高压直流三极输电系统的建模与仿真

高压直流三极输电作为一种新的输电方式可以有效提高交流输出线路的容量。文中首先介绍了高压直流三极输电的工作原理,设计了功率平衡控制器使功率保持恒定。基于PSCAD/EMTDC软件平台,建立了高压直流三极输电系统仿真模型,针对系统的稳态运行特性进行了分析,详细阐述了由暂态故障引起的单个换流站紧急停运以及直流线路发生瞬时性和永久性接地故障时的控制保护策略,当发生故障时,将系统切换为双极直流输电,可以保证系统继续稳定运行。仿真结果验证了控制策略的正确性和有效性,表明高压直流三极输电是一种适用于交流线路增容改造的可行方案。

Modeling and Simulation for Tri-pole HVDC Transmission System

Tri-pole high-voltage direct current (HVDC) is proposed as a new transmission technique to improve the AC line transmission capacity. This paper presents the basic principles of tri-pole HVDC and designs the power balance controller to make power stable. Based on the platform of PSCAD/EMTDC, a tri-pole HVDC simulation model is built. The operation performance of the system in the steady state is analyzed. Besides, a cooperation strategy for the control and protection under emergency outage of single converter station and under fault occurring in DC transmission line is fully elaborated. The system can be switched over to bi-pole HVDC under fault to maintain continued stable power transmission. The simulation results show that the proposed control strategy is correct and effective and the tri-pole HVDC is a practical way to enlarge AC transmission capacity.