Electrical outages. cyber attacks ?

A couple of corrections here. Wind turbines are actually asynchronous generators. Although they have a significant mechanical inertia, their grid connection is through an inverter, so none of the mechanical inertia counts. We used to be able to ride through issues like these, the trouble is that the majority of the inertia was in the coal fired stations that have been closed and mostly demolished. 


When you have generating sets trip, the frequency falls and you have two options - add more generation, or reduce the load to match the available generation. It looks like the first trip yesterday was going to be survivable, however, the second trip of generating plant was not. With the frequency falling rapidly, automatic  “demand reduction” relays will operate at certain agreed frequency points, and reduce the load (in fairly large chunks) until the system frequency recovers. This obviously worked as intended, as the majority of the country kept its power and reconnection time was fairly rapid. The only thing to look at from Grid’s point of view is I suspect whether too much load was cut away. However that is a very subjective question and not the easiest to find an answer to. What is more to the point, is the reason for the second trip, which just happened to be a wind farm. 


Regards,


Alan. 

A couple of corrections here. Wind turbines are actually asynchronous generators. Although they have a significant mechanical inertia, their grid connection is through an inverter, so none of the mechanical inertia counts. We used to be able to ride through issues like these, the trouble is that the majority of the inertia was in the coal fired stations that have been closed and mostly demolished. 


When you have generating sets trip, the frequency falls and you have two options - add more generation, or reduce the load to match the available generation. It looks like the first trip yesterday was going to be survivable, however, the second trip of generating plant was not. With the frequency falling rapidly, automatic  “demand reduction” relays will operate at certain agreed frequency points, and reduce the load (in fairly large chunks) until the system frequency recovers. This obviously worked as intended, as the majority of the country kept its power and reconnection time was fairly rapid. The only thing to look at from Grid’s point of view is I suspect whether too much load was cut away. However that is a very subjective question and not the easiest to find an answer to. What is more to the point, is the reason for the second trip, which just happened to be a wind farm. 


Regards,


Alan.