特高压直流中性母线过电压特性及抑制措施

Neutral Bus Overvoltage Characteristics and Suppression Measures for UHVDC Converter Stations

直流换流站的绝缘配合设计是特高压直流输电工程的关键技术之一。直流输电系统故障和操作过程可能在直流开关场中性母线上产生过电压,该过电压会影响直流换流站的绝缘配合,并有可能引起系统故障停运。通过建立准东—皖南±1100kV特高压直流输电线路仿真模型,研究双极、单极大地回线、单极金属回线运行的各6个故障点的情况下的中性母线过电压特性,分析了直流系统中性母线过电压产生的机理,并研究加装不同参数避雷器、释能间隙、冲击电容器等多种中性母线过电压的抑制措施,定量分析不同措施的抑制效果,推荐采用释能间隙结合加装多组避雷器来抑制中性线过电压。所做工作为特高压直流换流站中性母线过电压抑制提供了参考。

The insulation coordination of converter station is a key technology of ultra-high voltage direct current(UHVDC)transmission systems.During system operation,faults in converter station generate overvoltage on the neutral bus of the DC switching field,which can affect the insulation coordination of the DC converter station.In this paper,the simulation model of±1100 kV Zhundong-Wannan UHVDC transmission line was modelled.The neutral bus overvoltage characteristics in 6 different faults were studied,correspondingly in bipolar mode,monopolar ground return mode,monopole metal return mode.The mechanism of neutral bus overvoltage in converter station was revealed and discussed.The overvoltage level under different faults were analyzed,followed by the suppression solution investigations employing arresters,energy release gaps and impulse capacitors.Their effectiveness was analyzed and compared.As a result,the combination of an energy release gap and multiple arresters is proposed and recommended to suppress the neutral overvoltage.The work in the paper proposes the solution to suppress neutral bus overvoltage in UHVDC converter stations.