500 kV直流断路器快速机械开关典型故障特性及可靠性提升方法研究

Research on Typical Fault Characteristics and Reliability Improvement Methods of High-speed Mechanical Switch Used in 500 kV DC Circuit Breaker

直流断路器是构建柔性直流电网不可或缺的关键设备。快速机械开关是直流断路器中承载电流、实现快速分合闸、耐受分闸恢复电压的核心组件,其结构复杂、动作速度快、电气应力严酷、可靠性要求高,因而设计研制难度大,任一环节出现问题均会影响直流断路器乃至柔直电网的安全可靠运行。然而,目前快速机械开关由于存在设计选型不合理、工艺管控不严格、试验考核不完善等问题,导致在实际工程应用中故障率较高。针对已应用于张北柔性直流电网试验示范工程的500 kV直流断路器,分析了直流断路器研制、调试、运行过程中快速机械开关典型故障的特性及原因。在此基础上,围绕快速机械开关典型故障从设计选型、生产制造、试验考核等方面入手,有针对性地提出可靠性提升措施,为500 kV直流断路器快速机械开关设计研制和运维检修提供了指导和依据。

DC circuit breaker(DCCB)is an indispensable key equipment for building voltage source converter based high voltage DC(VSC-HVDC)grid.A high-speed mechanical switch(HMS)is the core component of DCCB to carry current,realize fast opening and closing,and withstand opening recovery voltage.HMS has a complex structure,high speed,severe electrical stress,and high-reliability requirements,so its design and development are difficult and any problem in any link of HMS will affect the safe and reliable operation of the DCCB and even the VSC-HVDC grid.However,at present,due to the problems of unreasonable design and selection,lax process control,and imperfect test and assessment,HMS has frequent faults in practical engineering applications of DCCB.The characteristics and causes of typical faults of HMS in the development,commissioning,and operation of 500 kV DCCBs that have been used in the Zhangbei VSC-HVDC grid project are analyzed.On this basis,focusing on the typical faults of HMSs,corresponding reliability improvement methods from the aspects of design and selection,production and manufacturing,test assessment,etc.are proposed,which provides guidance and basis for the design,development,operation,and maintenance of HMSs of 500 kV DCCBs.