Performance of a hydro power plant during black start and islanded operation

The black start units in a typical hydro-thermal power system will be the hydro power plants since they require very small power to restart after a total shut down, compared to a thermal power plant. They are supposed to start up and supply cranking power to the non-black start units in the system like steam and nuclear power plants. So the time taken for the hydro power plant to start up and start supplying power is an important factor in determining the whole restoration plan of a hydro-thermal power system. This time duration is mainly controlled by the governor and exciter controls during the black start.