【摘要】 “沙戈荒”大规模新能源经高压直流输电系统送出，在送端面临低短路比弱电网等挑战，在受端面临换相失败风险，亟需提出支撑新能源送出的新型直流换流技术。为此，聚焦换相失败对新能源经高压直流输电送出系统的影响，首先分析大规模新能源送出直流输电系统送端与受端系统之间的相互影响特性，指出送端交流系统故障会导致受端发生换相失败，受端换相失败又会增加新能源机组脱网风险。然后，从器件改良、拓扑改造、控制优化3方面综述换相失败抵御技术研究进展，指出现有方法难以根本消除换相失败风险。最后，结合基于集成门极换流晶闸管(integrated gate commutated thyristor,IGCT)的混合换相换流器(hybrid commutated converter, HCC)方案，提出基于模块化多电平换流器-混合换相换流器的新型特高压混合直流输电系统架构，该架构可支撑无常规电源支撑的千万千瓦级新能源远距离、高可靠送出，消除直流输电系统换相失败风险，同时具备容量大、成本低等性能优势。更多还原

【Abstract】 When large-scale new energy in desert-gobi-wasteland is sent out through a HVDC transmission system, it faces challenges such as low short-circuit ratio and weak AC grid at the sending end, and faces the risk of commutation failure at the receiving end. It is urgent to propose a new DC converter technology to support the transmission of new energy. This article focuses on the impact of commutation failure on the HVDC transmission system. Firstly, the interaction characteristics between the sending end and receiving end of large-scale renewable energy DC transmission system are analyzed; it is found that the fault of AC system at the sending end will lead to commutation failure at the receiving end, and the commutation failure at the receiving end will increase the risk of renewable energy off grid. Then, the research progress of commutation failure mitigation technology is reviewed from following three aspects: device improvement, topology improvement, and control optimization. The existing methods are difficult to eliminate the risk of commutation failure fundamentally. Finally, by integrating the hybrid commutated converter(HCC) based on the integrated gate commutated thyristor(IGCT), a novel ultra-high voltage hybrid DC transmission system architecture is proposed, utilizing modular multilevel converter-hybrid commutated converter. This architecture can support the long-distance, high-reliability transmission of tens of gigawatts of renewable energy without relying on conventional power supply support and can eliminate the risk of commutation failure, while demonstrating superior performance advantages including high power capacity and cost-effectiveness.更多还原