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National Grid, Low frequency disconnecting system.

broadgage
As is fairly well known, any excessive drop in UK grid frequency results in calls for increased generation from quick starting plant such as OCGT and pumped storage, and for increased output from already running generating capacity.

If this does not relieve matters, then areas are disconnected by frequency sensitive relays in order to preserve the rest of the system. This last happened in August 2019 IIRC.


My question is what will happen during the NEXT low frequency event ?

Will the SAME areas be blacked out via the same (or similar replacement) relays operating the same switchgear as last time.

Or are settings adjusted after a low frequency event, such that next time the burden will fall on different areas.


The first approach sounds simpler, but the second approach is fairer. Or are such low frequency events so rare that "fairness" is not considered important.
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    Chris Pearson:

    I think a very reasonable question and, presumably, only one which National Grid could answer. I suppose that the fairest response would be to shut down different regions at random, but I doubt that the engineering would cope.


    Is the "decision" man-made or machine-made?




    In the short term, the "decision" is machine made since a rapidly falling frequency needs very quick and automatic action to avoid a total collapse.

    Taking the longer term or wider view then the decision is man made, the frequency relays are installed and programmed by men, who must decide which national grid feeders are dissconected in what order and at what frequencies.

    So is this order altered after the event ? or is it the same each time ?


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  • 0
    Chris Pearson:

    I think a very reasonable question and, presumably, only one which National Grid could answer. I suppose that the fairest response would be to shut down different regions at random, but I doubt that the engineering would cope.


    Is the "decision" man-made or machine-made?




    In the short term, the "decision" is machine made since a rapidly falling frequency needs very quick and automatic action to avoid a total collapse.

    Taking the longer term or wider view then the decision is man made, the frequency relays are installed and programmed by men, who must decide which national grid feeders are dissconected in what order and at what frequencies.

    So is this order altered after the event ? or is it the same each time ?


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