基于MMC柔性多端直流配电系统的改进协调控制研究

Research on Improved Coordinated Control Based on MMC Flexible Multipoint DC Distribution System

针对模块化多电平变流器多端直流配电系统,提出了一种改进协调控制策略。该控制策略是对下垂控制改进,改进的策略避免了直流网络在功率发生较大程度变化时出现过电压。在此背景下,设计了基于半桥型模块化多电平换流器(Half-bridge Modular Multi level ConverterHBMMC)的四端柔性柔性多端直流配电系统。本文首先分析了模块化多电平换流器的基本原理,然后在此基础上设计了四个模块化多电平换流器的控制和内部环流并在基础上改进了协调控制策略,最后用PSCAD/EMTDC平台搭建了21电平MMC验证仿真模型,最后仿真结果验证了:稳定时,各级控制器间的相互配合使得所构建模型可行性;系统在任意一端换流站故障退出后仍具备稳定运行的能力,可以最大限度地维持直流电压的稳定。

Aiming at the multi-level DC power distribution system of modular multi-level converter, an improved coordination control strategy was proposed. The control strategy is to improve the sagging control, the improved strategy to avoid the DC network in a large degree of power changes occur when the over-voltage. In this context, a four-terminal flexible multi - terminal DC power distribution system based on half-bridge modular multi - level converter （HBMMC） was designed. In this paper, the basic principle of the modular muhi-level converter was analyzed, and then the control and internal circulation of the four modular multi-level converters were designed and the coordinated control strategy was improved. Finally, PSCAD / EMTDC platform was used to build a 21- level MMC verification simulation model, the final simulation results verify： stable, the coordination between the various levels of the controller to make the feasibility of the model; the system in any one end of the converter sta- tion failure to exit Stable operation of the ability to maximize the stability of the DC voltage.