Том 89, № 6 (2018)

Reducing electrical losses and increasing energy performance are priorities when designing electrical machines. In addition, increasing initial costs related to electric machine manufacturing owing to an increase in the consumption of active materials are relatively quickly compensated by decreasing operating costs. For single-phase motors, in particular, the capacitor induction motors with electric and magnetic asymmetry, improving ways of reduce electric losses is a very important problem, to solve which it is necessary to study processes of their symmetrization. The design procedure of working and energy characteristics of induction capacitor motors based on the results of solution of electromagnetic equations is proposed. The parameters of phase-shifting capacitor and the motor transformation ratio are determined at which there is a circular magnetic field within the air gap. It is shown that the calculation results can be used for building the graph dependences of transformation coefficient, capacitor capacitance, and capacitor voltage on slip and subsequent analysis of these curves to obtain the most appropriate solutions.

The absence of power reserve of transformers at substations has an acute effect upon failure of one of them. In addition, operation of the transformers within the hot season is often accompanied by their overheating and failure in the work of the cooling systems. The article describes a possibility of upgrading the cooling systems of the oil transformers. A device for additional cooling of the oil transformer with thermoelectric converters is considered, the principle of operation of which is based on the fact that, at night at the minimum ambient temperature, the cold is accumulated in the container due to formation of the ice layer on the extended surface of the thermoelectric converter fins, melting of which is used within the warm time of the day for additional cooling of the transformer oil in the transformer cooling systems. The mathematical description of the ice formation process on the fins with a constant thickness in the water is given. Results of investigations of assessment of the dependence of the ice thickness on different parameters are analyzed. It is shown that the ice layer thickness is distributed along the fin length as a parabola. In addition, the ratio of the maximum thickness and length of the frosting zone does not depend on the thermal mode, but depends almost only on the thermal conductivity of the fin. With an increase of the fin thickness, the ice layer along its length becomes more uniform at the same time interval of icing. It is necessary to increase the thermal conductivity of the fin due to its thickness, as well as the higher thermal conductivity coefficient of the fin material.

In recent years, almost all busbars have been created according to the package principle, in which busbars passing through insulation are tightly compressed into a package and placed in a protective metal case. Such design allows obtaining the minimum inductive reactance of the phase buses and, therefore, is characterized by minimum additional losses. However, the calculation of such systems is very tedious. As a result, nonoptimal structures are used. This article presents a simple calculation model taking into account the skin effect, proximity, and the screening effect. The theoretical data are compared to data obtained in practice at a full-scale plant test bench of domestic KLM-S trunk busbars.

The main factors that prevent the improvement of the running ability of electrical cables with polymer insulation have been considered. Today, compositions based on polyvinylchloride (PVC) are mainly used as polymer insulation in most electrical cables in Russia. PVC, as are most polymers, is rather sensitive to thermal aging, which is considered as one of the main reasons for the occurrence of various polymer-insulation defects that lead with time to short circuit and fire. It has been shown based on the experimental data that the sewn-in chains of polyene conjugated bonds are formed in PVS macromolecules during the thermal aging. The chains proper are the main reasons for deterioration of the dielectric properties of PVS insulation. The incorporation of conventional plasticizers like phthalates, phosphates, etc., into a polymer matrix plays a much smaller role. Thus, to develop a new generation of polymer insulation, first of all it is required to produce new types of stabilizers that can both efficiently eliminate the formed polyene conjugated carbon bonds during thermal aging and additionally improve all the physical, mechanical, performance, and technological properties of polymer insulation.

A control system for the orbital electric drive of a press coupler capable of reducing energy consumption is considered. Because the stator is not completely overlapped by rotors, it is proposed to reduce the power consumption by means of turning off the power supply from the unused part of the rotor. This requires use of a rotor-positioning sensor as well as an algorithm for determining the overlap area depending on the position of the rotors. A calculation algorithm, which can be applied to orbital electric drives of different configurations, is presented. The algorithm creates rotor and stator maps depending on the angle and the sought overlap area is obtained by overlapping one map on another. This allows applying the optimization methods for finding an optimal control algorithm.

Distribution networks are the direct end-consumer connection part of an electric power system. With the development of technology, advent of new current-using equipment, and increasing population density, these networks are becoming increasingly more and more complex, elements more loaded, and power and voltage losses on the line more significant, which leads to violations of standard requirements. These problems are considered using the example of a section of the Moscow oblast network. The study presented in this article is part of the research project aimed to improve the quality of electric power in the distribution network by analyzing the current state and elaborating corrective steps. The measurements were taken using electric power quality analyzers at maximal and minimal loads. To overcome a high negative voltage deviation, the reactive power compensation unit is proposed. The procedure proposed in this article to solve the given problem consists of two phases. In phase one, loss sensitivity factors (LSFs) are defined and candidate nodes selected for installing the compensation units. This makes it possible to considerably reduce the area of searching for the optimization algorithm and, therefore, cut down the calculation time and improve the algorithm’s convergence. In phase two, the hybrid particle swarm technique is applied to optimally arrange the compensation units among the selected nodes, and choose their capacity. The hybrid optimization technique includes the particle swarm technique (PST) and the quasi-Newtonian algorithm applied after meeting the PST stopping criterion. The quasi-Newtonian algorithm is applied to cut down the time for executing iterations and making the PST more convergent. Numerical modelling is performed in the MATLAB software environment. The measurements in the distribution network of the Moscow oblast served to construct a design model with 111 nodes. According to the measurement results, the voltage level in the consumer coupling nodes considerably overrides the limits defined by GOST (State Standard) 32144–2013. Serious problems with electric power in the mains are connected with inadmissible values of established voltage deviation. The proposed hybrid algorithm of arranging reactive power compensation units makes it possible to reduce the losses of electric power in the mains, reduce the voltage deviation, and increase the line power factor.