Harmonic resonance analyzing for wind farm based on eigenvalue decomposition

Abstract

With the growing scale of wind farms and the development of grid connected technology, the power quality problem has attracted more and more attention. Generally speaking, wind farms are mostly located in remote areas in China, featuring weak grid connection structure and long outgoing lines. The transformer leakage inductance, line reactance and distributed capacitance may cause harmonic resonance, which not only deteriorates electric power quality, but also endangers system stability. For example, LCL filter resistance burned accident was caused by harmonic resonance in remote wind farms. In this paper, output impedance model of inverter connected grid and static var compensator was established. Then the modal analysis was conducted, where eigenvalue decomposition method was used to analyze harmonic resonance. Finally, considering the impact of components parameters on harmonic resonance, simulation model based on actual parameters of wind farms was constructed. Compared with measured data, results of modal analysis were verified.