Letzte Aktualisierung am 05. Februar 2020.

Am Freitag, 9. August 2019, verursachte der Ausfall eines Gaskraftwerks (664 MW) und kurz darauf der zusätzliche Ausfall eines Windparks (406 MW) ab 16:54 Uhr (15:54 UTC) eine Großstörung im britischen Übertragungsnetz. Zunächst kam es zu einer massiven Unterfrequenz von 48,889 Hz (extranet.nationalgrid.com), wodurch gem. ENTSO-E Network Codes bei 49 Hz die erste Sicherheitsstufe ausgelöst wurde. Dies bedeutete den sofortigen Lastabwurf (Abschaltung) von rund 10 Prozent der Verbraucher (rund eine Million Menschen waren betroffen). In Folge stieg die Frequenz wieder bis 16:01 Uhr auf 50.246 Hz. Die Ausbreitung der Großstörung konnte erfolgreich verhindert werden. Die Stromversorgung konnte bis 17:40 Uhr wieder vollständig hergestellt werden (The power stations were back in action after 15 minutes and National Grid says local power suppliers were meeting demand by 17:40. But the knock-on effect is likely to be felt for several hours to come.).

Obwohl es zu keinem Blackout kam, verursachte die Großstörung bereits erhebliche Auswirkungen auf andere Infrastrukturen. In einem Krankenhaus gab es erneut Probleme mit der Notstromversorgung (siehe auch Berlin-Köpenick). Besonders lange dauerte die Wiederherstellung des Bahnbetriebes, was erneut darauf hinweist, mit welchen massiven Problemen zu rechnen ist, wenn der gesamte Bahn- und Flugverkehr unplanmäßig und chaotisch zum Stillstand kommt. Wie können diese Systeme wieder hochgefahren werden, bzw. wie lange wird es dauern, wenn der Stromausfall nicht nur 15 Minuten, sondern viele Stunden oder sogar Tage gedauert hat und es danach noch Tage dauern wird, bis die Telekommunikationsversorgung wieder funktioniert. Was passiert mit dem Personal in der Zwischenzeit, das auch irgendwo gestrandet ist? Und noch viel mehr Fragen, die sich hier auftun!

05.02.20: Fehlende Momentanreserve

Quelle: www.energie-chronik.de

Die Untersuchung ergab nämlich, dass nicht nur das GuD-Kraftwerk Little Barford von RWE und der Offshore-Windpark Hornsea 1 von Oersted vom Netz gegangen waren, wodurch binnen einer Sekunde die Einspeisung einer Leistung von mehr als 1.130 Megawatt entfiel. Außerdem kam es zum Ausfall von dezentralen Stromerzeugern im Verteilnetz, deren Schutzmechanismen auf den plötzlichen Frequenzabfall mit Abschaltung reagierten. Insgesamt entstand so nach Ofgem-Angaben ein kumulierter Erzeugungsverlust von mindestens 1.990 MW. Die ESO verfügte demgegenüber nur über rund 1.000 MW an automatischer Regelleistung, um das Defizit ebenso schnell auszugleichen wie es entstand. Ersatzweise trat deshalb ein weiterer Automatismus in Kraft, der die Teilabschaltung von Verteilnetzen mit allen daran angeschlossenen Verbrauchern bewirkte. Andernfalls wäre der Zusammenbruch des gesamten britischen Übertragungsnetzes mit einem landesweiten Stromausfall nicht mehr zu verhindern gewesen.

Die von Ofgem betonte Notwendigkeit einer ausreichenden Systemträgheit kommt nicht von ungefähr, denn deren Fehlen hat letztendlich die Stromausfälle am 9. August verursacht. National Grid hat in den vergangenen Jahren die klassische Primärregelung, die über die rotierende Masse der Generatoren von Großkraftwerken erfolgt, durch ein neues Verfahren namens „Enhanced Frequency Response“ ersetzt, das sich im wesentlichen auf Batteriespeicher stützt. Es reagiert bereits in Sekundenbruchteilen auf Frequenzänderungen und ermöglicht es so, dichter an der Normfrequenz von 50 Hertz zu bleiben, die im britischen Übertragungssystem höchstens um ein Prozent nach oben oder unten schwanken darf. Der erforderliche Aufwand an Regelenergie wird dadurch im Normalfall geringer und auch kostengünstiger.

Die Kehrseite dieses „verbesserten“ Verfahrens zur Frequenzhaltung ist jedoch, dass ein plötzlicher Erzeugungsverlust schon binnen einer Sekunde voll auf die Netzfrequenz durchschlagen und diese unter die Abschaltgrenze drücken kann, wenn nicht genauso schnell genügend positive Regelenergie zur Verfügung steht.Bei der klassischen Primärregelung verläuft dieser Prozess viel träger, weil die in den rotierenden Massen gespeicherte kinetische Energie dafür sorgt, dass die Drehzahl der Generatoren und damit die Frequenz weitaus langsamer sinkt: Im kontinentaleuropäischen Verbundsystem haben die an der Primärregelung beteiligten Kraftwerke bis zu dreißig Sekunden Zeit, um einer Änderung des Leistungsreglers in vollem Umfang zu folgen, indem sie die Stromabgabe ins Netz um zwei Prozent ihrer Nennwirkleistung erhöhen oder verringern. Hinzu werden hier plötzliche Einspeisungsverluste von einer vielfach größeren Anzahl von Kraftwerken aufgefangen als in Großbritannien.

Am 2. Dezember kündigte sie ein neues und schneller wirkendes Verfahren zur Frequenzhaltung an, das im neuen Jahr eingeführt werde. Kern der Neuerung sei die „Dynamische Eindämmung“ (dynamic containment) zur Weiterentwicklung der „Enhanced Frequency Response“. Gemeint ist damit ein neues Beschaffungsverfahren, um mehr Regelenergie für jene kritische Phase zu gewinnen, in der größere Abweichungen von der Normalfrequenz binnen einer Sekunde bzw. in Echtzeit ausgeglichen werden müssen. Diese besonders schnell einsetzbare Regelenergie wird als LFS (Low Frequency Static) bezeichnet. Sie wird nur aktiviert, falls der normale Regelmechanismus nicht ausreicht und die Netzfrequenz bis auf 49,6 Hertz absinkt. Dann muss sie binnen einer Sekunde voll zur Verfügung stehen und bis zu 30 Minuten lang vorgehalten werden.

Aber auch im kontinentaleuropäischen Verbundsystem wird sukzesive die Momentanreserve durch die Abschaltung von konventionellen Kraften reduziert! Zudem gibt es eine Erkenntnis aus der Systemwissenschaft, dass wenn in einem System zu rasch reagiert wird, es immer zum Kollaps kommt! 

Palmer and his colleagues at the Santa Fe Institute in Santa Fe, New Mexico developed a virtual stock market populated by virtual agents. Each of the agents could change its investment rules over time. They found that when agents could only update their investment rules slowly, then the market converged to the rational expectations hypothesis because the bad rules were weeded out over time, However, if the agents could update their investment rules quickly, then the virtual stock market exhibited bubbles and crashes just like the real stock market because bad rules could feed off each other.

11.01.20: Companies pay £10.5 million over 9 August power cut

Quelle: www.ofgem.gov.uk

• Hornsea One Ltd and RWE agree to pay out £4.5 million for not remaining connected after the lightning strike
• UKPN will also pay out £1.5 million after a technical breach of rules

Ofgem has concluded that two large power stations, Hornsea One Ltd (co-owned by Orsted) and Little Barford (operated by RWE) did not remain connected after the lightning strike. They have agreed to make a voluntary payment of £4.5 million each into Ofgem’s redress fund.

Ofgem found that local network operators disconnected and reconnected consumers in response to the loss of power as expected. However, UK Power Networks began reconnecting customers without being asked to by the ESO, which could have potentially jeopardised recovery of the system. This has no impact on 9 August and UK Power Networks has recognised this technical breach, taken swift action to prevent any future reoccurrence, and agreed to pay £1.5 million into Ofgem’s voluntary redress fund. All parties have fully cooperated with the regulator throughout its investigation. 

11.01.20: expert reaction to Ofgem report on the power outage of 9 August 2019

Quelle: www.sciencemediacentre.org

“The Electricity regulator, Ofgem, has published its report on the electricity system incident that happened on August 9^th.  It states that payments have been made into Ofgem’s “voluntary redress” fund by three major industry actors in recognition of direct impacts on electricity users or an impact that could easily have arisen in view of departure from correct procedures. These actors are two generating companies – Ørsted and RWE – whose plant disconnected from the system when it shouldn’t have, and a Distribution Network Operator (DNO) – UK Power Networks – that started to restore demand before receiving confirmation from the Electricity System Operator (ESO) that it was safe to do so.  

None of the contributing events on their own should normally have caused any interruptions to electricity users’ supply.

“The initiating event was a short circuit on a 400 kV overhead line caused by a lightning strike.  Such faults typically happen tens of times each year on the transmission network and do not cause losses of supply.  On this occasion, however, it caused a steam turbine at Little Barford combined cycle gas turbine power station, owned by RWE, to trip.  It is still not completely clear why this happened or why, to compound the problem, a gas turbine there also tripped a minute later.

“The voltage depression caused by the short circuit fault also led to the loss of almost all of the power being produced at Hornsea offshore wind farm.  This, again, should not have happened.

“The network fault and the loss of generation at Hornsea and Little Barford caused the loss of further generation, small scale ‘distributed generation’ connected to the distribution network.  The combination led to a period in which there was not enough generation to meet demand and the system’s frequency started to fall.  ‘Frequency containment reserve’ scheduled by the ESO, mostly from generators but also from batteries, was not enough to prevent the system’s frequency from falling so far below statutory limits that automatic ‘low frequency demand disconnection’ (LFDD) equipment was triggered.  This disconnected an estimated 1.1 million electricity users. 

“By international standards, electricity supply in Britain is very reliable and the event on August 9^th was small, largely because LFDD succeeded in preventing the situation from getting a lot worse. However, the impact on rail users in the south-east, in particular, was significant.  This was largely due, so it seems, to the inadvertent operation of protection equipment on certain types of trains operated by Govia Thameslink.  Some water supplies were also affected.

“Ofgem’s report questions whether the ESO and the DNOs take sufficient responsibility in ensuring that equipment connected to the system – generators, interconnectors and loads – behaves in a way that contributes to system stability rather than putting the system at unreasonable risk.  This is arguably becoming more difficult than in the past.  The volume of small scale ‘distributed’ generation capacity has grown from an estimated 7 GW in 2009 to more than 37 GW today.  This represents tens of thousands of individual installations in contrast to the hundreds of power stations that met demand for electricity up to recent years.  (The annual peak demand for electricity in Britain is expected to be around 60 GW over the Winter of 2019/20).  

14.09.19: Technical Report on the events of 9 August 2019 

Quelle: www.ofgem.gov.uk

Impact on Rail

Major disruption to parts of the rail network, including blocked lines out of Farringdon and Kings Cross stations along with wider cancellations and significant delays impacting thousands of passengers. A major contributor to the disruption relates to a particular class of train operating in the South-East area – approximately 60 trains unexpectedly shut down when the frequency dropped below 49Hz, half of which required a visit from a technician to restart. (The remaining 30 trains required a technician to attend each train with a laptop to reset the trains.The effects were exacerbated as the fleet was undergoing a software change which meant the train drivers could not recover trains which were operating on the new software. The train manufacturer, Siemens, are developing a patch which will allow the drivers to recover the trains themselves without the need for a reboot or technician to attend site. In addition Siemens will investigate how the train could be made to operate for a short time with a supply frequency of 48.5Hz.) The impact to the rail network was that there were 23 train evacuations and thousands of passengers had their journeys delayed with 371 trains cancelled, 220 part cancelled, and 873 trains delayed. London St Pancras and King’s Cross stations had to close for several hours due to overcrowding and London Euston went exit only for a period of time. 

Impacts to other critical facilities including Ipswich hospital (lost power due to the operation of their own protection systems) and Newcastle airport (disconnected by the Low Frequency Demand Disconnection scheme).

Conclusions and Recommendations

Based on our analysis we have identified the following areas where lessons can be learned:

• Communication processes and protocols, in particular during the first hour, should be reviewed to support timely and effective communication in any future event;
• The list of facilities connected to the LFDD scheme should be reviewed to ensure no critical infrastructure or services are inadvertently placed at undue risk of disconnection; and
• The settings on the internal protection systems on electric trains should be reviewedto ensure they can continue to operate through ‘normal’ disturbances on the electricity system.

While the processes and procedures in place on 09 August generally worked well to protect the vast majority of consumers, there was however significant disruption – over 1m customers were without power for up to 45 minutes, rail services were severely impacted and some critical facilities were without power. Therefore, reflecting on the scale of disruption caused to the public, there are some areas where we believe a wider review of policy, processes or procedures may be appropriate, this includes:

• A review of the security standards (SQSS) to determine whether it would be appropriate to provide for higher levels of resilience in the electricity system. This should be done in a structured way to ensure a proper balancing of risks and costs;
• Assessing whether it would be appropriate to establish standards for critical infrastructure and services (e.g. hospitals, transport, emergency services) setting out the range of events and conditions on the electricity system that their internal systems should be designed to cater for;
• A review of the timescales for delivery of the Accelerated Loss of Mains Change Programme to reduce the risk of inadvertent tripping and disconnection of embedded generation, as GB moves to ever increasing levels of embedded generation.

 

21.08.19: Interim Report nationalgridESO 

into the Low Frequency Demand Disconnection (LFDD) following Generator Trips and Frequency Excursion on 9 Aug 2019; Quelle: nationalgridESO 

Enlarge infographic; Quelle: nationalgridESO 

Summary of event

Prior to 4:52pm on Friday 09 August Great Britain’s electricity system was operating as normal. There was some heavy rain and lightning, it was windy and warm – it was not unusual weather for this time of year. Overall, demand for the day was forecast to be similar to what was experienced on the previous Friday. Around 30% of the generation was from wind, 30% from gas and 20% from Nuclear and 10% from interconnectors.

At 4:52pm there was a lightning strike on a transmission circuit (the Eaton Socon – Wymondley Main). The protection systems operated and cleared the lightning in under 0.1 seconds. The line then returned to normal operation after c. 20 seconds. There was some loss of small embedded generation which was connected to the distribution system (c. 500 MW) due to the lightning strike. All of this is normal and expected for a lightning strike on a transmission line.

However, immediately following the lightning strike and within seconds of each other:

• Hornsea off-shore windfarm reduced its energy supply to the grid Little Barford gas power station reduced its energy supply to the grid
• The total generation lost from these two transmission connected generators was 1,378 MW. This unexpected loss of generation meant that the frequency fell very quickly and went outside the normal range of 50.5 Hz – 49.5Hz.

The ESO was keeping 1,000 MW of automatic “backup” power at that time – this level is what is required under the regulatory approved Security and Quality of Supply Standards (SQSS) and is designed to cover the loss of the single biggest generator to the grid.

All the “backup power” and tools the ESO normally uses and had available to manage the frequency were used (this included 472 MW of battery storage). However, the scale of generation loss meant that the frequency fell to a level (48.8 Hz) where secondary backup systems were required to disconnect some demand (the Low Frequency Demand Disconnection scheme) and these automatically kicked in to recover the frequency and ensure the safety and integrity of the network

This system automatically disconnected customers on the distribution network in a controlled way and in line with parameters pre-set by the Distribution Network Operators. In this instance c. 5% of GB’s electricity demand was turned off (c. 1 GW) to protect the other 95%. This has not happened in over a decade and is an extremely rare event. This resulted in approximately 1.1m customers being without power for a period.

The disconnection of demand along with the actions of the ESO Control Room to dispatch additional generation returned the system to a normal stable state by 5:06pm. The DNOs then commenced reconnecting customers and supply was returned to all customers by 5:37pm.

Immediate consequences

There were a number of very significant consequences from these events, the most significant of which include:

• 1.1 million electricity customers were without power for between 15 and 50 minutes. A number of a particular class of trains operating in the South-East area were unable to stay operational throughout the event and, in a number of cases, required an engineer to be sent out to the individual train. This was likely a significant factor in the travel disruption on the rail network (nearly 1,500 trains cancelled or delayed).
• Some other critical facilities were affected including Ipswich hospital (lost power due to the operation of their own protection systems) and Newcastle airport (disconnected by the Low Frequency Demand Disconnection scheme).

Preliminary findings

Our preliminary findings based on analysis to date are:

• Two almost simultaneous unexpected power losses at Hornsea and Little Barford occurred independently of one another – but each associated with the lightning strike. As generation would not be expected to trip off or de-load in response to a lightning strike, this appears to represent an extremely rare and unexpected event.
• This was one of many lightning strikes that hit the electricity grid on the day, but this was the only one to have a significant impact; lightning strikes are routinely managed as part of normal system operations.
• The protection systems on the transmission system operated correctly to clear the lightning strike and the associated voltage disturbance was in line with what was expected.
• The lightning strike also initiated the operation of Loss of Mains (LoM) protection on embedded generation in the area and added to the overall power loss experienced. This is a situation that is planned for and managed by the ESO and the loss was in line ESO forecasts for such an event.
• These events resulted in an exceptional cumulative level of power loss greater than the level required to be secured by the Security Standards and as such a large frequency drop outside the normal range occurred.
• The Low Frequency Demand Disconnection (LFDD) system worked largely as expected.
• The Distribution Network Operators quickly restored supplies within 31 minutes once the system was returned to a stable position.
• Several critical loads were affected for a number of hours by the action of their own systems, in particularly rail services.

Update 21.08.19: Wichtige Rolle von Batteriespeichersystemen

Gem. Bericht waren 472 MW (!!) Batteriespeichersysteme bei der Netzstabilisierung involviert. Der Frequenz-/Speichereinsatzverlauf des Betreibers Statera Energy ist beeindruckend und zeigt auch die dringende Notwendigkeit von derartigen Systemen zur raschen Stabilisierung von Störungen auf. Wobei es natürlich immer um ein sowohl-als-auch geht. Denn diese Speichersysteme sind bei einem solch intensiven Einsatz ziemlich schnell leer. Dann müssen andere Systeme folgen, die die Leistung bei Bedarf auch länger aufrechterhalten können. 

07.09.19: Siehe auch: Batteriespeicher verhindern Totalausfall des Stromnetzes in Großbritannien

Ableitungen von Herbert Saurugg

Dieses Beispiele hat einmal mehr das Verhalten von komplexen Systemen gezeigt (auch wenn das Stromversorgungssystem noch eine überschaubare Komplexität aufweist):

• Kleine Ursache, große Wirkung – Dominoeffekte vor allem auch außerhalb des unmittelbar betroffenen Systems (systemische Risiken)
• Nicht-lineares Verhalten: Ein Ereignis, das immer wieder auftritt und beherrscht wird, verhält sich einmal anders (Überraschungseffekt); Systemelemente verhalten sich auf einmal anders, als erwartet
• Die bisherigen Vorhaltungen von Reserven scheinen nicht mehr unbedingt zu den neuen Herausforderungen zu passen: Siehe auch Chaotische Zustände im deutschen Stromnetz.

Extrem seltene Ereignisse („Schwarze Schwäne„) sind dennoch möglich. Daher geht es nicht um die Wahrscheinlichkeit, sondern um die Auswirkungen, die bei solchen Ereignissen auftreten können. Eine Blackout-Vorsorge ist für eine moderne Gesellschaft unverzichtbar und überlebenswichtig!

Erste Ableitungen nach dem Ereignis

• Überraschend war dieses Ereignis insofern, als dass man bisher davon ausgegangen ist, dass es vor allem im Winter und bei Temperaturen unter Null Grad im UK-Netz zu massiven Problemen kommen wird: Großbritannien kämpft gegen den Blackout
• Wie die Analyse der Erzeugungslandschaft zum Zeitpunkt der Störung zeigt, waren wahrscheinlich die rasch regelbaren Gaskraftwerke dafür ausschlaggebend, dass die Störung in sehr kurzer Zeit behoben werden konnte. Um 16:50 Uhr waren mehr als 18 GW bzw. über 50% (!!) Kohle-, Gas-, Nuklear-, der Wasserkraftwerke am Netz, die auch eine ausreichende Momentanreserve sicher stellten konnten! (Around 30% of the generation was from wind, 30% from gas and 20% from Nuclear and 10% from interconnectors.)
• David Hunter, energy analyst at Schneider Electric, told the BBC that although the grid is „pretty safe and pretty reliable“, this was a „wake-up call“ to the energy industry and businesses with critical infrastructure.
• Two power stations shutting down almost simultaneously is „a very rare event„, says David Hunter, energy analyst at Schneider Electric. „That took the National Grid by surprise.“ He says an investigation into the causes may show that the two failures were „coincidental and unconnected“, adding there have been occasions when two generators shut down independently before. But he said a power station dropping off the grid can also create a „domino effect“, where other generators buckle under the strain of making up for the shortfall in power.

Wäre eine solche Störung beispielsweise am vergangenen Wochenende in Deutschland aufgetreten, hätte wohl kaum eine Chance bestanden, diese abfangen zu können, da bei einer Last von rund 58 GW rund 53 GW aus EE und nur 16 GW aus konventionellen Kraftwerken (Momentanreserve; 1,5 GW aus rasch reaktionsfähigen Gaskraftwerken) erzeugt wurden. 

Detailbetrachtungen und Hintergrundinformationen

Frequenzverlauf

 

 

Zum Vergleich, im Jänner 2019 ist die Frequenz im ENTSO-E Netz auf 49,8 Hz gefallen (Normalbereich: 49,8 – 50,2 Hz). Bei der bisher größten Großstörung in Europa am 4. November 2006 ist die Frequenz in Westeuropa auf „nur“ 49 Hz gefallen.

Gem. europäischen Network Codes muss ab einer Frequenz von 49 Hz ein sofortiger Lastabwurf von rund 12,5% der Last erfolgen (1 Million Betroffene), um den Systemkollaps („Blackout“) zu verhindern. Diese Maßnahme hat gegriffen und war erfolgreich. Bereits bei 48,8 Hz wäre die nächste Stufe ausgelöst worden.

 

 

ENTSO-E Netz

Das britische Netz ist zwar mit dem kontinentaleuropäischen Netz verbunden. Durch die Gleichstromverbindung sollte aber grundsätzlich keine Störung überspringen können. Daher bestand keine unmittelbare Gefahr für Mitteleuropa.

Anmerkung Franz Hein: 

Aus meiner Sicht gibt es aber doch das Problem, dass ein (zu) hoher Lastsprung auftreten kann (könnte). Bisher meinen wir, dass die Momentanreserve zusammen mit der Primärreglung besonders im mitteleuropäischen Netz so groß bzw. so leistungsfähig ist, dass wir (derzeit noch einigermaßen „locker“) 3000 MW Lastsprung ausregeln können (müssten). Das ist aber nur die momentane Sicht. Wir sind dabei, im größeren Umfang Kraftwerke außer Betrieb zu nehmen und bauen dabei die Momentanreserve mit ab. Damit wird das Systemverhalten „spitzer“, d.h. ein Lastsprung verändert die Frequenz rascher und das Gesamtsystem wird fragiler. Wenn wir mehr an elektronisch geregelter Primärregelung bereits hätten, ist das wiederum beherrschbar(er). Aber das geht nicht unbegrenzt so weiter. Die Momentanreserve „erzeugt“ aufgrund des Energieerhaltungssatzes über die mechanische Energie in der Drehbewegung die Frequenz des Wechselstromes. Das ist die Kenngröße für die Regelungsaufgaben. Die Frequenz muss gemessen werden (können). Der Messvorgang muss so sein, dass das Messergebnis für die Regelung tauglich ist. Hier kommen wir irgendwann an physikalische Grenzen, die dann auch keine noch so schnell reagierende elektronische Regelung mehr beherrscht. Es muss immer das Ganze im Blick bleiben, auch wenn wir Teilaspekte uns herausgreifen.

 

Mögliche Ursachen

Wie immer gilt, dass eine Großstörung/Blackout nicht durch ein Einzelereignis sondern immer durch die Verkettung von an und für sich beherrschbaren Einzelereignissen ausgelöst wird. Daher muss man bei möglichen Ursachenzuschreibungen immer vorsichtig walten lassen.

• Industry experts said that a gas-fired power station at Little Barford, Bedfordshire, failed at 16:58 (664 MW), followed, two minutes later, by the Hornsea offshore wind farm disconnecting from the grid (406 MW).The two generator failures meant a loss of about five per cent of the grid’s power over 90 minutes.
• RWE, owner of the Little Barford power station, said it shut down temporarily as a routine response to a technical issue, and called for National Grid and Ofgem to investigate the „wider system issues“.
• And Orsted, the owner of the Hornsea offshore wind farm, said automatic systems on Hornsea One „significantly reduced“ power around the same time others failed.
• It was a rare and unusual event, the almost simultaneous loss of two large generators, one gas and one offshore wind, at 4.54pm.

Anmerkung Franz Hein zu „a rare and unusual event“: 

Und das war „nur“ ein gleichzeitiger Ausfall von zwei völlig unabhängig voneinander funktionierenden Komponenten. Die weiteren Ausführungen zeigen dann die Wirkungen von verketteten und voneinander abhängigen Komponenten als Teile von Prozessketten. Diese Sicht ist von Bedeutung und das wird leider viel zu oft übersehen (oder verdrängt). So gut vernetzte Prozessketten sind, sie haben die fatale Eigenschaft, dass schon der Ausfall eines Kettenglieds zum Ausfall der gesamten Kette führt. Es müssen dazu nur die Abhängigkeiten der Kettenglieder untereinander zu „starr“ sein und kein „atmen“ und autonomes Agieren einzelner Kettenglieder zulassen. Dieses „Atmen“ nenne ich in der von mir propagierten Energielogistik „Energiebevorratung“ bzw. „Energiepufferung“, „Energiewälzung“ und „Langfristspeicherung“. Und das muss autonom erfolgen, denn sonst gibt es wieder irgendwo eine zentrale (gemeinsame) Komponente, was zum Gesamtausfall führt. Das „Atmen“ und das „autonome Agieren“ schafft Toleranzbereiche und lässt „Dehnungen“ der Kettenverbindungen zu. Das wiederum verhindert eher ein Zerreißen. Aber natürlich ist auch das endlich (stabil).

 

Installierte Kraftwerksleistung in Großbritannien

• 28 GW Erdgas
• 16 GW Kohle
• 22 GW Wind
• 13 GW PV
• 9 GW Nuklear
• 2,5 GW Wasser

Quellen: Wikipedia, Wikipedia, Weitere Details siehe gridwatch.co.uk

 

Stromproduktion um 16:54 Uhr (BST)

Um 15:50 Uhr wurden 2,83 GW PV-Strom produziert. Offensichtlich spielt das 50,2 Hz-Problem keine Rolle. Den Ausfall des Gaskraftwerkes Little Barford konnten offensichtlich andere Gaskraftwerke kompensieren, da hier kein Leistungseinbruch zu erkennen ist und was auch die rasche Wiederherstellung der Frequenz und damit Systemstabilität erklärt. Dennoch bleibt offen, warum ein Leistungseinbruch von rund 1 GW bei einer Erzeugung von über 30 GW einen derart gravierenden Frequenzeinbruch verursachte. 

 

Auswirkungen

• Power was lost across Ipswich Hospital amid a national power failure after the back-up generator failed to work.The site was hit by a 30-minute power cut and staff are looking into why the back-up generators did not kick in.People at the hospital said „sirens went off“ as power was lost.
• King’s Cross was one of the worst-hit stations, with all trains suspended for several hours.
• David Hunter, energy analyst at Schneider Electric, said a power station dropping off the grid can also create a „domino effect“, where other generators buckle under the strain of making up for the shortfall in power.
• People stuck in trains for up to nine hours. Trains began to run out of Kings Cross late on Friday night after the station was shut down for several hours. Throughout the Friday evening rush hour there was huge disruption on the railways: police officers were called in to help travellers and delayed passengers were stranded for hours. Lawal Brown, who boarded a Thameslink train at Stevenage at 16:45. It took nearly six hours before he was evacuated onto another train and many more before he made it home.Network Rail said the blackout affected signalling systems and power supply equipment across a large part of the rail system, but backup systems stepped in.That still meant some delays because of safety requirements, says Nick King, network services director for Network Rail.But he says further difficulties were caused by a „major systems failure“ on „one particular fleet of trains“. Thameslink has acknowledged that its trains required a technician to restart them after the power cut. Nearly 1,500 trains cancelled or delayed
• According to power utilities around the country, nearly one million people had to grapple with the blackout, including 300,000 in London and southeast England and 500,000 in the Midlands, southwest England and Wales. Some 110,000 were affected in Yorkshire and northeast England.
• And Scott McKenzie, 31, from Cardiff, said „various alarms were going off“ during the 15-minute power cut at Newcastle Airport.

 

Statements / Artikel

The Observer view on Britain’s blackout

https://www.theguardian.com/commentisfree/2019/aug/11/observer-view-on-britains-need-for-new-energy-policy 

And while a multiple generator failure may be a rare event, it is far from unheard of – the last was in 2008. Britain’s energy network should be able to cope with a once-in-a-decade event without causing so much potentially dangerous disruption. Even though the culprit in this instance was not a cyber attack, it illustrates just how vulnerable we may be to a malign attack of this nature.

This should ring alarm bells about the resilience of British infrastructure to rare but far from unprecedented events. Resilience planning requires a joint effort by industry and government. But because Whitehall has been so consumed by Brexit in recent years, resilience planning – alongside many other big policy challenges facing the country, like a solution to the social care crisis – appears to have fallen by the wayside. What other vulnerabilities are there in the system that could be exploited by our enemies?

The power outage should function as a rude awakening to the brittleness of core parts of British infrastructure to cope with events that should not be debilitating. Is this really a country ready for the huge strain a no-deal Brexit would probably place on essential services? It hardly looks like it.

It could take months to work through the lessons of Friday’s failure (siehe dazu etwa auch den 10. Jänner 2019, wo der Bericht auch erst fast 5 Monate später zur Verfügung stand!)

Power Cut Statement

A National Grid Electricity System Operator spokesperson said: “We appreciate the disruption caused by yesterday’s power outage and investigations have continued overnight to better understand the situation.

“As the Electricity System Operator we do not generate power directly, but use the power made available by the industry to manage the system and balance supply and demand. The root cause of yesterday’s issue was not with our system but was a rare and unusual event, the almost simultaneous loss of two large generators, one gas and one offshore wind, at 16.54pm. We are still working with the generators to understand what caused the generation to be lost. 

“Following the event, the other generators on the network responded to the loss by increasing their output as expected. However due to the scale of the generation losses this was not sufficient, and to protect the network and ensure restoration to normal operation could be completed as quickly as possible, a backup protection system was triggered which disconnects selected demand across GB. 

“Following the incident, the system was secured, and the Electricity System Operator gave the all clear to the Distribution Network Operators (NDOs), power companies who are responsible for supply at a local level, within 15mins, so that they could start to restore demand. All demand was reconnected by the DNOS by 17.40pm. We appreciate the disruption cause and will continue to investigate, with the generators involved and wider stakeholders, to understand the lessons learned.”

U.K. Power Failure Leaves Commuters Frustrated at Infrastructure

The incident raises questions about the state of the country’s infrastructure, which has had less investment than most other countries in the Organization for Economic Co-operation and Development over the last three decades. Chancellor of the Exchequer Sajid Javid said Friday, before the outage, that he will publish a National Infrastructure Strategy in the autumn as the U.K. seeks to boost investment in areas including transport and digital connectivity.

Chaos loomed three times before

https://www.theguardian.com/world/2019/aug/13/tuesday-briefing-alarming-frequency-of-near-blackouts

The National Grid put Friday’s chaotic blackout down to “incredibly rare” circumstances, but the electricity network has had three near-misses in as many months leading up to it.

The Guardian understands that in every month since May there has been a “frequency excursion” – a severe dip in the grid’s frequency from its normal range of around 50Hz. On Friday the blackout was triggered when the frequency slumped to 48.88Hz. Industry sources have confirmed the grid’s frequency has also fallen below 49.6Hz three other times in recent months – the deepest falls seen on the UK grid since 2015.