Analysis and countermeasure on abnormal operation of one 110kv intelligent substation merging unit

The secondary circuit of substation is located in harsh EMI(electromagnetic interference) environment, and the intelligent device may be affected by the electromagnetic disturbance signal. At the same time, as the field installation of intelligent device, the electromagnetic disturbance becomes furthermore intensified. Recently, because the transformer substation's secondary circuit is affected by the interference of switch operations, many intelligent devices run abnormally. It is very important and meaningful to study the EMC(electro magnetic compatibility) problem of the transformer substation's secondary circuit. One 110kV intelligent substation merging unit runs abnormally. Firstly, the reason of abnormal operation of merging unit is analyzed by exclusive method. Secondly, the EMC experiments regulated by the IEC61000-4 standard and above the standard are carried out, and at the basis of the experiments, the structure of merging unit is improved. Thirdly, the electromagnetic disturbance signal is recorded; the characteristics of amplitude and time-frequency of the recorded signal are analyzed. Finally, some suggestions about improving the EMC performance of merging unit are put forward.