谐波干扰下DSOGI-PLL锁相精确度优化策略

Optimization Strategy of DSOGI-PLL Precision Under Harmonic Interference Conditions

在系统电压畸变的条件下,并网逆变器通过双二阶广义积分器(dual second-order generalized integrator,DSOGI)锁相环提取基频信号,从而实现电压定向矢量控制。但是系统电压中常含有较高的低次谐波,此时DSOGI的滤波效果将不理想,锁相环提取的同步信号出现波动。通过建立DSOGI的复矢量模型,分析了传统DSOGI锁相环输出电压包含谐波机理。根据二阶广义积分器(second-order generalized integrator,SOGI)的正交特性,推导了正交消谐法消除谐波。该锁相环对DSOGI输出电压进行微分运算,利用谐波电压微分方法逐次消除系统电压中的各次谐波,实现对系统电压中基频电压的准确提取。仿真表明,在系统电压谐波含量较高时,改进后的锁相环能有效提取基波的相位。

Grid inverters can extract fundamental signal with dual second-order generalized integrator(DSOGI)phase-locked loop under harmonic distorted system conditions,so as to ensure voltage oriented vector control.The synchronous signals extracted through DSOGI-PLL fluctuate when there are a large amount of low order harmonics among voltage sequence in system,which reduces the performance of second-order generalized integrator(SOGI).The complex vector model for DSOGI is established,the mechanisms that output voltage of the traditional DSOGI phase-locked loop contains harmonic can be analysized.According to the orthogonal characteristics of SOGI,the principle of eliminating harmonics is derived through the orthogonal harmonic elimination method.The phase-locked loop derivatives the DSOGI output voltage,and successively eliminates harmonics in system with a harmonic voltage differentiation method.And extract fundamental voltage of the system voltage accurately.Simulation shows that the fundamental phase angle can be obtained effectively in the case of multiple harmonics in system.