含锁相环的三相逆变器并网系统输出导纳研究

Research on Admittance of Three-phase Inverter Grid-connected System With Phase-locked Loop

直驱风电机组中,网侧变流器是并网的直接接口,其输出导纳特性直接反映了系统对电网扰动的抑制能力,因此对新能源发电系统的稳定性有重要影响。首先基于小信号建模,在旋转坐标系下建立了考虑锁相环扰动的变流器的导纳模型;其次,运用对称分量法得出正、负序坐标系下三相逆变器的导纳矩阵,并通过数字仿真分析了不同参数下的导纳特性;最后,利用数字仿真和RTLAB半实物扫频分别验证了导纳模型理论的正确性和工程适用性。

In the direct-drive wind turbine,the grid-side converter is the direct interface of the grid connection and its output admittance characteristic directly reflects the system's ability to suppress the grid disturbance,so it has an important impact on the stability of the new energy generation system.Based on small-signal modeling,the admittance model of the converter considering the phase-locked loop disturbance is established in the rotating coordinate system.Secondly,the symmetrical component method is used to obtain the guidance of the three-phase inverter in the positive and negative-sequence coordinate system.The admittance characteristics of different parameters are analyzed by digital simulation.Finally,the theoretical correctness and engineering applicability of the admittance model are verified by digital simulation and RTLAB semi-physical sweep.