No 32 (2019)
- Year: 2019
- Articles: 12
- URL: https://ered.pstu.ru/index.php/elinf/issue/view/220
- DOI: https://doi.org/10.15593/.v0i32
Articles
ALL-MODE PHASE SHIFTING TRANSFORMER MODEL IN ELECTRIC POWER SYSTEM
Abstract
The phase shifting transformer in the electric power system (EPS) provides more efficient control of EPS modes by voltage and active power flow regulation. However, nowadays quasi-steady and transient processes in the EPS become more complicated. As a result, the commonly used simulation tools apply decomposition of EPS processes to quasi-steady and transient, simplification of mathematical models of EPS elements, limitation of the simulation time interval. Mentioned simplifications and limitations in general lead to an uncertain loss of completeness of EPS modeling. The concept of software and hardware tools of phase shifting transformer simulation, presented in the article, allows to solve this problem. The software and hardware of phase shifting transformer simulation are the tools of hybrid simulation, which include analog, digital, and physical approaches of the simulation. The analog approach is the solution of the differential equations system, describing the phase shifting transformer processes by continuous implicit integration. The digital approach provides the control of the electronic switches, the phase shifting transformer parameters, such as leakage inductance, active resistance etc. The physical approach is the connection and switching in the EPS elements as in real EPS. The article presents the all-mode thyristor-controlled phase shifting transformer model, developed by hybrid simulation approach and adapted for use in the Hybrid Real Time Power System Simulator developed in Tomsk polytechnic university. The appropriate research of phase shifting transformer in the EPS was carried out by Hybrid Real Time Power System Simulator, in which the Tomsk EPS (region of Russia where there is a problem of non-synchronous operation of the northern and southern parts) is implemented. By means of the Tomsk EPS model and developed phase shifting transformer model, the purpose of which was to interconnect two asynchronously operating parts of the Tomsk EPS and experimental research were carried out.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):7-21
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APPLICATION OF LINEAR INDUCTORS WITH OPPOSITE DIRECTION TRAVELLING MAGNETIC FIELDS IN EDDY-CURRENT SEPARATORS
Abstract
The improvement of technologies for the collection and primary processing of secondary non-ferrous metals is a prerequisite for the development of secondary non-ferrous metallurgy and the establishment of solid waste processing enterprises. One such technology is eddy-current (electrodynamic) separation in a traveling magnetic field. The main structures of electrodynamic separation installations are considered. Widely distributed separators based on linear inductors. Such separators easily fit into technological lines and are used in the extraction of non-ferrous metals from various types of metal-containing solid waste (automobile scrap, mixed production and municipal waste, cable and electronic scrap, etc.), as well as in the processing of complex non-ferrous scrap in preparation it to metallurgical redistribution. Еlectrodynamic separation problems can be conditionally divided into two groups. The first group includes the tasks of separating non-ferrous metals from non-metals, and the second group involves more complex tasks of sorting metals according to their physical properties. In both cases, the final results of separation depend on the combined action of electromagnetic and mechanical forces on metallic particles. This article describes some of the results of studies of electrodynamic separators based on linear inductors. The prospects for the use of linear inductors that create opposite direction traveling magnetic fields are shown. The use of such linear inductors in electrodynamic separators to remove non-ferrous metals from solid waste allows for an increase in the yield of metals. The use of opposite direction traveling magnetic fields in the induction sorting of metals and alloys provides increased plant productivity and improved sorting quality. It is shown that the distribution of the magnetic field and electromagnetic forces along the inductors depend on the three-phase winding circuit. The main attention is focused on the choice of the three-phase winding of the linear inductor, which provides these advantages. The article presents the results of experimental studies of prototypes of electrodynamic separators based on linear inductors, created in the laboratory of the Department of Electrical Engineering and Electrotechnological Systems of the Ural Federal University. The article presents the results of studies of of dual-purpose linear induction machines created in the laboratory of the Academic Department of Electrical Engineering and Electrotechnological Systems of the Ural Federal University.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):22-37
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DEVELOPMENT OF A METHOD FOR ANALYZING A DC MOTOR HIGH-POWER WITH CLAW POLES DESIGNED FOR PILGER MILL FOR THE MANUFACTURE OF SEAMLESS PIPES
Abstract
The article presents the design method of brushless DC motor with claw-type poles designed for the pilger mill drive for producing seamless tubes. Motors of this class are widely used for drives of small and medium capacity, but in world practice there are no examples of the production of such engines with dimensions up to 10 meters and a power of several megawatts. The article shows the feasibility of using such large and powerful electric motors for drives operating in severe conditions. This is due to the possibility of assembling a magnetic system with high-coercive permanent magnets without additional expensive tooling. But it should be noted that the calculation of the inductor with claw-type poles is quite complex. There are great technical risks to develop an inefficient design with a small magnetic flux. The article proposes to divide the problem into 2 stages. At the first stage, the problem of determining the optimal geometry based on nonlinear programming methods is solved. The authors propose a synthesis program implemented in the Delphi. The program contains several levels of optimization and covers a large number of project situations. At the second stage, the task of analyzing the optimized motor design is implemented. We use a well-tested in practice program Ansys Electronics Desktop. At this stage, the authors are faced with the need to use powerful computer resources and a large time in a few hours to calculate one option. This is due to the fact that the construction with claw-like poles does not have 2d symmetry and it is necessary to solve a 3d field problem. The article proposes an effective method of solving this problem. The authors propose a simplification of the computational model without significantly reducing the accuracy of the calculation. A motor with claw-type poles is replaced by a motor with tangential magnets, which has a 2d symmetry and can be calculated by solving a 2d field problem. The design of the stator and the magnetic fluxes of the motor standard motor and identical twins, respectively, losses, currents and voltages are also equivalent. The effectiveness of such a replacement is shown on a real project. Calculation time at acceptable quality is reduced to several minutes. This approach is recommended for the creation of design systems of other types of machines.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):38-57
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RESEARCH OF ADAPTIVE CONTROL OF THE DYNAMIC OBJECT OF THE SECOND ORDER TO OPTIMIZE THE WORK OF GAS TURBINE INSTALLATIONS
Abstract
The article explores the possibilities of building automatic control systems for gas turbine power plants. Modern trends in the development of adaptive management and prospects for its use in the power industry are being studied. It is known that the enterprises of the domestic aviation engine-building produce gas-turbine installations (GTU) not only for aviation, but also for the construction of power plants of various capacities. It is known that a gas turbine unit is operable only if there is an automatic control system (ACS); therefore, serious attention is paid to the tasks of improving the ACS of a gas turbine unit. In gas turbines designed for power plants, there is a need to ensure the specified indicators of the quality of electricity in a constantly changing electrical load and changes in operating modes of the power plant, which increases the requirements for ACS. We consider ways to significantly improve the parameters of automatic control systems through the use of tabular adjustment of regulators, the introduction of adaptive ACS with a reference model. The possibilities of their construction are investigated, their advantages and disadvantages are analyzed. As an adaptation method, it is advisable to choose a method based on the Lyapunov function, in order to reduce the search time for an extremum. A simplified dynamic model of Aviadvigatel OJSC (Perm) is used as a model of a gas turbine unit. It is intended for testing control algorithms and using them as part of semi-natural test benches. As a model of the ACS, the program code of the standard ACS of the electric power GTU is used. We confirmed the assumption that by choosing the matrix Q, it is possible to improve one adjustable variable at the expense of another. Results were obtained by varying the values of Kd, h, dt and the method for solving differential equations.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):58-74
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DIGITAL GRINDING CONTROL
Abstract
Based on the analysis of the dynamics of the process, the article proposes a method of digital automatic control of grinding by using expert systems for monitoring and diagnosing the parameters of the technological process of abrasive processing, followed by a decision to change the presets in real time, taking into account the results of diagnosis. To obtain the required quality indicators of effective processing, it is necessary to edit the grinding wheel at a time when its cutting properties are reduced to critical. The use of fuzzy logic in the control algorithm of abrasive processing allows to obtain a digital control strategy, similar to the process of associative thinking of a person. Such an artificially intelligent system allows in the process of digital control to use the knowledge stored in memory for the implementation of decision - making taking into account the initial conditions (logical conclusion.) The use of fuzzy logic controllers to describe the system makes it possible to use expert knowledge rather effectively instead of differential equations. These applications of the theory of fuzzy sets, in this case are expressed by means of linguistic variables in a natural way. In the process of grinding control, it is convenient to use expert systems based on fuzzy controllers, which adjust the parameters of the direct loop controller depending on changing conditions and are used in an additional control loop. Conventional regulators are used in the direct loop of combined digital optimal control systems. The effectiveness of the digital control system and the quality of decisions can be significantly improved by the use of expert systems. Based on the analysis of the parameters of the quality of the technological process, it was possible to reduce the consumption of the tool while maintaining the high quality of the manufactured products and increase productivity due to a reasonable increase in the number of shafts between edits. During the experiment, the number of processed shafts between edits of the circle was increased more than twice, which provided significant savings of expensive tools while maintaining high quality processing.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):75-89
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RESEARCH THE THERMAL SENSITYVITY OF A FIBER OPTIC SENSOR CREATED WITH THE CATASTROPHIC FUSE
Abstract
Today, a separate direction of fiber optics is the development and research of sensors based on optical fibers. The actual direction is the creation of sensors in the core of the fiber, using the fuse effect as well as the combination of a temperature sensor with a fiber diffuser. Existing medical therapy fiber probes do not have built-in temperature sensors. For these purposes, separate probes are used. Therefore, it is urgent to create devices that combine the properties of the sensor and therapeutic probe. The purpose of the study is to study the temperature sensitivity of a therapeutic probe with a cylindrical lens. A fiber laser doped with ytterbium oxides was manufactured for creating diffusers based on the fuse effect. The probe was created on a multimode 62,5/125 mcm fiber. The formation of the scattering structure and the sensor occurs under the action of the melting effect of the core. During the experiment, the light diffuser was placed in a heat chamber, in which the temperature increased every 10 minutes abruptly by 1 degree in the range from 30 to 42 °C. The shift of the spectral characteristic of the sensor under the influence of temperature determines its sensitivity. To simplify the analyzing circuit, a Bragg grating was introduced into the support arm of the interrogator. As a result, of the study of the characteristics of a single-mode diffuser, a calibration graph was obtained for the dependence of the amplitude of the power of reverse radiation on temperature. This proves that the developed and manufactured diffuser can be used as a temperature sensor. The accuracy of determining the temperature was 1,25 °C. To use such a sensor for medical purposes, it is recommended to increase the accuracy to 0,1 °C
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):90-104
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QUESTIONS ON PROVIDING EFFECTIVENESS OF LASER COMMUNICATION BETWEEN NODES OF DISTRIBUTED MEASUREMENTS NETWORKS
Abstract
The article is devoted to questions on providing effectiveness of laser communication between nodes of distributed measuring networks. One of major impacting factors leading to attenuation diode laser signals is divergence of beam which can reach 3-8 mrad. Another important factor is atmospheric turbulence which occurs due to difference of temperatures of the Earth surface and atmosphere. In atmospheric laser communication lines major impacting factors are mist, snow and rain. In view of said factors the new model of attenuation of laser signal in open communication network between the central node and distributed receiving nodes is suggested. In suggested model such parameters as distance between center and distributed nodes, visibility at the distance and scattering particles distribution parameter are considered as major ones. The new indicator of effectiveness of communication in distributed laser networks is suggested. The task on analysis of suggested indicator is formulated and solved. On the basis of solution of optimization task the recommendations on choosing interrelation between length of distance and visibility at the distance are given. It is concluded that in laser communication network the worst effectiveness on chosen relevant parameter between central node and distributed ones can be obtained upon increasing type of functional dependence between distance and visibility i.e. when increase of visibility is caused by increase of distance till chosen receiving node. Heuristic alternative in this case is organization of inverse dependence between distance and visibility, i.e. when decrease of distance is accompanied by increase of visibility.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):105-116
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RESEARCH OF PROCESSES RESISTIVE HEATING OF PIPELINES
Abstract
One of the ways of heating pipelines in the oil and gas industry is a system of resistive heating, the main element of which is the heating (heating) cable. In this paper, we consider a flat three-core cable with insulation of cross-linked polyethylene, PVC inner shell, metal screen in the form of braid and the outer polyvinyl chloride shell. The pipeline is covered with a layer of thermal insulation to reduce heat loss to the surrounding area. The input parameters for the calculation of pipeline resistive heating systems are the geometric dimensions of the insulated pipeline, thermal parameters of thermal insulation, the design of the heating cable, the maintained temperature of the pipeline and the conditions of heat exchange with the environment. At the first stage, the thermal losses of the heat-insulated pipeline to the surrounding space are calculated, taking into account which the temperature modes of the heating cable are determined at the second stage. Thermal losses of the system of resistive heating of pipelines are found using the thermal equivalent circuit and the theory of similarity of thermal processes. To determine the temperature conditions of the heating cable, a mathematical model of stationary thermal conductivity is proposed, the numerical implementation of which is carried out by the finite volume method in the engineering calculations Ansys Fluent. The influence of ambient temperature, wind speed, thickness of thermal insulation of the pipeline on the amount of heat losses in the surrounding space is studied. For the considered conditions of heat exchange with the environment, the temperature fields of the system of resistive heating of pipelines with a heating cable are constructed. According to the results of numerical studies, the possibility of using the considered cable for heating the pipeline for the given conditions of heat exchange with the environment is estimated.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):117-129
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MODEL IMPLEMENTING REQUIREMENTS FOR THE PROTECTION OF INFORMATION OF OBJECTS OF CRITICAL INFORMATION INFRASTRUCTURE
Abstract
The problem of information security has been analyzed in information systems. The arguments has been listed which is cause an increasing number of information security incidents, statistics on the growth of information security threats and which is relate to the active implementation of information technologies. Most requested areas has been listed which is require protection security in this article. The task has been formulated protection of critical information infrastructure. Protection security significant object is part of the work on creation (modernization), operation and decommissioning of significant object. Requirements protection security of critical information infrastructure are information security tasks during creation, and decommissioning. The directions has been listed for rationale requirements on protection information, which is define of legislation. The conclusion has been drawn about the sources of requirements, which is include in the technical task for the creation of the security subsystem of a significant object. Model relationship has been demonstrated, which is reflect requirements on protection security, which include the model of information security threats and the security system model. The feasibility of developing many options for implementing security systems has been shown. The process of generating information security requirements has been analyzed, which is reflect in the technical task for the system. Requirements specification has been define, based on the classification features of the critical information infrastructure object. Formal description of the subject area of the critical information infrastructure object has been submitted, based on analyzed data about it. Decision rules for withdrawal are formulated. Critical infrastructure facility model has been designed, based on a model for listing its vulnerabilities and specified requirements. Formal formulation of the security system synthesis problem has been implemented to selected criteria.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):130-147
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CAPACITIVE RESISTANCE OF THE SCATTERING OF THE TRANSFORMER WINDING
Abstract
The total reactance of dispersion of a transformer with concentric cylindrical windings depends on the thickness of the coils and the size of the gap between them. The existing methods do not allow measuring the scattering reactances for each winding of the transformer separately, therefore, for simplicity, they are often considered to be equal to each other. In fact, as applied to the case under consideration, they are not substantially equal. In fact, the calculation of the flux linkage of the external winding shows that its dissipation reactance is greater than the total dissipation resistance of both windings. Two circumstances follow from this. The first is that the internal winding of the transformer absorbs the magnetic flux to a greater extent than it dissipates (dissipates its magnetic flux, absorbs from the external winding). The second is that its (equivalent) leakage reactance is capacitive. The purpose of the study is to substantiate the possibility of experimentally determining the scattering reactance for each winding of the transformer separately. The relevance of the work due to the widespread distribution of transformers. The scattering reactance of each winding of the transformer separately can be determined by at least three experimental methods that give satisfactory agreement of the results. An almost paradoxical result - the capacitive nature of the resistance to dissipation of the internal winding of a transformer was obtained only for concentric cylindrical windings. It should not be generalized to other types of windings. The presented experimental methods are not tied to the nature of the reactivity of scattering resistance. They are universal - they can be used in all types of round-hank. The obtained results are recommended to use when designing and researching transformers
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):148-159
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“THE THREE-PHASE PMSG - CONTROLLED BRIDGE RECTIFIER” SYSTEM WITH ADDITIONAL REACTOR IN NEUTRAL: OPERATING MODES AND CONDITIONS OF THEIR EXISTENCE
Abstract
The results of the analysis of operating modes and conditions of their existence in a system consisting of a synchronous generator with permanent magnets (PMSG) and a controlled (thyristor) bridge rectifier with an additional choke connected to the generator neutral and the midpoint of the bipolar output voltage of the rectifier are presented. This simple modification of the known Larionov scheme is intended for use in electrical AC voltage power supply complexes with intermediate DC voltage link. In such systems, PMSG is the variable shaft speed primary source and the voltage inverter (VI) is used as load power parameters stabilizer. The load neutral is connected to the midpoint of the bipolar output voltage of the rectifier. The need for the introduction of an additional choke is to form a circuit of the load current constant component in its presence bypassing the DC link capacitors of the system. The introduction of the choke changes the operating modes of the circuit, which are characterized by a different number and duration of thyristor conduction intervals on the period of the generator voltage frequency. The article presents the results of the first stage of electromagnetic analysis required for systems with PMSG and rectifier at zero value of the load current constant component. The system of differential equations of a three-phase permanent magnets synchronous generator (PMSG) is supplemented by the equation for neutral voltage and neutral current, the appearance of which is due to the introduction of an additional choke. The expressions obtained in relative values allow to define the conditions for the existence of modes in the modified scheme in a wide range of changing generator shaft speed, control angles, phase generator inductance and rectifier input inductance (generator feeder inductance). The results of this analysis stage are the foundation for the next step - considering the influence of the load current constant component of the VI.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):160-182
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CALCULATION OF TRACTION FORCE OF A CYLINDRICAL LINEAR BRUSHLESS ENGINE FOR DRIVING A PLUNGER PUMP
Abstract
Currently, cylindrical linear valve motors are used universally.They are used in electric drives of reciprocating electric drives of various general industrial mechanisms, including deep plunger pumps.The use of sucker rod pumps is less cost effective than other methods of oil production.The operation of such units is accompanied by high financial costs.The use of pumps of a similar design in low-rate wells becomes completely unprofitable from an economic point of view.Such wells are no longer used.Currently, in the Russian Federation a huge number of low-yield wells are not in operation.The use of sucker rod pumps also have an additional drawback - they cause wear of tubing and rods.The large mass and dimensions of the rocking machines make it difficult to transport.It is for this reason that there is a need for research in order to obtain new technical solutions.Studies have confirmed the cost-effectiveness of plunger-type deep well pumps.The drive of such pumping units can be a cylindrical linear induction engine or a cylindrical linear valve engine.The use of this engine is possible with a known pulling force.It is calculated in this article.The calculation is made according to a simplified model of a cylindrical linear valve enginein a Cartesian coordinate system.This model is obtained by introducing some assumptions.The device and the principle of operation of a cylindrical linear valve engineare investigated.According to the calculated data, the dependences of the tractive effort and useful power on the current value of the inductor winding were built.Net power was determined in the range of ultra-low frequencies from 1 to 7 Hz.The obtained research results were analyzed and recommendations on the use of a cylindrical linear valve enginewere given.
PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems. 2019;(32):183-198
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