Design and Control Strategy of Wind Power Grid-Connected Inverter Based on LCL Wave Filter

Abstract

LCL wave filter can effectively suppress the high-order harmonics of current and reduce the total inductance. It is suitable for larger capacity wind power generation. However, its third-order characteristics may produce high-order resonance, which may cause the grid-connected system to be unstable. This paper takes 2MW doubly-fed wind power generation as the research object. According to the working principle of LCL wave filter, the main circuit parameters are determined. The values of wave filter inductors L1, L2 and filter capacitors C are determined without dividing the two inductors equally. The mathematical model of three-phase grid-connected inverters is established, and the PR control strategy is improved to solve the problem that the system may not be effectively implemented without static error tracking control. The simulation results show that the inverter based on LCL meets the requirements of IEEE standard. THD of harmonics above 35 times is only 0.23%, which is lower than 0.3 % of the standard requirement. The harmonic content in grid-connected current of wind power generation system with improved PR control strategy is less, which can ensure that 2MW doubly-fed wind power generation system delivers high power factor power to the grid.