The article is devoted to the study of the sterilization of waste materials and animal feed meal. It was revealed that at the last stage of waste processing of animal origin, as a result of fine grinding in the crusher, feed meal of low biological value is obtained. As a result of research, a technology of multistage sterilization of raw materials has been developed with obtaining feed meal of animal origin of high biological value due to cooking-sterilization (stage 1), drying-sterilization (stage 2), steam sterilization (stage 3). As a result of the final sterilization, i.e. steam sterilization of feed meal from animal waste revealed that when the temperature drops below 110 °C and sterility is not achieved when the warm-up time is less than 25 minutes and when the temperature rises above 134 °C and the warm-up time is more than 50 minutes, the degradation of the sterilized materials begins. It is revealed that the total number of microbes in 1 g of flour is completely eliminated due to the use of multistage sterilization technology.
More than 60 % of electric energy in industry and agriculture is consumed by an electric drive. In a number of production mechanisms, machines and aggregates of various industries, synchronous rotation of several electric motors connected to each other mechanically, electrically or technologically is needed. This requires the use of more complex methods of controlling electromechanical systems, since two or more electric motors must work in concert for one load, which, in turn, entails the use of a new element base, power and control, allowing to implement these technological cycles of work. The object of research is a three-motor electromechanical system interconnected and operating according to the “electric working shaft” (EWS) system. The main fundamental difference from earlier works is that they consider a system of coordinated rotation of only two asynchronous motors, respectively, only one misalignment angle between two asynchronous motors was taken into account. At the same time, the conclusions of the moments and currents of the motors were significantly simplified. In the proposed study, the number of consistently (synchronously) rotating motors from three and above is taken into consideration. In this case, the number of misalignment angles is assumed to be equal to the number of engines, that is, three involved in rotation. The analytical expressions of the basic electromechanical relations of the “electric working shaft” system with the regulation of the supply voltage are developed. A method is proposed for calculating the statistical characteristics of the regulated EWS system, which is easy to use and allows calculations in a wide range of rotor misalignment angles at various engine loads
The relevance of the research is related to the development of a new type of renewable energy source ‒ a vortex wind device with a vertical axis of rotation without wind guidance mechanisms. The main purpose of the study is to develop a vortex wind turbine using mathematical modeling of vortex motion and laboratory experiments on the model. The object of the study is a vortex wind device consisting of a concentrator with curved channels, inside which there is a wind wheel, and a vertical pipe mounted on the concentrator. The calculations are based on the method of modeling large vortices with the solution of averaged Navier-Stokes equations. As a result of the research, the velocity distribution in the concentrator, inside the structure and the discharge pipe were obtained. The computational experiment shows that the narrowing channels of the concentrator create a stable vortex motion inside the structure and the vertical pipe. The methods used for calculating turbulent flows allow to study aerodynamic processes in wind turbines with a vortex effect. The absence of a rotary mechanism reduces the risks of breakdowns of rotational elements due to their absence. The concentrator perceives the wind flow from any side and creates a vortex motion inside itself due to curved channels. The outlet openings of the curved channels are directed to the blades of the wind wheel, which increases the maximum transfer of wind flow energy to the blades of the wind wheel. The vortex motion inside the concentrator creates a steady rotation of the wind wheel. An additional important point is the removal of the exhaust air flow from the vortex wind device. Existing wind farms have wind guidance mechanisms, which complicates the design, a stable rotation mode of the wind wheel is not created. All these problems of operating stations can be solved with the help of a vortex wind device
PURPOSE. Conduct a detailed analysis of existing wind turbines. Analyze the role, place and features of the functioning of wind power plants. Provide various options for generators and schemes for converting wind energy into electricity. Provide recommendations for improving the reliability of wind turbines in smart grids.METHODS. The article was prepared using analytical methods, statistical, theoretical, factorial and technical methods.RESULTS. A fixed speed asynchronous generator used in a wind power conversion system (WECS) without a power converter interface draws a significant portion of the reactive power from the grid. This configuration features simple, reliable operation. Wind turbine asynchronous generator with dual power supply. can improve overall power conversion efficiency by performing maximum power point tracking (MPPT), and an increase in speed of about 30% can improve dynamic performance and increase resilience to system disturbances that are not available for turbine types 1 and 2. The use of full-scale 100% power converters will significantly increase the productivity of SPEV wind energy conversion systems, but will slightly increase the cost of the power converter, up to 7% - 12% of the total equipment cost. By using a large number of pole pairs for all types of permanent magnet synchronous generator (PMG), the turbine gearbox can be removed. This type of wind energy conversion system is more resilient to grid disruptions compared to type 1, 2 and 3 wind systems. The review shows that types 3 and 4 technologies are used to most efficiently sell and recycle wind turbines in electricity markets.CONCLUSION. The article analyzes the features of the functioning of wind power plants operating on the grid. Various options for generators and schemes for converting wind energy into electricity are presented. A detailed analysis of existing wind turbines is provided. Recommendations are given for improving the reliability and efficiency of wind power plants in smart grids.
The paper describes special aspects of using the wind power plants (wind turbines) in the power grid. The paper provides the classification and schematic presentation of AC wind turbines, analyzes the role, place and performance of wind power plants in Smart Grid systems with a large share of renewable energy sources. The authors also reviews a detailed analysis of existing AC wind turbines in this paper. Recommendations are given for how to enhance the wind power plants in smart grids in terms of reliability, and introduce the hardware used in the generation, conversion and interface systems into the existing power grid. After the wind power plants had been put online, the relevance of the Smart Grid concept for existing power grids was obvious. The execution of such projects is assumed to be financially costly, requires careful study, and development of flexible algorithms, but in some cases this may be the only approach. The analysis of using wind turbines shows that the structural configuration of wind power plants can be based on the principles known in the power engineering. The approaches may differ, not fundamentally, but in engineering considerations. it is necessary to point out that the method of controlling dual-power machines is quite comprehensive so that their wide use will face operational problems caused by the lack of highly professional specialists in electric drives. Therefore, it seems advisable to use square-cage asynchronous generators in wide applications. The paper shows that as the renewable energy sources are largely used in power grids, there is an issue of maintaining the power generation at a required level considering the variability of incoming wind energy. This results in the malfunctions in the operation of relay protection devices and emergency control automatics (RP and ECA), and the complicated control. Also, the standards of the CIS countries and regulatory documents miss the requirements for the wind turbine protections, taking into account their specialty causing the inefficient standard protective logic, which does not work correctly in a number of abnormal and emergency operating modes, and especially Smart Grid in power grids.
One of the most common types of AC electric machines are asynchronous electric motors. Because of their simple and reliable design, they are used in many industries. In this paper, the object of research is an asynchronous electric motor with a short-circuited rotor. To ensure the normal operation of an asynchronous electric motor, the heating temperature of its active parts should not exceed the maximum permissible values, which are determined by the corresponding class of heat resistance of the insulation system used in the electric motor. In asynchronous electric motors, the stator winding is the most thermally vulnerable node, which is the first to fail when the temperature of the electric motor increases. Thermal protection devices protect an asynchronous electric motor from emergency operating modes accompanied by an unacceptable excess of the temperature of their windings. In order to build an indirect system of protection against overheating of the stator windings, a temperature observer has been developed using already available signals in a frequency-controlled electric drive. Simulation studies were performed in Matlab/Simulink application software packages. Simulation studies were carried out on the basis of asynchronous electric motors of the 4A series with a capacity of 30, 75 and 110 kW in the temperature range from 20 °C to 250 °C. As a result of the research, it was found that the error of indirect calculation of the temperature of electric motors, taking into account the correction factor, does not exceed 1 %. The proposed temperature observer can be used to build protections for asynchronous electric drives
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