Towards the prospection of an optimal thermal response of ZnO surge arrester in HV power system

In order to understand the thermal and electrical properties of surge arrester under standard climatic conditions, it would be useful to evaluate the heating progression in its different elements. These are constituted of heterogeneous materials, which have physical and electrical nonlinear properties along the surge arrester. Temperature predicting solutions for zinc oxide ceramic blocks provide fundamental elements of the electrothermal material characteristics in view of the lifetime estimation. Electrothermal phenomenon analysis of surge arresters is based on empirically-determined parameter models, using finite element method (FEM) simulated on COMSOL Multiphysics software which is a more precise approach compared to the existing models. In this paper, the behavioural model has been developed to study the surge arresters in both cases: the steady state and overvoltage state (lightning). Previous published works validate the first simulation results. This work is therefore extended to consider other operating states, which illustrate the dependence of the type of surge on the amplitudes and durations of electrothermal phenomena

Comparative study of two PWM control wind system based on DFIG and multilevel NPC inverter

The present paper is a comparative study of two supplying modes of a wind energy conversion system (WECS) based on Doubly Fed Induction Generator (DFIG). This work is conducted with a multi-level neutral-point inverter (NPC) supplying a DFIG.The first method based on conventional pulse width modulation (PWM) while the second is based on space vector modulation (SVM). This work aimed to control active and reactive power delivered to the electrical networks and satisfying the distribution requirements. The performance evaluation of each method is performed using spectral analysis to calculate total harmonic distortion (THD). Simulation results have showed that the harmonic rate (THD) is reduced. Therefore; the quality of the produced power by this type of wind chain is efficient. The results obtained with SVM have revealed that this technique uses inverter DC bus voltage more efficiently, reduces power losses and minimizes torque ripples.Keywords: DFIG, NPC, Multilevel, PWM, THD, Power contro