Influence of excess eddy current core losses of saturable reactor on the process of semiconductor valve turn-on

Abstract

In this article the transient process was analyzed when the semiconductor valve turn-on with a new modernized equipment of the Vyborg HVDC scheme. It was found that transient processes occur at high frequencies of about 50-60 kHz. During high-frequency transients when the valve turn-on current can reach zero and negative values. This oscillation can lead to premature valve turn-off and even to its destruction, depending on the switching conditions. The paper deals with issue of damping of the turn-on high-frequency current oscillation witch can be achieved by effective eddy-current resistance due to excess eddy current magnetic core losses of the saturable reactors. Calculation energy losses in thin structures of laminated magnetic core of the saturable reactor were carried out using obtained data of transient process and Comsol Multiphysics modeling. This gave a numerical estimate of the effect of these losses on the transient process. In terms of obtaining data modificated equivalent electrical circuit was proposed. This modification allows to estimate the influence of excess eddy current core losses of saturable reactor on the semiconductor valve turn-on.