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U.K. Blackout: One Lightning Strike Sparks a Cascade of Probes

A preliminary report indicated that lightning was the initial cause for the Aug. 9 event

(Bloomberg) -- The lightning strike that triggered Britain’s biggest blackout in more than a decade has also spawned a flurry of investigations by groups ranging from the government to railway operators.

National Grid Plc’s preliminary report published by the regulator Ofgem last week indicated that lightning was the initial cause for the Aug. 9 event. That quelled some of the early blame in the national press that the blackout was due to the variability of wind farms, a symbol of the country’s increasingly diversified electricity system.

Lightning strikes cause faults on the transmission network throughout the year, but usually don’t set off the chaos seen earlier this month, according to Keith Bell, professor of electrical engineering at the University of Strathclyde.

“Provided network protection operates correctly, no generation should be lost from the system as a consequence of such faults,” Bell said. “One main question now is exactly why protection or control equipment at the two generators responded as they did and caused the loss of generation.”

Over the coming weeks, a wave of probes are set to get to the bottom of what exactly happened and who is to blame. Here is a roster of who’s involved and what’s coming:

The Regulator

Ofgem kick-started its probe into the incident Tuesday after National Grid handed in a preliminary report last week. The regulator will examine a range of issues including whether the grid had enough reserve power on hand and if Orsted A/S and RWE AG, which operate the offshore wind farm and gas plants that failed, should face any sanctions.

National Grid

For its part, National Grid is expected to present a further, more detailed technical report to the regulator on Sept. 6. It says it will look at ways of shoring up the grid as the U.K. transitions to a zero-carbon power system. It will also look more deeply to understand the exact failure at Hornsea One offshore wind farm and Little Barford gas plant. National Grid plans to support all the other investigations with its data and technical knowledge.

The Government

Energy Emergencies Executive Committee, a partnership between the government, Ofgem and industry, will probe the power cut. It will submit an interim report in four weeks to Business Secretary Andrea Leadsom, followed by a more complete report. The committee previously met to review the performance of distribution network operators during the storms of Christmas 2013.

The Power Companies

Both Orsted and RWE launched investigations into what happened at their facilities.

Orsted concluded last week that it found a technical fault that led the Hornsea One wind farm shutting down. The company continues to investigate what happened and to cooperate with the government investigations.

RWE is investigating the root cause of what happened. It has so far found that the turbine generator automatic control system detected an abnormality and initiated a safety shutdown of the plant. 

The Local Networks

National Grid has cast some of the blame on the network operators that oversee the final leg of power distribution and were the ones to shut down electricity to consumers. The networks are cooperating with all the ongoing National Grid and government investigations into their role in the power cuts.

The Trains

While power was restored in minutes, trains were disrupted for hours. The main problem was that a particular kind of train wouldn’t restart after the power dropped. An engineer had to physically go to about 30 of those trains to get them running. Train operator Govia Thameslink Railway is probing the issue of its locomotives, while Network Rail is investigating what happened with the rail infrastructure.

--Jeremy Hodges and William Mathis

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