新型模块化多电平变流器 在电力系统无功补偿中的应用研究

模块化多电平变流器(MMC)是一种新型的多电平电压源变流器,每个桥臂由数个具有独立直流源的子模块单元串联而成。随着子模块增加,其空间矢量调制算法也越来越繁杂。提出一种基于60°坐标系下MMC任意电平逆变器的空间矢量脉宽调制通用算法;并将模块化多电平变流器并联接入电力系统中实现无功补偿技术,实现了内环解耦控制和外环的子模块电容电压平衡控制,最后通过仿真结果验证了60°坐标系空间矢量脉宽调制算法和该无功补偿装置控制算法的正确性和扩展性。

The Application Research of Reactive Power Compensation in Power System Based on New Modular Multilevel Converter

Modular multilevel converters (MMC) are one of the newly developed multilevel converters; the bridge of a MMC consists of several sub modules in series with independent DC sources. With increase of the number of sub modules, the space vector pulse-width modulation (SVPWM) of multilevel converters is getting more complex. This paper proposes a novel SVPWM generalized algorithm for arbitrary-number-level converters based on 600 coordinate frame; based on the PWM of two-level space vector, the transition matrix for action period between multilevel voltage vectors and two-level voltage vectors is derived based on 600 coordinate frame. And taking reducing switching loss and distortion of output voltage waveform as object, the method to choose redundant voltage vectors and the optimal synthetic sequence of voltage vectors are determined. And the reactive power compensation in power system which is based on MMC is introduced; the dynamic mathematic model is analysis. With the introduction of current feed forward control strategy and SVPWM based on 600 coordinate frame, the dynamic decoupling strategy and capacitor voltage of sub model with balance control is proposed. At last, simulation results show that the proposed algorithm is correct and extensible.