基于DSVPWM的PMSG并联型GS-NSC研究

PARALLEL GS-NSC BASED ON DSVPWM FOR PMSG WIND POWER SYSTEM

为提高九开关变换器直流侧电压利用率,减少开关损耗,采用一种不连续空间矢量脉宽调制(DSVPWM),同时将九开关变换器用于直驱式永磁同步风力发电机(PMSG)网侧构成并联型网侧九开关变换器(GS-NSC)。在对并联型GS-NSC控制策略、故障穿越方案进行理论分析的基础上,建立PMSG并联型GS-NSC仿真模型,设计多种电网电压故障工况对其进行仿真研究。结果表明,在电网电压正常工况下,并联型GS-NSC可维持电网电流的正弦波特性。在电网电压跌落工况下,并联型GSNSC可向电网注入无功电流辅助电网电压的恢复,并通过提升并网电流幅值减少卸荷电路的功率损耗,降低PMSG散热负担。在电网电压骤升工况下,并联型GS-NSC可动态分配直流母线电压,避免因直流侧过压而导致PMSG退出运行。

In order to improve the utilization of the DC side voltage of the nine-switch converter and reduce the switching loss,a discontinuous space vector pulse width modulation(DSVPWM)is proposed. At the same time,the nine-switch converter is used in the direct-driven wind turbine with permanent-magnet synchronous generator(PMSG)on the grid side to form a parallel grid-side nineswitch converter(GS-NSC). Based on the theoretical analysis of the parallel GS-NSC control strategy and fault ride-through scheme,a PMSG parallel GS-NSC simulation model is established,and a variety of power grid voltage fault conditions are designed for simulation research. The results show that the parallel GS-NSC can maintain the sine wave characteristics of the grid current under normal working conditions of the grid voltage. Under the condition of power network voltage plummeting,the parallel GS-NSC can inject reactive current into the grid to assist the recovery of the grid voltage,and reduce the power loss of the unloading circuit by increasing the grid-connected current amplitude and reduce the PMSG’s heat dissipation burden. Under the condition of voltage surge,the parallel GS-NSC can dynamically distribute the DC bus voltage to avoid the PMSG from exiting operation due to overvoltage on the DC side.