A grid-connected three-phase (Y-connected) synchronous generator nameplate reads 200 MVA and 22kV. The generator is supplying 100 MW at 0.8 power factor leading at its rated voltage. The synchronous reactance of the generator is 1.0 per unit using the rating as base values. Neglect all losses. Regard the terminal bus voltage as the reference phasor. Give your final answer in SI units. (a) Calculate the generator line current magnitude. (b) Calculate the internal emf phasor. (c) Calculate the steady state active and reactive power provided by the generator if the torque applied by the generator prime mover is increased by 25% and the field current is decreased by 10%. Assume the frequency and the terminal voltage remain the same.

A grid-connected three-phase (Y-connected) synchronous generator nameplate reads 200 MVA and 22kV. The generator is supplying 100 MW at 0.8 power factor leading at its rated voltage. The synchronous reactance of the generator is 1.0 per unit using the rating as base values. Neglect all losses. Regard the terminal bus voltage as the reference phasor. Give your final answer in SI units. (a) Calculate the generator line current magnitude. (b) Calculate the internal emf phasor. (c) Calculate the steady state active and reactive power provided by the generator if the torque applied by the generator prime mover is increased by 25% and the field current is decreased by 10%. Assume the frequency and the terminal voltage remain the same.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.56P: Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit...

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Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit leakage reactance, are connected as a three-phase extended autotransformer bank, as shown in Figure 3.36(c). The low-voltage winding has a 110 volt rating. (a) Draw the positive-sequence phasor diagram and show that the high-voltage winding has a 479.5 volt rating. (b) A three-phase load connected to the low-voltage terminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Draw the per-unit impedance diagram and calculate the voltage and current at the high-voltage terminals. Assume positive-sequence operation.
Consider a three-phase generator rated 300MVA,23kV, supplying a system load of 240 MA and 0.9 power factor lagging at 230 kV through a 330MVA,23/230Y-kV step-up transformer with a leakage reactance of 0.11 per unit. (a) Neglecting the exciting current and choosing base values at the load of 100 MVL and 230 kV. Find the phasor currents IA,IB, and IC supplied to the load in per unit. (b) By choosing the load terminal voltage IA as reference, specify the proper base for the generator circuit and determine the generator voltage V as well as the phasor currents IA,IB, and IC, from the generator. (Note: Take into account the phase shift of the transformer.) (C) Find the generator terminal voltage in kV and the real power supplied by the generator in MW. (d) By omitting the transformer phase shift altogether, check to see whether you get the same magnitude of generator terminal voltage and real power delivered by the generator.
A synchronous generator is rated 645 MVA, 24 kV, 0.9 pf lagging. It has a synchronous reactance 1.2 . The generator is feeding full load at 0.9 pf lagging at rated voltage. Calculate: (a) Excitation emf (E,) and power angle & (b) Reictive power drawn by the load Carry out calculations in pu form and convert the result to actual values.
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6. A 3 phase fault occurs at point F as shown in figure. Determine the critical clearing anglefor the system. The generator is delivering 1.0 p.u power under prefault conditio
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two alternators A and B having 5% speed regulation are working in parallel at a station. Alternator A is rated at 15 MW while B is at 20 MW. When the total load to be shared is 12 MW, then how much of the load will be shared by the alternator B?
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