Simulation of Lightning Transients on 110 kV overhead-cable transmission line using ATP-EMTP Kresimir Fekete 1 , Srete Nikolovski 2 , Goran Knezević 3 , Marinko Stojkov 4 , Zoran Kovač 5 # Power System Department, Faculty of Electrical Engineering Osijek K. Trpimira 2B, 31000 Osijek, Croatia 1 kresimir.fekete@etfosr.hr 2 srete.nikolovski@etfos.hr * Faculty of Mechanical Engineering Slavonski Brod I. B. Mažuranić 2, 35000 Sl. Brod, Croatia 4 marinko.stojkov@gmail.com Croatian Transmission System Operator K. Franje Shepera 1A, 31000 Osijek, Croatia 5 zoran.kovac@hep.hr Abstract—Due to construction of a highway in the eastern part of Croatia, a new 110/x kV substation was built with two parallel connecting underground cables. Cables were connected to already existing 110 kV overhead lines. At the place where the transition between overhead lines and cables is made, surge arresters were installed. In this paper lightning stroke at the grounding wire on the overhead line and its impact on underground cables were studied. Transient program Electromagnetic Transients Program (ATP-EMTP) is used to create a model of the system and to perform simulation of the transient process during lightning stroke. The results of the simulation are briefly presented and discussed in the paper. I. INTRODUCTION In the process of designing new facilities in the power system (substations, cables, overhead lines etc.), lightning overvoltages are important from the viewpoint of the insulation and surge arrester coordination. Due to construction of the highway in the eastern part of Croatia, a new 110/x kV substation was built with two parallel connecting underground cables as well. Cables were connected to already existing 110 kV overhead lines. A more detail presentation of the system is presented in Chapter II. At the place where the transition between overhead lines and cables is made, surge arresters were installed. In order to make surge arrester coordination it is necessary to investigate the impact of lightning overvoltages. It is very hard to observe the lightning overvoltages experimentally, and thus a numerical simulation is used to investigate it. The EMTP has been widely used for the time domain transient solution. It was first developed at Bonneville Power Administration (B.P.A.) from Dommel’s basic work [1]. Nearly all system components can be represented by built- in elements in ATP-EMTP like overhead lines with line and ground wires and towers as well as underground cables [2]. In this paper ATP-EMTP is used to create a model of the power system and to simulate lightning stroke at the grounding wire on the overhead line and its impact on underground cables and surge arresters. The structure of this paper is as follows: first, a brief explanation, regarding the part of the transmission system where the new substation and cables are built, is given. The main features of the ATP-EMTP model and method are explained in Chapter III. In Chapter IV, simulation and results are presented. Based on the results, the conclusion is given in the last chapter. II. DESCRIPTION OF THE POWER SYSTEM The part of the Eastern Croatian transmission system that is studied in this paper is shown in Fig.1. The new substation TS 110/20 kV Djakovo 3 is supplied from two substations TS 220/110 kV Djakovo and TS 400/110 kV Ernestinovo. The new substation is modelled only with passive load. At the place where overhead line and cable are connected, ABB Pexlim Q surge arresters are installed. Fig. 1. Single line diagram representing the part of the transmission system that is studied Parameters of the 110 kV overhead lines which are made of Al/Fe conductors with cross sections 240/40 mm 2, and underground cables type NEXANS which has a cross section of 1000 mm 2 are shown in Table I. 978-1-4244-5794-6/10/$26.00 ©2010 IEEE 856