Analysis Of Electromagnetic Protection Measures About Intelligent Components In Substation

Firstly, the shielded cable broadband electrical parameters and the transfer impedance were computed and KWP2-22 shielded cable unit length distribution parameters are obtained. Combining these electrical parameters, a simulation model of the disturbance on the shielded cables which is caused by the TEV is established, and the inhibitory effect about electromagnetic disturbance by dispersed ground of the secondary cable shield is analyzed. In the laboratory, the simulation model is verified by test using a grounding strip. The simulation results show that when using grounding strip, shield dispersed ground cannot suppress electromagnetic disturbance, but when using grounding network, the voltage from wire to shield drops significantly as grounding points increases. The test results in the laboratory shows that the simulation results of the circuit model established in this paper can predict realistically the variation trend of the voltage from wire to shield. In substations, grounding system is constituted by the ground network, so shield dispersed ground can suppress electromagnetic disturbance significantly in substations. Then combining GIS intelligent switching equipment layout, Three-dimensional simulation model of GIS and shielded cables were established and simulated. The simulation results show that the inhibiting effect by shield dispersed ground is obvious when the electromagnetic disturbance above 50MHz. In this paper a surge suppressors is designed to suppress the electromagnetic disturbance on the port of the intelligent components. This surge suppressors can suppress transient disturbance, steady disturbance, high frequency and low frequency disturbance. Finally, immunity tests are done on a combined unit, and the immunity characteristics were examined.