Frequency-dependent equivalent circuit for the representation of synchronous machines

A frequency-dependent equivalent circuit is developed to encapsulate the standstill frequency response (SSFR) of synchronous machines. A new method, which uses a hybrid genetic algorithm, is proposed to identify the circuit parameters. As a result the local minima problem associated with deterministic approaches is overcome. The equivalent circuit used has only one damper branch, but its capacity to reproduce the SSFR data is very good. This leads to a very simple representation of the machine, which can be readily used to compute transient conditions. In addition, the equivalent circuit can also be used to store the results of complex finite-element models, which are not readily available to power system engineers, providing a simple representation of the frequency response of the machine.