Research on Analytical Method to Calculate the over Voltage and Surge Impedance of Tower under Lightning
|Keywords||tower surge impedance surge response MATLAB electromagnetic field theory model|
Because of the lighting has a very badly destroy. Especially in the power system, lots of accidents are caused by the lighting. Its loss is also very large. It is necessary to have a deep research on the electromagnetic field of the lighting so we can have a better understanding of the identity of the lighting. In the electric power system we must consider the lightning proof when we design the tower.This paper describes analytical and experimental studies on tower surge response, including the effects of return stroke current. Based on electromagnetic field theory, a new method of calculating electromagnetic field caused by lightning current and transmission tower response including the effects of return stroke current is proposed.The tower surge response calculated by the model agrees well with the tower response obtained from scale model tests and field tests. A new calculation model is given to research electromagnetic field radiation from lightning strokes to tall structures. The proposed model consists of the lightning current propagation and distribution model and the electromagnetic radiation model.As for surge impedance of vertical conductor including transmission tower, correlative theoretical formula and development of studies in this field are given. In this research, the derivation process of these formulas is simply presented. Through experimental and simulation analysis of surge impedance, validity of the proposed theory is verified. MATLAB is also applied to calculate the scale potential caused by lightning stroke current based on the forenamed model. Comparison between the results obtained from MATLAB and that from some calculating software proves the applicability of MATLAB in computation of electromagnetic field and the validity of the theoretical model.