An engineering approach to calculation of channel-base lightning current parameters

An alternative approach to calculation of the channel-base lightning parameters using a well-known Heidler function without discontinuity of its first derivative at t=0 of the lightning current is presented in the article. Based on a graph-analytical method, the lightning parameters of the Heidler current can be derived from statistical characteristics of the registered lightning activity such as the current peak, the current rise-time and decay-time to half of the peak value. The effect of the lightning current wave-shape on the estimated over-voltages has been studied during lightning strikes to a 500 kV overhead power line in a vicinity of a transformer-generator block of a power station using the Heidler and double exponential functions. It appears that the calculated over-voltages in power systems depend on the adopted channel-base lightning current. This becomes very critical for fast transient processes of less than 2μs current rise-time with reactive electrical plants in the circuit.