Final Report » 15 July 2021 Main Report Disclaimer
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» Continental Europe Synchronous Area Separation on 08 January 2021 ICS Investigation Expert Panel » Final Report » 15 July 2021 Main Report Disclaimer The following Final Report, concerning the system event This Final Report presents facts and analyses of the which occurred on 08 January 2021 in the Continental sequence of the events and where necessary consequent Europe Synchronous Area, has been prepared and issued recommendations. It is not the intention of the Expert by the Incident Classification Scale Investigation Expert Panel to express judgements which may prejudice the Panel and is based on information as known on 29 June assessment of liability of any TSO, third party or person. 2021. The individuals having prepared this report, as any Even if not explicitly stated, the analyses and the simula- other Expert Panel member, including their agents or tions presented in this report are based on information representatives, shall not be liable in whatever manner provided by the TSOs. No audit was done. Everything for the content of this report, nor for any conclusion what- expressed in this report refers to the specific events and soever that any person or third party, could draw from its findings will not constitute any binding general refer- the report. ence to the involved TSOs or other parties mentioned in the report. Expert Panel Members Frank Reyer Amprion, Expert Panel Gjorgji Shemov ENTSO-E Secretariat Chair Ioannis Theologitis ENTSO-E Secretariat Tahir Kapetanovic APG & Chair of the Uros Gabrijel ACER ENTSO-E System Operations Committee Maria Barroso Gomes ACER Brendan Lyons NGESO & ENTSO-E Francois Beaude ACER Steering Group Stefano Bracco ACER Operations Convenor Vincenzo Trovato ACER and ICS representative Jochen Gerlach BNetzA, German NRA Laurent Rosseel RTE & ENTSO-E Regional Group Nicolas Krieger BNetzA, German NRA CE Convener and Pierrick Muller CRE, French NRA representative of Julio Quintela Casal CRE, French NRA the affected TSOs Jacques De Saint Pierre CRE, French NRA Jens Møller Birkebæk Nordic RSC & Representative Francesco Cariello Arera, Italian NRA of the six RSCs Marco Pasquadibisceglie Arera, Italian NRA Mihai Cremenescu Transelectrica & Rodrigo Mangas Calvo CNMC, Spanish NRA representative of Zsolt Topa MEKH, Hungarian NRA TSO at system separation line Dániel Szendy MEKH, Hungarian NRA Danko Blazevic HOPS & representative Marko Poljak HERA, Croatian NRA of TSO at system Katharina Bauer E-control, Austrian NRA separation line Alina Poanta ANRE, Romanian NRA Dusko Anicic EMS & representative of TSO at system separation line 2 // CE SA Separation on 08 January 2021 – ICS Final Report / Main Report Contents Introduction 4 Background 4 Classification of the incident according to ICS Methodology 4 Structure of the final report 6 1 System conditions before the incident 8 1.1 Conditions in the transmission system of Balkan Peninsula 8 1.2 Real time situation 12 1.3 Review of coordinated security analysis 25 1.4 Further legal aspects 40 2 Dynamic behaviour of the system during the incident 41 2.1 Sequence of events 41 2.2 Dynamic stability margin 43 2.3 Recommendations 55 3 Frequency Support and Analysis 56 3.1 Frequency Containment and activation of automatic system defence measures 56 3.2 Disconnection of generation units and loads 63 3.3 Frequency Containment Analysis 66 4 TSO Coordination 72 4.1 Manual countermeasures and system stabilisation in individual areas 72 4.2 Resynchronisation process 86 4.3 Communication of coordination centres / SAM and between TSOs 90 5 Market aspects 100 5.1 Market aspects of system conditions in Continental Europe 100 5.2 Market aspects of system conditions in Balkan Peninsula 100 5.3 Capacity calculation 103 5.4 Day-ahead and intraday schedules 107 5.5 Day-ahead and intraday prices, 08 January 2021 120 5.6 Market impact of the incident in selected areas 126 Conclusion 134 Summary 134 Derived recommendations 135 Overall assessment and conclusion 136 List of Abbreviations 138 List of Figures 140 List of Tables 142 CE SA Separation on 08 January 2021 – ICS Final Report / Main Report // 3 Introduction Background On 08 January 2021 at 14:05 Central European Time (CET), the Continental Synchro- nous Area in Europe was separated into two areas (the north-west area and the south-east area) due to the tripping of several transmission network elements. The system separation resulted in a deficit of power in the north-west area and a surplus of power in the south-east area, leading in turn to a frequency decrease in the north- west area and a frequency increase in the south-east area. The automatic response and the coordinated actions Based on the legal obligations in the System Operation taken by the Transmission System Operators (TSOs) in Guideline (SO GL), a mandatory classification of the inci- Continental Europe ensured that the situation was quickly dent according to the Incident Classification Scale (ICS) restored close to normal operation. Resynchronisation methodology has been performed. Following the clas- of the north-west and south-east areas was achieved sification of the incident, an expert investigation panel at 15:08 CET. with TSOs, National Regulatory Authorities (NRAs) and Agency for the Cooperation of Energy Regulators (ACER) was established on 04 March 2021. Classification of the incident according to ICS Methodology The following analysis was performed based on the analysis of the incident, which will later be described in greater detail. The event started with flows that were higher than of the grid led to a region with over frequency and a had been foreseen in the grid models. This higher flow region with under frequency. In the region with under resulted in an N-state overload on the busbar coupler of frequency, the deviation of more than 200 mHz lasted less Ernestinovo (classification ON2). The reason for this classi- than 30 seconds. In the over frequency region, the devia- fication is that there was at least one wide area deviation tion of more than 200 mHz lasted more than 30 seconds from operational security limits after the activation of (classification F2). The criterion for an F2 was met because curative remedial action(s) in N situation. The overloaded there was an incident leading to frequency degradation busbar tripped, and thereafter several other network (200 mHz for more than 30 seconds). elements also tripped (classification T2). This criterion was met because there was at least one wide area devi- All aforementioned classifications are scale 2 incidents ation from operational security limits after the activation (extensive incidents) according to the ICS methodology. of curative remedial action(s) in N situation. There were Furthermore, there were some scale 1 incidents (signif- also wide area consequences on the regional or synchro- icant incidents). This covers minor voltage deviations nous area level, resulting in the need to activate at least (classification OV1). In addition, only minor losses of one measure of the system defence plan. The cascading load were reported. The largest loss of load was in the of several line trips led to the system split (classification Transelectrica grid where approx. 191 MW of load was RS2). This criterion was met because the separation from reported to have been disconnected. This was more than the grid involved more than one TSO and because at least 1 % and less than 10 % of the load in the TSO’s control area one of the split synchronised regions had a load larger (classification L1). than 5 % of the total load before the incident. The splitting 4 // CE SA Separation on 08 January 2021 – ICS Final Report / Main Report The priority of each criterion is shown in Table 1 below, by the scale 2 and scale 3 incidents must inform their denoted by a number from 1 to 27, where 1 marks the national regulatory authorities before the investigation criterion with highest priority and 27 marks the criterion is launched according to article 15(5) of SO GL. European with lowest priority. When an incident meets several Network of Transmission System Operators for Electricity criteria, the incident is classified according to the crite- (ENTSO-E) must also inform ACER about the upcoming rion that has the highest priority; however, information investigation in due time, before it is launched and no regarding all sub-criteria are also collected. The highest later than one week in advance of the first meeting of criterion from ICS methodology for this incident is thus F2: the expert panel. ‘Incidents leading to frequency degradation’. Each TSO must report incidents of scale 2 and 3 classified For incidents of scale 2 and 3, a detailed report must be in accordance with the criteria of ICS in the reporting tool prepared by an expert panel composed of representatives by the end of the month following the month in which from TSOs affected by the incident, a leader of the expert the incident began, at the latest. As the incident occurred panel from a TSO not affected by the incident, relevant on 08 January 2021, the affected TSOs had to classify the RSC(s), a representative of SG ICS, the regulatory author- events during this incident according to the ICS method- ities and ACER upon request. The ICS annual report must ology before 28 February 2021. An expert investigation contain the explanations of the reasons for incidents panel with TSOs, NRAs and ACER was established on 04 of scale 2 and scale 3 based on the investigation of the March 2021 and thus now publishes its mandatory final incidents according to article