4. An isolated power station has the following parameters Turbine time constant tT=0.5 sec Governor time constant tg = 0.2 sec Generator inertia constant H = 5 sec Governor speed regulation R per unit. The load varies by 0.9% for a 1.8% change in frequency, The governor speed regulation is set to R=0.025 per unit. The turbine rated output is 0500MW at nominal frequency of 50Hz. A sudden load change of 75 MW occurs. Find the steady-state frequency in Hz.