光伏并网逆变系统低压穿越新型锁相环的设计

Design of a New Phase-locked Loop of Photovoltaic Grid-connected Inverter System Low Voltage Ride Through

针对传统锁相环(PLL)在电网电压发生不对称跌落故障时锁相失败的情况,引入一种双二阶广义积分器(DSOGI)以达到前级滤波效果的PLL结构。该PLL利用相序分离法滤除电网电压不对称跌落时产生的负序分量,进而使系统能够精确、快速地跟踪电网电压相位,从而在电网电压跌落时保护并网逆变器,并允许其穿越瞬态故障。通过对改进的PLL系统进行仿真实验可得出,该方案能使光伏电站应对多种形式下的电压暂降故障。

A phase-locked loop （PLL） with the second-order generalized integrator（DSOGI） technology is proposed for lock failure occurs of the traditional PLL when the grid voltage asymmetrically drops.The PLL uses sequence separation to filter negative sequence component which is generated when the grid voltage asymmetrically drops, so as to achieve the purpose of tracking the phase of grid voltage quickly and accurately, when the grid voltage drops to protect the grid inverter,and allow it to pass through the transient fault.Through the simulation experiments,it can confirm that the pro- gram can make photovoltaic power station response to various forms of voltage dips faults.