(a) A two-area primary control LFC system with a load change of +200 MW that occurs in Area 1 have the following characteristics: Area 1: R = 0.011 p.u D = 0.85 p.u Base MVA 1000 Area 2: R2 = 0.018 p.u D = 0.95 p.u Base MVA = 1000 The system nominal frequency is 50 Hz. (II) (111) Determine the new steady-state frequency. [5 marks] Determine the tie-line power flow deviation. [3 marks] If the load disturbance also occurs simultaneously in Area 2 by +100 MW, determine the frequency and tie-line power changes. [4 marks] (b) An isolated 50 Hz system is rated at 9000 MW and has an inertia constant, H = 4. The governor droop on all generators is set to 4%. The turbine and generator time delay constant is 0.8 sec and 0.3 sec respectively. The integral controller gain is 2.6. The system is delivering full load output power at nominal frequency when it suffers a sudden large loss of load of 2000 MW. The remaining load may be assumed to have a load-frequency characteristic of 1.73 % load change per 1% frequency change. (ii) Obtain an expression for the variation of frequency with time for a period of 60 seconds. [7 marks] An overspeed relay is liable to trip generators if the speed exceeds 50.6 Hz for a certain time. Determine the minimum value of this time setting if no generator tripping should occur during this event. [1 mark]