Back-to-Back HVdc Link using Multi-Level Converter Configuration

Abstract

This paper proposes to use a multilevel converter configuration for back-to-back (BTB) HVdc Link. A multilevel converter is a kind of voltage sourced converter (VSV). IBC can control its reactive power independently from transmitting real power. Therefore, VSC has much better stability and controllability than conventional line-voltage commutated thyristor converter (LCC). However, VSC has some disadvantages. One is large switching loss. The cause of this loss is snubber circuit used for voltage balancing of series connected switching devices. A multilevel converter can reduce this loss since it decreases the number of series connected switching device and the switching frequency. We investigated the stability and controllability of multilevel converter used for BTB HVdc Link by computer simulation. The results show good stability in DC voltage and substantially quick response in real and reactive power control.