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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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    AJJewsbury:

    Wasn't there some umming and ahhing after the last incident that resulted in changes being made to some of the parameters? If so it's likely that 'next time' will result in a different outcome anyway.

       - Andy.


    Yes, IIRC there were adjustments mad to the settings of protection relays for large wind farms and large PV arrays, this should help a bit by allowing such installations to "ride through" grid frequency or voltage disturbances rather than tripping and making the situation worse.

    I think that protection settings for NEW (not yet installed) domestic sized grid tied PV were also altered for the same reasons. I do not believe that settings on EXISTING domestic sized grid tied inverters were altered. Who would do this and at at whose expense ?


    These alterations should tend to reduce the risk of a similar event happening again. OTOH the growth in generating capacity connected via static inverters, and the reduction in classic steam turbine capacity would tend TO INCREASE the risks of instability and a repeat of August 2019.


    So I see some risk of it happening again.


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  • 0
    AJJewsbury:

    Wasn't there some umming and ahhing after the last incident that resulted in changes being made to some of the parameters? If so it's likely that 'next time' will result in a different outcome anyway.

       - Andy.


    Yes, IIRC there were adjustments mad to the settings of protection relays for large wind farms and large PV arrays, this should help a bit by allowing such installations to "ride through" grid frequency or voltage disturbances rather than tripping and making the situation worse.

    I think that protection settings for NEW (not yet installed) domestic sized grid tied PV were also altered for the same reasons. I do not believe that settings on EXISTING domestic sized grid tied inverters were altered. Who would do this and at at whose expense ?


    These alterations should tend to reduce the risk of a similar event happening again. OTOH the growth in generating capacity connected via static inverters, and the reduction in classic steam turbine capacity would tend TO INCREASE the risks of instability and a repeat of August 2019.


    So I see some risk of it happening again.


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