Estimation of magnitude and time duration of temporary overvoltages using ANN in transmission lines during power system restoration Seyed Abbas Taher * , Iman Sadeghkhani Department of Electrical Engineering, University of Kashan, Kashan 87317-51167, Iran article info Article history: Received 1 October 2009 Received in revised form 2 December 2009 Accepted 21 January 2010 Available online xxxx Keywords: Artificial neural networks Switching overvoltages Harmonic resonance Power system restoration Transmission lines energization Nonlinear input–output mapping abstract In most countries, the main step in the process of power system restoration, following a complete/partial blackout, is energization of primary restorative transmission lines. Artifi- cial neural network (ANN) is employed for performing a nonlinear input–output mapping in this work, in order to estimate the temporary overvoltages (TOVs) due to transmission lines energization. In the proposed methodology, Levenberg–Marquardt second order method is used to train the multilayer perceptron. Proposed ANN is trained with equivalent circuit parameters of the network as input parameters, trained ANN has therefore satisfac- tory generalization capability. Both single and three-phase line energizations are analyzed. The simulated results for 39-bus New England test system, indicate that the proposed tech- nique can estimate the peak values and duration of switching overvoltages with acceptable accuracy. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction During the early stages of restoring high voltage overhead and underground transmission lines, concerns are with three related overvoltages: sustained power frequency overvoltages, switching transients (surges), and harmonic resonance. In the early stages of the restoration, the lines are lightly loaded; resonance therefore is lightly damped, which in turn means the resulting resonance voltages may be very high [1–4]. In recent years, due to economic competition and deregulation, power systems are being operated closer and closer to their limits. At the same time, power systems have increased in size and complexity. Both factors increase the risk of major power outages. After a blackout, power needs to be restored as quickly and reliably as possible and, consequently, detailed restoration plans are necessary [1,5]. Switching overvoltage is a primary importance in insulation co-ordination for extra high voltage (EHV) lines. The objec- tive of simulating switching overvoltage is to assist a proper insulation co-ordination which would lead to minimize damage and interruption to service as a consequence of steady state, dynamic and transient overvoltage [6–9]. At the beginning of a system restoration, temporary overvoltage is an important issue. During the early stages of the res- toration procedures following a partial or complete blackout, the power system is lightly loaded and resonance conditions are different from normal operations. The magnitude and shape of the switching overvoltages vary with the system param- eters and network configuration. Even with the same system parameters and network configuration, the switching overvol- tages are highly dependent on the characteristics of the circuit breaker operation and the point-on-wave where the switching operation takes place. 1569-190X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.simpat.2010.01.016 * Corresponding author. Tel.: +98 9131614352; fax: +98 3615559930. E-mail address: sataher@kashanu.ac.ir (S.A. Taher). Simulation Modelling Practice and Theory xxx (2010) xxx–xxx Contents lists available at ScienceDirect Simulation Modelling Practice and Theory journal homepage: www.elsevier.com/locate/simpat ARTICLE IN PRESS Please cite this article in press as: S.A. Taher, I. Sadeghkhani, Estimation of magnitude and time duration of temporary overvoltages using ANN in transmission lines during power system restoration, Simulat. Modell. Pract. Theory (2010), doi:10.1016/j.simpat.2010.01.016