Analysis of forced oscillations in a multimachine power system

The origin of forced, low frequency oscillations introduced in power systems by low-speed diesel generators is investigated. The linear models of a multimachine power system are presented for both interconnected and autonomous systems. Particular emphasis is given to the calculation of the electromechanical oscillation frequencies. A three-machine test system exhibiting a very strong resonance is analysed. The method of analysis is based upon the computation of the frequency response of a multivariable system. Finally, the electromechanical oscillation analysis and the frequency response computation are applied to the electric power system of the island of Crete, where a number of large low-speed diesel engine driven generators have recently been installed