Analysis On Interference Coupling Characteristic Of Cable In Seconary Of Substation Due To Lightning Impulse

With the constant improvement of the substation voltage grade and switchgearintellectualization, electromagnetic environment of substation is becoming increasinglycomplex. This leads to higher requirements on the security and reliability of UHVtransmission system. Secondary cable is important equipment to ensure the safety ofoperation and also is weakness in the system. Therefore, how to improve anti-interferencecapability of secondary cables is great significance.The paper studies substation secondary cable under the interference of lightningimpulse, and then analyzes the interference channel of lightning invasion to substationsecondary cable. According to the formation process of the interference on secondary cable,the lightning is divided into inductive lightning and the lightning. And then analyze ofinterference from the direct lightning to the secondary cable. By ways of the combinationof experiment and simulation to research the following questions: shielded cableparameters and equivalent parameters of grounding unit. Incase to get accurate cableparameters, with example of five-core shielded cable of RVVP300/300, according to themulti-conductor transmission line theory, the paper uses impedance analyzer to measurethe inductance and capacitance parameters of the cable and compares with the calculatedvalue by the finite element analysis software of ANSYS. The equivalent circuit of groundnetwork is established in distribution parameters by considering the effect of groundingunit length, radius, buried depth and other factors. The equivalent circuit of cable andgrounding are established in ATP.The impact of shield grounding method, injection pointof lightning current and soil resistively on interference voltage of secondary cable isanalyzed.In addition, through a case of420kV GIS in Vadodara, electrical equivalent models ofmajor equipment, equivalent circuit of shielded cable and grounding are established inATP.Using vector matching method to fit amplitude-frequency characteristic curve ofvoltage transformer, and get the rational fraction of frequency response about the voltagetransformer and then the equivalent circuit of voltage transformer is established. And thenthe interference of lightning invasion wave to the secondary is analyzed when the tower is struck by lightning at the line segments. The impact of secondary cable length and filtercapacitor at the second device ports is discussed. All above provides a reference for takingeffective measures to improve the anti-jamming capability of secondary cables.