摘要
同步旋转坐标系(dq)下的比例积分控制在并网变流器中得到广泛应用。由于滤波器和数字延迟的dq模型均存在轴间耦合并且两者相互影响,低开关频率下LCL型并网变流器的建模和解耦控制变得极具挑战。针对该问题,在对同步旋转坐标系下的LCL型并网变流器采用复矢量进行建模的基础上,通过双边频响特性曲线和零极点图对传统状态反馈和相位补偿进行了系统分析,揭示了不同位置相位补偿对系统相位裕度和解耦性能的影响关系,在此基础上提出了一种改进解耦控制方法,通过在状态反馈环内和调节器输出端依次设计相位补偿,在有效调节和改善动态性能的同时保证系统具有较好的解耦性能。最后,仿真及实验结果表明所提方法具有很好的解耦效果,同时能有效减小系统超调量和调节时间。
Proportional integral(PI) control in synchronous rotating frame(dq) is widely applied in grid-connected converters. As axe-cross-couplings exist both in the filter and delay models of dq frame and the cross-couplings interact each other, modeling and decoupling of LCL-filtered grid-connected converter with low switching frequency become much more challenging. To address this issue, based on modeling of LCL-filter grid-connected converters in dq frame with complex vector, a systematic analysis for traditional state feedback and phase compensation is conducted with double-sided frequency response and pole-zero map, where the effects of phase compensation at different positions on phase margin and decoupling effect are revealed. Based on this, an improved decoupling control strategy is proposed to effectively regulate and improve system dynamic performance and ensure good decoupling effect at the same time by respectively designing phase compensations at output of regulator and within state feedback loop. Finally, simulation and experimental results show that the proposed method can provide good decoupling effect and reduce overshoot and settling time effectively.
引文
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