2. Consider two identical three-phase, 13.8 kV, 100-MVA, 60-Hz generators, each with a synchronous reactance of...

 

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2. Consider two identical three-phase, 13.8 kV, 100-MVA, 60-Hz generators, each with a synchronous reactance of 1.10 per unit, operating in parallel supplying a total load of 150 MVA at 0.8 lagging power factor, rated voltage, and rated frequency. Calculate for each generator (i) the real power, (ii) the reactive power, (iii) the armature current, (iv) the power factor, (v) the excitation voltage, and (vi) the power angle, under the following conditions (Ignore part © ): (40 points) (a) If the prime movers are adjusted so that the machines share the real power equally, and the field excitations are adjusted so that the reactive power output of each machine is the same. (b) If the machines deliver equal real power, but with the field excitation of one of the generators (say, generator 1) increased by 20% above its value in part (a), while the field current of the other generator is adjusted so that the terminal voltage remains constant at rated value. (c) If the excitation of generator 1 is kept constant at the value as in part (b) while the input to the prime mover is increased by 20%, and adjustments are made in the field current of generator 2 and its prime mover such that the frequency and the terminal voltage remain at their rated values. 2. Consider two identical three-phase, 13.8 kV, 100-MVA, 60-Hz generators, each with a synchronous reactance of 1.10 per unit, operating in parallel supplying a total load of 150 MVA at 0.8 lagging power factor, rated voltage, and rated frequency. Calculate for each generator (i) the real power, (ii) the reactive power, (iii) the armature current, (iv) the power factor, (v) the excitation voltage, and (vi) the power angle, under the following conditions (Ignore part © ): (40 points) (a) If the prime movers are adjusted so that the machines share the real power equally, and the field excitations are adjusted so that the reactive power output of each machine is the same. (b) If the machines deliver equal real power, but with the field excitation of one of the generators (say, generator 1) increased by 20% above its value in part (a), while the field current of the other generator is adjusted so that the terminal voltage remains constant at rated value. (c) If the excitation of generator 1 is kept constant at the value as in part (b) while the input to the prime mover is increased by 20%, and adjustments are made in the field current of generator 2 and its prime mover such that the frequency and the terminal voltage remain at their rated values.