Ensuring of rational voltage mode by means of automatic change of power transformer under load (OLTC) transformation coefficient under conditions of load parameters variation and configuration of supplying lines is considered. The technique of a choice of a determining voltage mode of connection in power supply system of enterprises on extraction, transportation and processing of mineral resources with application of methods of the theory of fuzzy sets is offered. Parameters are used, which allow describing the state of distribution lines and electric consumers, dispersion of load along them, damage at a voltage deviation from a rational level in real time. The structure of control system based on fuzzy logic is given. The graphs of the membership functions of five parameters, the totality of which determines the power supply line mode, are given.
The work is devoted to the problems of voltage mode regulation of electrical installations at the enterprises of mining industry. The method of voltage mode regulation by means of automatic change of power transformer transformation ratio under load (RAP) at voltage deviation from the rational level and technical means of regulation and their design are considered. A block diagram of a voltage mode regulating device is given. An algorithm for the decision making by the regulating device for the issuance of control action to regulate the voltage in the automatic control unit is developed. A diagram showing the dependence of the lifetime of contacts from the load current of one of the ABB tap changers, as well as daily graphs of voltage on the buses of substations before and after the introduction of automatic regulation is presented.
Under the conditions of rising prices for electric power, the improvement of consumption modes acquires special importance. Analysis of the use of technical means showed that group voltage regulation in networks of mining enterprises is carried out mainly with the help of mechanical devices for voltage regulation under load (AVR) - power transformers with capacity above 1 MV-A. Among many ways to improve modes of consumption a special place belongs to voltage mode regulation, as it allows to reduce power component for 10-15%, to maintain stability of electrical equipment operation and increase its service life. The article reviews the design of on-load tap changers, shows the methodology of selecting the settings of on-load tap changer operation for enterprises, where there are electric consumers, power supply of which is carried out by long lines, as well as electric consumers working in heavy load conditions (coal and shale mines, coal and ore pits, etc.). The calculation methodology is given, which allows to determine the economic effect obtained by introduction of the on-load tap-changer and the target function of economic efficiency of regulation is built, clearly demonstrating the advantages of application of such devices.
