An Investigation of Frequency Fluctuation Impact on Isolated Power System Self-Excitation

In this paper self-excitation phenomena which may occur in no-load generator with a long line is investigated. With the analysis of the physical process of self - excitation and adoption the Pi-type equivalent model for the line, the effect of frequency on self-excitation is evaluated, and an expression of self-excitation at the critical frequency is proposed. Note that systems may experience transition from normal operation to self-excitation, when the frequency exceeds its critical value. The new generator operating limit, with consideration for the self-excitation phenomena, is derived, providing a theory to protect isolated power stations from self-excitation. PSCAD / EMTDC is used for simulation, which proves the correctness of the conclusion.