Mathematical model and computer software for EMT analysis in HV and MV grids

The paper presents a computer program, intended for calculations of electromagnetic transients, related to short-circuit and earth faults in distribution grids. Appropriate mathematical models of the main power system devices are developed with the instantaneous currents and voltages. The authors propose a universal structural approach for combining all device models into a single mathematical state-space description. This approach allows easy extension of the models library. The paper also proposes three methods for the solution of the state-space model. The presented comparative calculations prove the adequate modelling and show the advantages of the developed computer program.