Research on Optimal Control of MMC-HVDC System Under AC Side Asymmetric Fault
Author:
Affiliation:
Fund Project:
摘要
|
图/表
|
访问统计
|
参考文献
|
相似文献
|
引证文献
|
资源附件
摘要:
基于模块化多电平 S 换流器的柔性直流输电系统(Modular Multi-level ConverterHigh Voltage Direct Current,MMC-HVDC)在交流电网发生不对称故障时,故障侧 MMC的内部 特性和系统运行都受到较大影响. 基于MMC桥臂平均值模型,提出一种不对称工况下MMCHVDC系统的优化控制策略,增强柔性直流输电系统的故障穿越能力. 该策略主要由交流侧电 流控制和环流抑制两个部分组成,在交流侧利用基于双二阶广义积分器锁相环(Phase Locked Loop Based on Double Second Order Generalized Integrator,DSOGI-PLL),在不对称工况下精确提 取电压电流的正负序分量,配合双矢量控制器抑制负序电流,实现交流侧三相电流平衡. 在MMC 内部采用由PI控制器和重复控制器串联组成的嵌入式重复控制器(Proportional Integral and Re? petitive Control,PI-RC)抑制环流中的二倍频正负零序分量,实现直流侧功率的恒定传输 . 在 MATLAB/Simulink软件中搭建MMC-HVDC系统仿真模型,验证了所提优化控制策略的有效性.
Abstract:
The internal characteristics and system operation of MMC on the fault side are greatly affected when an asymmetric fault occurs in the AC power grid of MMC-HVDC based on a modular multilevel converter. Based on the average value model of the MMC bridge arm, this paper proposes an optimal control strategy for the MMC-HVDC system under asymmetric conditions, which enhances the fault ride-through capability of a flexible HVDC system. The strategy is mainly composed of two parts: AC current measurement control and circulating current suppression.On the AC side, the phase-locked loop based on a double second order generalized integrator (DSOGI-PLL) is used to extract the positive and negative sequence components of voltage and current accurately under asymmetric conditions, and the negative sequence current is suppressed with a double vector controller to control the three-phase current bal? ance on the AC side. The Proportional Integral and Repetitive Control(PI-RC)composed of PI controller and repetitive controller in series is used in MMC to suppress the positive and negative zero sequence components of double frequency in circulating current, so as to realize the constant transmission of DC power. Finally, a simulation model of the MMCHVDC system is built in MATLAB/Simulink software to verify the efficiency of the proposed optimal control strategy.