基于多端柔性直流系统的附加阻尼控制器设计新方法

摘要

针对包含多端柔性直流输电(voltage source converter based multi-terminal direct current transmission,VSC-MTDC)的交直流混合系统中出现的次同步振荡(sub-synchronous oscillation,SSO),研究设计了适用于系统各种运行方式、更具通用性的次同步阻尼控制器(sub-synchronous oscillation damping controller, SSDC).首先针对研究交直流混合系统的拓扑结构,分析了其运行方式、变换器控制模式及对SSO抑制的影响;然后提出了适用于变换器多种控制模式的更具通用性的SSDC设计新方法;随后分析了用该方法设计的SSDC对系统电气阻尼特性的改善情况;最后在PSCAD/EMTDC上搭建335电平仿真模型.仿真结果验证了SSDC设计新方法的正确性和有效性.研究表明:利用新方法设计的SSDC可以显著增强系统的电气阻尼,有效降低系统处于各种运行方式下发生SSO的风险,通用性强.%Aiming on the sub-synchronous oscillation (SSO) of hybrid AC-DC system which contains voltage source converter based multi-terminal direct current transmission (VSC-MTDC), a novel sub-synchronous oscillation damping controller (SSDC) which suits the system's multiple operational mode and has better universality was designed.Firstly, aiming on the studied hybrid system, the system's operational mode, the convertor's control mode and their effects on restraining SSO was analyzed.Then, a new SSDC design method suiting the changes of convertor's control mode was proposed.Then, the new SSDC's effect on improving system's electrical damping characteristic was analyzed.Finally, the simulation model with 335 levels was built on PSCAD/EMTDC, and the results validated the correctness of this design method and the effectiveness of the new SSDC.It was found that the SSDC designed by this new method has a better universality and it can strengthen the system electrical damping observably as well as decrease the risk of occurring SSO efficiently in all operational mode.