Simulation of electrical power systems

Abstract: This report deals with protection relays and simulation of electrical power systems. It starts with a description of different kinds of relays and selectivity. The simulation program Matlab/Simulink with the toolbox SimPowerSystems, is presented with different blocks and functions. After the theory part of the report a few models of electrical power systems, used in course TNDE 85 Elsystem och CAD at Linköping University, are simulated. The models contain time-overcurrent relay protection. The model of an overcurrent relay has instantaneous and definite-time characteristic modeled in Simulink. A way to simulate overcurrent relay protection with inverse-time characteristic is presented. Linköping Kraftnät has planned to perform a couple of ground-fault experiments. Some of them are simulated and presented in this report.