一种用于电力电子式VSG的新型控制方式

A New Control Strategy for VSG in Power Electronic Form

在风电机组的研发阶段需验证其低电压穿越(LVRT)能力,因此需一种能模拟电网故障的电压跌落发生器(VSG)。采用两个三电平的脉宽调制(PWM)整流器经"背靠背"的方式连接构成三相VSG的主电路,连接电网的一侧采用直流电压稳定控制策略。采用一种新的故障分类方法,并根据电压跌落的类型、特征值直接合成故障发生时各相电压的表达式,经坐标变换作为空间矢量脉宽调制(SVPWM)模块的输入量,利用开环控制方式模拟产生电网电压跌落故障。仿真和实验表明,所提方案控制方式简单,可产生具有不同跌落类型、跌落深度及跌落时间的电压暂降故障类型,能满足直驱式风电机组的测试要求。

In the research and development phase of wind generation system, it is required to verify the ability of low voltage ride through （LVRT）.Therefore, a voltage sag generator （VSG） can simulate the power grid faultis required.Two three-level pulse width modulation （PWM） rectifiers with the back-to-back connected form the main circuit of three- phase VSG.DC voltage stability control strategy is used in the side connected to grid.A new classification method of fault type is proposed.When the fault occurs, the voltage expression of each phase is got based on the fault type and characteristic value of voltage.After coordinate transformation,the input of space vector pulse width modulation （SV- PWM） module is gotten.Then the fault simulation of power grid voltage sag fault is generated with an open loop control mode.Simulation and experiment show that proposed control scheme is simple and the voltage sag fault with different sag type, sag depth and sag time can be produced which can meet the requirements of wind generation system test.