Mathematical and Simulation Models of the External Power Supply System During Three-Phase Short Circuits in the External Network

This article presents the results of the study on the characteristics of residual voltage that occurs during three-phase short circuits in external networks of 110–220 kV. The research is based on the decomposition of the power supply scheme relatively the busbars of the system-forming substation into two parts: the external grid and power supply utility. The decomposition of the power supply system had led to the investigation of the residual voltages generated during three-phase short circuits and facilitated the identification of their characteristics. The paper provides parameters (magnitude of the initial component, decay constant) of the non-periodic component of the residual voltage and demonstrates their dependencies on network parameters, the location, and the phase of the short circuit occurrence. The obtained results enabled the formulation of a mathematical model of the external power supply grid. This mathematical model was used to develop a simulation model of the external power supply grid. The simulation model was based on an active four-pole terminal network in the Matlab (Simulink) environment.