Analytical Response of Synchronous Generators during Load Rejection and Field Short-circuit Tests

Abstract

In a recent work, the authors developed what they called a numerical hybrid state model and used it to predict the performance of a saturated synchronous generator during load rejection tests. The state matrices were presented in compact numerical form and may prove tedious to implement for a given application. Therefore, the purpose of the present article is to derive these matrices in terms of the generator's physical parameters using symbolic software. For direct and easy computation of the model output variables, time-variant analytical waveforms of the phase voltages and the field current following a generator tripping (load rejection) and an open stator field short-circuit are also developed in terms of the generator parameters using the state model solution of the linear control systems theory. Two full-load rejection tests, one with an inductive load, other with a capacitive load and a standard field short-circuit test with the stator in open circuit are performed. Comparisons are made between the simulation results and actual data obtained from a laboratory machine to assess the suitability and effectiveness of the proposed synchronous generator framework analysis.