适用于柔性直流电网的500 kV级直流电缆与架空线路并联运行控制及保护策略

高压直流电缆是跨海长距离输电和新能源并网的重要装备,高电压等级、高通流能力的直流电缆还处于研发阶段。为推进高压直流电缆研发,考验长期运行性能,依托国内某±500 kV柔性直流电网工程建立了直流电缆综合试验站。该柔性直流工程线路主要采用架空线,试验站位于其中一个换流站单极出线处,采用直流电缆与架空线路并联运行方式,其运行控制和保护配合复杂、可靠性要求极高,尚无工程经验可循。针对500 kV级直流电缆试验段与架空线路并联切换运行的接线方式,提出了试验站直流电缆监视和投入退出控制策略、故障保护策略以及过负荷运行控制保护策略。仿真试验结果证明,所提策略可保证直流电缆接入柔性直流电网后可靠运行。

Operation Control and Protection Strategy of Domestic 500 kV DC Cable in Flexible DC Grid

High-voltage DC cables are important equipment for cross-sea long-distance power transmission and new energy grid integration. DC cables with high voltage levels and current capacity are still in the research and development stage.In order to promote the research and development of high-voltage DC cables and test the long-term operation performance, this paper relies on a domestic ±500 kV flexible dc grid project to establish a DC cable comprehensive test station.The DC line of the domestic ±500 kV flexible dc grid project mainly adopts the overhead transmission line scheme. The test station is located at the single-pole outlet of one of the converter stations, and the trial DC cable runs in parallel with the overhead line.The operation control and protection coordination are complex, the reliability requirements are extremely high, and there is no engineering experience to follow.In this paper, aiming at the connection mode of parallel switching operation between 500k V DC cable test section and overhead line, the DC cable monitoring and input and exit control strategy, fault protection strategy and overload operation control protection strategy in the test station are proposed for the first time, and are verified by simulation experiments, it can realize reliable operation of DC cable access to flexible DC grid.