弱电网下,公共耦合点处电压易发生畸变,使锁相环输出相位偏离,从而降低系统相位裕度,进而造成并网电流畸变。为补偿产生的相位差,提出一种基于小信号补偿的控制策略,推导系统的小信号输出阻抗模型,分析相位偏差产生的原因。通过采用改进的小信号补偿控制策略来补偿因耦合作用造成锁相环输出相位的偏移,确保系统在电网阻抗发生突变时也能保持一个良好的相位裕度。通过样机实验说明了所提理论推导的准确性和改进方法的可行性。
Abstract
Under the weak grid, the voltage at the common coupling point is prone to distortion, which causes the output phase of the phase-locked loop to deviate, thereby reducing the system phase margin and causing grid-connected current distortion. In order to compensate the phase difference, a control strategy based on small signal compensation is proposed. The small signal output impedance model of the system is derived, and the causes of phase deviation are analyzed. By adopting the improved small signal compensation control strategy, the offset of the output phase of the phase-locked loop caused by the coupling effect is compensated to ensure that the system can maintain a good phase margin when the grid impedance changes. The accuracy of the theoretical derivation and the feasibility of the improved method are illustrated by the prototype.
关键词
光伏发电 /
弱电网 /
并网逆变器 /
相位补偿 /
锁相环
Key words
photovoltaic power generation /
weak grid /
grid-connected inverter /
phase compensation /
phase-locked loop
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