Computer simulation of the operating modes of the 0.4 kV electrical network with a network partitioning device

Applicable rural 0.4 kV electrical networks are poorly protected against single-phase short circuits. A device for partitioning 0.4 kV power transmission lines with tapping was developed to solve this problem. The device was put into trial operation at the branch of Rosseti Center - Orelenergo PJSC. The correct configuration of the protective equipment and automation of the developed device (a multi-contact switching system of the MSS-2-3B type) provides for studying the operating modes of the 0.4 kV electrical network, in which it is installed. Such a study was based on computer simulation using the MATLAB Simulink software product. The electrical network considered during the simulation consists of a ТМ-250 kVA power transformer and a 0.4 kV power transmission line with tapping. The power transmission line is made of A-35 wire. The partitioning device is installed at a distance of 500 meters from the low voltage input of the transformer. Two 250-meter sections of the electrical network are connected to the device. The paper investigates the load operating modes of the 0.4 kV electrical network with an unbalanced phase load, as well as the emergency modes of a single-phase short circuit in one of the sections connected to the device. The study covers electrical parameters typical for the considered modes: phase currents and currents in the zero wire, phase voltages. The parameters were calculated for the point of the electrical network where the MSS-2-3B is installed. The simulation revealed features which allowed identifying the section of the network with a single-phase short circuit and correctly configuring the protection and automation devices of the partitioning device.