Propagation d'une onde de choc sur une ligne de transmission protégée par des parafoudres : résolution d'un modèle non linéaire par Recuit Simulé

Abstract

The purpose of surge arresters is to divert potentially damaging transient currents safely to ground through property changes to their varistor. In the power industry, they are often used to protect valuable equipment connected to transmission lines against surges due to lightning. A surge arrester can be in two states: it conducts little to no current for normal operating voltages but acts as a regular conductor during overvoltages, conducting current with very little potential drop. A surge arrester has a very high resistance during normal system operation, and a relatively low resistance during transient overvoltages. Therefore, it must have a nonlinear voltage versus current (V-I) characteristic. A transient analysis of a circuit containing surge arresters is usually performed in the timedomain, surge arresters being conveniently represented by piecewise nonlinear resistances. However, the frequency dependence of the elements in the circuit (e.g., resistance, inductance and transmission line tower surge impedances) have to be obtained by other methods. Approximations are usually required in computing the equivalent impedances in the circuit. (Fortin et al., 2002) proposed an alternative approach, studying the lightning performance of the surge arrester and solving the complete network directly in the frequency domain. Once the responses of the network including surge arresters are obtained, the voltage and current through the surge arresters, in the time domain, are obtained using the inverse Fourier transform. The advantage of this approach is that the frequency dependence of the conductor is fully taken into account. The goal of this research is to propose a more efficient method for finding solutions of nonlinear systems of equations through stochastic global optimization. The original problem as stated by (Fortin et al., 2002) is transformed into a global optimization one by formulating an objective function where the global minima will also be solutions to the original system. This global optimization task is carried out using the stochastic method known as Simulated Annealing (SA).

Date	4 Jan 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Alain April (Supervisor) & Jean-Marc Lina (Co-supervisor)