基于APF模态切换的高频谐振有源阻尼镇定策略

APF mode switching based active damping stabilization strategy for high-frequency resonance

LCL型并网逆变器引发高频谐振是造成并网系统失稳最严重的原因之一,对系统的可靠运行造成了巨大的威胁。传统的基于逆变器自身端口阻抗重塑的有源阻尼方法不具备通用性,同时加大了控制环路的复杂程度,不利于用作多电力电子设备并网系统的谐振抑制。关注到有源电力滤波器(active power filter,APF)动态控制环节的特点,基于无源性理论分析了APF用作阻尼输出的可行性及优势,提出了对APF进行模态切换以实现高频谐振的阻尼控制策略。该方案对谐振频率具备良好的跟踪效果,能够准确地识别系统模态并使APF迅速动作于对应频段的有源阻尼模态切换,具有通用性强、可靠性高、实现成本低的特点。通过仿真平台PLECS对提出的APF模态切换及高频谐振镇定策略进行验证,其结果与理论分析相符,进一步印证了APF用作有源阻尼抑制谐振的有效性。

High-frequency resonance caused by LCL-filtered gird-connected inverters is one of the most serious causes of instability for grid-connected system,which poses a significant threat to the reliable operation of the system.The traditional active damping method based on the inverters'terminal impedance reshaping is not versatile,as well as increasing the complexity of the control loop,which is unfavorable to be applied for resonance suppression in multi-power-electronics-connected system.This paper focuses on the characteristics of the dynamic control loop of active power filter(APF)and analyzes the feasibility and advantages of the APF-based damping output according to the passivity-based theory,thus proposing a damping control strategy that switches the modes of APF for high-frequency resonance stabilization.The scheme achieves good tracking effect on the resonance frequency,can accurately identify the system modes and enable the APF to quickly operate as an active damper in corresponding resonance frequency band.It is highly versatile,reliable,and inexpensive to be implemented.The proposed APF mode switching and high-frequency resonance stabilization strategies are verified by simulations in PLECS,and the results are consistent with the theoretical analysis,which further confirms the effectiveness of the APF as an active damper to suppress resonance.