基于光伏并网逆变系统的改进锁相环设计

Improved PLL design of PV grid inverter system

针对光伏并网系统中的传统锁相环在电网电压不平衡的情况下存在的锁相精度不高的问题,提出了一种能快速、精确地提取电网电压相位的一种双二阶广义积分锁相环(DSOGI-SPLL)。系统通过采用双二阶广义积分和标准的三相锁相环有效地过滤电网电压负序分量,从而提取出电网电压正序分量,达到精确检测电网电压正序分量的相位的目的。最后,对电网电压两相跌落和三相不平衡跌落分别进行仿真,采用DSP样板对仿真进行验证。仿真实验结果表明,该锁相环能够向并网逆变器提供更精确的控制基准,提高了并网发电系统并网的稳定性和有效性。

The paper presents a PLL based on double second-order generalized integral （DSOGI-PLL） of abstracting grid voltage phase quickly and accurately for low accuracy and slow dynamic response of traditional PLL in the case of the unbalanced grid voltage in grid-connected PV systems. It can effectively extract the grid voltage positive sequence component, by using generalized integral and standard three-phase locked loop. Finally, the paper builds simulation for two-phase grid voltage drop and three-phase grid voltage unbalanced drop, and then uses DSP to verify it. Simulation results show that the PLL can provide more precise control reference for the grid-connected inverter, by which the stability and effectiveness of grid power generation systems are improved.