一种基于常规直流输电系统的混合直流改造方案

A Novel Refurbishment Scheme for Reforming the Existing LCC-HVDC to Hybrid HVDC

通过对现有的常规直流系统进行柔性化改造,将受端换流站改造为柔性直流换流站,是一种构成混合直流输电系统较为经济可行的方式。介绍了一种将现有常规直流受端换流站改造为柔性直流换流站的方案,将常规换流阀替换为柔性直流换流阀,保留并利用了原有的换流变压器、交流穿墙套管等设备,降低了改造成本。首先,对受端柔性直流换流站几种潜在的主接线方案进行了初步对比;在此基础上,对所提出的柔性化改造方案进行主回路参数设计。设计结果表明,所提出的改造方案能够显著降低对子模块电容、桥臂通流能力的要求,降低了换流阀的成本和体积。最后通过PSCAD/EMTDC仿真验证了该方案的可行性和主回路参数设计的正确性。

Refurbishing the existing line commutated converter based HVDC （LCC-HVDC） by reforming receiving-end station to voltage source converter based HVDC （VSC-HVDC） station, is an economical scheme to form a hybrid HVDC system. This paper introduced a novel refurbishment scheme which simply replaces the LCC valves with VSC valves, reserving converter transformers and bushings of LCC-HVDC. This can utilize the existing equipments and reduce the cost. Several main connection schemes were compared firstly. Based on the results, designing process of main circuit parameters of the proposed refurbishment scheme was elaborated. The designing results show that the proposed refurbishment scheme can greatly reduce the request for sub-module capacitor and current capacity, therefore reduce cost and volume of valves. Finally, simulation results in PSCAD/EMTDC verify the feasibility of proposed refurbishment scheme and the validity of main circuit parameters designing.