Title: Firing thyristors with negative firing angle using multilevel current reinjection concept: an experimental evaluation

Authors: Bhaba Priyo Das; Neville Watson; Yonghe Liu

Addresses: Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand ' Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand ' Department of Information Engineering, Inner Mongolia University of Technology, Hohhot, China

Abstract: Thyristor based multilevel current reinjection (MLCR) current source converter (CSC) provides self-commutation capability to thyristors. It also has high quality line current waveform by accurately shaping the DC bus current using an auxiliary reinjection bridge. However the theoretical and PSCAD/ETDC simulation analysis do not take into account the inevitable stray capacitances and inductances which may influence the thyristor turn-on/off and the simulation switching model may not represent the switching characteristics of the main bridge thyristors fully or accurately. Questions have been raised about the ability to achieve self-commutation with thyristors and the possibility of operating thyristors with negative firing angles. Therefore, it is necessary to experimentally verify whether neglecting the real-world artefacts actually impedes the performance of thyristor based MLCR CSC. The experimental results presented in this paper prove that the auxiliary reinjection circuit can force the thyristor to commutate independently from their respective line-to-line voltages and thyristor converter can operate with a negative firing angle.

Keywords: alternating current; direct current; AC-DC conversion; firing angle; harmonics; multilevel current reinjection; self-commutation; thyristors; current source converters; simulation; switching models; modelling.

DOI: 10.1504/IJPELEC.2015.075422

International Journal of Power Electronics, 2015 Vol.7 No.3/4, pp.166 - 184

Received: 11 Sep 2014
Accepted: 09 Aug 2015

Published online: 22 Mar 2016 *

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