全光纤电流互感器故障原因分析及改进措施

Fault cause analysis and improvement measures of all-fiber optic current transformers

全光纤电流互感器(all-fiber optic current transformer,AFOCT)作为换流站内重要的测量设备,是保证直流系统安全稳定运行的基础。以某±800 kV换流站交流滤波器不平衡AFOCT测量数据异常导致断路器跳闸事件为例,首先,详细阐述了AFOCT的基本工作原理,并推导得出其测量原理;其次,通过保护动作正确性分析、现场故障排查、现场验证、保偏光缆振动影响试验等方法深度研究分析,最终得出引起测量数据异常的根本原因,以及保偏光缆受振动影响的故障机理;最后,针对保偏光缆易受振动干扰导致测量数据异常问题,提出了具体的改进措施和工程建议,为后期换流站AFOCT的工程设计、现场施工验收、可靠性提升提供理论支撑。

As an important measuring device in converter stations,the all-fiber optic current transformer(AFOCT)is essential for ensuring the safe and stable operation of DC systems.This paper presents a case study of a circuit breaker tripping event caused by abnormal measurement data from an unbalanced AC filter AFOCT in a±800 kV converter station.Firstly,the basic working principle of AFOCT is described in detail,followed by the derivation of its measurement principles.Secondly,an in-depth research is conducted through methods including correctness analysis of protection actions,on-site fault troubleshooting,on-site verification,and vibration impact testing of the polarization-maintaining cable.The root cause of the abnormal measurement data is identified,as well as the fault mechanism related to cable vibration effects.Finally,specific improvement measures and engineering suggestions are proposed to address the issue of abnormal measurement data caused by vibration interference,providing theoretical support for the engineering design,on-site construction acceptance,and reliability enhancement of AFOCT in converter stations.