Digital simulation of flexible topology power electronic apparatus in power systems

The authors introduce special modifications to the basic Dommel algorithm to expedite simulation of systems including arbitrary configurations of individual power-electronic switching devices. The techniques have been implemented in a prototype transients simulation program. Two time-step sizes are used. Individual switching devices are represented according to simple characteristic curves. The modified algorithm includes iteration of a time-step when required to provide solutions on the curves. A technique is described for removing numerical oscillations of currents in capacitive loops and voltages at inductive nodes. Simulation results are presented for an example power electronic apparatus