Three turbine generators of 20 mw capacity are supplying a load of 48 mw and the load suddenly increases to 50 mw. two of the units are set with a speed droop of 9% and speed adjustment of 6%. the third unit is operating at zero speed droop and zero speed adjustment. determine the change in system frequency due to the sudden load change. what wi the speed change be if the load increases to 54 mw?