风电经混合型MMC-HVDC并网的交直流故障穿越策略

为实现内陆大规模风电的可靠并网,采用高压直流输电技术和架空线路进行远距离电能传输是有效的解决方案。由于架空线易发生线路故障,采用具有故障自清除能力的换流器拓扑是主要解决途径之一。采用混合型模块化多电平换流器来进行风电并网,设计了不依赖于换流站间通信的并网系统交直流故障无闭锁穿越策略。系统无闭锁故障穿越期间并网点交流电压可控,风机可维持正常运行。考虑到故障期间风机持续并网输出功率,设计了耗散电阻和与风机内部斩波电阻相配合的策略,以耗散多余的能量。最后,通过PSCAD/EMTDC的多组仿真,验证了并网系统无闭锁穿越交直流故障及快速恢复的有效性。

AC and DC Fault Ride-through Analysis of Hybrid MMC-HVDC Integrating Wind Power System

To achieve the reliability of integration for inland large-scale wind power gird, using high voltage direct current(HVDC)transmission technology and overhead lines is an effective way to transmit wind power over long distance. The use of fault self-cleaning converter topology is one of the main solutions as faults easily occur on overhead lines. This paper proposes hybrid modular multilevel converters(MMCs)to integrate wind power to the grid. Based on the no blocking fault ride-through ability of the hybrid MMC, AC and DC fault ride through strategies are designed, which makes the whole system does not depend on the communication between MMCs. Besides, the AC voltages can be controlled during the procedure of the unblocking fault ride-through, which makes the wind turbine maintain at normal operation. Considering the continuous output of wind power connected to the grid during the fault, the co-operate strategy of the dissipation resistance and DC chopper resistance in the full power converter fan is designed to dissipate the surplus energy. Finally, through the simulation of PSCAD/ EMTDC, the integration system is verified to have abilities of fast recovery and riding through AC and DC fault without being blocked.