电网不平衡故障下风电并网变流器的控制综述

在电网电压发生不平衡故障情况下,由于引入了负序分量,导致了直流母线电压以及并网变流器输出功率产生二倍频的波动,交流输入电流产生谐波畸变。为了保证风电系统在电网不平衡故障下正常运行并提高风电并网变流器的并网电流质量,研究电网不平衡故障下的风电并网变流器控制策略已成为了迫切需求。在电网不平衡故障下,针对正负序分量的分离、控制目标的选取、电流参考值的计算、电流内环/功率内环的控制以及谐波控制等并网变流器控制的关键技术方面,对现有文献的控制策略进行综述。

An Overview on Control of Wind Power Grid-connected Inverter Under Unbalanced Grid Fault

In the case of unbalanced power grid,due to the introduction of negative sequence components,the DC bus voltage and the output power of grid-connected inverter will generate secondary fluctuation,and the input current will produce harmonic distortion. In order to ensure normal operation of wind power system under unbalanced grid fault and improve the grid-connected current quality of grid-connected inverter,it is urgent to study the control strategy of grid connected inverter under unbalanced grid fault. Under the unbalanced grid fault,aiming at the following important technical aspects that separation of positive and negative sequence components,selection of control targets,the calculation for the reference value of the current,control of current inner loop/power inner loop and the control of harmonic,an overview of the control strategies of the existing literatures was present and evaluated.