Question

A 450 MVA, 26-kV generator is connected to a 345-kV power system through a 500MVA, 26-kV:345-kV transformer which can be represented by a series reactance of 95 m Ω when referred to its low-voltage terminals. The generator has a saturated synchronous reactance of 1.73 per unit and a rated-open- circuit-voltage field current of 2140 A. Under normal operating procedures, the generator is operated under automatic voltage regulation set to maintain its terminal voltage at 26 kV. In this problem you will investigate the possible consequences should the operators forget to switch over to the automatic voltage regulator and instead leave the field excitation constant at 2140 A. c) If the power system is represented simply by a 345-kV infinite (ignoring the effects of any equivalent impedance), can the generator be loaded to full load? If so, what is the power angle δ corresponding to full load? If not, what is the maximum load in MW that can be achieved? d) Find the value of field current which would be required to achieve rated load in MW at rated terminal voltage. Calculate the generator reactive power output under this operating condition. e) Repeat part (a) with the power system now represented by a 345 kV infinite bus in series with a reactive impedance of 12.4 Ω.

Answer 1

3 anera ator rs fu( ļcoded

2 eachve paoe -a3 (3-62.xto'o).&uSX(o'oj 3