Research on Transient Electromagnetic Disturbance Suppression Measures for Substation Secondary System in the Process of Power Grid Intelligentization

With the gradual deepening of substation intelligence, secondary devices such as sensors, communication and relay protection play a more and more important role in the power grid, but at the same time, these secondary devices are vulnerable to transient high frequency disturbances. The electromagnetic environment in the substation is complex. The transient disturbances such as VFTO (very fast transient overvoltage), continuous lightning strike, abnormal fault and strong electromagnetic pulse have the characteristics of strong energy and high amplitude. These disturbances can be coupled to the terminal wires of the protection chamber by secondary cables, which will affect the normal work of the secondary equipment and even lead to safety accidents. Therefore, according to the injection method, the cable models of different lengths are established in an electromagnetic simulation software called CST Studio Suite. The transient high frequency disturbances of 3MHz and 30MHz are applied at the switch field end, and the voltage induced by the terminal wire of the protection chamber is measured. Then, the influence of cable length and grounding mode on secondary disturbance is analyzed, and the effect of adding filter capacitor and magnetic ring on secondary disturbance is discussed. The simulation results show that the cable length can restrain the secondary disturbance to a certain extent. Different grounding modes have different suppression effects on the secondary disturbance, with the shielding layer having the most obvious suppression effect on double terminal grounding. Adding filter capacitor and magnetic rings to the secondary equipment can have a suppression effect on the secondary disturbance. The results of this paper can be used to suppress secondary disturbances in substations, which has a positive significance.