基于三自由度内模解耦控制的VSC-MTDC性能分析

Performance analysis on the VSC-MTDC based on three-degree-freedom internal model decoupling control

为了解决一般解耦控制器参数整定比较复杂、解耦效果不理想的问题,探讨了用于VSC-MTDC系统的多自由度内模解耦控制方法。一自由度和三自由度内模控制可以实现有功、无功功率的解耦控制,但一自由度内模解耦控制只用一个内模控制器调节系统的跟随性、鲁棒性和抗干扰性,使系统的解耦效果和动态性能受到限制。针对其不足,文中提出一种用于柔性直流输电系统的三自由度内模解耦控制方法,其反馈控制器用于调节系统的鲁棒性、前馈控制器用于调节系统的抗干扰性、给定的内模控制器用于调节系统的跟随性能。在PSCAD/EMTDC中搭建了一个三端的直流输电系统,进行仿真验证。结果表明,三自由度较一自由度内模解耦控制具有更好的跟随性、鲁棒性和抗干扰性。

This paper researched the multi-degree- freedom internal model decoupling control method applied to VSC-MTDC system in order to solve the problems that the parameter tuning of general decoupling controller is complex and its unsatisfactrory decoupling performance. One-degree-freedom and three-degree-freedom internal model control can achieve the decoupling of the active and reactive power. However,in the control of one-degree- freedom internal model decoupling,only one internal model controller is used to regulate the output tracking,robustness and anti-interference of the system,making the decoupling and dynamic performance of system limited. In order to overcome the shortcomings,three-degree-freedom internal model decoupling control method used in VSC-HVDC is proposed in this paper. The feedback controller is applied to regulate the robustness,the feed-forward and given internal model controllers are applied to regulate the performance of anti-interference and output tracking respectively. A VSC-HVDC system of three terminals is built and simulated in PSCAD / EMTDC. The results validate that three-degree-freedom internal model decoupling control has a better output tracking,robustness and anti-interference than that of one-degreefreedom internal model decoupling control.