【摘要】 并网电网不对称故障会在网侧电压电流中产生2倍工频的正序和负序分量,2倍工频分量会导致并网电流畸变,甚至损坏并网变流器,影响直流母线电压稳定运行。针对风电不对称故障引起的电压波动,提出一种基于超导磁储能(SMES)的不对称故障穿越改进控制策略,分析不对称故障时并网变流器的功率模型特点,在传统不对称故障电流闭环控制中引入零序电流控制环,消除并网负序电流和有功功率波动;考虑电网故障会在直流侧堆积有功功率,造成直流母线电压波动,改进传统斩波器电压电流环,引入功率校正环节,及时消纳故障期间直流侧有功功率堆积,降低直流母线电压波动,最后构建仿真和实验平台验证所提方法的有效性。更多还原

【Abstract】 Asymmetrical fault in grid-connected power grids will generate positive sequence and negative sequence components of twice the power frequency at grid side voltage and current.Two times of power frequency component will cause grid-connected current distortion,even damage the grid-connected converter,and affect the stable operation of DC bus voltage.Aiming at the voltage fluctuation caused by wind power asymmetrical fault,a control strategy based on superconducting magnetic energy storage(SMES) for improving asymmetrical fault ride through is proposed.The characteristics of the power model of the grid-connected converter in case of asymmetrical fault are analyzed,and then the zero sequence current control loop is introduced into the traditional closed-loop control of asymmetrical fault current to eliminate the negative sequence current and active power fluctuations in the grid.Considering that the grid fault will accumulate active power on the DC side,causing the voltage fluctuation of the DC bus,the traditional chopper voltage and current loop are improved,and the power correction link is introduced to prevent the accumulation of active power on the DC side during the fault.The simulation and experiment platform are constructed,and the results verify the effectiveness of the proposed method.更多还原