Scientific Journal of KubSAU

This article is devoted to solving the critical task of improving the reliability of the power systems for agricultural processing plants. The article’s material is exploratory in nature, reflected in the fact that the proposed mathematical models for the analysis of groups of high-voltage induction motors will allow to investigate various modes of symmetric groups of asynchronous motors more effectively. We present the analysis of the existing mathematical models of induction motors considering the design features of such machines that directly affect the dependence of resistance and inductance on the rotor current frequency. The assumptions taken into consideration to obtain a more accurate mathematical model of the induction motor are also formulated. The article provides a comparison of different reference frames used in the mathematical modeling of asynchronous motors. It is proved that the use of the generalized coordinate vector for mathematical modeling of asynchronous motors is the most optimal approach. The equivalent circuit of asynchronous deep-bar motor in generalized vector coordinates derived in the work is used for analysis of transient behavior as well as the steady state operation. The results of the study are suitable for transient analysis of electrical power supply systems of agricultural enterprises with large number of high-power electric motors, for example, CHP of sugar processing plants and grain elevators

The article presents mathematical models for both salient pole and non-salient pole synchronous motors represented as electrical circuits with dependent sources, which can be used for the transient analysis of agricultural electrical power systems

This article presents a synchronous motor model in generalized vector space. This model can be used to study synchronous motor transients as well as evaluate their influence on sugar mill processing in plant technological process

The article is devoted to solving the urgent task, which is improving the accuracy of transient simulation modes of power supply systems of sugar factories. The material of the article is exploratory in nature, manifested in the fact that we have studied various mathematical models designed for the analysis of symmetric modes of deep bar induction motors. A number of the provisions of article have scientific novelty, which lies in the approach to the choice of the coordinate system for modeling deep bar induction motors. We have formulated the requirements for transient analysis method for deep bar induction motor. We have developed the mathematical models of high-voltage induction motors in different coordinate systems for the analysis of steady-state and transient modes of operation. Based on double-circuit rotor model of induction motor, an analytical expression for the frequency characteristic of the deep bar induction motor is obtained. As an example, we have calculated and presented real and imaginary parts of the frequency characteristic of the induction motor type 2АЗМ-2000 with slip s = 1. The mathematical models of induction motors allow using mathematical apparatus more efficiently to explore different symmetrical modes of engines. The study proposed to use transients in the power supply systems of sugar factories for the analysis. The authors suggest an approach to modeling, which can also be useful for modeling induction generators

The article is devoted to the solution of the urgent task, which is to increase the reliability of the power supply systems of enterprises for processing agricultural products. The material of the article has a research character, which consists in the fact that the obtained expressions for the frequency characteristics of high-voltage induction motors allow us to investigate the symmetric modes of their operation by means of a more efficient and simple apparatus. A number of provisions of the article have a scientific novelty, which consists in obtaining frequency characteristics for induction motors as a result of the experiment. A convenient procedure for obtaining the frequency response of an induction motor based on the results of an experiment using the mathematical model of an induction motor in the coordinates of the generalized vector and the Fourier transform has been developed. As an example, oscillograms of the stator current of an induction motor of the A-12-52-4 type are given for the initial stage of the start-up. For the stator current of this induction motor, a transition is made from the phase coordinate system to the coordinates of the generalized vector. The dependences of the stator current on the D and Q axes on time are constructed. The real and imaginary parts of the frequency characteristic of the engine are calculated for sliding s = 1, the calculations are illustrated by the corresponding graphical characteristics. The results of the study are proposed to be used for the calculation of transients in power supply systems for enterprises engaged in the processing of agricultural products