CONTROL ALGORITHM for GROUP OF PHASE SELECTION DEVICES IN 0.4 kV ELECTRIC MAINS
Authors: Orlov Aleksandr I. , Volkov Sergei V. , Garipov Ilsur Kh. 
Published: July 2024

In long 0.4 kV power transmission lines, at areas located far from the power supply center, voltage deviations may exceed the values set by the standard.

The purpose of the work is to develop an algorithm for controlling a group of phase selection devices that minimizes voltage deviations at the end of the line and losses in the line as a whole. The scientific novelty lies in determining the effect of algorithms on the indicators of asymmetry and loss in the line.

Materials and methods. The methods of the theory of linear electrical circuits, mathematical and computer modeling, and inductive generalizations were used in the paper. The ways of solving the problem of voltage deviations in 0.4 kV power transmission lines are considered, these include: the use of devices for connecting a single- or two-phase load to a three-phase network; switching type devices; semi-conductor devices that redistribute instantaneous power between phases of the electrical network. The object of the study is a group of phase selection devices, the power part of which includes three remotely controlled single-pole contactors that allow one to connect the load to one of the phases of the network.

Results. The following values are taken as values characterizing the operating mode of the line, averaged over a certain period of time: currents and voltages of each phase and neutral wire at the beginning of the line; voltages at the end of the line; current of each consumer connected through a phase selector device; current phase; phase voltages at the connection point of the device. Two variants of the algorithm for controlling a group of phase selection devices have been developed: the first is aimed at minimizing voltage deviations at the end of the line; the second is aimed at equalizing phase conductivities at the beginning of the line. As a result of numerical experiments on a mathematical model of the line, it was found that minimizing voltage deviations at the end of the line or equalizing currents at the beginning of the line is not always accompanied by a decrease in line losses in the end; an algorithm aimed at minimizing voltage deviations at the end of the line is more preferable from the point of view of accepted criteria.

Conclusions. A classification of methods for minimizing voltage deviations is proposed. A scheme of a phase selection device and a scheme for connecting a group of such devices to a 0.4 kV supply network are proposed. Algorithms have been developed for controlling a group of phase selection devices aimed at: a) minimizing voltages at the end of the line or b) equalizing currents at the beginning of the line. A mathematical and computer model of the line and phase selection devices has been developed. It is shown that minimizing voltage fluctuations at the end of the line or equalizing currents at the beginning of the line is not always accompanied by a decrease in losses in the line as a whole. Based on the selected efficiency criteria, an algorithm aimed at minimizing voltage deviations at the end of the line is more preferable.