弱电网下基于PSO的并网逆变器锁相环参数设计方法

Phase-locked Loop Parameter Design for Grid-connected Inverter Based on PSO inWeak Grid

在弱电网下,锁相环(phase-lockedloop,PLL)的参数会对并网逆变器系统的稳定性和动态特性产生较大影响,当其参数设计不当时会引起系统失稳。传统的锁相环参数设计只考虑了稳定性,而未考虑动态特性和电流环的影响。为了解决上述问题,提出一种基于粒子群优化(particle swarm optimization, PSO)算法的锁相环参数设计方法。首先,建立考虑锁相环的并网逆变器系统的小信号模型,利用阻抗法分析锁相环参数、电流环带宽和短路比对系统稳定性的影响;然后,根据系统的稳定裕度要求和动态特性分析,利用PSO算法对PLL参数值进行设计;最后,将该方法用于同步坐标系锁相环(synchronous reference frame PLL, SRF-PLL),通过仿真证明了所提方法能够有效提高系统的稳定性和动态特性。

In the weak grid,the parameters of phase-locked loop(PLL)will have a great impact on the stability and dynamic characteristics of the grid connected inverter system.When its parameters are not designed properly,the system will be unstable.The traditional PLL parameter design only considers the stability without the influence of dynamic characteristics and current loop.In order to solve the problems above,a PLL parameter design method based on particle swarm optimization(PSO)algorithm is proposed.Firstly,the small signal model of the grid connected inverter system considering the phase-locked loop is established,and the influence of PLL parameters,current loop bandwidth and short-circuit ratio on the system stability is analyzed by impedance method.Then,according to the stability margin requirements of the system and the dynamic characteristic analysis,the PLL parameter values are designed using the PSO algorithm.Finally,the method is applied to the synchronous reference frame phase locked loop(SRF-PLL).Simulation results show that the proposed design method can effectively improve the stability and dynamic characteristics of the system.