An Improved Proportional Quasi-Resonant Control of Wind Power GCI under Unbalanced Grid Conditions

with conventional control strategy under unbalanced grid conditions, power fluctuations will be generated in the input active power and reactive power of the wind power Grid Connected Inverter (GCI). In this paper, a novel sequence extraction method is proposed in the voltage components decomposition. Based on second order generalized integrator (SOGI) with PLL, a decomposition module with an ability of frequency adaptation is built up, called FA-SOGI. To avoid the sequence extraction of grid current, a novel proportional quasi-resonant controller implemented also by FA-SOGI within αβ stationary coordinate system is introduced to improve innerloop current control performance. With two objectives of active power fluctuation suppression and reactive power fluctuation suppression, the proposed strategy is verified by simulation and experiment. The results show that the sequence decomposition module is correct and the power fluctuations can be obviously suppressed and DC-bus voltage can be steady. Key-Words: proportional quasi-resonant (PQR), power fluctuations, unbalanced grid, grid connected inverter (GCI), second order generalized integrator with frequency adaptation (FA-SOGI)