Operation of a Distributed Generation Plant in a Power Supply System with Non-linear and Asymmetric Load

This paper presents the results of research on the influence of asymmetric and nonlinear load on the operating mode of a low-power turbine generator, which simulation takes into account automatic excitation and rotor speed controllers. The results of computer and physical modeling show the occurrence of the following negative effects: a noticeable negative-sequence current appears; the generator begins to generate higher harmonics into the network; the amplitude of the forced oscillations of the excitation current increases; additional mechanical vibrations of the rotor arise, which can lead to the accelerated wear and loss of stability. To ensure the operation of low-power generators with asymmetry and harmonic distortions, it is necessary to limit their load. As a criterion, the maximum current difference in the phases can be used, which should not exceed 12% of the rated current. In addition, it is required to use special means to protect generators: DC links; harmonic filters; negative-sequence protection of generators; automatics for limiting the excitation current.