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线电压级联型功率变换器是一种以传统两电平六开关电压源型变换器为单元,通过线电压级联方式构成的多重化变换器。由于其具有易于模块化,扩展性强,所需隔离直流电源数少等优点,因此更适合作为网侧变换器用于风力发电系统。通过分析其工作原理与结构特点,提出一种载波移相空间矢量脉宽调制(space vector pulse width modulation,SVPWM)策略;并建立统一的等效开关电路模型;通过分析传统的采用集成控制思想所设计的控制系统的不足,从而提出一种改进的控制策略。该策略不仅具备集成控制的优点,且通过增加均压补偿控制环及负序电流抑制环,实现了对多重化变换器中各组成单元传输功率的控制,解决了因各单元传输功率不均衡而造成的直流侧电容电压不均等与交流侧三相线电流不对称等问题。实验结果表明了所提出的控制策略的正确性与有效性。
Line voltage cascaded power converter is a kind of traditional two-level six-switch voltage source converter as a unit, formed by the cascaded line voltage multiple converter. It is more suitable as a grid-side converter for a wind power generation system due to its advantages of being easy to modularize, scalable and requiring a small number of isolated DC power supplies. By analyzing its working principle and structure characteristics, a space vector pulse width modulation (SVPWM) strategy for carrier phase shifting is proposed. A uniform equivalent switch circuit model is established. By analyzing the traditional method of using integrated control idea The design of the control system deficiencies, thereby proposing an improved control strategy. The strategy not only has the advantages of integrated control, but also achieves the control of the transmission power of each component unit in the multiplex converter by adding the equalization compensation control loop and the negative-sequence current suppression loop, and solves the problem that, due to the unbalanced transmission power of each unit Caused by the DC side of the capacitor voltage is not equal to the exchange side of the three-phase line current asymmetry and other issues. The experimental results show that the proposed control strategy is correct and effective.