LCL型三相光伏并网逆变器新型控制策略研究

LCL滤波型并网逆变器是高阶多变量控制系统,传统并网电流单一控制方法,不能确保系统稳定性良好的同时又较好的改善并网电流质量。为此提出了一种基于LCL型并网逆变器的新型复合电流控制技术。文中详细分析了LCL滤波器的特点,其在谐振频率处存在谐振尖峰,通过在电流环中增加陷波器的方法实现了LCL滤波器的有源阻尼,提高系统稳定性的同时又不需要额外增加传感器;并网电流调节器将重复控制(RC)和准比例谐振控制(QPR)有机结合,提高了系统的动态响应速度,且降低本地非线性负载扰动和电网电压频率波动对并网电流质量造成的影响,实现对基频信号的无静差跟踪控制和单位功率因数并网。通过Matlab/Simulink仿真测试,验证了陷波器有源阻尼及重复准PR复合控制策略的正确性和有效性。

New control strategy for three-phase PV grid-connectedinverter with LCL filter

LCL filter type grid-connected inverter is a high-order multi-variable control system,while the traditional grid-connected current single control method cannot ensure system stability well and better improve the quality of gridconnected current.A novel composite current control technology based on LCL type grid-connected inverter is proposed.In this paper,the characteristics of LCL filter are analyzed in detail,LCL filter has resonant peaks in resonant frequencies,the active damping of the LCL filter is realized by adding the notch filter in the current loop to improve the stability of the system without the need of additional sensor.The repetitive control (RC) and quasi-proportional resonance control (QPR) are combined by the grid-connected current regulator to improve the dynamic response speed of the system and reduce the influence of local nonlinear load disturbance and grid voltage frequency fluctuation on the quality of the grid-connected current,achieve non-static error tracking control of fundamental signal and unit power factor grid-connected.The correctness and validity of the active damping of the notch filter and repetitive QPR complex control strategy are verified by Matlab/Simulink simulation test.