Interconnector Fault Causes Problems for Wind Farms During Beast from the East

As the "Beast from the East" hit Ireland on the 28th February, things were looking good for wind farmers. The east winds were predictable and constant, unlike the variable westerlies that hit Ireland most of the time. Wind energy became baseload power for the first time on the Irish grid. On the 1st March, the capacity factor for wind was 80%, a power output normally reserved for coal or gas generation. However, a problem occurred on the morning of the 28th. The interconnector to the UK (East West interconnector) tripped out. This meant that surplus wind generation could no longer be exported to the UK. High amounts of wind generation would have to switched off or "curtailed".

Wind generation and forecasted wind during Beast from the East. Note how accurate the forecast was
with one notable exception (see later)

East West interconnector fault on 28th February

A further problem happened on the 2nd March as the storm reached it's peak. Power cuts became a frequent event. Power cuts are inevitable of course during storms and periods of extremely high winds, which is very unfortunate for wind farmers as demand for their product, electricity, is reduced just when their supply is at it's highest. In fact, over the four or five days of the "Beast", demand was relatively normal. This is in stark contrast to the Big Freeze event of 2010 where demand reached over 5,000MW (and wind generation was abnormally low). During the Beast, demand reached a high of about 4,600MW on the 28th February. The periods of highest winds (1st - 3rd march) saw demand reach only 4,200MW.

Demand all time peak 2010 Vs Demand during Beast from the East 2018

Power cuts on the 2nd March

 On 1st March, wind energy was generating about 59% of the total electricity production, one of the highest penetrations ever. However, by the next day, as power cuts became widespread, wind energy was been curtailed by as much as 45%. Nearly 1,200MW of wind was been shut down at 4am. 

The period from 1st to 2nd March was when the storm was at it's most intense in Ireland. 
Wind curtailment can therefore be calculated as the difference between forecast wind and actual wind. 
Forecast wind generation was actually equal to demand at times.

The frequency of electricity, normally static at 50Hz, became erratic during the storm as the grid
operator struggled to manage high wind penetrations. This is from the 2nd March.

Had the interconnector been in operation, 500MW of this surplus wind could have been exported.  Demand, in fact, dropped by 10% on the 2nd March compared with the day before, presumably due to the power cuts. 

These are problems that will only intensify as more wind capacity is added and more and more generators are looking to get a piece of the demand "pie". Interconnectors, like storage, seem like an easy solution in theory, but in practice things are often different.