合并单元内部延时故障对主变保护的影响

Impact of Internal Delay Faults in the Merging Unit on the Protection of the Main Transformer

合并单元是智能变电站广泛应用于电气量采集、处理及输出的设备,随着智能变电站自动化技术的发展,对合并单元的功能和性能要求越来越高,其内部参数的隐蔽性也使现场缺陷分析变得更难发现。分析了一起500kV智能变电站CSD-602合并单元内部延时故障引起的主变保护动作告警事故。通过现场调取录波报文分析,并结合二次CT回路连接结构,发现公共绕组CT回路电流存在相角异常情况,最终判定CSD-602合并单元内部延时故障导致差动电流增大引起主变保护动作告警。通过事故反推演和仿真分析,进一步证明了CSD-602合并单元内部延时故障这一隐蔽性问题造成主变保护动作告警。

The merging unit is a device widely used in intelligent substations for electrical data acquisition,processing,and output.With the development of automation technology in intelligent substations,the requirements for the functions and performance of the merging unit are becoming higher and higher.The concealment of its internal parameters also makes on-site defect analysis more difficult to detect.This article analyzes a main transformer protection action alarm accident caused by an internal delay fault in the CSD-602 merging unit of a 500 kV intelligent substation.Through on-site analysis of waveform recording messages and combined with the connection structure of the secondary CT circuit,it was found that there was an abnormal phase angle in the CT circuit current of the common winding.Finally,it was determined that the internal delay fault of the CSD-602 merging unit caused an increase in differential current and caused the main transformer protection action alarm.Through accident reverse deduction and simulation analysis,it has been further proven that the hidden problem of internal delay fault in the CSD-602 merging unit caused the main transformer protection action alarm.