模块化多电平换流器电容电压均衡排序算法综述

A Review of Ranking Algorithms for MMC Capacitor Voltages Balancing

高压大容量模块化多电平换流器(modular multilevel converter,MMC)在世界的柔性直流输电工程得到了广泛的应用,有关MMC的电容电压均衡排序算法已成为研究热点与难点。论文针对适合高电平的MMC电容电压均衡排序算法,对国内外已有的涉及排序算法的主要文献进行整理和归纳,从而探索该领域的研究前沿和关注的重点。将不同的均压排序算法根据降低计算复杂度、降低器件开关频率等优化目的进行了分类,并研究了其核心思想;探讨了MMC电容电压均衡排序算法评价指标;对其中降低复杂度的3种均压排序方法的排序复杂度进行比较,且通过仿真对比了它们的电容电压均衡效果;对其中采用保持因子降低开关频率的排序方法进行了比较。最后,针对MMC实时仿真,讨论了均衡排序算法的发展方向。

Modular multilevel converter （MMC） system with high voltage and capacity has been widely applied among the VSC-HVDC projects in the world. In MMC application,capacitor voltage balancing ranking algorithms became a hot topic. This paper respectively focused on voltage balancing ranking algorithms suited for high-level MMC to summarize the state of the art literatures of this field methodically,and then to explore the cutting-edge research to show the core issues and concerns in the area. The sorting methods are clarified according to the purposes of reducing time complexity or switching frequency and the collective main ideas of them are extracted. This paper also explored the evaluating indicators for MMC ranking algorithms. By simulations,the capacitor voltage balancing effects of three algorithms with different complexities are compared. The switching frequencies of algorithms with maintaining factor are measured. In the end of this paper,the development direction of ranking algorithms in FPGA（field program gate array）for MMC real-time simulation is discussed.