Scientific Journal of KubSAU

One of the important issues in the design of static converters of electric power, i.e. rectifiers and inverters, is to calculate the parameters of the output and the input filters. Output filters are designed to improve the quality of output voltage of inverters, and input filters are created to reduce ripple of the input voltage of the converter that occur when commuting power semiconductor devices, and smoothing fluctuations of the current consumed from the power supply. The complexity of analytical description of the harmonic composition of the output and the input of the voltage rectifiers and inverters makes it difficult to develop some accurate methods for calculating the parameters of their filters. At the same time, considering the discreteness of the number of possible parameters of real elements of the filter, the practical value of such techniques with a high analysis accuracy of the harmonic components is negligible. In this article, we suggest the technique of the simplified calculation of output and input filters for passive LC filters rectifiers and inverters. At the same time, the practice of mathematical modeling and design of transducers has shown that the calculations of the filter parameters for rectifiers and inverters are not significantly different from each other. Therefore, the analytical expressions for calculation of the filter parameters of rectifier used ripple coefficient, and if necessary the calculation of the filters of the inverter, instead of the pulse number in the formula can be substituted with the value of the harmonic; in addition, we have also taken into account the value of the load power factor

Currently operating in autonomous systems of power supply DC voltages power sources are secondary sources for operation devices, protection and control of generators, motors, stabilizers and inverters have relatively low operational performance. The work proposes to improve the weight and the size of power supplies to apply a high frequency link in their designs. We provide structural designs and the peculiarities of operation of secondary power sources with a high frequency link. This article discusses the fundamental electrical circuits of pulse regulators, converters based on resonant inverters and transformers with rotating magnetic field. The use of resonant inverters in power sources will significantly improve their weight and overall dimensions. In addition, the use of secondary sources of supply for transformers with rotating magnetic field will simplify their design and reduce the level of electromagnetic interference generated by semiconductor devices. The features of operation of pulsed regulators and prospective structuralschematics converters discussed in the article, performed on resonant inverters and transformers with rotating magnetic field, will increase the effectiveness of pre-work on the development of secondary power sources with improved operational and technical characteristics for devices of operating, control and protection

Modern universities do not have effective techniques for evaluating the quality of education of students and effectiveness of teachers' activity that allows controlling and directing its activities. We have proposed to perform the quality evaluation of students preparation based on the results of intermediate assessments, examinations, and test results of the teachers, who held their classes. The article provides analytical expressions for calculating the quality of the current preparation of students and the quality of education of graduates, the effectiveness of teachers in core activities (educational, methodical and scientific work). In assessing the quality of education, we have considered the learning outcomes, employment potential, i.e. educational and labor activity. The proposed techniques will increase the objectivity of the assessment of the quality of graduates’ education in technical universities and the effectiveness of teachers. This will allow us to make changes in the organization of educational process and the content of working programs of training, educational and methodical and material and technical support, to change the contents and technologies of improvement of qualification of the teaching staff that will contribute to increase demand for graduates in the labor market

In agricultural production, the direction of introduction of renewable energy for power consumers remote from the external electrical network is relevant. Here, prospects are revealed in front of the solar PV stations. One of the main functional units of solar power is inverters that convert the DC voltage of the solar panels into alternating current. The article describes the advantages and disadvantages of the main methods of voltage regulation of the autonomous inverters of solar photovoltaic power plants. We have proposed new structural designs of autonomous voltage inverters, described their advantages, features of design and operation for voltage stabilization. We suggest stand-alone inverters designed using high frequency link, which will significantly improve mass and dimensions parameters of the converter. Due to the use of single-phase transformer with a rotating magnetic field in stand-alone inverters, we improve the efficiency of the converter and the reliability of the work. Patents of the Russian Federation confirmed the novelty of technical solutions of the considered schemes of autonomous voltage inverters. Structural schematics of the voltage regulators considered in the article, as well as features of their work, will allow to increase efficiency of preliminary works on development of autonomous voltage inverters with improved operational and technical characteristics for solar photovoltaic power plants

The article reveals the basic principle of stabilizing the DC voltage, providing automatic control of electrical devices and electrical equipment, control systems, control and protection, etc. There are functional diagrams (operated and promising) of DC voltage stabilization with a device included in the input and output power circuits of the rectifier, and a new structural solution to a functional circuit of the rectifier made of two controllable power electronic devices and transformer with midpoint. The article lists peculiarities of the circuits of the voltage regulators and their main advantages and disadvantages. We have reviewed functional diagrams of existing and new solutions of the stabilizers and the characteristics of their work; it will increase the effectiveness of pre-project works on the development of stabilizers of the DC voltage with improved performance characteristics. This article might be useful for post-graduates and research workers who are involved in the development of DC voltage stabilizers

The main structural units of the University are departments; the results of their work influence the quality of knowledge, skills and competence of graduates and the image of the University. The article reveals the reasons of unproductive interaction of the departments with divisions, providing educational process; it also discusses suggestions that will improve the performance of the main indicators of assessment of the efficiency of activities of the University. It is shown, that a systematic approach is the basis in the organization of work of structural divisions of the University, but it is difficult to implement, if managers and supervisors do not have authority. To improve the quality of graduates and their demand in the labor market, it requires exempting the Department from administrative work. These functions can be redirected to the management, departments and services with modern electronic information processing system. To achieve high results in training in-demand graduates is possible when the offices and the departments will work as a team with the lecturers, in cooperation and understanding

Today, the questions of accelerated development of science are essential; it has become a real productive force, the most powerful factor influencing the level of scientific and technical progress. The most important part of the research work is experimental studies. The article reveals the methodology of experimental research involving the content of laboratory and industrial research, main stages, as well as graphic presentation and the analysis of the results of studies; as well as the methodology for the general analysis of theoretical and experimental studies, the sequence of introduction of the results of the research and criteria for evaluating their effectiveness. The main issues of the methodology of experimental researches discussed in the article will increase the effectiveness of scientific and research work of scientific collectives of organizations and companies

Perspectives of science in high schools were always defined by prospects of development of scientific teams. The author proposes to divide (depending on the contents of research targets) unities of the research process and the results of research teams of the Department into three categories: a scientific group, a scientific school and a leading scientific school. Research teams are characterized by not only quantitative and qualitative composition, but the annual results. We reveal functional duties of leaders of research teams and the head of the Department for their effective management. One of the main tasks of the Department is to create conditions for the disclosure of scientific and creative abilities of students. The article describes general concepts and the content of scientific researches, including the formulation of themes, goals and objectives of the research, as well as the basics of research methodologies required for students in conducting the research work. The structure of research groups of the Department, the content of their work, the main functional responsibilities of heads of scientific disciplines and the head of the Department, basics of scientific research methodology discussed in the article, will increase the organization's effectiveness and the efficiency of R & D Department

The article discusses the features of design and operation in the different modes of functioning of autonomous hybrid power plants based on renewable and traditional energy sources. We have given a structural scheme of such a plant. It is shown that the algorithm of the system in the autumn-winter period should be adjusted according to the monthly monitoring; and standby generator of independent source can be run at a deeper discharge of batteries. It is known that the most expensive and the weakest link in the solar PV plants is rechargeable battery. In addition, the larger the number they have in the system, the more complicated the fulfillment of all conditions of proper operation is. We have proposed to extend the lifetime of batteries through the use of passive balancing, which allows to increase the reliability of operation and reduce the cost. It is shown that a real possibility of improving the technical and economic performance of autonomous hybrid power plants is their execution on the basis of solar photovoltaic power plants. We have also discussed the features of construction and operation of hybrid power plants, which will increase the efficiency of preliminary works on development of high-performance structural circuit design of the stations

The high speed of solar energy development in the modern world allows us to assert that in the near future it will become one of the main sources of electricity. The authors describe a classification of solar power plants, which can be of two types – thermodynamic and photovoltaic, as well as the features of design and operation of these plants. There is a structural and schematic solution of autonomous solar power stations and ones operating in parallel with the external power grid. The features of their design and operation, including the main advantages and disadvantages were shown. It is shown that to improve the reliability, including uninterrupted power supply, a promising direction is the development of combined systems which in addition to the solar power plant may use wind power, gas or diesel power, etc. In addition, such stations may provide power from the external power supply. We have given one of the variants of structural designs of combined systems of energy and disclosed recommendations for the design of energy-efficient combined systems of power supply, made using renewable and conventional sources of electricity. The final version of the combined system of electricity supply and the degree of participation of traditional and renewable energy sources in electricity production is determined on the basis of the analysis of the energy balance and electromagnetic compatibility of the main functional elements of the system