Hybrid Line Commutated Converter With Fast Commutation Characteristic Based on IGCT for HVDC Application: Topology, Design Methodology, and Experiments

Abstract

In order to effectively mitigate commutation failure of line commutated converter (LCC), a concept of hybrid converter is proposed. The converter replaces a part of the thyristors by the integrated gate commutated thyristors (IGCT). In this article, the hybrid line commutated converter is further developed and reverse blocking IGCTs (RB-IGCT) are applied in each bridge arm to achieve fast commutation characteristic. RB-IGCT is capable of withstanding bidirectional voltages, and owing to the device control method of self-turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> , has almost zero commutation time and gives play to the advantage of fast commutation, thus earning recovery time for the thyristors. Therefore, the commutation performance of the hybrid converter is enhanced greatly. The topology, control strategy, and the hybrid device characterization analysis with fast commutation are introduced. On the basis, the design methodology of hybrid line commutated converter with fast commutation characteristic (FC-LCC) is presented. Finally, the simulation results based on CIGRE standard system and experimental results of a 30 kV/4.5 kA FC-LCC prototype verify the proposed converter's effectiveness and correctness and the fast commutation characteristic can provide sufficient safety time margin for system. The converter shows promising prospects for high voltage direct current system and has significant value for engineering application.