多目标约束下逆变器阻抗的电流矫正方法

Current correction method for grid-connected inverter impedance under multi-objective constraints

中文关键词  并网逆变器  弱电网  锁相环  稳定性  阻抗重塑

英文关键词  grid-connected inverter  weak grid  phase-locked loop  stability  impedance reshaping

中文摘要

      弱电网下锁相环与电网阻抗间的耦合会造成系统不稳定. 含前置低通滤波器锁相环的并网逆变器虽能改 善并网系统稳定性, 但存在并网电流相位滞后问题. 本文通过将滤波器从锁相环支路“拆分”, 提出了一种电流二 阶校正的阻抗重塑法, 以基波电流控制性能、相角裕度、低频幅值为约束建立了多目标约束函数, 单独优化设计了 二阶校正环节参数, 提高了并网逆变器的弱网稳定性, 实现弱电网下的单位功率因数并网. 最后在StarSim实验平台 验证了所提控制方法的有效性.

英文摘要

      Under a weak grid, the system instability can be jeopardized by the interaction between the phase-locked loop and the grid impedance with increasing impedance. Although the stability of grid-connected system can be improved by a phase-locked loop with a serial low-pass filter (LPF), it leads to a lag phase of injected grid current. Based on the equivalent transformation and frequency division optimization, an impedance reshaping method with second-order correction of the current is proposed. Then a multi-objective constraint function is established with the constraints of base-wave current control performance, phase angle margin, and low-frequency amplitude. And the parameters of the second-order correction link are optimally designed by this function. The method improves the weak grid stability of the grid-connected inverter and realizes the grid connection with unit power factor under the weak grid. Finally, the effectiveness of the proposed control method was verified on the StarSim experimental platform.