一种可再生能源并网逆变器的多谐振PR电流控制技术

在介绍三相并网逆变器电流双环控制策略的基础上,对基于LCL滤波器的并网逆变器在两相静止坐标系下建立完整的开关周期平均模型。在电流环中,应用多谐振比例谐振(proportional resonant,PR)调节器来达到无静差跟踪正弦电流基波给定并减小输出电流中特定次数的谐波含量,以提高并网电流质量。针对多谐振PR调节器阶数高、设计难的问题,采用根轨迹理论分析PR调节器参数、系统延时以及LCL滤波器参数对闭环系统极点的影响,并基于此理论分析设计极点位置,选择合适参数,在保证系统稳定的前提下使电流环达到最佳的性能。最后搭建一台10 kW并网逆变器样机,验证多谐振PR调节器对并网电流的改善作用以及基于根轨迹理论设计多谐振PR调节器的实用性与可行性。

A Multi-resonant PR Current Controller for Grid-connected Inverters in Renewable Energy Systems

Based on the dual-loop current control strategy for grid-connected inverter,an average switching model of grid-connected inverters with LCL-filters was built under the stationary frame,and a multi-resonance proportional resonant(PR) regulator was adopted in the current-loop to track the given fundamental sinusoidal current as well as eliminating certain harmonics to improve the quality of grid currents.Because the system is of high order and complicated,the theory of the root locus was applied to analyze the PR regulator parameters,the digital delay and the LCL-filters,based on which the poles can be properly selected to guarantee the stability of the system and the performance of the current-loop.Finally,a 10?kW prototype of grid-connected inverters with LCL-filters was set up to verify the effectiveness of the multi-resonance PR regulator and the practicality and feasibility of the design method based on root locus.