Vol 29, No 4 (2021)

Informatics, Computer Science and Control

Algorithm for automatic compensation of thermal deformations of thermally loaded load-bearing structures

Borodulin B.B.


The paper considers a possible algorithm for the automatic control system of the thermal modes of load-bearing structures of the information-measuring system of autonomous objects. Thermo-deformation component of information-measuring error, which is the cause of distortion of operating and service information of an autonomous object, is reduced due to compensation of thermogradient by automatic control system of operation modes of distributed controlled heat sources. The system provides a significant reduction in the level of thermal deformation error of measurements, the cause of which is the deformation of supporting structures due to unstable and uneven heat release of information-measuring instruments placed on the structure. To compensate for thermal deformations, the system includes controlled heat sources that compensate for the thermal gradients of the supporting structure arising under the influence of the information-measuring system instruments and external thermal radiation on the structure. An effective rational control algorithm, providing compensation of the thermal gradient of the load-bearing structure to an acceptable level, is proposed. The control algorithm and the system structure are designed to be implemented by special software of the onboard computer.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):6-19
pages 6-19 views

Adaptive system for automatic control of the fine drawing process

Lysov V.E., Sinykov A.P.


The paper considers the technological process of deep drawing, taking into account the high degree of deformation of the metal and the small thickness (0.5 mm) of the workpiece. Given the high complexity of the process and the impossibility of its representation in an analytical form, the paper uses its representation in the form of a phase portrait in the plane of the drawing force and movement of the hydraulic press punch. Phase trajectories in the mentioned plane determine the geometric dimensions of the product, characterize stresses and deformations during the process and determines the structure of the process control algorithm. The digital positional tracking system considered in the work includes electromechanical, hydraulic, pneumoelectric and electronic links. The system provides precision positioning of the hydraulic press punch with control and control of its movement speed. The paper provides an ideal mathematical model of the extraction process. As a result of comparing the phase trajectories of the model and the real process, a possible difference is revealed due to the interference in the real process. The resulting difference makes it possible to form an additional control effect on the punch speed control circuit in the system in order to compensate for the resulting misalignment. Thus, the stabilization of the drawing force in the function of the movement of the punch is realized. The paper provides mathematical descriptions of all parts of the system, provides dynamic characteristics of the process. As disturbing effects on the drawing process, the following are considered: metal hardening, the unstable friction force that occurs when the workpiece is pressed, the change in the drawing force when the parts of the workpiece are drawn into the matrix, corrugation, metal thinning during the transition of the bottom part to the side wall of the product. The mentioned disturbances without the system in question did not fully ensure the quality of the products. As a result of the resulting marriage, significant production costs took place. The materials of the work and numerical data of the links of the technological process system were obtained by the example of manufacturing a cylinder of an OP-2(3)-ABCE powder fire extinguisher produced at the ZPO plant Itself (fire fighting equipment plant).

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):20-31
pages 20-31 views

System for maintaining effective axial load on the bit when drilling wells

Mikheev S.A.


The destruction of rock at the bottom by mechanical means is impossible without creating an axial load on the chisel. The efficiency of the entire process depends on the correct choice of the value and control of this parameter. Control of the axial load on the rock-breaking tool is one of the main methods of controlling the process of rock destruction in any drilling method. In this regard, a device for automating the search for an effective axial load on the bit is proposed, which allows reducing the time to find the optimal values. The operation of the device is based on the method of a braked drum. Its essence is to find the values of the tool weight corresponding to the maximum of the dPoс/dt function, i.e. the maximum of the mechanical drilling speed. The block diagram of the device and the functional diagram of the computing unit are presented. The time diagrams of fluctuations of the axial load on the chisel and the appearance of signals at the outputs of the device blocks are given.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):32-43
pages 32-43 views

Analysis of the energy intensity of the galvanic complex of machine-building production

Romanova A.S., Mikushin M.B., Voevodin A.Y.


Considered are the problems of energy efficiency of products of a large machine-building enterprise associated with the impossibility of regulating steam consumption and the seasonality of changes in energy consumption. The analysis of the consumption of energy resources by a typical large machine-building enterprise of small-scale and unit-type production is carried out. The reasons for the additional costs of the enterprise with centralized steam supply associated with condensate losses have been identified. It has been established that the most power-consuming is the galvanic complex. The reasons for the increased energy consumption of the galvanic complex are considered. The energy balance of the technological section - the galvanic complex, was compiled, reflecting the calculated thermal loads when heating the electrolyte and maintaining the thermal regime, depending on the operating time of the baths and the mass of the processed parts, taking into account the peculiarities of the operation of technological equipment. The most effective methods of energy supply have been determined depending on the load factor and the fuel and energy resource used for two typical baths of the galvanic complex. Three options of technological power supply are considered, depending on the load factor of the equipment and the technical possibility of its parallel-sequential connection. It was found that with all three schemes for connecting to alternative sources of heat supply, there is an increase in the energy efficiency of the use of fuel and energy resources, as well as a decrease in the cost of energy supply of technological processes in comparison with centralized steam supply. It was revealed that when organizing the operation of technological equipment in a parallel-sequential scheme, uniform efficient loading of steam generators and high energy efficiency of galvanic production are ensured. For the power supply of the galvanic complex, a combined scheme of heat supply by local heat sources from the power grid and gas steam generators is proposed, taking into account their fullest load.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):44-55
pages 44-55 views

Electrical Engineering

Analysis of existing types of protection against single-phase earth faults and their application conditions

Andreev A.A.


Currently, the problem of determining a single-phase earth fault in networks with isolated and compensated neutral mode is still relevant. According to the existing data, according to the time of elimination of these technological violations, the conclusion arises, according to which the effectiveness of existing protections is called into question. This issue is particularly acute for electric grid companies that serve urban electric networks, since the mass of lines laid next to each other and the heterogeneous nature of the load makes the network mode not suitable for the use of modern protections. Therefore, as a definition of damage, the method of sequential disconnection and the method of dividing the network into sections, which were used half a century ago, are used. Therefore, the analysis of the existing earth fault protection will help to identify the existing problem more clearly, as well as set the direction for further scientific research in this area. The methodological basis, in this article, is the analysis. The information for this method is taken from the theoretical and empirical information of previously published works. In particular, the existing types of protection against single-phase earth faults are considered. Their analysis and conditions of applicability for the electric economy of urban electric networks are made. In the course of the analysis, it was found that the existing protection against single-phase earth faults can reduce the search range of OZZ, but, so far, they can not provide absolute selectivity for the conditions of urban electrical networks made by cable lines. Since such electrical networks are typical for densely populated areas, the above problem is relevant and requires a quick solution.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):56-70
pages 56-70 views

Method for aligning the load graph powerful induction plants

Bazarov A.A., Danilushkin A.I.


The paper deals with the issues of load balancing in the shop power supply system containing powerful electrothermal installations. There is a cyclical change in load parameters with significant variations in current and power factor during operating multi-section induction installations of methodical action. The largest deviations of these parameters occur in transient modes at heater start or at changing the billets nomenclature. It is shown that when the load changes in starting modes, an increase in power and a decrease in the power factor can lead to unacceptable current overloads of the power supply. Correction during start-up of section currents and power factor allows us to reduce current fluctuations, to provide a smoother power diagram and eliminate power supply overload. It is possible to implement current and power factor correction using semiconductor frequency converters in each section. This approach prevents decreasing the voltage quality indicators and reduces possible deviations of the billets temperature distribution. The parameters of the heater sections in transient modes are calculated. The ranges of power, voltage, current and frequency variation are determined, corresponding to the capabilities of semiconductor frequency converters used in these installations. The proposed start-up algorithm provides the smallest of all possible power fluctuations.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):71-85
pages 71-85 views

Automatic control system of the reactive power factor of the power supply system of the industrial enterprise

Kotenev V.I., Kotenev A.V., Stulov A.D.


Considered is the control of the reactive power factor of the power supply system of an industrial enterprise, which includes: electrical receivers with asynchronous load; workshop transformer substations with and without regulated capacitor units, as well as the main step-down substation with synchronous motors powered from it. It is proposed to consider electrical receivers with capacitor units and a transformer substation as an object of reactive power factor control, on the basis of which the corresponding automatic control system (ACS) is built. An ACS with an algorithm formed as a function of active and reactive power of electrical receivers is considered. The ACS was developed by the reactive power factor of the power supply system of the entire enterprise with shop combined loads. A method is given for calculating the capacity of capacitor units of shop substations. The use of this control system will allow meeting the regulatory requirements for ensuring the limiting values of the reactive power coefficients and thereby reducing losses during the transportation of electricity and increasing the throughput of the electrical network.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):86-98
pages 86-98 views

Method of calculating the distortion coefficient sinusoidality of the voltage curve created by three-phase straight lines

Osipov V.S.


The existing calculation methods in various sources represent rectifier installations as sources of higher harmonics. In this case, the current value of the primary winding of the transformer in the form of rectangles is decomposed into a Fourier series and harmonic components of the current are obtained, except for the main harmonic higher 5, 7, 11, 13, 17, 19 The amplitudes of the current of the higher harmonics are multiplied by the inductive resistances of the supply network corresponding to the frequencies, the results are squared and summed up. Obviously, all terms are of equal magnitude, since with an increase in the harmonic number, its amplitude decreases by n times compared to the first harmonic, while the frequency and inductive resistance increase by the same number of times. The non-sinusoidal coefficient Ku is defined as the ratio of the square root of the sum to the magnitude of the phase voltage. The disadvantage of determining Ku is some arbitrariness in the number of harmonics taken into account. If we take, for example, 9 harmonics, we get Ku = 7.22%, if 4 harmonics, then Ku = 4.81%. When the current of the primary winding of the transformer flows, the voltage amplitude on the substation tires decreases by only 1.9 V. At the same time, the coefficient of non-sinusoidality cannot be equal to 7.22%. In all literature sources, when calculating current harmonics, there are no recommendations for which harmonic numbers should be installed at the substation resonant filters. It is no coincidence that in the new GOST-2013, the value of the distortion coefficient of the sinusoidal voltage curve K(U is calculated as a percentage as a result of the i-th observation according to the formula, (that is, no calculation is made by current harmonics). In this paper, another approach is made to determine the distortion coefficient of the sinusoidal voltage curve. Rectifier installations are not sources of harmonics, but are electrical receivers with a nonlinear characteristic of electric current consumption, while the shape of the sinusoid curve of the supply voltage is distorted. This distorted sine wave is the source of the higher harmonics, which in this paper is decomposed into a Fourier series, while the calculation of the integral functions of the coefficients of the Fourier series is performed in the Mathcad program. The solution is made for three rectifier circuits. Harmonics for the installation of resonant filters are determined. As a result, a developed method is proposed for calculating the higher voltage harmonics and determining the distortion coefficient of the sinusoidal voltage curve based on the Fourier series expansion of the distorted voltage sine curve during operation of three-phase uncontrolled rectifiers.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):99-115
pages 99-115 views

Algorithm for calculating the optimal value of the field substation voltage

Starikov A.V., Tabachnikova T.V., Kazantsev A.A., Kosorlukov I.A.


The article is devoted to improving the energy efficiency of mechanized mining by selecting the optimal voltage level at the field substation, which provides the required optimization criterion. An unbranched line extending from the field substation, which supplies an arbitrary number of electrical complexes of producing wells, is considered. It is shown that these complexes can contain both submersible centrifugal pumps and rod borehole pumping units driven by asynchronous motors. Mathematical models of electrical complexes of producing wells are nonlinear and are described by high-order differential equations. Therefore, the problem of finding the optimal voltage level of a field substation can only be solved using numerical methods. An algorithm for calculating the optimal voltage value is developed, taking into account the technological features of mechanized oil production. It is a search algorithm that contains three internal cycles: voltage variations at the asynchronous motor farthest from the field substation, sorting out the nodes of the outgoing line, and equalizing the voltage at the nodes when the load of the electrical complexes of the producing wells changes. Well-known analytical expressions are given for calculating the active, reactive and full load of step-up and step-down transformers used in the considered electrical complexes, as well as power losses on these elements and on air and cable lines. A distinctive feature of the presented algorithm is the calculation of the speed of submersible and ground asynchronous motors when the supply voltage changes, taking into account the mechanical characteristics of centrifugal and plunger pumps. An example of calculating the optimal voltage value of a field substation feeding a hypothetical outgoing line with three nodes is given. It is noted that the developed algorithm is a reflection of the method of choosing the optimal voltage of the field substation. Moreover, this algorithm can be adapted to any outgoing line, no matter how complex and branched it is.

Vestnik of Samara State Technical University. Technical Sciences Series. 2021;29(4):116-131
pages 116-131 views

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