Generator Responses during the 2020 Mumbai Blackout

A major grid disturbance occurred in the Mumbai region on 12th October 2020, which led to the splitting of the system into islands. The precipitous frequency drop could not be controlled in time by the under-frequency load-tripping scheme, resulting in the collapse of Tata Power island. This island had a mix of steam and hydro-turbine driven generators, and a combined-cycle gas plant. The behaviour of these generators, as captured by the disturbance recorders, is presented in this paper. The generator responses exhibit rarely observed features of practical and educational interest. These features are highlighted and analyzed by playing back the disturbance recorder waveforms to the simulation models.