Implementation of Recorded Lightning Current Waveforms in ATP-EMTP Software for Fast-Front Transient Simulations

This study deals with the implementation of recorded lightning current waveforms in ATP-EMTP. These can be employed as excitation in fast-front transient simulations. A generalized code is developed in MODELS language to import arbitrary waveforms expressed in the form (time, voltage/current) pairs. An investigation is presented on the influence of the time interval used for digitizing recorded lightning current waveforms and of the interpolation method applied between points. ATP-EMTP simulations of direct lightning strikes to 150 kV overhead transmission lines are performed. Fast-front overvoltages are computed across line insulators and the minimum backflashover currents are determined. Cases with Line Surge Arresters (LSAs) are also treated and the energy stressing the LSAs is computed. It is shown that the digitization time interval is not important as long as it reproduces the main features of the recorded waveforms. This applies also for the interpolation method.