# Vol 27, No 3 (2019)

**Year:**2019**Articles:**11**URL:**https://journals.eco-vector.com/1991-8542/issue/view/1269

## Informatics, Computer Science and Control

### Overview of metaheuristic optimization techniques applied to solving power engineering problems

#### Abstract

The rapid growth of electric power systems around the world in the XX century, and the imperfection of computer technology at that time led the emergence of a number of problems associated with the management and distribution of electricity. The most important tasks solved in the design of new and modernization of existing systems are the problems of managing power flows, planning loads and reactive power, choosing the network configuration and others. All of them belong to a number of optimization problems, which for many years have been solved using traditional numerical methods: Newtonian methods, interior point, branch and bound method, nonlinear and quadratic programming, and others. In addition, the use of numerical methods led to difficulties in calculation of first and second order, which led to finding suboptimal solutions. The birth of heuristic and then metaheuristic optimization methods made it possible to simplify the preparation of mathematical models, and reduce the time of performing calculations, and the universality of new algorithms ensured their applicability for a wide range of tasks. The article describes the general sequence of performing optimization tasks using metaheuristic methods, describes the most important problems faced by modern electric power industry, lists popular metaheuristic optimization algorithms, describes their strengths and weaknesses, and lists the main areas of their application.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):6-19

### The smart city infrastructure object: a system for environmental monitoring and public information / warning

#### Abstract

One of the possible tools to improve the living standards of citizens is automation of urban infrastructure management using information and communication solutions. An original system for environmental monitoring and public informing / warning as an infrastructure object of the smart city is reviewed. The design and software implementation of the client and server parts of the project based on the Alpine Linux operating system, the Python programming language, the Django web framework, and the Docker containerization technology are described. One of the implemented hardware and software client solutions using Wi-Fi, 4G / LTE and LoRaWAN wireless data transfer technologies is reviewed. The final consumers of this system are both government institutions and private enterprises. The methods of use are not strictly regulated, the implementation from smart transport stops to factory and city distributed public information / warning systems with environmental monitoring is recommended and tested. This work is an extension of the author’s project of a distributed information and emergency public warning system. The scientific novelty lies in the implementation of additional authentication of control actions based on hidden marking of information flows, independently calculated and produced on the client and server side through meta-information about previous network interactions (trace route, commands, timestamps, etc.). To achieve this, the convolution function is used. Data of arbitrary length is converted into an output bit string of a set dimension, followed by signature matching with a table of actions that do not interfere with network communication and are not detected by network traffic self-similarity tools. The architecture provides for the possibility of integration with author's knowledge-intensive solutions: a system for intelligent adaptive management of the enterprise network infrastructure, as well as a self-organizing virtual secure communication channel module based on stochastic multilayer encryption and overlay technologies.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):20-34

### Managing the process of reduction gas in gas pipelines

#### Abstract

The control laws of the high-pressure control valve on the gas reduction unit are considered. The system performance testing using the classical law of PID regulation in the SCADA-module Zond 2006 was performed. Identified problems and destabilizing factors affecting the quality of process control. Proposed and aprobirovany combined method that combines adaptive PID controller auto-tuning with the (table autotuning). This method has significantly improved the quality of regulation, and allowed to maintain the set value of the pressure at a constantly changing pressure at the inlet of the pipeline.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):35-46

### The method of determining the frequency quantization of the zero-order extrapolator

#### Abstract

In this paper we consider a method for determining the quantization frequency of the zero-order extrapolator in the frame of the digital position-tracking system. The analysis is carried out by the frequency approach. Amplitude frequency specifications of discrete systems are defined as the sum of the shifted amplitude-frequency characteristics of the analog part of the system. In this connection, it is necessary to determine the shifting frequency of the amplitude frequency characteristics of the system’s continuous part so that their sum in the frequency band of the reference signal does not exceed the specified error regarding the analog prototype. The obtained value of the quantization frequency of the extrapolator will determine the interval of discreteness.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):47-56

### Teletrafic models based on dual systems with hyperexponential and erlang distributions

#### Abstract

This paper presents the results of studies on queuing systems (QS) H_{2}/E_{2}/1 and E_{2}/H_{2}/1 with second-order hyperexponential and Erlang input distributions. Considered QS are of type G/G/1. The use of these higher-order distribution laws is hindered by increasing computational complexity. For such second-order distribution laws, the classical method of spectral decomposition of the solution of the Lindley integral equation for G/G/1 systems makes it possible to obtain a solution in closed form. The article presents the obtained spectral decompositions of the solution of the Lindley integral equation for the considered systems and the formula for the average waiting time in the queue. The adequacy of the results is confirmed by the correct use of the classical method of spectral decomposition and the results of numerical simulation. For practical application of the results obtained, the probability theory moments method is used. Systems of the G/G/1 type are widely used in the theory of teletraffic when modeling data transmission systems. For example, according to the average waiting time in the queue, packet delays in packet switching networks are estimated when they are modeled using QS.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):57-67

## Instrumentation, Metrology and Informative-measurings devices and systems

### Linear approximation of artificially colored surfaces reflection spectra by the principal component analysis

#### Abstract

The surface reflection spectrum is the necessary information for calculating color coordinates in the colorimetric systems of the International Commission on Illumination (CIE), such as Lab or XYZ. These values determine the color sensations of the standard observer. Based on them, the accuracy of color reproduction is estimated, which is regulated by international standards for various industries. Simple and accurate methods of approximation of the spectra are required in the development of effective measuring and control systems for technological processes for obtaining artificially colored surfaces. The specified color of the surface can be obtained with a previously prepared ink mixture or by an autotypical printing method, i.e., by controlling the area of periodic micro-dots of four primary colors. At present, the methods of linear approximation of spectra for mixed ink systems are well studied. The principal component analysis (PCA) provides good accuracy of approximation using only 4–6 basis functions. Information about similar studies for autotyping systems was not found in the literature. Therefore, a comparative analysis of the approximation accuracy of spectral curves using the PCA for mixed and autotype systems is of great interest. The paper discusses the variants of the least-squares function approximation of the 24 spectra of the standard ColorChecker scale (X-Rite) and the 1944-field autotype test scale printed on a digital printing machine. Comparison is made by three criteria: to color, mean square and maximum deviations. For the most accurate approximation of the reflection spectra, an individual approach to each technological system is required. The spectra of mixed inks systems differ significantly from the spectra of autotype systems, and the last are structurally more simply and better modelled. In autotype systems, a representative set can consist of several dozen spectra. Apparently, it is impossible to create a universal set of basis vectors for approximating the reflection spectra of a wide range of industrial systems for obtaining a given color of surfaces.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):68-80

### Error estimation of measurement of power the operated gas-distributing units main gas pipelines

#### Abstract

At operation of the gas-distributing unit (GDU) existence of a reliable data of power of the gas-turbine drive is necessary for management of a duty of the gas transmission system and timely determination of technical condition of a gas-distributing inventory. In work the assessment of accuracy of determination of operational values of power of GDU by the techniques approved by the specifications and technical documentation of Gazprom in the conditions of the concrete compressor station is carried out. Taking into account the accepted assumptions: distribution of the making errors corresponds to the normal distribution law of Gauss and components of errors have no correlation communication, are considered as independent from each other, the main dependences of influence of biases of the GDU parameters (temperatures, pressure, rotation frequencies of rotors) are brought to an error of power rating of GDU. As the error of power rating depends on a method and conditions of measurement, quality of measuring apparatuses and other factors, power rating with a margin error 1.5%-2%, will allow to use its values in the GDU diagnostic models and regulation of a duty of the gas pipeline.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):81-93

## Electrical Engineering

### The energy efficiency of cooling the natural gas With variable frequency drive fans

#### Abstract

The relevance of the problem of reducing energy costs for gas cooling at compressor stations of main gas pipelines is determined by the high energy intensity of cooling plants. The article deals with the energy performance of gas cooling units with discrete and continuous speed control of air cooling fans. The method of estimation of increase of power efficiency at use of continuous regulation is developed. The estimates of electricity consumption in the assumption of a harmonic law of change of temperature of external air during the day, the results of calculations allow us to estimate the energy saving potential, and can be used to predict energy consumption.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):94-104

### Simulation of electromagnetic and thermal processes in an inductive crystallizer of silicon

#### Abstract

This publication describes a set of questions on computer simulation of electromagnetic and thermal processes in an induction crystallizer of a silicon melt, in which forces are created between the melt and the inductor coil, compressing a column of liquid material and preventing direct contact of the melt with the crucible walls. In the well-known induction systems using electromagnetic pressure on the molten metal, the parameters of the inductor are chosen for crystallization so that with sufficient force there will be no increase in temperature due to internal heat sources. The solution to this problem is achieved by reducing the frequency of the current. Heat removal mainly occurs through contact with a water-cooled support surface.

The aim of the work is to determine the process parameters at which the formation of the required electromagnetic force on the wall of the melt takes place, taking into account the sharp decrease in current density at the interface between the solid and liquid phases of silicon. Silicon in a liquid state has a low value of electrical conductivity, which is reflected in the reduction of currents. Mathematical modeling of thermal processes in the melt takes into account the process of transition from a liquid to a solid state with the release of heat of melting. The use of built-in mathematical tools in the software package allows for the correct selection of the finite element mesh and parameters of the procedure for approximating the crystallization process by obtaining a local change in the specific heat capacity to obtain the temperature distribution in space during the movement of the crystallization front.

In determining the parameters of induction crystallizers, the temperature dependences of the thermophysical properties were used. Investigations of the implementation of the inductor, allowing to cover the entire volume of the melt or its part under the condition of continuous movement after solidification of the metal, which is accompanied by a change in the electrical conductivity of silicon and the power of internal heat sources. The results of the study showed the possibility of using the mold at different ratios of the height and diameter of the melt column, and the cooling intensity. The efficiency of the process for silicon increases with decreasing height and increasing the radius of the melt column.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):105-119

### Development and research of a three-phase induction device for heating and mixing liquids

#### Abstract

The questions of the development of design and operating parameters of a three-phase induction device combining the functions of heating and mixing viscous liquids, in particular oil and viscous oil products, are considered. Specific features of the process of transporting viscous fluids through pipelines are noted. It is shown that the high viscosity of the pumped fluids leads to high energy costs. One way to reduce energy consumption is to heat the liquid before transporting it. To increase the intensity of heat transfer between the pipe wall and the heated fluid stream, an induction device built into the pipeline system is proposed that simultaneously performs the function of driving the rotation of the mixer wheel and the heating device. The results of a numerical calculation of the electrical parameters of the device are presented. It is shown that the power supplied to the inductor is distributed into two flows - the power of internal heat generation in the rotor wall and the power of rotation of the rotor. The relationship between the thermal energy released in the rotor wall and the energy used to rotate the rotor on the frequency of rotation of the inductor field is established. Calculations showed that an increase in frequency leads to an increase in the fraction of power for heating, and a decrease in frequency leads to an increase in torque. The resulting conclusion allows you to use the frequency to select the effective mode of operation of the mixer. The proposed device is advisable to use in multi-section heating systems in order to optimize the design and operating parameters of a multi-section heater.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):120-132

### Mathematical model of the short circuiting process in the electrical power network with the current-limiting device based on liquid metal self-healing fuse

#### Abstract

The paper claims that fast response and current-limiting properties of the liquid metal self-healing fuse are of interest regarding their using in power supply systems. However, the level of researches, both in our country and abroad, does not allow us to proceed with the development of production prototypes of liquid metal self-healing fuse. Further research is necessary.

To investigate the short-circuiting process in the alternating current mains, a mathematical model is proposed, which, compared to the known one, allows to investigate the current-limiting properties of liquid metal self-healing fuse more carefully for removing short-circuiting current, alike a current-limiting reactor. The model includes resistance of the electric arc during the switching process. The period of arcing can be divided into infinitesimal sections, the arc resistance at each one is assumed to be linear.

The results of the calculation are presented in the form of oscillograph records. The analysis of calculated oscillograph records allows us to state that the nature of current changes in the electric circuit with the liquid metal self-healing fuse is in full accordance with the main provisions of electric circuit theory, and the mathematical model adequately shows a clear picture of the short-circuiting process.

The comparison of calculation results with the oscillogram received from the experiment shows their complete identity, which confirms the adequacy of the proposed mathematical model to physical processes in the short circuit with the liquid metal self-healing fuse. It is recommended to use the model to determine the requirements for protection device parameters based on the liquid metal self-healing fuse during their development, design and operation.

**Vestnik of Samara State Technical University. Technical Sciences Series**. 2019;27(3):133-146