MMC电容电压直流偏移现象试验验证研究

Research on Test Verification of DC Deviation Phenomenon in MMC Capacitor Voltage

模块化多电平换流器(MMC)是柔性高压直流(VSC-HVDC)输电系统中的关键换流装备。对MMC子模块电容电压的直流偏移现象进行理论分析与试验验证。首先,建立MMC子模块电容电压直流分量的精确定量解析模型;然后,基于该模型,详细分析了子模块电容电压直流偏移量的变化规律,指出交流端口的无功输出是影响MMC子模块电容电压直流偏移量变化的主导因素;最后,基于试验室所搭建的MMC小容量物理样机,开展了典型工况下的试验研究,验证了理论分析的正确性。

The modular multilevel converter(MMC)is a critical converter equipment in voltage source converter-based HVDC(VSC-HVDC)transmission systems.A theoretical analysis and test verification are presented for the DC devia-tion phenomenon in the capacitor voltage of MMC submodules.Firstly,a precise quantitative analytical model is estab-lished for the DC component of the capacitor voltage of MMC submodules.Secondly,the variation principle in the DC deviation of the capacitor voltage of submodules is analyzed in detail based on this analytical model.It is emphasized that the primary factor influencing the variation in capacitor voltage DC deviation of the MMC submodules is the out-put reactive power of the AC port.Finally,test studies under typical operating conditions are conducted using a small-scale physical prototype of the MMC built in the laboratory to validate the correctness of the theoretical analysis.