Impact of Grounding Systems Frequency Dependency on Lightning Arresters Transient Response

The paper presents a frequency-domain method for the analysis of lightning surge response of overhead transmission lines equipped with surge arresters. The model takes into account the frequency dependence of the grounding system. The transmission line is represented in frequency domain by making use of the BLT (Baum- Liu-Tesche) equations while the grounding system, to which the arrester station is connected, is simulated using general electromagnetic model solved by means of the Method of Moment (MoM) in frequency domain. The lightning-originated overvoltages in presence of the surge arrester are then calculated in frequency domain using the Arithmetic Operator Method (AOM). The validity of the proposed approach is tested by comparing its results with those obtained using the Electromagnetic Transient Program (EMTP), for a simple configuration. The efficiency of the proposed technique is demonstrated considering the case of a more complex grounding system.