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The aim of the research presented in the article was to develop computer models for determining the electromagnetic fields (EMF) generated by three-phase 25 kV traction power supply systems (TPSS). In contrast to traditional single-phase TPSS, three-phase systems are electromagnetically balanced, provide symmetric loads of substations, increase voltages at current collectors of rolling stock, reduce asymmetry and non-sinusoidality in 110 - 220 kV supply networks. However, the issues of quantitative assessment of electromagnetic safety conditions in three-phase traction networks remain unstudied. To implement the formulated goal, we used the methods of modes and EMF simulation developed at the Irkutsk State University of Railway Transport, the distinctive feature of which is the use of phase coordinates; in this case, the models of TPSS elements are formed on the basis of lacelike equivalent networks. The simulation was carried out for three-phase TPSS schemes of different complexity, in which case the complex traction network was implemented by modifying the model of a real TPSS of one of the main railroads of Eastern Siberia. Simulation results indicated that compared to the typical TPSS 25 kV, the maximum electric field strength increases by 2.5 % in the three-phase system. The maximum value of the magnetic field strength decreases by 26 %. Similar indicators for average values are 2.6 and 19 %. The proposed methodology and the developed computer models can be used in the design of promising three-phase TPSS. In the conditions of power engineering digitization, the application of this technique in practice will allow to apply a scientifically validated approach to the analysis of electromagnetic safety conditions traction networks and to develop its improvement.

The article presents a criterion for choosing the optimal type of wavelet function for digital processing of current and voltage values in the analysis of the electric network mode. The increase in the share of electric receivers that distort the quality of electricity sets the task for researchers to use more advanced mathematical tools for analyzing and modeling such power supply systems. The discrete wavelet transform allows the harmonic analysis of currents and voltages under non-stationary non-sinusoidal modes. One of the key tasks in the development of digital technologies in the electric power industry is the creation and development of intelligent electric networks with the introduction of new algorithms for digital data processing and decision making. In this case, algorithms for compression and remote recovery of data on the consumption and production of electrical energy in the cloud should be developed. The wavelet transform eliminates the negative spreading effect characteristic of the Fourier transform in the analysis of non-sinusoidal non-stationary modes. Based on the Parseval equality, the wavelet transform makes it possible to determine the spectrum energy of individual frequency ranges determined by the depth of decomposition and the sampling frequency of the signal under study. The calculation of the energy of the spectrum of wavelet coefficients allows the compression of the flow volume of instantaneous values of voltages and currents. The article presents the results of continuous and discrete wavelet current conversion when switching a battery of static capacitors. Information compression ratio exceeded 5.3. The wavelet transform was performed using eight different wavelet functions. The criterion for choosing the optimal mother wavelet determines the condition of the maximum energy of the spectrum and the minimum standard deviation when restoring the original signal.

Recently, for the analysis of complex nonlinear processes, more and more attention is paid to the mathematical apparatus of wavelet transform. This is due to the fact that unlike the traditional Fourier transform, the wavelet transform provides information about the signal under study in the time-frequency domain. The purpose of research is to analyze and simulate a non-sinusoidal non-stationary mode based on the packet wavelet transform, the use of this method for transmitting the digital data stream of the signal under study. The simulation was carried out using the software package Simulink. In the study found that packet wavelet transform with high precision allows to determine the presence of higher harmonics in the power system, the efficiency of using wavelet transform to compress digital data stream of the test signal.

A mathematical model for diagnosing the state of solid insulation of high-voltage transformers based on an informational assessment of indirect indicators, i.e. entropy, for example, by the content of impurities of various gases dissolved in transformer oil, which allows to determine the technical condition without removing the workload. The values of the average information on the working and faulty state of insulation for various types of gas impurities are calculated.

This article presents an algorithm and a method for calculating power flow of an open electric network with a voltage of 6-35 kV, taking into account the temperature dependence of active resistances. Calculation of the electric and thermal conditions of the electric network is carried out with a joint solution of the equations. The determination of stresses in the nodes is carried out using the inverse matrix of the nodal and intrinsic conductivities. The inverse matrix of nodal and intrinsic conductivities is determined based on the well-known direct Jordan-Gauss method. The equation of the heat balance of the wire used to calculate the actual temperature is solved numerically. Convective heat transfer is recorded only for forced convection, because wires of overhead power lines with a voltage of 6 kV and higher are located on various types of poles, at a height of at least 10 m. This fact allows us to abandon the use of formulas for natural convection and use expressions only for forced convection. Accounting for solar radiation in the presented algorithm is possible on the basis of two methods: simplified and considered in the standard of PJSC FGC UES, which allows you to take into account the actual location of the wire relative to the north. Using the test circuit as an example, the steady-state mode was calculated taking into account the temperature dependence of the active resistances. The results of a numerical experiment are presented, confirming the operability of the developed algorithm. The refinement in determining active power losses with and without taking into account the heating factor for the considered circuit is about 13%. Verification of the algorithm that implements the method of calculating the steady state (SS) of an open electrical network of a medium voltage class taking into account the temperature dependence of active resistances showed that in technically acceptable modes the developed algorithm has good accuracy in comparison with the RastrWin3 software package.

Coal is one of the main sources of energy of the 21st century. New plasma-energy technologies are being developed to improve the efficiency of coal combustion. Today, pulverized coal CHP plants worldwide generate more than 50% of electric and thermal energy, the share of coal in the fuel balance of the CHP is growing. At the same time, the quality of coal is reduced. Traditional methods of reducing fuel oil consumption at thermal power plants (increasing the dispersion of the grinding dust, high preheating of the air mixture and secondary air, etc.) used to improve fuel ignition and burning stabilization, have exhausted themselves, therefore a radical increase in fuel efficiency can only be associated with the development and development of completely new technologies. Plasma technology seems to be the most promising among the alternative technologies available to solve the above problems. This technology provides a significant increase in economic efficiency and environmental performance of power plants operating on solid fuel.

Using the example of operating gas fields in the Western Siberia, the issue of the correct choice of voltage class, considering all the periods of gas fields life cycle, appears. Wrong choice of the voltage class leads to braking development of a gas field. Gas field technological scheme during the each period of the life cycle is considered, the dynamics of the electrical load is estimated. The analysis of existing methods of choosing the voltage class is carried out and their flaws are revealed. Mathematical models of the optimal voltage class calculation and discounted costs calculation are developed using the theory of experiment planning. An algorithm of choosing the optimal voltage is developed and the distribution and supply networks of the external power supply system of the existing gas fields in Western Siberia are investigated. Progressive voltage class for power supply and distribution network is proposed. Conclusions are made.

The results of mathematical modeling of the optimization of maintenance cable lines are presented in article. The results can be used to calculate the optimal frequency and number of major repairs and substitutions of cable lines.

Currently, according to regulatory documents, the resistivity of power line wires is assumed to be the same for any permissible load current and the heating temperature of the wires is equal to 20 degrees. This account of resistivity causes significant errors that significantly affect the operating modes of power transmission lines. This article analyzes the influence of outdoor air temperature, load current, solar radiation intensity, wind speed and direction on the heating temperature of overhead power lines, and as a result, on the value of the resistivity of the wires and power and electricity losses in them. The example of the BAM highway shows that even in the conditions of one region, the outdoor air temperature varies, depending on the time of year, within a very wide range. This in turn requires careful consideration of the dependence of the resistivity value of the line wires on the external air temperature. At the same time, it is shown that it is permissible to ignore the intensity of solar radiation, wind speed and direction on the heating temperature of overhead power lines due to the lack of comprehensive information about these factors and their opposite direction. However, this assumption will only be valid for operating currents in the range from zero to double the current value corresponding to the economic density. When calculating power losses, especially in heavily loaded lines, it is necessary to take into account all external temperature influences. Due to the appearance of sensor temperature sensors, it is proposed to use them directly to measure the heating temperature of line wires and then calculate their resistivity.

The use of new self-supporting insulated wires and high-temperature wires in the operation of power lines allows increasing the capacity of lines and, as a rule, reducing operational costs. An optimal utilization of the power line load capacity depends on the precise determination of the permissible current loads. The values of permissible currents and steady-state temperature are the main parameters of the line operating mode, affecting the strength and sag of the conductor. The temperature of the wire depends on weather conditions and current load. There are methods for determining the temperature and permissible currents for widely used traditional wires such as AC. They are partially outlined in the EIS (Electrical Installation Standard) and the standard of PJSC FGC UES (Federal Grid Company of Unified Energy System) of 2013. However, there is lack of studies in new types of wires. The paper considers the effect of weather conditions and load on the temperature and real-power losses in insulated and high-temperature wire, and solar radiation is under special consideration. For comparison, we present the results of calculations on traditional AC wires. The research shows that solar radiation, being taken into account, provides an increase of real-power losses of about 2 % with the given values of load and weather conditions. Calculations of permissible current values according to the developed technique for classical AC wires reveal a high coincidence with the values from PJSC FGC UES standard. The relative error is within two percent, and the proposed method is more generalized. It allows simultaneous analysis of both uninsulated and insulated wires. Due to the widespread use of self-supporting insulated wires, power industry experts can use the developed software in the design and operation of modern power lines to optimize capacity.