基于电流源换流器的混合型海上风电直流输电系统

基于二极管整流器(DR)的海上风电并网方案能大幅降低投资成本,但其控制和启动问题难以解决.主动换相型电流源换流器(CSC)具有较高的功率密度和较强的控制性能,但成本相对较高.文中提出一种基于DR与辅助CSC混合级联的海上风电直流输电并网系统,既能实现海上平台轻型化,又能解决DR的控制和启动问题.首先,对拓扑结构和数学模型进行分析;然后,提出海上风电并网系统的稳态控制策略和黑启动控制策略,并基于PSCAD/EMTDC进行仿真验证;最后,对所提方案进行经济性分析.结果表明,混合级联型海上风电并网系统能平稳完成风电场黑启动,具有良好的稳态特性,并能适应风电出力的波动.

Hybrid DC Transmission System for Offshore Wind Power Based on Current Source Converter

The offshore wind power grid-connected scheme based on diode rectifier (DR) can greatly reduce the investment cost, but the problems of control and start-up are difficult to be solved. The actively commutated current source converter (CSC) has high power density and great control performance, but its cost is relatively high. This paper proposes a hybrid cascaded DC grid-connected transmission system for offshore wind power based on DR and auxiliary CSC, which can realize the miniaturization of offshore platform and solve the problems of control and start-up. First, the topology and mathematical model are analyzed. Then, the steady-state control strategy and black start control strategy are proposed for the offshore wind grid-connected system, and the simulation verification is performed based on PSCAD/EMTDC. Finally, the economic analysis of the proposed scheme is carried out. The results show that the hybrid cascaded offshore wind grid-connected system can smoothly complete the black start of wind farms, has good steady-state characteristics, and can adapt to the fluctuations of wind power output.