PWM静止无功补偿器的多桥叠加消谐技术

Multi-Bridge Overlapping Harmonic-Elimination Technique in PWM Static VAR Compensator

本文详细推导了具有任意桥路数的 PWM静止无功补偿器 ( PSVC)采用多桥叠加技术消除谐波的内部机理。从理论上证明了 :通过多桥叠加 ,可以使各个桥路所产生的谐波电流部分地相互抵消 ,从而使补偿电流中的谐波含量大大减小 ;通过分析得出 :在满足相同谐波含量要求的情况下 ,开关频率与桥路数成反比。因此 ,在相同补偿容量下 ,多桥 PSVC的开关频率可以远远低于单桥的开关频率 ,从而使整个装置的开关损耗降低 ,效率提高。

A novel PWM static var compensator with the multi bridge overlapping technique is presented in this paper.It is proved in theory that the harmonic currents,produced in each bridge,can partially kill each other with the adoption of the multi bridge overlapping technique,so the total harmonic distortion(THD)in the compensation current is reduced greatly.It is analytically deduced that the switching frequency is inversely proportional to the number of the bridge to satisfy the same THD request.Therefore the switching frequency of the multi bridge PSVC can be much lower than that of the single bridge PSVC with the same capacity as the multi bridge one.Thus the switching loss decreases and the efficiency increases.The validity of the theoretical analysis is proved by the results of the computer simulation.