基于归一化标准面积差的多端LCC-MMC-HVDC高灵敏性主保护判据OA北大核心CSTPCD

HVDCs with a large-capacity line commuted convertor(LCC)converter as a sending end and several full-half-bridge modular multilevel converter(FHMMC)as multi-terminal receiving ends,naming the LCC modular multilevel converter based HVDC(LCC-MMC-HVDC),is a significant recent advance in the field of DC power transmission,and it has long been a hot issue for the protection technique,especially for main protection elements.In this paper,the initial wave feature of each relay location,under internal/external fault scenarios,is analyzed and summarized,and the general feature of the forward/backward traveling waves is deduced.Based on the feature difference of the initial backward wave under internal/external fault conditions,a protection criterion is put forward based on normalized area difference.Internal fault is distinguished from external ones according to the polarity of the normalized area difference,which is positive under internal fault conditions and negative in external fault scenarios.Reverse faults are avoided reliably with the help of the active inserted noise.Simulation results indicate that the proposed protection has definite selectivity,and the sensitivity can be as high as 600 Ω,which is sufficient in terms of a power system of 800 kV.