Analysis Of Lightning Invasion Wave In 35kV Substation Based On Field-circuit Combination

There is a large number of 35 kV transformer substations in China’s electric power system,and the 35 kV transformer substations are very important to the entire electric power system’s safety operation.As the 35 kV system’s insulation level is not high,lightning over voltage wave can easily invade into the transformer substation along the line,and seriously threats the equipment in the transformer substation.According to the practical operation experiences,35 kV transformer substation’s damages due to lightning invasion wave are still serious,although it’s under the protection of existing anti-lightning measures.In this paper,we take a 35 kV transformer substation as an illustration.In the first,this thesis uses element software ANSYS to analyzes magnetostatic field and electrostatic field in the 35 kV transformer to calculate the relevant parameters,like longitudinal capacitance,ground capacitance and winding inductance,then builds the electromagnetic transient calculation model of transformer when lightning wave invades.This paper puts the transformer substation and the incoming line as a whole,then establishes the electromagnetic transient models of the electrical equipments including the transmission line,the tower,the insulator string and the transformer.Considering lightning strike point,lightning current,power frequency voltage,grounding resistance of the tower and so on,this thesis simulates lightning shielding failure and lightning counterattack by ATP-EMTP,then analyzes the influences of lightning on the incoming line and the process of lightning invasion wave in transformer winding.The final step is to install the line lighting arrester and the transformer neutral point lighting arrester from the economic and practical point of view based on the simulation results.Then the effects of this lightning protection optimization measure is simulated,the simulation result shows that this measure can effectively reduce the threats of the lightning invasion wave to the transformer,and improve lightning withstand level of the incoming line at the same time.