The redundancy of MMC converter is closely related to the loss and the reliability in flexible HVDC sys-tem. In this paper,the working principle of the MMC converter is analyzed. And based on the working principle of the MMC,the analytical formulas of the loss rate and the reliability of the supply of power are deduced. The analy-sis shows that with the improvement of the redundancy of the converter,the reliability increases gradually,but the loss will increase. In order to improve the economic performance and the reliability of MMC converter,the genetic algorithm is used to optimize the loss and reliability,and the comprehensive objective function is obtained by linear weighted sum method,and the weight value is obtained according to engineering practice. When the DC bus volt-age is ± 800kV and the rated capacity is 500MV·A,the optimal redundancy is 0.055.%柔性直流输电系统中,模块化多电平(MMC)换流阀冗余度与阀损耗、可靠性有着密切的联系.本文分析了MMC换流阀的工作原理,推导出全桥MMC换流阀损耗率、供电可靠性关于冗余度的解析表达式.分析表明,随着换流阀冗余度的提高,可靠性逐渐升高,但损耗也会加大.为了兼顾MMC换流阀的经济性和供电可靠性,本文采用遗传算法对换流阀的冗余度进行优化,通过线性加权和法得到综合目标函数,根据工程经验赋取权值.采用直流母线电压± 800kV、额定容量5000MV·A进行计算,得到最佳冗余度为0.055.
展开▼
