低压微网中小型直驱永磁风电机组低电压穿越技术研究

Research on Low Voltage Ride Through for Small Direct-driven Permanent Magnet Wind Turbine in Low Voltage Microgrid

针对低压微电网中发电机侧不可控整流型永磁风力发电机组低电压穿越问题,主要对电网电压跌落时永磁同步发电机组运行特性进行研究。在分析直流环节电压失稳机理基础上,提出一种基于卸荷电路和网侧变流器最大电流输出联合控制的低电压穿越策略。通过监测风力发电机组运行状态从而完成卸荷电路和网侧变流器的联合控制。重载情况下,采用卸荷电路控制直流环节电压,网侧变流器以最大电流输出;轻载情况下,直流环节电压采用传统电压环控制,利用网侧变流器剩余电流容量发送无功。系统仿真结果表明:2种工况下,发电机侧不可控整流型永磁风力发电机组均可有效实现低电压穿越。

Aiming at the problem of low voltage ride through(LVRT)of the generation side uncontrollable rectifying permanent magnet wind turbine in the low voltage microgrid,the operating characteristics of the permanent magnet synchronous generator(PMSG)wind turbine during the grid voltage drop were researched.Based on the analysis of the DC link voltage instability mechanism,a LVRT control strategy was proposed combined operation method of the maximum current output of the grid side converter and chopper circuit.After judging the operating status of the wind turbine,the chopper circuit and the grid-side converter were coordinated controlled.In the case of full load,the DC link voltage was controlled by the chopper circuit,and the grid-side converter outputs the maximum current.In the case of light load,the DC link voltage was controlled by a conventional voltage loop,and the residual current capacity of the grid-side converter was used to transmit reactive power.The simulation results of the system show that LVRT can be achieved effectively by the generation side uncontrollable rectifying permanent magnet wind turbine under two working conditions.