Determination of Equivalent-circuit Parameters of a Synchronous Generator Based on the Standstill DC Decay Test and a Hybrid Optimization Method

The parameter estimation of a salient-pole synchronous generator using the DC decay test at standstill is presented in this article. A dedicated experimental setup for this test was constructed, and it consists of a Labview program, a data acquisition system, sensors, and a mercury relay. The parameter estimation is performed using the stator and field current responses from the d-axis test, while for the q-axis, the stator current response is used. The two-axis theory is used to model the generator and, hence, equivalent circuits are used to represent it. The genetic and Gauss-Newton algorithms are employed in the estimation process of the fundamental model parameters, where data from the standstill DC decay experiment are used. The estimated parameters correspond to a low-level excitation perturbation, and to see their validity under a large disturbance, the sudden three-phase short-circuit fault was chosen. It is found that a model with the DC decay based parameters can predict with good accuracy the sudden short-circuit fault. The experiments are made on a 7-kVA, 220-V, 1800-rpm, 60-Hz synchronous generator.