Study On Characteristics Of Lightning Induced Overvoltage Of Overheah Distribution Lines

The over voltage on the distribution overhead lines caused by the nearby lightning strike is one of the important reasons for power supply failure. Although the peak value of lightning induced over voltage is smaller than that of direct lightning strike, it deserves more attention due to its frequent occurrence. To study the characteristic of lightning over voltage on distribution lines is the base for taking appropriate prevention measures.The methods of electromagnetic field calculation are reviewed, and one of them is chosen as the one used in the subsequent chapter. Five commonly used return stroke models are compared, and the corresponding results are given.Several commonly used field-to-line coupling equations are studied, and the contribution of every electromagnetic component is separated. Corona is taken into account by means of dynamic capacitance describing a charge-voltage diagram, it is found that corona acts to increase the magnitude of these over voltages.The embedded calculation in EMTDC/PSCAD is implemented, and numerical oscillation caused by time delay is removed by a back-ward interpolate technique. The results obtained in different conditions are given.