Identification of Chemical Reactor Plant’s Mathematical Model

This work presents a solution of the identification problem of chemical reactor plant’s mathematical model. The main goal is to obtain a mathematical description of a chemical reactor plant from experimental data, which based on plant’s time response measurements. This data consists sequence of measurements for water jacket temperature and information about control input signal, which is used to govern plant’s behavior

Vector Control System Design for Four Degree-of-Freedom Dynamic Flexible Simulation of the Variable-Frequency Drive

In the present work we investigate the control system development of the drive simulators to train driver/operator driving skills, taking into account the ever-changing terrain. In order to meet the required response of the four degree-of-freedom motion platform servomotor current studies have been focused on the vector control of the resistance motor angular velocity from the sensor being incremental encoder. In proposed system the standard security of the frequency converter is realized. It leads to overload capacity of two times within minutes determined by servomotor inertia. Further, we represent the algorithms: positional limitation, reliable acceleration and restraint, frequency break. As well as we demonstrate the position switches implement in software. As a result, the control system commands the control of the angular position of the platform in coordinates

Algorithm and Software for Operative Calculations of the Short Circuits Modes

Smart power grids provide efficient control of power flows or other grid variables, such as voltages or short circuit currents. Most essential the control has become, if the consumers are electrical systems of high power capacity. These systems are able to reconfigure the grid structure for emergency situations. The developed algorithm is intended for carrying out operational calculations of short-circuits modes in electrical grids of voltage 0,4kV to 220kV. In the calculation the following methods have been used: methods of node voltages, method of superposition and method of branch expansion to form the node voltage matrix according to the graphs theory. In the software the short circuit inflow from all electrical motors and nodes with generalized load is taken into account as opposed to other algorithms. The calculated circuit can have up to 700 nodes; there is ability to decrease number of branches and nodes and to form the calculative model of the grid part. Calculation algorithm of the short circuit currents is implemented as a sequence of software calculations. Software of systems and grids, in which short circuits are altered, allows carrying out operational calculations of the short circuit modes to adjust settings of relays protection devices, to check electrical equipment and to replace it, to choose optimal operational circuits. Actuality of the calculations is caused by need of the software implementation to maintain, upgrade and design the electrical grids of enterprises that have their own power plants

A Batch Feeder for Inhomogeneous Bulk Materials

The work includes the mechanical analysis of mechanical feeders and batchers that find application in various technological processes and industrial fields. Feeders are usually classified according to their design features into two groups: conveyor-type feeders and non-conveyor feeders. Batchers are used to batch solid bulk materials. Less frequently, they are used for liquids. In terms of a batching method, they are divided into volumetric and weighting batchers. Weighting batchers do not provide for sufficient batching accuracy. Automatic weighting batchers include a mass controlling sensor and systems for automatic material feed and automatic mass discharge control. In terms of operating principle, batchers are divided into gravitational batchers and batchers with forced feed of material using conveyors and pumps. Improved consumption of raw materials, decreased loss of materials, ease of use in automatic control systems of industrial facilities allows increasing the quality of technological processes and improve labor conditions. The batch feeder suggested by the authors is a volumetric batcher that has no comparable counterparts among conveyor-type feeders and allows solving the problem of targeted feeding of bulk material batches increasing reliability and hermeticity of the device

AUTOBALANCING DEVICES OF HAND GRINDING MACHINES

A mathematical model of a hand grinding machine with an autobalancing device has been developed. The scientific statements, conclusions and recommendations are based on the analysis of the solutions of the movement equations corresponding to the stable balancing conditions of the rotor with the help of balls, by using Puankare - Lyapunov's method. The required capacity of the autobalancing device (ABD) at force and kinematic excitation of oscillations has been determined. The influence of ABD on the wear of the grinding wheel has been determined, the form of the wheel being corrected and its service life being increased for the same efficiency. A possibility of using and the field of efficient application of the ABD of the hand grinding machines have been defined. The theoretical results have been substantiated by the data obtained as a result of numerous experimental studies, as well as by the serviceability tests of the developed balancing devices and their commercial operation. The results of the work have been introduced at "AvtoVAZ" Production Complex through manufacturing smallbatch machines equipped with the ABD. The latter can be used for balancing the rotors of the machines in which the duty change of the rotor disbalance takes place and is connected with the technological process performedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Evaluative research of induction traction electric motor with low-level power supply for mine locomotive

The relevance of the research is caused by the need to solve the problem of ensuring energy-efficient operation modes of traction electric drives of underground locomotive used to transport metal ore in ferrous and nonferrous mines from the place of mining to place of storage for further transportation to the surface. One of the main tasks of underground rail transport is to reach marginal traction characteristics of variable-frequency induction motors in conditions of limited magnitude of supply voltage of the contact network DC of underground transport for electrical safety reasons. The aim of the work is to study the possibility of using induction motors with reduced voltage power supply for traction electric underground mining locomotives; to determine the conditions of conformity of mechanical characteristics of induction traction motor with reduced voltage regarding the characteristics of a standard voltage. Object of research: traction induction motor with reduced supply voltage, increased tractive effort and low sensitivity to vibration and shocks. Research methods. The research was performed by analyzing the analytical dependences of induction motor characteristics and simulation results in the Simulink/MatLab. The comparison was carried out at static and dynamic characteristics, energy performance and structural features of the considered motors. Results. A special crane induction motor, produced by «Sibelektromotor», designed for frequency regulation of speed, was selected as a prototype of induction traction motor. The paper introduces the method for calculating the equivalent circuit parameters of induction traction motor by passport data at reduced voltage to the stator; its simulation model was designed. The principal mechanical and electromechanical properties and characteristics of traction induction motor with the switching scheme of connection of phase windings of the stator from the «star» to «triangle», recalculated to a low voltage, correspond to characteristics of induction traction motor with standard voltage. To ensure vibration and shock resistance the authors justified a change in the design of induction traction motor with replacement of cast iron housing on the welded steel housing with additional supports for fixing to the frame of the locomotive

Determining rational modes of mechanical processing of titanium body elements of oil and gas equipment by end-end machines (according to SS 23248-78) and wave-shaped cutters

Актуальность исследования обусловлена тем, что одним из важнейших факторов безотказной работы нефтегазового оборудования являются требования к коррозионной стойкости. Свойства титановых сплавов: высокая коррозионная стойкость в агрессивных средах, высокая прочность в сочетании с малой плотностью, позволяют получать изделия с большой прочностью и малой массой при работе в условиях агрессивных сред. Однако применение титановых сплавов при изготовлении деталей, работающих в условиях агрессивной среды, в том числе для нефтегазового оборудования, ограниченно вследствие неудовлетворительной обрабатываемости резанием, что обусловлено малой теплопроводностью таких сплавов, а также склонностью к интенсивным вибрациям. Объект: производительность и экономическая эффективность от применения фрез при изготовлении детали типа «корпус» из титанового сплава. Цель: разработка рациональных режимов механообработки и геометрии инструмента для фрезерования корпусных элементов из титановых сплавов. Рациональные режимы и геометрия фрезы должны обеспечивать максимальную стойкость инструмента, качество механообработки, производительность и экономическую эффективность. Методы: проведение производственных испытаний фрез с разной геометрией их режущих кромок методом многофакторного эксперимента с использованием вибродиагностического комплекса для определения зон с минимальным уровнем вибрации при механообработке детали типа «корпус» из титанового сплава. Результаты. Разработаны рекомендации по снижению вибрации при фрезеровании корпусных элементов из титановых сплавов. Методика позволяет в условиях производства, в стадии отладки технологического процесса, определить рациональные режимы резания по критериям наибольшей производительности и максимальной стойкости инструмента.The relevance of the research is caused by the fact that one of the most important factors in the failure-free operation of oil and gas equipment is the corrosion resistance requirements. Titanium alloys properties like high corrosion resistance in corrosive environments and high strength combined with low density make it possible to obtain products with high strength and low weight when operating in corrosive environments. However, titanium alloys usage in the manufacture of details that operate in an aggressive environment, including for oil and gas equipment, is limited due to both low machinability and low thermal conductivity, as well as the technological system predisposition to intense fluctuations. Object: productivity and economic efficiency from using mills for manufacturing hull details like «case» type from titanium alloy. The main aim of the research is a development of rational machining modes and tool geometry for milling hull elements from titanium alloys. That can ensure maximum tool life, machining quality, productivity and economic efficiency. Methods: production tests of mills with different geometry of cutting edges by the multifactor experiment method using a vibro-diagnostic complex for determine the minimum vibration level zones during machining of the "case" type part from titanium alloy. Results. The authors have developed the recommendations to reducing vibration during milling hull elements from titanium alloys. This method allows finding the rational cutting conditions according to both the highest productivity and maximum tool life criteria in production conditions during the stage of debugging the technological process

Determining rational modes of mechanical processing of titanium body elements of oil and gas equipment by end-end machines (according to SS 23248-78) and wave-shaped cutters

Актуальность исследования обусловлена тем, что одним из важнейших факторов безотказной работы нефтегазового оборудования являются требования к коррозионной стойкости. Свойства титановых сплавов: высокая коррозионная стойкость в агрессивных средах, высокая прочность в сочетании с малой плотностью, позволяют получать изделия с большой прочностью и малой массой при работе в условиях агрессивных сред. Однако применение титановых сплавов при изготовлении деталей, работающих в условиях агрессивной среды, в том числе для нефтегазового оборудования, ограниченно вследствие неудовлетворительной обрабатываемости резанием, что обусловлено малой теплопроводностью таких сплавов, а также склонностью к интенсивным вибрациям. Объект: производительность и экономическая эффективность от применения фрез при изготовлении детали типа «корпус» из титанового сплава. Цель: разработка рациональных режимов механообработки и геометрии инструмента для фрезерования корпусных элементов из титановых сплавов. Рациональные режимы и геометрия фрезы должны обеспечивать максимальную стойкость инструмента, качество механообработки, производительность и экономическую эффективность. Методы: проведение производственных испытаний фрез с разной геометрией их режущих кромок методом многофакторного эксперимента с использованием вибродиагностического комплекса для определения зон с минимальным уровнем вибрации при механообработке детали типа «корпус» из титанового сплава. Результаты. Разработаны рекомендации по снижению вибрации при фрезеровании корпусных элементов из титановых сплавов. Методика позволяет в условиях производства, в стадии отладки технологического процесса, определить рациональные режимы резания по критериям наибольшей производительности и максимальной стойкости инструмента.The relevance of the research is caused by the fact that one of the most important factors in the failure-free operation of oil and gas equipment is the corrosion resistance requirements. Titanium alloys properties like high corrosion resistance in corrosive environments and high strength combined with low density make it possible to obtain products with high strength and low weight when operating in corrosive environments. However, titanium alloys usage in the manufacture of details that operate in an aggressive environment, including for oil and gas equipment, is limited due to both low machinability and low thermal conductivity, as well as the technological system predisposition to intense fluctuations. Object: productivity and economic efficiency from using mills for manufacturing hull details like «case» type from titanium alloy. The main aim of the research is a development of rational machining modes and tool geometry for milling hull elements from titanium alloys. That can ensure maximum tool life, machining quality, productivity and economic efficiency. Methods: production tests of mills with different geometry of cutting edges by the multifactor experiment method using a vibro-diagnostic complex for determine the minimum vibration level zones during machining of the "case" type part from titanium alloy. Results. The authors have developed the recommendations to reducing vibration during milling hull elements from titanium alloys. This method allows finding the rational cutting conditions according to both the highest productivity and maximum tool life criteria in production conditions during the stage of debugging the technological process

Design of full order observer with real time monitoring of load torque for submersible induction motors

The operation of electric submersible pump for oil wells is complicated by a number of factors, which include gas inclusions in the pumped liquid, the presence of asphalt and tar paraffin sedimentation, raising of sand and other abrasive particles, deposition of various salts on the working parts of submersible pumps, in particular, calcium carbonate CaCO3, calcium sulfate CaSO4, barium sulfate BaSO4 and sodium chloride NaCl. As the submersible pump operates under these conditions, the load torque gradually increases, with total decrease in the efficiency of the pump up to a partial or full jamming of the shaft. The increase in the load torque during the wedging additionally statically loads the walls of the tubing. The presence of gas inclusions leads to disturbance in the stationary of the flow of injected liquid, and as a consequence, additional stresses of alternating character appear in the walls of the tubing in a wide range of vibrations. In a number of cases the fatigue destruction of tubing and «downfall» of submersible equipment occur at the wellhead. Therefore, it is time to develop the methods and means for monitoring the load torque on the shaft of a submersible induction motor in real time. Direct measurement with the help of a torque sensor or the restoration of torque estimates by electrical measurements directly on the terminals of a submersible induction motor is not advisable for technical and economic reasons. The most promising is the development of a full order state observer, taking into account the properties of the submerged cable by measuring the currents and voltages at the output of the step-up transformer - at the input of the cable line. Setting up such an observer of the original structure is of scientific and practical interest. The aim of research is to develop and test the mathematical models of the original structure of the full-order state observer with the real time monitoring of the load torque for submerged induction motors feeding on a long submersible cable. The main material and studies are based on the use of the theory of full order state observers, numerical methods for solving systems of ordinary differential equations, numerical integration methods, automatic control theory, and the theory of signal filtering. Conclusion and outlines. The original structure of the full order state observer is proposed with on-line monitoring of the load torque on the shaft of a submersible induction motor power supplying from a long cable. For observer functioning, one need the information on the magnitude of currents and voltages at the input of the submersible motor cable, as well as signals on the estimates of parameters of the replacement circuit and the moment of inertia from the additional device, the parameter identifier (not discussed in this article). It is demonstrated that the structure of the observer provides the user with estimates of the orthogonal projections in the axes a [alpha], [beta] of the rotor flux coupling, the speed, the torque and the load torque on the shaft of the submersible induction motor in real time, both in steady-state conditions and in transient regimes: starting motor, on-off loading. The advantage of the observer is a high indicator of the quality of the evaluation with a small number of configurable parameters and rather simple setting. It is shown that the use of filter-post filters according to the Butterworth scheme improves the quality of evaluation of the load torque on the shaft of a submersible motor. The presence of signals evaluating the projections of the rotor flux linkage and the speed of the rotor makes it possible to recommend such an observer for electric drives made according to the scheme «frequency converter - induction motor». The studies shown that the integral errors of estimation during the observer working out of protracted transient processes are at an acceptable level: according to the speed estimation, they do not exceed 0,5 %, and according to the estimation of the load torque on the shaft no more than 20 %. The estimation error in steady-state regimes and in the absence of parameter variations is less than 1 %

Resonant oscillations with a limiting amplitude in a vibration electromagnetic activator

Актуальность исследования обусловлена тем, что вибрационные электромагнитные активаторы являются перспективными для применения в различных технологиях, связанных с добычей и транспортировкой георесурсов, в том числе при приготовлении буровых растворов и разжижении вязких нефтепродуктов. Вибрационный электромагнитный активатор представляет собой электрическую машину возвратно-поступательного движения с якорем-активатором, образующим в жидкой обрабатываемой среде турбулентные затопленные струи. В первом попупериоде якорь-активатор притягивается к стенке за счет импульса тока в катушках, при этом в упругой пружине накапливается потенциальная энергия. Этот режим является режимом вынужденных колебаний в механической системе вибрационного электромагнитного активатора. Во втором полупериоде ток в катушках отсутствует, а якорь-активатор отталкивается от стенок за счет энергии пружины - это режим свободных колебаний в механической системе. С точки зрения улучшения энергоэффективности следует настраивать вибрационный электромагнитный активатор на резонансную частоту. Резонансная частота не является постоянной и зависит от свойств обрабатываемой жидкости. Форма вынуждающей колебания силы должна быть такой, чтобы обеспечивать колебания в механической системе на резонансной частоте с предельной амплитудой, что обеспечит повышение энергоэффективности и производительности вибрационного электромагнитного активатора. Цель: провести аналитические исследования, позволяющие обеспечивать резонансные колебания с предельной амплитудой в вибрационном электромагнитном активаторе. Методы исследования основаны на использовании обыкновенных дифференциальных уравнений, преобразования Лапласа, амплитудно-частотных характеристик, систем нелинейных алгебраических уравнений, спектрального анализа, сопоставления аналитических и экспериментальных характеристик. Результаты. На основе линеаризованной математической модели механической системы вибрационного электромагнитного активатора рассмотрен режим свободных колебаний якоря-активатора с предельной амплитудой. Режим вынужденных колебаний предлагается рассматривать как естественное дополнение к режиму свободных колебаний с вынуждающей силой, действующей половину периода и имеющей специальную форму. Показано, что режимы свободных и вынужденных колебаний существенно зависят от параметров механической системы, которые определяются свойствами обрабатываемой жидкой среды. Проведен спектральный анализ вынуждающей силы, обеспечивающей резонансные колебания с предельной амплитудой в механической системе вибрационного электромагнитного активатора. Предложено техническое решение, обеспечивающее управление вибрационным электромагнитным активатором с автоматической настройкой на резонансную частоту и предельную амплитуду колебаний якоря-активатора. Такой режим обеспечивает максимизацию энергоэффективности и производительности процессов перемешивания жидких обрабатываемых сред. На основе сопоставления аналитических и экспериментальных частотных характеристик подтверждена гипотеза о допустимости линеаризации математической модели механической системы вибрационного электромагнитного активатора при аналитическом исследовании вынуждающей силы оптимальной формы.The relevance of the research is caused by the fact that vibration electromagnetic activators are promising for use in various technologies. These technologies are associated with extraction and transportation of georesources, including preparation of drilling fluids and liquefaction of viscous oil products. Vibrating electromagnetic activator is an electric machine of reciprocating motion with an armatureactivator, which forms turbulent submerged jets in a treated liquid medium. In the first half-period, the armature-activator is attracted to the wall due to a current pulse in the coils and potential energy is accumulated in the elastic spring. This is a mode of forced oscillations in mechanical system of a vibrating electromagnetic activator. In the second half-period there is no current in the coils and the armature-activator is repelled from the walls due to the spring energy. This is the mode of free oscillations in the mechanical system. Vibration electromagnetic activators should be tuned to the resonant frequency to maximize energy efficiency. The resonant frequency is not constant and depends on the properties of the treated fluid. The shape of the force-induced oscillation must provide oscillations in mechanical system at the resonant frequency with a limiting amplitude. This fact will increase the energy efficiency and performance of a vibration electromagnetic activator. The main aim of the research is to conduct analytical research to provide resonant oscillations with a limiting amplitude in a vibration electromagnetic activator. Methods of the research are based on using ordinary differential equations, Laplace transform, amplitude-frequency characteristics, systems of nonlinear algebraic equations, spectral analysis, comparison of analytical and experimental characteristics Results. The authors have considered the mode of free oscillations of the armature-activator with the limiting amplitude based on linearized mathematical model of the mechanical vibration electromagnetic activator system. The mode of forced oscillations is proposed to be considered as a natural addition to the mode of free oscillations with a driving force that acts half the period and has a special form. It is shown that the modes of free and forced oscillations substantially depend on the parameters of the mechanical system. Such parameters depend on the properties of the treated liquid medium. The authors carried out the spectral analysis of the driving force, providing resonant oscillations with a limiting amplitude in the vibration electromagnetic activator mechanical system. The paper introduces the technical solution that ensures the control of the vibration electromagnetic activator with automatic tuning to the resonant frequency and the limiting amplitude of oscillations of the armature-activator. This mode maximizes the energy efficiency and productivity of the mixing liquid processed media. Based on a comparison of analytical and experimental frequency characteristics the authors confirmed the hypothesis of admissibility of linearizing the mathematical model of vibration electromagnetic activator mechanical system in an analytical study of the driving force of the optimal form