Development Of High-frequency Impedance Test Device Of Electronic Equipment In Substation

With the construction of intelligent electric grid and the use of massive power electronic devices,the electromagnetic interference in substation electronic equipment is getting increasingly serious.Especially in GIS substation,switching operation will lead to very fast transient overvoltage(VFTO)to form conductive electromagnetic interference on the electronic equipment,which also cause that substation intelligent electronic equipment can not work properly,resulting in the problem of electromagnetic compatibility.Therefore,the power supply port of the electronic equipment is normally provided with a EMI power filter to restrain the conduction electromagnetic interference.But in long-term operation process,filter inductors,capacitors and other parameters appeared the inevitable phenomenon of aging,this will weaken its suppression of electromagnetic interference performance,the power grid safe operation will be affected.So it is necessary to carry out on-line detection to anti-conduction interference performance of electronic equipment in Substation,which has important significance to find the electromagnetic compati-bility fault in time and ensure the safe and reliable operation of the system.Firstly,the mechanism of conduction EMI caused by switching operation in substation and coupling mode is analyzed.Then,the simulation model of a 1100KVGIS substation and the equivalent circuit of intelligent electronic equipment are built by using ATP-EMTP soflware.Using simulation to analyze the influence of VFTO conduction electromagnetic interference generated by switching operation on the electronic equipment.On this basis,the simulation model of EMI power filter is established,and it is added to the port of intelligent electronic equipment to carry out simulation.In order to verify the influence of the change of input impedance characteristics of EMI filter on the performance of the suppression of conduction interference,the simulation analysis is carried out by changing the parameters of the filter step by step.The main research results are as follows:the conduction electromagnetic interference voltage for electronic equipment changes from 13KV to about 3V after EMI filter being added and EMI filter can effectively suppress the conduction EMI generated by switching operation.When the inductance of EMI filter decreases,conduction interference voltage for electronic equipment will be gradually increased and the safe operation of electronic equipment can not be guaranteed.Finally,a high frequency impedance on-line test device is developed,which is designed to inject a high frequency signal into the power network.The high frequency input impedance of the test electronic device is calculated by using theorthogonal multiplication method of the collected response signal and the reference signal.To judge the change of the performance of its anti conduction interference by high frequency impedance.The field test shows that the device can accurately obtain the high frequency impedance of the equipment,and provides a method and basis for the research of the anti conduction interference performance of the electronic equipment in substation.