SOLUTION OF THE PROBLEM OF OPTIMAL POWER DISTRIBUTION OF INDIVIDUAL COMPENSATING DEVICES FOR A GROUP OF ASYNCHRONOUS MOTORS FOR A STABLE OPERATING MODE AND FOR A GRINDLY VARIABLE LOAD
Petrochemical, oil refineries, tire factories are characterized by large production areas, they have mainly radial power supply circuits, through which a huge number of 0.4 kV asynchronous motors with a power of up to 200 kW are supplied. They are powered with copper or aluminum cables, which, given their length, have significant resistance. In this regard, the losses of active power during the transmission of electricity to asynchronous motors acquire tangible values, and it becomes necessary to solve the problem of reducing them. The purpose of the study: reduction of active power losses in 0.4 kV cable lines at petrochemical and oil refineries. Methods: it is proposed to solve the optimization problem according to the criterion of minimum active power losses in the radial power supply scheme by means of optimal distribution of reactive power of a given value between compensating devices. A single-line diagram of the power supply of a group of pumps of a technological unit of an oil refinery is considered, a mathematical model of the optimization problem is compiled according to the criterion of the minimum active losses generated during the flow of reactive power in 0.4 kV cable lines. The mathematical model includes an objective function, boundary conditions and constraints. The analysis of possible ways of solving a system of linear algebraic equations by the number of mathematical operations for finding the optimal values of reactive power values is presented. Results: the optimization problem was solved according to the criterion of the minimum active losses in the cable lines of the radial power supply of the group of pumps of the technological unit, the optimal values of the reactive power of the capacitor units connected to asynchronous motors and providing the given power factor on the bus sections were obtained. Losses of active power in cable lines supplying asynchronous motors are calculated with optimal power distribution of capacitor units for various modes of motor load. Practical significance: solving the problem of optimal distribution of reactive power compensation devices leads to a decrease in active losses in the radial power supply circuit of the pumps of the technological unit, as well as in power transformers and higher elements of the power supply circuit, which ultimately leads to a decrease in the cost of manufactured products. A schematic diagram of an automated electrical complex for a group of asynchronous electric motors with an optimal power distribution of compensating devices for a group of pumps of a technological unit has been developed.