电网电压不对称工况下模块化多电平变换器控制策略  

Modular Multilevel Converter Control Strategy Under Unbalanced Grid Condition

作　　者：欧朱建 王广柱[1] 

机构地区：[1]电网智能化调度与控制教育部重点实验室(山东大学)

出　　处：《中国电机工程学报》2018年第1期258-265,共8页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51541708)~~

摘　　要：基于模块化多电平变换器（modularmultilevelconverter，MMC）各部分之间的功率关系，提出一种适用于电网电压不对称工况的MMC综合控制策略，包括直流母线电压控制、桥臂电容电压控制和交流侧电流控制。其中，桥臂电容电压采用层次化方法控制，在电网电压不对称时，通过调整直流母线功率在MMC三相桥臂间的分配，实现交流侧电流对称。内环采用桥臂电流直接反馈控制，可实现交流侧电流、直流母线电流和环流的三重控制，在电网电压不对称时无需交流侧三序电流控制器以及三序环流控制器。提出通过在桥臂电流参考值中添加零序电流抑制器，消除由桥臂不对称损耗引入直流母线的基频零序电流。搭建了10kVA三相MMC实验样机，实验结果验证了所提控制策略的可行性和有效性。Upon the power analysis of modular multilevel converter （MMC）, this paper proposed a comprehensive control strategy for the DC-link voltage, the capacitor voltages and the AC-side currents of MMC under unbalanced grid condition. Multi-hierarchy method was adopted to control the capacitor voltage. Under unbalanced grid condition, the AC-side currents were controlled to be symmetrical by adjusting active power distribution among three legs of MMC. Inner current loop employed arm current direct control, which can simultaneously control AC-side currents, DC bus current and circulating currents, removing the need for the three-sequence AC-side current controllers and the three-sequence circulating current suppressing controllers under unbalanced grid condition. A zero-sequence current canceller was proposed to add in arm current reference, and this could eliminate the zero-sequence fundamental-frequency current which is caused by the asymmetrical arm power losses and will flow to the DC-link. A 10kVA experimental prototype of the three-phase MMC was developed. The experiment results verify the feasibility and effectiveness of proposed strategy.

关 键 词：电网电压不对称 零序电流抑制器 模块化多电平 变换器 桥臂电流控制 

分 类 号：TM46[电气工程—电器]