TABLE OF CONTENTS The computer implementation of power electronic devices in electromagnetic transient programs has taken much of the development effort in recent years, aiming at preserving the elegance and efficiency of the EMTP algorithm. The main feature that characterises power electronic devices is the use of frequent periodic switching of the power components under their control.
The incorporation of power electronics in EMT simulation is discussed in this chapter with reference to the EMTDC version but appropriate references are made, as required, to other EMTP-based algorithms. This is partly due to the fact that the EMTDC program was specifically developed for the simulation of HVDC transmission and partly to the authors' involvement in the development of some of its recent components. A concise description of the PSCAD/EMTDC program structure is given in Appendix A.
This chapter also describes the state variable implementation of a.c.-d.c. converters and systems, which offers some advantages over the EMTP solution, as well as a hybrid algorithm involving both the state variable and EMTP methods.
In a complex power electronic system, such as HVDC transmission, valves consist of one or more series strings of thyristors. Each thyristor is equipped with a resistor-capacitor damping or snubber circuit. One or more di/ dt limiting inductors are included in series with the thyristors and their snubber circuits. It is assumed that for most simulation purposes, one equivalent thyristor, snubber circuit and di/ dt limiting inductor will suffice for a valve...
