基于CSC和VSC的混合多端直流输电系统及其仿真

Simulation Study for a Hybrid Multi-terminal HVDC System Based on VSC and CSC

研究了一种新型混合多端直流输电系统,其换流器可以分别由电压源换流器(VSC)和电流源换流器(CSC)构成,各个换流器之间以并联方式连接。为验证该直流输电模式的有效性和可行性,建立了一个混合三端直流输电系统仿真模型,包含1个电流源整流器、1个电流源逆变器和1个电压源双向换流器,并分别设计了2种控制策略。当采用第1种控制策略,即电流源整流器采用定电流控制,电流源逆变器采用定电流控制,电压源双向换流器采用定直流电压控制和定交流电压控制时,混合多端直流输电系统在启动、稳态运行、直流和交流故障等情况下具有良好的运行特性,不失为一种有效的直流输电模式,能够综合利用常规直流输电和轻型直流输电各自的优点,有效扩展常规直流输电系统的适用范围。

A novel hybrid multi-terminal HVDC （MTDC） system, composed of line commutated thyristor current source converters （CSC） and GTO voltage source converters （VSC）, is proposed for the extension of the conventional HVDC system. To verify the feasibility of the proposed system, a simulation model for the hybrid three-terminal HVDC system is developed, which consists of a VSC terminal, a CSC rectifier, and a CSC inverter. Based on the developed MTDC system, two control schemes are proposed. The performance of the HVDC system is studied by simulation under the following conditions： start-up, normal operations, and faulted conditions in the DC links as well as in the AC systems. Simulation results show that the first control scheme is more effective for the hybrid MTDC system, and such system is able to exploit the advantages of both the conventional HVDC system and the VSC-HVDC system. The results also show a new application for the conventional HVDC system.