[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-324807-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-324807-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","grid-incident-in-czech-republic-factual-report-19-december-2025","Grid Incident in Czech Republic - Factual Report - 19 December 2025","","Technical factual report describing the system event in the Czech Republic on 4 July 2025, prepared by the Incident Classification Scale Investigation Expert Panel based on information available up to 8 December 2025. The document provides an objective, evidence-based account of event evolution and subsequent restoration, covering system state and market conditions beforehand, the factual sequence, protection performance, preliminary causes, and restoration and balancing processes. 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It aims to support transparency, learning, and continuous improvement in system operation across Europe. While this report is based on most reliable data made available to the Expert Panel by a range of data providers, no representation or warranty, express or implied, is made as to the fairness, completeness or correctness of information and opinions contained in this document. Importantly, the report is not intended to allocate liability or responsibility to any party and may, therefore, not be interpreted in such way.  \nIt serves solely as a factual record to transparently inform stakeholders and governance bodies, and to facilitate further discussion and evaluation within the context of the final report referred to hereafter. This report has been agreed and prepared by the Expert Panel and is without prejudice to any investigation or enforcement action that may be taken by the competent authorities.  \nCONTENTS  \n1 MANAGEMENT SUMMARY 4  \n1.1 Introduction 4  \n1.2 System state and market conditions before the incident 4  \n1.3 Evolution of system conditions during the event 5  \n1.4 Preliminary causes of the initial faults 5  \n1.5 Restoration process 6  \n1.6 Regional coordination processes 6  \n1.7 Incident classification based on ICS methodology 6  \n1.8 Next steps 6  \n2 SYSTEM STATE AND MARKET CONDITIONS BEFORE THE INCIDENT 7  \n2.1 Information about topology 7  \n2.2 Weather conditions 28  \n2.3 Market situation 30  \n3 EVOLUTION OF SYSTEM CONDITIONS DURING THE EVENT 37  \n3.1 Factual sequence of events 37  \n3.2 Generation and load 47  \n3.3 Island operation capability as the ancillary service 49  \n3.4 System’s dynamic behaviour during the event 52  \n3.5 Protection system performance during the event 65  \n4 PRELIMINARY CAUSES OF THE INITIAL FAULTS 69  \n4.1 Technical reasons and information about V411 disconnection 69  \n4.2 Information on generation disconnection 70  \n5 RESTORATION PROCESS 71  \n5.1 Restoration sequences 71  \n5.2 Communication and coordination during the restoration process 75  \n5.3 Generation recovery actions 75  \n5.4 Load recovery actions 77  \n5.5 End of restoration 84  \n5.6 Balancing during restoration 85  \n5.7 Market suspension and restoration 88  \n6 REGIONAL COORDINATION PROCESSES 90  \n7 INCIDENT CLASSIFICATION BASED ON ICS METHODOLOGY 92  \n7.1 RCC investigation threshold 93  \n7.2 Scale of incident 93  \n8 NEXT STEPS 94  \nLIST OF ABBREVIATIONS 95  \nEXPERT PANEL MEMBERS 96  \n1 MANAGEMENT SUMMARY  \n1.1 Introduction  \nOn 4 July 2025, the power system in the Czech Republic experienced a sequence of events lasting about 8 minutes, starting with the tripping of the V411 Hradec–Výškov 400 kV line at 11:51:08 CEST and ending with a loss of about 28 % of consumption in the ČEPS control area. The operation of the interconnected European grid continued as usual, and no other country was affected by the incident. This factual report outlines the events of that day, including the operational planning, the conditions before the incident, the evolution of the  \nincident and the subsequent restoration. It provides information on both the operational and market perspectives. Transmission system operators (TSOs), distribution system operators (DSOs), and significant grid users (SGUs) in the Czech Republic, as well asthe relevant regional coordination centres (RCCs), provided the relevant information in this report. It will serve as a basis for the final report, which will analyse the information and draw recommendations.  \n1.2 Sys","cbCaie1sY7IMSkH9","https://ap.wps.com/l/cbCaie1sY7IMSkH9","pdf",10490178,98,"English","# MANAGEMENT SUMMARY\n## Introduction\n## System state and market conditions before the incident\n## Evolution of system conditions during the event\n## Preliminary causes of the initial faults\n## Restoration process\n## Regional coordination processes\n## Incident classification based on ICS methodology\n## Next steps\n# SYSTEM STATE AND MARKET CONDITIONS BEFORE THE INCIDENT\n## Information about topology\n## Weather conditions\n## Market situation\n# EVOLUTION OF SYSTEM CONDITIONS DURING THE EVENT\n## Factual sequence of events\n## Generation and load\n## Protection system performance during the event\n# PRELIMINARY CAUSES OF THE INITIAL FAULTS\n## Technical reasons and information about V411 disconnection\n## Information on generation disconnection\n# RESTORATION PROCESS\n## Restoration sequences\n## Communication and coordination during the restoration process\n## Generation recovery actions\n## Load recovery actions","[{\"question\":\"What incident and timeframe does the report cover?\",\"answer\":\"The report covers the sequence of events in the Czech Republic on 4 July 2025, lasting about 8 minutes, starting with the tripping of the V411 Hradec–Výškov 400 kV line at 11:51:08 CEST and ending with a loss of about 28% of consumption in the ČEPS control area.\"},{\"question\":\"What is the purpose and intended use of the report?\",\"answer\":\"The report provides a technical, objective, and evidence-based account to support transparency, learning, and continuous improvement in system operation across Europe. It is prepared to inform stakeholders and facilitate further discussion and evaluation and is not intended to allocate liability or responsibility.\"},{\"question\":\"How does the report structure the analysis of the incident?\",\"answer\":\"It includes a management summary, details of system state and market conditions before the incident, the evolution of system conditions during the event (including a factual sequence and system behavior), preliminary causes, the restoration process, and regional coordination, followed by incident classification using the ICS methodology and next steps.\"}]","Grid Incident in Czech Republic - Factual Report - 19 December 2025 | PDF",1789968925,247]