LCL逆变器型直驱风电机的稳定性

Stability of PMSG based on LCL grid-connected inverter

为提高直驱风电机组大规模并网的稳定性,以LCL逆变器型直驱风电机为研究对象,在同步旋转坐标系下推导了其等效阻抗模型,应用广义奈奎斯特判据分析了不同的电网强度,电流内环控制参数及锁相环控制参数的并网稳定性。结果表明:当电网电感由0.5 mH增大至1.5 mH及电流环比例系数由0.6减小至0.2时,直驱风电机系统的奈奎斯特曲线逐渐包围稳定判别点(-1,j0),说明系统稳定性开始下降;锁相环比例系数由40增大至200时,奈奎斯特曲线始终未包围判别点,对系统稳定性影响不大。该研究保证了基于LCL逆变器型直驱风电机系统的并网可靠性。

This paper aims to improve the stability of large-scale grid connection of D-PMSG with power electronic equipment.The improvement is obtained by deriving its equivalent impedance model in the synchronous rotating coordinate system by taking LCL inverter as the research object;and analyzing the grid connection stability of different current loop control integral parameters and different PLL control proportion parameters under the weak system by applying the generalized Nyquist criterion.The results show that when the power grid inductance increases from 0.5 mH to 1.5 mH and the current loop control integral parameters from 0.6 to 0.2,the Nyquist curve gradually surrounds the stability discrimination point(-1,j0),indicating that the system stability begins to decline;and when the PLL control proportion parameters increases from 40 to 200,the Nyquist curve never surrounds the discrimination point,producing little effect on the stability of the system.This research could ensure the grid connection reliability of the LCL inverter based D-PMSG system.