to meet our response,inertia and voltage requirements.By 2023 the maximum ZCO limit w
118、ill rise to 87%-90%.This increase is due to the work we are doing to drive towards our ambition.For example,our new response products,the stability pathfinders,the implementation of the Frequency Risk and Control Report methodology,the voltage pathfinders and reactive reform.All of these development
119、s are increasing our ability to operate a zero carbon system by either increasing the operability envelope where secure system operation is possible,or by enabling new zero carbon providers for the ancillary services we need.As the work continues through 2023 and 2024,we expect that this will furthe
120、r increase our ability to operate a zero carbon system.By 2025 we expect that periods of 100%zero carbon operation will be possible,albeit in specific conditions.There is a zone where operational interventions are minimised because system conditions are favourable.Transmission demand will be neither
121、 too high or low,but can be supplied exclusively from interconnectors,nuclear,wind and solar.Stability and voltage requirements will need to be met without dispatching fossil fuelled generation.This results in a ZCO operability window where demand is between 25GW and 65GW,but more likely at the lowe
122、r end of this range.This is more likely to happen during Spring or Autumn,or during the Christmas break,when it is windy and demand is lower.Our ambition is to be able to operate a 100%zero carbon system when the market delivers such a solution.However since April 2021,there have been no settlement
123、periods where the market has delivered a 100%zero carbon generation mix.For every settlement period,there has always been 500MW+of either biomass and/or gas.The closest has been where there was 95.5%zero carbon generation in November 2021 and the lowest carbon MW was 679MW in August 2021.The chart s
124、hows the carbon generation mix for the 100 settlement periods with the lowest carbon MW since April 2021.Where the market supplied carbon MW is minimisedZero Carbon Operability020002400500600Average Carbon Intesnity gCO2/kWhOperability Strategy Report/Zero
125、 Carbon Operability/24Operability Strategy Report/Zero Carbon Operability/24Our focus is to ensure the lowest cost solution when operating the network.The price of carbon is fed through to the prices we see through other regulatory and market mechanisms.Therefore,while our ambition is about preparin
126、g the ESO to operate a zero carbon system if market forces deliver the conditions,importantly we will not schedule plant to meet our ambition if it increases overall consumer costs.Whilst our ability to operate a zero carbon system has continued to increase,the actual carbon intensity of the system
127、has temporarily plateaued rather than continue the steady decline that we have seen over the last few years.This is shown in the following chart.This is because the growth in renewables has been offset by the decommissioning of the nuclear fleet and the increase in interconnector exports.This has in
128、creased the running time of fossil fuelled generation.GB Carbon Intensity gCO2/kWhMore information on our zero carbon progress can be found on our and website .We also have a free app with more data including a regional carbon intensity breakdown,electricity records and the cleanest time of day to u
129、se power.This can be downloaded via Google Play and the App store or see our website.Zero Carbon OperabilityReliable NetworkOperability Strategy Report/Reliable Network/26Operability Strategy Report/Reliable Network/26Operating the national electricity transmission system to deliver power safely and
130、 reliably requires management of power system characteristics locally,right across the network.The Thermal,Voltage,Stability and Restoration workstreams ensure that we can:Manage power flows across constraint boundaries Maintain voltage within safe limits Ensure the system is stable enough to cope w
131、ith faults Recover the power system in the event of a partial or total shutdown of the networkWe operate the transmission system second by second,monitoring characteristics of a high voltage electricity system and taking actions to keep these characteristics within safe limits of operation.These lim
132、its and requirements are set out in the Security and Quality of Supply Standards(SQSS)and the Electricity System Restoration Standard(ESRS).The physics of a high voltage power system require certain system services to be delivered at,or near,the point of need.Historically,most of these needs were me
133、t by large dispatchable generation,delivering reactive power for voltage management,and short circuit current for managing faults.These generators were well spread around the network and near to demand centres,which made them well placed for restoring the network following a power outage.It also min
134、imised the actions required to resolve thermal constraints.Managing locally to deliver nationallyOperability Strategy Report/Reliable Network/27Operability Strategy Report/Reliable Network/27The system services used,both historically and now,to manage the network are not directly valued by the energ
135、y market.We are the sole buyer of these services and currently must procure them to maintain a safe,reliable,and compliant network.Therefore,we are wholly responsible for the resilience of these services and ensuring that they are delivered effectively and efficiently for consumer benefit.As the ele
136、ctricity system decarbonises,we have access to less dispatchable generation but we are finding new sources to meet these challenges and locational needs.Power must be able to flow right across the network,from wind generation in Scotland to interconnector exports in South East England The network mu
137、st be able to be restored using more variable sources of generation and assets on the distribution networks,whilst meeting the future restoration standard New sources and providers of reactive power and short circuit current are needed in the right locations of the networkThese reliable network work
138、streams cover the challenges in more detail and the potential solutions available.Managing locally to deliver nationallyStabilityOperability Strategy Report/Reliable Network/29Operability Strategy Report/Reliable Network/29SummaryAs decarbonisation of the electricity system leads to less dispatchabl
139、e generation and subsequent loss of traditional stability sources,we need to introduce alternative capabilities that can provide stability services separately from active power.The reduction of the inherent stability of the system means we need to ensure that dispatchable generation can provide syst
140、em stability in a way that supports our zero carbon ambition,or that asynchronous generation can be adapted to provide a more stabilising effect on the system.We also need to continue to ensure standards for capabilities like loss of mains protection and fault ride through remain fit for purpose as
141、the system changes.What do we mean by stability?Stability is the inherent ability of the system to quickly return to acceptable operation following a disturbance.The term is used to describe a broad range of topics,including inertia,short circuit level and dynamic voltage.If the system becomes unsta
142、ble it could lead to a partial or total system shut down leading to the disconnection of consumers.StabilityOperability Strategy Report/Reliable Network/30Operability Strategy Report/Reliable Network/30What are our obligations and what are the future operability challenges?We have an ambition to ope
143、rate the system carbon free for periods by 2025,in order to achieve the governments target to operate a fully decarbonised electricity system by 2035.Decarbonisation of the electricity system leads to more asynchronous generation.This generation does not have the same inherent stabilising effect on
144、the system as dispatchable generation.This results in a steady decline in the inherent stability on the system meaning we need to learn to operate a more dynamic system than has traditionally been the case.The Security and Quality of Supply Standard(SQSS)requires that we operate the system such that
145、 it remains stable following specific secured events.These obligations are enduring,and we are required to ensure they are met at all times even when system conditions change.The term stability is used to describe a broad range of operational and technical challenges,the most significant are covered
146、 here.InertiaBy 2025,our ambition is to maintain a minimum inertia of 102GVAs,based on a future state of securing a largest loss of 1800MW and keeping Rate of Change of Frequency(RoCoF)within 0.5Hz/s.Today,we operate the system at 140GVAs which keeps RoCoF below 0.125Hz/s for a loss of 700MW.This po
147、licy was established as,historically,RoCoF has been the determining factor for managing system inertia.140GVAs ensured that RoCoF was no greater than 0.125Hz/second and ensured no subsequent disconnection of embedded generation.This policy was implemented before recent operational changes to the sys
148、tem including the Accelerated Loss of Mains Change Programme(ALoMCP),the implementation of Dynamic Containment(DC)and the Frequency Risk and Control Report(FRCR),a combination of which means we have been able to relax our policy on how we manage large losses and associated frequency risks.A combinat
149、ion of these changes also means that we can begin to review the minimum level of inertia required on the system as the current 140GVAs level is now less closely linked to system conditions,given the progress made across our frequency strategy in the areas mentioned previously.This will enable a grad
150、ual reduction from current 140GVAs operational limit,to the future 102GVAs.StabilityOperability Strategy Report/Reliable Network/31Operability Strategy Report/Reliable Network/31Short circuit level(SCL)In a system dominated by synchronous generation,short circuit current is provided by synchronous m
151、achines which are capable of setting their own voltage waveform.A system with a high penetration of synchronous generation means it is more capable of maintaining voltage and frequency during a fault,or can ride through faults.Today we see more short circuit current coming from more asynchronous gen
152、eration.During a fault,this technology will act as a current source,injecting current into the system but will not set a voltage waveform.Inverter based generation therefore does not contribute to system strength.More asynchronous generation(without Grid Forming capability)leads to declining system
153、strength,therefore impacting system stability.We must find alternative ways of managing system strength where the current trend is declining short circuit levels.Short circuit ratio(SCR)is a widely used measure of system stability,calculated as:SCR=SCL(MVA)Connected IBR Capacity(MVA)We currently cal
154、culate the SCR at each busbar on the network and set this against a defined threshold to highlight areas in the network where system stability is considered to be low.The threshold that we currently adopt is based on studies conducted by CIGRE whereby SCR should be 2.This threshold is applied as an
155、indicator for further detailed studies to be conducted in an area,rather than a specific indicator of system instability.It is also widely acknowledged that there are limitations to the traditional indicator of SCR and whilst there are numerous other options for more accurate metrics of system stren
156、gth,there is no single universally agreed methodology within industry.There are numerous factors to consider when looking to identify the most optimal solution(such as system impedance or interaction factors)and we have been working with other TSOs across the world,as well as other Transmission Owne
157、rs to review short circuit level methodologies for managing systems with ever increasing asynchronous generation.StabilityOperability Strategy Report/Reliable Network/32Operability Strategy Report/Reliable Network/32What capability do we need to meet these changing operability challenges?The stabili
158、ty challenges seen today and into the future,are primarily caused by less dispatchable generation,more asynchronous generation and more variable sources of generation.We anticipate that technologies with grid forming capability will be a significant contributing factor to future stability of the sys
159、tem,alongside other stability services to effectively manage a net zero power system.The non-mandatory specification in the Grid Code provides guidance on minimum requirements for enhancing the capability of asynchronous generation to act with similar characteristics to synchronous generation.We ant
160、icipate that future market arrangements for stability services will form the basis of where future grid forming technology could be procured.In addition,we need to develop both modelling and analytical skill required for further detailed Electromagnetic Transient(EMT)simulations.This capability will
161、 support with studying the increasing challenges regarding system stability and the need to further analyse areas of the network where stability issues may emerge.We have set out plans to enhance this capability within our RIIO2 Business Plan(deliverable A15.6).Alongside both of these new capabiliti
162、es to support future system stability,we will need to standardise the process for defining stability requirements,by creating a year-round process for analysing the ever-changing need.This will provide both transparency for industry when aligned with a future stability market,as well as consistency
163、in future requirement setting.What are the requirements for 2025 (zero carbon ambition)and beyond to 2030?To identify our future stability requirements,we calculate inertia and short circuit level(post-fault voltage recovery and retained voltage)from transmission connected generation dispatched in o
164、ur BID3 models.This provides a baseload level of system stability services,which we then include contributions from embedded generation and demand,as well as the three stability pathfinders,based on their planned start dates(2022,2024 and 2025 respectively for phase 1,2&3).Operationally,our requirem
165、ent to maintain system inertia at 102GVAs could be met through a combination of dispatched generation,demand and stability pathfinders.If the forecasted dispatched generation plus additional stability services were to differ from that studied,we could meet our inertia requirement by synchronising ad
166、ditional units.Therefore,our future requirement for inertia does not represent a compliance shortfall,however any future procurement would be conducted to ensure the most economic and efficient methods are chosen to manage our stability requirements,rather than for system security reasons.For short
167、circuit level,we apply a similar methodology for calculating requirements as undertaken for inertia and we also study retained voltage,phase-locked loop and post-fault voltage recovery stability.Based on the latest studies,our requirements for additional short circuit levels are sufficient until 202
168、9.We are currently investigating the optimal solution for future procurement of stability services.StabilitySteady Progression 2030System Transformation 2030Leading the Way 2030Consumer Transformation 20300%20%40%of year with additional requirementAdditional GVA.s requirement60%80%100%051015202530Op
169、erability Strategy Report/Reliable Network/33Operability Strategy Report/Reliable Network/33StabilityHow do requirements change under differing Future Energy Scenarios?Our stability studies are based on an assessment of our four FES 2021 scenarios.The volume of dispatchable generation and the speed
170、at which asynchronous generation is connecting to the system varies across these scenarios,and drives our requirement for stability capability on the system.These variables differ across each of the FES scenarios and whilst asynchronous generation increases across all scenarios,in Steady Progression
171、,there is a more gradual decarbonisation of the power sector,compared with other scenarios such as Leading the Way.In Leading the Way,40GW of offshore wind is achieved by 2029 and continues to increase through 2030s whereas in Steady Progression,only 30GW of wind is achieved by 2030.This means that
172、whilst the general pattern of our requirements remains broadly the same,the requirement manifests in earlier years,depending on the scenario in question.The chart provides a characteristic view of the distribution of the additional inertia requirement across the year,against the minimum requirement
173、of 102GVAs.This is based on our forecast of baseload inertia from market dispatch,plus contribution from stability pathfinders.As the first phase of our Stability Pathfinders(phase 1)ends in 2026,we observe an additional inertia requirement from 2027 onwards as these contracts fall away.Whilst we fo
174、recast that we have sufficient assets on the system to provide our required inertia should we need to instruct this,we acknowledge that this is not necessarily the most cost effective solution for managing future stability needs.Therefore,our Stability Market Design work is working to design the opt
175、imal procurement structure for future requirements.In addition,given the patterns and duration of any additional inertia requirement,which generally manifests as a small,additional need for(on average)20%of the assets rated MW(this is also true for a battery which is consuming power).Having greater
176、access to this capability will help voltage management and reduce the need to synchronise dispatchable generation at high cost.Responses to the Request for Information(RFI)which we published in May 2022 shows that there is,and will be,generous volumes of reactive power capability at 20%of rated MW,a
177、nd greater reactive ranges at all levels of MW output.We are exploring ways to access this capability for efficient voltage management.In July 2022 we submitted a proposal(CM085)to modify the System Operator Transmission Owner Code(STC)so that Offshore Transmission Owners(OFTO)will have to provide r
178、eactive power capability at 20%rated MW,where they have the capability to do so.This will increase available capability,reducing the need to synchronise generation in some areas of the network.Operability Strategy Report/Reliable Network/40Operability Strategy Report/Reliable Network/40VoltageWhat a
179、re the requirements for 2025 (zero carbon ambition)and beyond to 2030?Each year we publish a voltage screening report,which identifies regions which are or could face high voltage issues in the next 5-10 years.The 2022 voltage screening report provides a high level assessment of voltage needs,focuss
180、ing on:Areas with a high dependency or reliance on limited assets or generation;Areas with high voltage management costs;and Network faults which could have led to voltages exceeding SQSS planning limits.The screening report does not,however,indicate the actual reactive requirements or route to deli
181、ver solutions.We will be incorporating the screening report and assessment of future needs into future ETYS processes.The ongoing Network Planning Review will fundamentally transform how we undertake network planning.We are reviewing how we will communicate future system needs including voltage as p
182、art of the enduring Centralised Strategic Network Planning Process.The methodology for assessing these granular requirements has been further developed during 2022.We have used this methodology and worked with NGET to further assess and refine the residual reactive power requirements for 2025,which
183、we published in last years Operability Strategy report.The studies looked at overnight minimum demand periods during the summer months with low wind output.We are now using the methodology to assess reactive requirements from 2026-2030.Operability Strategy Report/Reliable Network/41Operability Strat
184、egy Report/Reliable Network/41VoltageWhilst the residual requirement for 2025 has increased compared to last years view,we have investigated further the existing ability to meet these residual requirements.Most of these requirements can be met by synchronising dispatchable generation.However,we reco
185、gnise the potential for significant consumer costs solving voltage needs using this mechanism.We are therefore developing other options which we will share in the near future,acknowledging the need for swift progress to deliver consumer savings from 2025 onwards.In addition to needing reactive capab
186、ility to meet the needs of the system,we also need to improve our forecasting capability of reactive power demands across the system.In our last report we touched on the declining trend in reactive power demand on the transmission system;one of the key factors in the increasing reactive requirements
187、.This declining trend began around 2005 and has resulted in reactive power being injected onto the transmission system instead of being absorbed by the distribution system.Whilst we understand some of the reasons for this decline,we do not have a view when this declining trend will stop.We are devel
188、oping an innovation project to investigate the drivers behind the trend and develop forecasting methods and tools for the future.Region2025 MVAr need OSR 2022(residual requirement)2025 MVAr need OSR 2023(residual requirement)LONDON300MVAr500MVArW_MIDLANDS300MVAr600MVArS_WALES and S_CENTRAL600MVAr700
189、MVArSW_ENGLAND200MVAr125MVArE_ENGLAND200MVAr300MVArOperability Strategy Report/Reliable Network/42Operability Strategy Report/Reliable Network/42VoltageGreen represents regions which can largely be operated at zero carbon,amber represents regions which can be operated at zero carbon under certain sc
190、enarios,and red represents regions which cannot be operated at zero carbon.GB existing transmission systemClick to expandNW_SCOTLAND NE_SCOTLAND W_SCOTLAND E_CORRIDOR W_CORRIDOR DUM_GALLOWAY MERSEY N_WALES NW_ENGLAND S_YORKS E_MIDLANDS HUMBER W_MIDLANDS E_ENGLAND S_WALES LONDON SW_ENGLAND SE_ENGLAND
191、 S_CENTRAL Legend400kV Circuit275kV Circuit220kV Circuit132kV CircuitHVDC Circuit400kV Substation275kV Substation132kV SubstationDespite the challenges faced,we are still driving towards meeting our zero carbon operation in 2025 ambition.As in previous Operability Strategy reports,we have provided a
192、 map showing which voltage regions could be managed using zero carbon solutions.Key changes since last year are:North East Scotland this region can now be managed almost always using zero carbon solutions North Wales this region can now be managed almost always using zero carbon solutions South Wale
193、s new connections in the region reduce the reliance on fossil fuelled generation South West England many system conditions lead to a need to run fossil fuelled generation West Midlands expected investment and new connections could mean zero carbon operation from 2026 East England should be manageabl
194、e with zero carbon options by 2025TopMiddleBottomOperability Strategy Report/Reliable Network/43Operability Strategy Report/Reliable Network/43How do requirements change under differing Future Energy Scenarios?As we have discussed,reactive requirements are localised,and are driven by many factors in
195、cluding demand,generation and system conditions.Across the scenarios we expect the need for reactive services to increase.During summer minimum periods voltages are raised due to reduced power flows across the network,cables which are in service,and there is a reduced ability to take circuits out of
196、 service to help with voltage control.During winter,periods of high demand coupled with high renewable output lead to increased power flows.We need to ensure that the system is secure for faults which could otherwise lead to low voltages outside of SQSS limits.Increasing interconnection will lead to
197、 higher flows on the system,particularly during exports.When interconnector flows switch between import and export,this can stress network assets and result in high volts swapping to low volts.Leading the Way has significantly more interconnector capacity by 2030 than the other scenarios.The market
198、dispatch of fossil fuel generation differs greatly between the Falling Short and Leading the Way scenarios.Whilst this doesnt affect our ability to maintain a compliant network,it will have a significant impact on consumer costs.We are progressing ways to mitigate these costs.What is the next big op
199、erational challenge?Less dispatchable generation and generation moving to different areas are removing the provision of dynamic reactive power from key locations across the network.In many regions where asynchronous generation is replacing dispatchable generation,there is sufficient reactive power c
200、apability to maintain voltages within limits.However,where overall growth in GB asynchronous generation is displacing reactive power provision in other regions,we must source new zero carbon solutions.Loss of access to this dynamic reactive power capability will make voltage management more challeng
201、ing,more costly or both.We need to ensure there is sufficient dynamic capability available in the right locations to manage the future variability in network flows,demand and generation.VoltageThermalOperability Strategy Report/Reliable Network/45Operability Strategy Report/Reliable Network/45Therma
202、lSummaryThe ambition to operate a zero carbon network in 2035 and enable net zero by 2050 requires significant investment in the transmission network to accommodate more asynchronous generation,generation moving to different areas and changing sources of demand.In July 2022 we published our first Ho
203、listic Network Design alongside a refreshed Network Options Assessment.Together they recommend 94 asset investments to deliver a network which can accommodate the Governments ambition of 50GW offshore wind by 2030.The Future Energy Scenarios indicates the need for a demand side strategy to avoid was
204、ting renewable energy.Incentivising new demand to connect in the right locations can help effectively alleviate constraint costs.We are working on two innovation projects to demonstrate how green hydrogen can support constraint management,and develop a probabilistic model which quantifies the risk o
205、f energy flow congestion.As part of our Net Zero Market Reform programme,we have stated that introducing dynamic locational signals via nodal pricing could offer a solution to addressing thermal constraints.BEIS is considering nodal pricing as one of several options to improve locational signals in
206、its Review of Electricity Market Arrangements(REMA).Alongside market reform,there are significant challenges with network capacity and connections which could hinder solutions or investment.What do we mean by thermal?The transmission network has limited capacity to transport power.The thermal workst
207、ream covers how we manage this capacity.Operability Strategy Report/Reliable Network/46Operability Strategy Report/Reliable Network/46What are our obligations and what are the future operability challenges?ObligationsAs the Electricity System Operator,it is our responsibility to identify the future
208、transmission network needs as we drive towards operating a zero carbon electricity system,and enable the transition to net zero.Planning the future transmission network starts with the Future Energy Scenarios(FES).These scenarios indicate how energy could be produced and consumed.We use these scenar
209、ios to determine generation capacity,peak demand and transmission network power flows.We can then identify where additional network capacity is needed and this is published in our Electricity Ten Year Statement(ETYS).Stakeholders are then invited to propose solutions which could meet these requireme
210、nts,and we assess these in our annual Network Options Assessment(NOA).The NOA makes recommendations for the most economic and efficient solutions to proceed,and others to hold or stop.These recommendations are often for new network build or to reinforce existing network but can also be for commercia
211、l solutions.Where network capacity is not sufficient to transfer the flow of energy generated,the ESO must resolve the boundary constraint by reducing the output of(constrain)generation behind the constraint.As we move towards a net zero future,more generation must connect to the electricity network
212、.Careful management of where this generation connects is required,or appropriate processes in place to plan a network fit for the future.If not,significant costs will be incurred constraining low and zero carbon generation because there isnt sufficient network capacity.Often,these costs are incurred
213、 as the ability to connect new generation occurs at a pace greater than delivery of new infrastructure.Therefore,future network planning will likely require a move to more strategic and anticipatory investment.It is also important that we make sure there are markets in place which support flexibilit
214、y in operational timescales.A local constraint market(LCM)will be delivered in early 2023 to help address the high cost on managing thermal constraints on the B6 boundary,focusing on generation turn-down and demand turn-up from new providers of flexibility in Scotland.The LCM is intended to be an in
215、terim solution before Regional Development Programmes can be delivered in Scotland.The LCM will help to inform our thinking on local markets.ThermalOperability Strategy Report/Reliable Network/47Operability Strategy Report/Reliable Network/47Future challengesThere are many challenges to overcome to
216、enable the transition to a carbon free network by 2035 and net zero by 2050.The Future Energy Scenarios show that demand for energy will increase with the electrification of transport,heat and industrial processes.Generation is moving to different areas,requiring network investment/reinforcement.Net
217、work planning is needed now to meet the network needs out to 2050.Earlier this year,we published the Pathway to 2030 Holistic Network Design,which sets out network needs to enable 23GW of offshore wind to connect by 2030.We are also conducting our own review into network planning(NPR)and are engagin
218、g with the BEIS and Ofgem network reviews.As covered in previous editions of this report,the thermal challenges we experience are generally a cost issue,rather than security related.Annual transmission costs have increased ten times since 2010 and are expected to continue to rise.Whilst FES22 predic
219、ts at least 15TWh of curtailed energy by 2030 in the net zero scenarios,this is due to excess generation.There will still be a need to constrain considerable volumes of generation for constraints.We must find ways to reduce these constraint costs,whilst enabling much of this new generation to connec
220、t and consumers to benefit from zero carbon generation.Turning down generation for constraints requires the energy to be replaced elsewhere on the network,and this is typically done by increasing generation on dispatchable generation.But by 2035,unabated fossil fuel generation will only be for secur
221、ity of supply,so we must find other ways to balance the energy when managing constraints.NOA modelling indicates that much of the energy balancing from 2030 will be on interconnectors.We published a paper on the modelled constraints in August 2022.NOA7+HND redispatch for constraintsBiomassCCGTOffsho
222、re windOnshore windInterconnectorsOtherTotal Redispatch Costs-3,500-2,500-1,,5002,5003,500-50-40-30-20-50203020334203520362037203820392040Annual constraint costs(m)Net annual redispatch volume for constraints(TWh)In all the future energy scenarios,GB is a net exporte
223、r of electricity by 2030.This requires us to plan and operate the network to transfer power from generation to interconnector locations.Most of these are in the South of England,and we experienced in July 2022 the impact of a network which struggled with the demand for exports.Interconnector flows a
224、re driven by the spread between wholesale prices in different countries or zones,typically flowing from the zone with lower prices to the zone with higher prices.In July,energy scarcity intensified on the continent,resulting in exports on all South East interconnectors.Expensive actions were require
225、d on the interconnectors at 9500/MWh to resolve constraints.The GB wholesale price does not reflect locational signals which can lead to interconnector flows exacerbating constraints.Clearly,it is not sustainable to operate the network with prices like this in future.ThermalOperability Strategy Repo
226、rt/Reliable Network/48Operability Strategy Report/Reliable Network/48What capability do we need to meet these changing operability challenges?Network capacityThe existing processes for assessing network capacity and identifying economic solutions are well defined.The Future Energy Scenarios indicate
227、 how energy could be produced and consumed.This informs the assessment of network capability in the Electricity Ten Year Statement.The Network Options Assessment then recommends which economic solutions should be progressed.The existing process assumes a generation and demand background evolving und
228、er the existing single national wholesale market price,where the Transmission Network Use of System(TNUoS)charge provides the locational signals for investment.If market arrangements were to change as a result of the Review of Electricity Market Arrangements(REMA),there could be stronger locational
229、signals for new investment.This could alter aspects of our NPR,BEIS OTNR and Ofgems ETNPR and the wider Centralised Strategic Network Plan(CSNP).In April 2022,the UK Government published the British Energy Security Strategy with an ambition for 50GW of offshore wind to be connected to the GB network
230、 by 2030.In July 2022 we published recommendations for network investment which would facilitate the connection of this volume of offshore wind.The HND project and NOA refresh have identified 94 schemes,at a cost of 22bn,that are required to enable the Governments ambition for 50GW of offshore wind
231、by 2030.Not only do we need network capacity to transfer power from generation to consumption,but we also need capacity which allows for connection of generation and new forms of large scale demand on the transmission network.Enabling the connection of renewable generation and flexible demand is key
232、 to reaching a zero carbon network in 2035 and net zero in 2050.We are working with stakeholders to achieve an improved connections process,in both the short and long term.In October 2022,we opened an amnesty for transmission entry capacity,offering industry the opportunity to terminate connection a
233、greements and free up connection capacity.Across the network we are seeing changes in the connection landscape.There are changes in demand at interface points;an example being the metro in South Wales.Areas of the network are struggling for capacity due to the significant volume of generation wantin
234、g to connect;for example,East Anglia.We are also learning to manage the connection of large scale modern technology demand which can operate 24/7.This uses up a lot of demand capacity and can cause difficulty for DNOs wanting to connect more domestic demand.ThermalOperability Strategy Report/Reliabl
235、e Network/49Operability Strategy Report/Reliable Network/49Constraint managementBeyond network investment,constraint costs are typically managed by turning down generation to reduce the transfer of power across the affected boundary.Generation is then increased on the other side of the boundary to b
236、alance the energy.The future of constraint management needs to consider demand flexibility,particularly from large flexible demand such as data centres and electrolysis.FES22 considers the need for a demand side strategy to efficiently balance renewable generation with demand and reduce reliance on
237、unabated fossil fuel generation.This demand side strategy is required to ensure that during periods of high renewable generation,energy isnt wasted due to oversupply.In the context of constraint management,effective incentives to increase demand from large flexible demand during periods of oversuppl
238、y and active network constraints would mitigate the need to curtail and constrain renewable energy.In the short term,we are introducing stronger market signals through projects such as the Local Constraint Market but believe that in the longer term the introduction of stronger locational signals wou
239、ld be beneficial,as set out in our Net Zero Market Reform programme.We are working with industry partners to understand the capability of large flexible demand and what market signals are required to take advantage of demand flexibility to produce green products,such as green hydrogen.The ESOs Marke
240、ts Roadmap,due in March 2023,will disseminate the findings from an upcoming innovation project seeking to understand the technical and commercial models of a range of service providers,including large flexible demand units.Where appropriate,this publication will consider how the ESOs markets can be
241、designed to provide optimal signals to harness this flexibility.An innovation project aims to demonstrate the benefits of green hydrogen to support network constraints.We are also progressing an innovation project which aims to develop probabilistic forecasts of power flows to reduce the uncertainty
242、 resulting from variable sources of generation.When managing network constraints,less power is allowed to flow across the boundary than the rated capacity.This is to allow for the loss of circuits/assets which reduces the boundary capacity.Part of this reduced power flow is also to account for uncer
243、tainty in energy forecasts.Reducing the uncertainty around variable sources of generation will result in increased power flows and reduced constraint costs.ThermalOperability Strategy Report/Reliable Network/50Operability Strategy Report/Reliable Network/50What are the requirements for 2025 (zero ca
244、rbon ambition)and beyond to 2030?In last years Operability Strategy report we highlighted that constraint costs are expected to rise out to 2030 and the delivery of large NOA recommended network investment may by delayed ahead of mitigating much of these costs.We are working with Ofgem to help the a
245、ccelerated delivery of strategic transmission investment.This would help ensure a large proportion of these projects will be delivered in time for 2030.In the meantime,we are progressing further ways to mitigate some of these costs ahead of network investment.We have delivered a second tender round
246、of the Constraint Management pathfinder,for the B6 boundary intertrip service.We have developed another constraint management intertrip service for East Anglia to help manage the significant volume of offshore wind connecting in the region.We are continuing to work with TOs to identify enhanced serv
247、ices such as dynamic line ratings,HVDC run back schemes and new ways of working regarding post fault actions to provide increased constraint limits.We are working with stakeholders and innovation projects to better understand the capability of large scale demand and how it can deliver benefits for c
248、onstraint management.This would be both for increased demand to reduce the need to constrain renewable generation,but also for decreased demand to avoid turning up fossil fuelled generation or high price actions on interconnectors.Across all Future Energy Scenarios 2022,we will be a net exporter of
249、electricity by 2030.In July 2022,we experienced the effects of a network which did not have the available capacity to allow for high demand and full exports on interconnectors in the South East.Power markets on the continent and impacts of the war in Ukraine led to GB gas being traded at significant
250、 discount to the continent.This resulted in exports on all South East interconnectors.Combined with demand in London,this drove significant power flows across the LE1 and SC boundaries.We have worked with NGET to increase the LE1 boundary to the highest its ever been.However,planned and unplanned ou
251、tages had reduced the capacity of these boundaries.With all available generation in the South East running,trades were required on interconnectors to reduce the power flow in to the South East.The generation scarcity on the continent,and alert states by European TSOs,drove the extreme prices(9500/MW
252、h)to reduce interconnector exports.We need to find ways to manage the network in future which doesnt expose the consumer to extreme prices and costs.Reflecting network congestion in the wholesale price is likely to have mitigated this event by reducing incentives for the interconnectors to export an
253、d demand to be connected at the periods with highest costs.ThermalOperability Strategy Report/Reliable Network/51Operability Strategy Report/Reliable Network/51The Pathway to 2030 HND and NOA 2021/22 refresh make recommendations to proceed with 94 asset-based options,delivered by 2030.Of these,56 pr
254、ojects are required for a compliant network against the design rules.However,Government support is required to enable accelerated delivery of 11 of these projects due to existing regulatory and consenting processes.A further 38 projects are optimal for delivery before 2030 to significantly reduce co
255、nstraint costs.It is clear that significant investment and support from Government is required to reach the BESS ambition of 50GW offshore wind by 2030.ThermalOperability Strategy Report/Reliable Network/52Operability Strategy Report/Reliable Network/52How do requirements change under differing Futu
256、re Energy Scenarios?The different Future Energy scenarios generally share a common narrative.The energy transition will increase power flows from North to South and from offshore generation to inland.Network investment is required to accommodate this transition but the pace at which the change happe
257、ns differs.The FES22 indicates that 50GW offshore wind could be as early as 2030 under Leading the Way,or as late as 2040 under Falling Short.In the Leading the Way scenario,there is 42GW of solar generation in 2030 and 70GW in 2040.What is the next big operational challenge?As weve seen throughout
258、this chapter,much of the future operational challenges come from the scale and pace at which generation and demand grow.This growth is needed to meet the ambitions for a zero carbon electricity network by 2035 and net zero by 2050.Enabling growth in network investment,increased capacity for new conn
259、ections and new tools for constraint management all form part of meeting this big operational challenge.We are progressing our Network Planning Review to inform Ofgems Electricity Transmission Network Planning Review and the development of a Centralised Strategic Network Plan.We are continuing to de
260、velop the Holistic Network Design process,sharing recommendations with developers in Q1 2023 and publishing the second HND later in 2023.Considerable constraint costs are expected throughout the rest of the decade.These are largely resulting from considerable renewable generation connecting to a net
261、work which currently cannot accommodate the volume of power and transfer it to the point of demand.Point of demand will also become less well defined as we move to a world with large scale demand connecting across the transmission and distribution networks.Potential market incentives need to align w
262、ith these constraint costs and mitigate their increase.ThermalRestorationOperability Strategy Report/Reliable Network/54Operability Strategy Report/Reliable Network/54RestorationSummaryThe key change to our requirement for restoration capability between now and 2030 is the introduction of the Electr
263、icity System Restoration Standard(ESRS).This provides an industry agreed standard which will drive changes to services,codes and network solutions required.We are working with industry through a series of working groups established through Grid Code change GC0156 to establish the specific changes re
264、quired.Meanwhile decarbonisation of the electricity system means we will continue to look at ways to diversify our portfolio of services through the Distributed Restart project and competitive procurement exercises.What do we mean by Restoration?In the unlikely event that the lights go out,the ESO h
265、as a robust plan to restore power to the country as quickly as possible.NET ZEROCARBONOperability Strategy Report/Reliable Network/55Operability Strategy Report/Reliable Network/55What are our obligations and what are the future operability challenges?System restoration has historically been highly
266、dependent on large,dispatchable generation.As the UK moves to cleaner,greener and more decentralised energy,new options must be developed.The enormous growth in asynchronous generation,presents an opportunity to develop a radically different approach to system restoration.The greater diversity in th
267、e provision of restoration services and our reduced reliance on traditional sources,will improve resilience and increase competition leading to reductions in both cost and carbon emissions.The Electricity System Restoration Standard(ESRS)was introduced through a policy statement from BEIS in April 2
268、021,highlighting the need to introduce a legally binding target for the restoration of electricity supplies in the event of a National Electricity Transmission System(NETS)failure.This was followed with a consultation from Ofgem to modify the ESO licence to provide the framework by which this standa
269、rd can be implemented.It requires us to:a)ensure and maintain an electricity restoration capability;andb)ensure and maintain the restoration timeframe.The timeframe set out within our licence is set at:60%of electricity demand being restored within 24 hours in all regions;and 100%of electricity dema
270、nd being restored within 5 days nationallyTo meet this requirement and ensure restoration services can support our ambition for zero carbon operation of the system by 2025,we are currently proposing a number of changes to all relevant codes,such as the Grid Code,CUSC,STC and Distribution Codes,to fa
271、cilitate the direction from BEIS and standards set out in our licence.There are also significant technical,organisational and commercial challenges to address to ensure these diversified sources of restoration can be implemented effectively.These are being addressed through GC0156.RestorationOperabi
272、lity Strategy Report/Reliable Network/56Operability Strategy Report/Reliable Network/56What capability do we need to meet these changing operability challenges?Restoration services have traditionally been procured bilaterally from large dispatchable generation.In June 2022 we released a tender for t
273、he South East region which was the first of its kind to include learnings from the Distributed ReStart project,to enable the potential participation of distribution led restoration,as well as transmission led solutions.These solutions will be available for delivery from July 2025.In October 2022,we
274、also launched a tender for the Northern region,for service go live in November 2025.In addition,we released a nationwide,wind-only tender in August 2022 to prove the feasibility of getting both onshore and offshore wind energy supplying restoration capability at full service(i.e.the same technical r
275、equirements as traditional transmission-led generators).More detail on all of these tenders can be found on our website.The Distributed Restart project explored how asynchronous generation could be used to provide restoration services,from diverse technologies across Great Britain.The aim of the pro
276、ject was to demonstrate a bottom-up approach to restoration by utilising distribution level resources through to transmission level to restore the system.We are now in the process of moving from Innovation to BAU by using learnings from this project to supplement existing providers of restoration se
277、rvices and increase both our flexibility and resilience when procuring restoration services for the future.A key challenge for all future restoration services is ensuring that engineering solutions,organisational coordination and commercial and regulatory frameworks can all work together to ensure r
278、esilience and flexibility in the operation of the network.We need to ensure that all providers have the required capabilities to ensure effective and efficient system restoration in the event of a partial or total shutdown of the network.RestorationOperability Strategy Report/Reliable Network/57Oper
279、ability Strategy Report/Reliable Network/57What are the requirements for 2025(zero carbon ambition)and beyond to 2030?Grid Code modification GC0156(implementation of the Electricity System Restoration Standard)has been established to clarify the requirements on CUSC parties,Restoration Service Provi
280、ders(RSPs)and Distribution Network(DNO)taking part in restoration activities of their obligations so that we can satisfy our new licence obligation.It was originally organised into seven working groups,focusing on the different requirements needed to ensure effective and coordinated restoration of t
281、he system.However,since the establishment of GC0156,only four of the seven workgroups have been progressed further.These four workstreams are detailed here whilst the outputs from the other three working groups have also been considered in the overall ESRS solutions.Future networks:identifies the de
282、velopment needs of the networks to accommodate changes in the generation mix across GB to implement ESRS.This could be the level of connected generation required(during different time periods i.e.peak demand)as well as the time required by different generation to synchronise.This workstream also loo
283、ks at the requirements for DNOs such as their network design and resilience as well as different options for restoration zones.Markets and funding:the aim of this workstream was to understand how we can further remove market barriers(real or perceived)and assist in the development of agile solutions
284、 for restoration.It establishes the key procurement principles that we will adhere to during the development and delivery of competitive procurement tenders.Whilst significant changes have been implemented to broaden participation and reduce barriers to entry,(such as introducing competitive procure
285、ment events),the process for achieving restoration has historically been developed on the basis of a top-down restoration strategy.We are therefore using learnings from the Distributed Restart project to deliver new commercial frameworks and procurement mechanisms to access Restoration services from
286、 DER utilising a bottom-up approach,rather than a top-down.Assurance framework:this defines the assurance activities that should be progressed across the industry for restoration.This also includes resilience of network plant,relevant checks on services(including restoration tests),and training for
287、engineers.Communication infrastructure:provides the high-level requirements for communication infrastructure,focusing on themes such as band width of communications and any upgrades required,inter-control centre comms and cyber security.The Distributed Restart project has created a functional specif
288、ication for resilient&cyber secure comms for DER/DNO interfaces.Compliance with the ESRS is required by 31 December 2026.BEIS expect that any code changes should be in place by September 2023.RestorationOperability Strategy Report/Reliable Network/58Operability Strategy Report/Reliable Network/58How
289、 do requirements change under differing Future Energy Scenarios?Each of the FES scenarios assume a different generation mix with varying levels of asynchronous generation across each scenario.All scenarios,however,assume a greater level of asynchronous generation on the system than is currently the
290、case meaning we will need to ensure we can use all available technologies for future restoration.The ESRS is aiming to ensure at least three technologies per DNO licensed area to allow for redundancy.In addition,peak demands increasing in the future mean that greater amounts of generation will be ne
291、eded to achieve this level of restoration.By 2030 the lowest predicted average cold spell(ACS)Peak System Demand will be 62.7GW(Leading the Way),compared to 58GW in 2020.With more variable sources of generation,more generating units will need to be included in the restoration to achieve the same ele
292、ctrical energy output.What is the next big operational challenge?Currently,the System Operator-Transmission Owner Code(STC)Black Start procedure does not recognise offshore networks as contributing to Restoration.With the future growth for offshore wind targets set at 50GW by 2030,it is likely that
293、the bulk of generation in future will come from offshore sources.A fundamental part of the ESRS is exploring the need to integrate offshore networks into the solution,this is being considered as part of the Regulatory Frameworks workgroup under GC0156.It will reflect the necessary changes required t
294、o the STC.The Offshore Transmission regime was first introduced in 2009,based at the time largely on radial connections where offshore transmission was classified as any offshore circuit operating at 132kV and above.When the technical requirements for offshore networks were developed,it was not appr
295、opriate to specify a wider reactive capability at the offshore Grid Entry Point as the effect of the cable gain would have limited benefit to the onshore system(although there is scope for a wider reactive capability range when agreed between the OFTO,Generator and ESO).Therefore,specific requiremen
296、ts for reactive capability were introduced at the Transmission Interface Point.Going forward many of the offshore networks are likely to be meshed HVDC networks and complex in their configuration and design.Therefore,and as part of the design stage of the offshore coordination project,consideration
297、will need to be given to Restoration as part of the wider Offshore Network and Holistic Network Design work.RestorationBalancing the SystemFlexibility for Frequency(30 minutes)Managing imbalances second by second,mainly acting within a settlement periodWithin-day Flexibility(24 hours)Managing period
298、s of over and undersupply from renewables lasting for days,weeks and monthsTWhGWhMWhMinutesHoursDays to YearsOperability Strategy Report/Balancing the System/60Operability Strategy Report/Balancing the System/60One of the most fundamental requirements of an electricity system is that supply and dema
299、nd are always balanced.The wholesale market currently provides the majority of system balancing during the day,with the ESO performing the residual balancing and balancing on a second-by-second basis.For us to achieve this energy balancing we need flexibility,in both supply and demand,adjusting both
300、 sides to ensure they always match.The Frequency,Within-Day Flexibility and Adequacy workstreams all share this core objective,but each focuses on a different timescale.The Frequency workstream is the most mature of the three;as the system moves towards zero carbon operation,the system need will sta
301、rt to include longer durations and larger volumes of energy imbalance.We set the boundaries between these three categories of flexibility at 30 minutes and 24 hours,although there will be some overlaps and gaps at the boundaries.Energy balancing over different time scalesOperability Strategy Report/
302、Balancing the System/61Operability Strategy Report/Balancing the System/61Energy balancing over different time scalesThe energy imbalances in the electricity system are driven by differences between variable supply and variable demand.Within a settlement period these imbalances are caused by variati
303、ons in supply and demand,over seconds and minutes,caused by faults,forecast errors and other unexpected changes.Within-day,the imbalances are mainly caused by variable sources of generation and demand(e.g.cooking and lighting)changing with daily human behaviour.Over longer periods the imbalances are
304、 mainly caused by changes in wind generation,driven by weather patterns that can last for days,weeks and months,and by seasonal changes in demand for heat.Energy balancing,over all three timescales,is usually thought of as a system-wide need,which can be met with non-locational solutions.However,the
305、re are interactions between this system-wide need for energy and the location specific needs covered in the Reliable Network section.For example,an action taken for energy balancing reasons might increase the supply in one area,with impacts on thermal constraints,voltage and short circuit levels in
306、that area.Therefore,we need some locational information,even for non-locational services.In the future,as we operate the system with lower inertia levels,the locational aspects of energy balancing may get more important.Energy balancing is currently mostly delivered by markets,with some intervention
307、s by the ESO at all three timescales.Energy balancing within a settlement period is delivered by the ESO,mainly using frequency products,sold on liquid,day-ahead markets.Energy balancing within-day is mainly delivered by wholesale electricity markets,with multiple buyers and sellers,volumes of suppl
308、y and demand leading to a price,and the price then influencing supply and demand.The ESO also intervenes when necessary to ensure that balancing is achieved at an efficient cost.The ESO also intervenes when necessary to ensure that balancing is achieved at an efficient cost.Energy balancing over lon
309、ger time periods,to ensure supply adequacy,is currently achieved through a mixture of wholesale energy markets and the Capacity Market.The amount the ESO has to intervene to balance the system has been increasing over time.Half hourDayYear-0.5-0.5 1.0 1.5 2.006:0006:0106:0206:0306:0406:0506:0606:070
310、6:0806:0906:1006:1106:1206:1306:1406:1506:1606:1706:1806:1906:2006:2106:2206:2306:2406:2506:2606:2706:2806:29Variation GWVariation in DemandVariation in SolarVariation in WindVariation in wind generation,solar generation and demand over a settlement period(06:00-06:30 16/08/21)0%5%10%15%20%25%30%35%
311、40%45%0%10%20%30%40%50%60%70%200820092000019Renewable share of generation(%)(BOAs+Trades)/National Demand(%)SO role is residual,mostly repositioning market(5%)1Increasingly wide variations in SO balancing requirement(0-65%)2.and increasing proportionof large interven
312、tions.3Operability Strategy Report/Balancing the System/62Operability Strategy Report/Balancing the System/62Energy balancing over different time scalesIn the future,we want energy balancing to continue to be mainly delivered by price signals and markets,with the ESO acting as a“residual balancer”.W
313、e expect energy balancing within settlement periods to work very similarly to how it does today,with a suite of frequency products designed for the future system needs.In a future operating model with a centrally dispatched wholesale market,there might also be co-optimised procurement of energy bala
314、ncing and reserves.Energy balancing within-day should continue to be mainly delivered by supply and demand responding to price signals in liquid markets.As markets for zero carbon sources of Within-Day Flexibility develop and mature,there may be times when the ESO needs to intervene,to ensure price
315、signals can incentivise efficient response from parties that can provide flexibility.We expect energy balancing over longer time periods will continue to be delivered by a mix of wholesale electricity markets and interventions,with future interventions addressing both undersupply and oversupply.Effi
316、cient zero carbon balancing of long periods of over and under supply will require a mix of long duration storage,baseload generation,dispatchable generation,dispatchable demand and curtailment.The responsibility for resilience of energy balancing is shared between the ESO and the Department of Busin
317、ess,Energy and Industrial Strategy(BEIS).We are responsible for managing the frequency;we decide the mix and volume of products and services to buy,and we instruct them to deliver.For Within-Day Flexibility and Adequacy we act mainly as an advisor to BEIS who determine the market arrangements that d
318、eliver these services.For example,BEIS decide the capacity to be purchased in each Capacity Market auction(see the Capacity Market Auction Parameters for July 2022),they will set the security standards for Energy Smart Appliances(see the Smart and Secure Electricity System consultation),and they are
319、 reviewing electricity market arrangements(see Review of Electricity Market Arrangements (REMA)consultation).ESO trades and instructions as a share of national demand(2008-2019)FrequencyOperability Strategy Report/Balancing the System/64Operability Strategy Report/Balancing the System/64Summary Freq
320、uency control is achieved through two types of service:response and reserve.Frequency response services are automatically activated using a measurement of frequency to determine an appropriate change in active power.Reserve is dispatched manually by a control room operator following an observed even
321、t or in anticipation of a system need.Both response and reserve can deliver a change in active power,provided by a source of either generation or demand.The fundamental aim of our frequency control strategy is to maintain system frequency at the target of 50Hz.While maintaining the frequency,we must
322、 also balance the costs and impacts of our actions against the residual level of risk and benefits delivered to the end consumer.In this chapter we look at the frequency control obligations and how these translate into requirements for response and reserve services.We also look at factors that might
323、 influence or change our requirements between now and 2035.What do we mean by Frequency?Frequency is a measure of the balance between supply and demand.We use response and reserve services to correct imbalances and maintain system frequency close to the target of 50Hz.Frequency49.649.749.849.950.050
324、.150.207:00:0007:05:0007:10:0007:15:0007:20:0007:25:0007:30:0007:35:0007:40:0007:45:0007:50:0007:55:0008:00:0008:05:0008:10:0008:15:0008:20:0008:25:0008:30:0008:35:0008:40:0008:45:0008:50:0008:55:0009:00:00Frequency(Hz)Time21543a3bOperability Strategy Report/Balancing the System/65Operability Strate
325、gy Report/Balancing the System/65What are our obligations and what are the future operability challenges?ObligationsThe Security and Quality of Supply Standards(SQSS)describes the requirements for controlling frequency,both pre-fault(steady-state)and post-fault(transient).It requires that we operate
326、 the network and avoid unacceptable frequency conditions in a number of scenarios.These unacceptable conditions are split into two categories and are defined below:1.Steady-state frequency moving outside of 49.5Hz or 50.5Hz2.Transient frequency deviations outside of 49.5Hz or 50.5Hz unless infrequen
327、t and tolerableSteady-State FrequencyThe first of these obligations relates to regulating frequency during normal operating conditions.System frequency can be moved away from 50Hz not only by unexpected faults,but by gradual supply and demand imbalances and independent generator actions.For these re
328、asons services are required to manage steady-state frequency.This frequency trace can be broken down into 5 key stages to show the need for steady-state frequency management.In the example there have been no faults,but we had to rely on automatic response and manual reserve services to ensure freque
329、ncy is regulated between 49.5Hz and 50.5Hz.FrequencySystem Frequency Operability Strategy Report/Balancing the System/66Operability Strategy Report/Balancing the System/66Transient DeviationsTransient frequency management mitigates the impact of faults on system frequency,this can be described as po
330、st-fault containment.The frequency obligations around post-fault containment have remained largely unchanged since the introduction of the Frequency Risk and Control Report(FRCR)in 2021.The FRCR is reviewed annually and defines which events and deviations are classed as infrequent and tolerable.The
331、FRCR states that frequency is allowed to deviate between-0.8Hz and+0.5Hz depending on several factors:The event which causes the deviation The size of the deviation The duration of the deviation The likelihood of the deviation occurringTherefore,the FRCR informs both the ESO and wider stakeholders a
332、bout the two key factors relating to transient frequency deviations:The events that must be secured The standard to which the events must be secured (i.e what is tolerable)Later in this chapter we look at how these obligations translate into requirements for response and reserve services.Recovery an
333、d RestorationThe System Operator Guidelines(SOGL)describes the obligations on all system operators in Europe,and these obligations are now part of UK law.For GB the obligations are:That frequency must be recovered to+/-0.5Hz within 60 seconds And restored to+/-0.2Hz within 15 minutesThese obligations have helped to shape key design elements of the new reserve services we are launching over the nex