Bergero Model Application Research For Lightning Over-Voltage Of The 500kV Leshan Substation

The project of 500kV Leshan substations is very important in power system in Sichuan province in China. Because 500KV substations are the load-center substation in the whole electric network, Once these load-center substations are damaged by lightning stroke, safe operation of large electric network and main electric network would not be insured. So reliable measures against lightning stroke are necessary.From this paper,we know that there are two source of lightning stroke damages in a substation: direct lightning stroke and lightning incoming surge. Because the chances of directly lightning stroke on lines are more than the chances of directly lightning stroke on substation, lightning incoming surge that intrudes the substation along the lines are one of the main minatory modes to electrical equipments of substations.According the simulation calculation of over-voltage by lightning stroke to the electrical equipment of substations, we can find out the rule of over-voltage's distribution and change so as to refer valuable consultation and optimize the projection design of substations.On the other hand, the significant meaning and developing state of lightning over-voltage calculation of the power system are presented in this paper. Moreover analysis of basic theories and methods are given in this paper too. Among them, Bergeron method has the greatest significance in calculating lightning over-voltage. Some mathematical models for transmission line, capacitance, inductance and resistance are set up basing on the Bergeron method,. The distributed transmission line model are represented by the parallel connection of a resistance and a isotonic current source. Two terminals' electric quantities are independent on topological structure, to choose the isotonic current source represent the lightning performance alone. So, it is more simplified and easy to be programmed.Based on Matlab 6.5, this paper made a program synthesizing the substation and its incoming lines, and distinguishing the near lightning stroke and the far lightning stroke to calculate and analysis the lightning over-voltage of the 500kV Leshan substation. The results could be consulted when lightning protection design of the substation is set about, and it can also be the reference in some other similar cases.