Digital implementation and transient simulation of space-vector modulated converters

Voltage-source converters (VSCs) are building blocks of high-power electronic apparatus used in modern power networks. Pulse-width modulation is used widely for the synthesis of ac voltages at the terminals of a VSC. A powerful alternative for this purpose is the space-vector modulation, in which the converter is placed in a finite number of known states in order to best approximate the reference voltage. This method offers better utilization of the dc bus voltage and provides several degrees of freedom for enhancement of the harmonic spectrum. The paper presents a digital implementation of the technique in a transient simulation program (PSCAD/EMTDC). The developed model, which covers both linear and nonlinear modes of operation, is very useful in the design and analysis of modern power networks (and drive systems) with embedded power electronics, and also allows comprehensive harmonic analysis to be conducted. The usefulness of the method is demonstrated through an example

I. Introduction

HIGH-power electronic converters are known to provide convenient means for the regulation of real and reactive power flow, voltage support, and improvement of dynamic performance of power networks. Use of such converters, in particular voltage-source converters (VSCs), within the context of modern power systems has been accelerated with the advent of fast switching devices with higher ratings as well as development of advanced techniques for their control.