风电背靠背PWM变流器直流能量平衡新方法

DC energy balance scheme for back-to-back PWM converters of wind power system

针对基于背靠背PWM变流器的永磁同步发电机(PMSG)风力发电系统,从能量平衡角度出发,分析了引起直流侧能量波动的2个主要因素,即风机能量波动和电网电压波动,并基于小信号模型分析,利用功率平衡关系提出了网侧变流器的输出电流补偿控制策略。仿真和实验结果表明,所提出的电流控制策略不仅能在风机能量波动时保证直流侧电压稳定,还能在电网电压故障时最大限度地利用变流器的容量,协助风电机组实现穿越,同时降低直流电容容量要求。

Wind energy fluctuation and grid voltage fluctuation are main factors causing the DC-side power fluctuation of PMSG（Permanent Magnetic Synchronous Generator） wind power system based on the back-to- back PWM converters,which are analyzed in terms of energy balance. Based on the small signal model,a control scheme of output current compensation for the grid-side converter is proposed according to the power balance relationship. Simulative and experimental results validate that,the proposed scheme not only stabilizes the DC-side voltage during wind energy fluctuation,but also makes full use of the converter capacitor during grid voltage fault to achieve the fault ride through of wind power system and reduce the capacity of DC-side capacitor.