基于功率同步控制的逆变器并网相位误差机理

Phase Error Features of Grid-tied Inverter Based on Power Synchronization Control

在并网逆变器中,以锁相环(phase-locked loop,PLL)为代表的电网同步技术得到了广泛应用。然而,由于PLL的引入降低了并网系统的稳定性,使得包括功率同步控制(power synchronization control,PSC)在内的无PLL逆变器控制技术逐渐受到重视。针对PSC的同步技术,现有研究缺乏小扰动下的相位误差模型和理论分析,其同步特性与PLL之间的异同也尚未涉及。为此,在小扰动下首先建立PSC的相位误差模型,并对影响PSC相位误差特性的控制参数进行理论分析。利用所建立模型的频率特性,在相等带宽条件下,对比PSC与传统PLL相位误差之间的差异。仿真和实验证明了PSC相位误差模型的准确性,并且在相等带宽下PSC的同步响应速度显著优于PLL。该文结果可为PSC的控制参数设计、同步理论分析提供一定参考。

In the grid-connected inverter,the grid synchronization mechanism represented by phase-locked loop(PLL)is widely used.However,the introduction of PLL has a potential to degrade the system stability.Because of this phenomenon,the control strategy without PLL including power synchronization control(PSC)has received significant attention.When it comes to the synchronization characteristic of PSC,the existing research lacks phase error model under the condition of perturbation.And the discrepancy between the synchronization characteristic of PSC and PLL has not been clarified.In order to solve this problem,this paper derives the phase error model of PSC under the condition of perturbation and conducts a theoretical analysis of the impact that control parameters exert on the PSC phase error.Based on the built model,the difference of phase error between PSC and traditional PLL is compared under the same bandwidth.The simulation and experiment results prove the correctness of PSC phase error model and show that under the same bandwidth,the synchronization of PSC is superior to PLL.The results of this paper provide reference for the parameter design and synchronization analysis of PSC loop.