Introduction. With the increasing number of electrical loads with non-linear volt-ampere characteristic, there are problems with distortion of the shape of the supply voltage and current curve. These distortions can lead to undesirable effects such as network overload, harmonic distortion, unacceptable voltage and current ripple, etc. Goal. To investigate non-sinusoidal modes of operation of electrical equipment in the power supply system to predict the quality of electrical energy and develop measures to ensure electromagnetic compatibility of electrical equipment in power supply systems. Materials and methods. The simulation model developed in MATLAB/Simulink software complex allows to analyze the operation of the power supply system with semiconductor converters under different conditions and predict its behaviour under different loads and external influences. Results and discussion. In the course of work it was found that in the absence of reactive power compensation devices, the levels of the total coefficient of higher harmonic components of voltage KU(n), in the power supply system with 12-pulse converter exceed the permissible values during 95% of the measurement interval time in accordance with GOST 32144-2013 (in the connection points of 6 kV). The values of the coefficient of the n-th harmonic component of voltage at 11, 13, 23, 25, 35 37 harmonics in some cases exceed the permissible values during 100% of the measurement interval time. When using compensation means (batteries of static capacitors, resonant filter), the values of the total coefficients of voltage harmonic components do not exceed the permissible values. Conclusion. According to the results of the study, it is clear that the widespread use of rectifier devices leads to a significant distortion of the voltage curve. However, it should be noted that the existing GOST regulates only the value of harmonic components of voltage and does not take into account the harmonic components of current, which in turn also have a detrimental effect on the elements of the electrical network.

Subject of research: this paper analyzes the impact of electromagnetic fields on personnel safety, as well as the safety and performance of unmanned aerial vehicle flights in the operation of 110 kV transmission lines. Purpose of research: building a picture of the electromagnetic field of transmission lines 110 kV and above for the purpose of safe operation of live electrical installations by personnel using unmanned aerial vehicles. Object of study: 110 kV power grids. Methods of research: modeling of permissible (safe) distances to live parts of power lines in COMSOL Multiphysics program. Main results of research: the pictures of electric and magnetic fields of the wire of 110 kV transmission lines at a distance of 1 m from the current-carrying part are constructed.

The paper presents a simulation model of an electric power supply system with a nonlinear load operating in a non-stationary mode. To analyze the non-sinusoidal mode, the use of a batch wavelet transform is proposed. The wavelet transform has a number of advantages, which can be used to implement electricity quality indicators into a monitoring system. Subject of research: power quality indices. Purpose of research: proof of the advantage of the wavelet transform in the analysis of non-sinusoidal non-stationary modes. Object of research: a power supply system with a voltage of up to 1 kV with non-linear loads that distort the quality of electricity. Methods of research: analysis, computer modelling. Main results of research: еhe prospects of using the wavelet transform for the organization of a system for monitoring electricity quality indicators have been proved; the absence of the spectrum spreading effect is shown.

Relevance. The need to develop correction coefficients for selecting cable sections when laying in the polymeric cable channel in the Russian Federation. Currently, there are no recommendations fixed by the state standards for laying cable power lines in polymer pipes. Aim. To develop correction factors for laying cable power lines in the polymer cable channel. Objects. Cable transmission lines laid underground in polymer pipes. Methods. Numerical simulation of combined frequency-stationary method; determination of correction factors based on interpolation of model results; evaluation and analysis of comparison of cables in corrugated and smooth polymer pipes. Results. Calculations of the long-term current load for cables laid in the polymeric cable channel showed the effectiveness of this method of laying cable lines. The use of pipes with smooth walls makes it much more efficient to remove heat from cables into the environment (compared to a corrugated pipe), which allows you to increase the capacity of the same cable by about 25%, depending on the number of pipes laid nearby. Based on the results of the simulation of the thermal mode of corrugated and smooth polymer pipes, it can be concluded that corrugated pipe significantly complicates heat removal from the cable system to the environment (soil). This is due to the presence of air gaps in the ribbed structure of the corrugated pipe. The gaps filled with air act as a heat-insulating layer, unlike a smooth pipe in which this gap is absent. The developed coefficients will take into account the influence of the location of cables on their allowable current already at the design stage, which will reduce the cost of power transmission losses due to the wrong cable cross-section and high temperature.

In some countries of the EU middle load power lines operate with a balanced neutral. In this mode a ground-fault neutralizer is usually shunted with a resistor. Line-to-ground short circuit is the most common fault in this kind of power lines. The article presents an adaptation mechanism for a ground-fault neutralizer with mathematical apparatus of descrete wavelet transform, which gives data both in amplitude-frequency and frequency-time range. Wavelet transform has several advantages comparing with short-time Fourier transform (STFT), especialy in nonsteady modes. The suggested algorithm allows excluding high-frequency interference and distortions from the voltage signal in zero-phaze sequence circuit. After WPT of the voltage signal, approximating and detalizing coefficients smaller than the investigated voltage signal operate in the algorithm. Welch's t-test, applied to determine free frequency performs well in non-stationary mode. This algorithm can be applied in control units for ground-fault neutralizers to compensate capacity earth-fault currents.

Subject of research: methods for predicting electrical load schedules. Purpose of research: improvement of the forecasting method for assessing the growth of minigrid energy consumption. Methods and objects of research: elements of the theory of wavelet transform of time series, approximation methods were adopted as a research method. Main results of research: as a result of the study, the method for predicting the load power of an isolated low-power electrical system (minigrid) was modernized; as an element of modernization, the use of wavelet transforms for filtering the high-frequency component of the power consumption graph is proposed. The paper also discusses the basic principles of operation of wavelet transforms, their advantages and possibilities of application in forecasting problems, and also provides an example of the successful use of this method.

Subject of research: methods for calculating and analyzing non-sinusoidal non-stationary modes of electrical networks. Purpose of research: development of a method for calculating active and reactive power, as well as the power of distortion of non-sinusoidal modes of electrical networks based on the theory of wavelet transform. Object of research: electrical networks and power supply systems containing a non-linear load, which is the cause of non-sinusoidal modes. Methods of research: packet wavelet transform of currents and voltages; theory of electrical circuits. Main results of research: The paper proposes the idea of using the wavelet transform for frequency decomposition of currents and voltages of non-sinusoidal non-stationary modes of electrical networks. Based on the wavelet coefficients, it is proposed to calculate the active, reactive power and distortion power of non-sinusoidal modes.

Subject of research: methods for selective determination of an outgoing line with a single-phase earth fault based on the relative measurement of higher harmonics. Purpose of research: to develop a method for software filtering of high-frequency components and a method for identifying a line with a single-phase ground fault. Object of research: distribution networks 6-35 kV. Methods of research: wavelet-transformation of zero-sequence currents and voltages. Main results of research: the article proposes the idea of using the wavelet transform to organize software filtering of the zero-sequence current in order to increase the sensitivity of the admittance protection. On the basis of the wavelet transform, a modernization of the algorithm for determining a power line with a single-phase earth fault is proposed according to the principle of relative measurement of the energy of the spectrum of higher harmonics. The paper proposes to determine the energy of the spectrum by the wavelet coefficients of the discrete wavelet transform.

The article represents a calculation method for steady state in open-loop power lines with voltage 6–110 kv with the account of temperature dependence of ohmic resistance. The authors conduct calculation of electrical and thermal conditions in power lines with the inner temperature offset. Stress calculation in nods is based on inverse matrix of nod and intrinsic conductivities, determined on the bases of LU/LUP decomposition. We consider insolation in this algorithm in four ways. The authors pay special attention to the way described in the corporate standard of the PJSC FGS UES. We conduct calculation for steady state on the example of test schemes IEEE 33 and 69 Bus with the account of temperature dependence of ohmic resistance. Results of simulation exercise, which prove efficiency of the calculating method, have been represented.

The article presents analysis technique for power quality parameters and transient switching processes with the help of wavelet transformation. Recommendations have been given on the choice of the optimal mother wavelet function. The criterion takes into account the power spectrum of the range covered. The second condition of the suggested criterion is that root-mean-square deviation of the initial and reconfigurable signal should tend to zero due to wavelet transform. Switching processes in capacitor banks and power lags have been studied. The authors compare 5 mother wavelets basing on the suggested criterion. Wavelet db10 has minimum mean square deviation at signal restoration. An opportunity to apply detailizing wavelet coefficients responsible for localization of high-frequency components, to identify changes in operating parameters of the power system has been described. Increase in amplitudes of detailizing coefficients is connected with discontinuity of higher derivatives, when operating parameters change. A numerical experiment to determine operating values of higher harmonics currents has been given.

The digital transformation of the electric power industry is one of the priority tasks for the development of the industry. Wavelet transform is widely used in the electric power industry to analyze the dynamics of complex non-linear non-stationary processes. The article proposes a method for calculating transient processes in electrical networks based on a recursive algorithm. The approximating and detailing wavelet coefficients of the discrete wavelet transform are used as the voltage signal. To select the optimal wavelet function, it is proposed to use a criterion that takes into account the accuracy of the signal recovery as a result of the inverse wavelet transform. The nature of the change in the calculation result with an increase in the number of iterations is shown. The results of a numerical experiment for a 110 kV network when calculating a three-phase short circuit showed an acceptable accuracy of the developed technique. The proposed technique makes it possible to compress the volume of transmitted digital data on normal and emergency modes of electrical networks.

A feature of the geographical location of the Khanty-Mansiysk Autonomous Okrug - Yugra is the presence of a large number of zones of decentralized power supply. For a comparative environmental assessment of renewable energy installations, it is necessary to take into account the emissions of the entire life cycle. Throughout the presented cycle from mining to the production of power plant structures and then the disposal of the facility, a significant part of CO2 emissions is present. The problem of dismantling and recycling of spent structures of wind power plants is becoming essential. Wind turbines cause the death of birds, violate the conditions of comfortable living for people and animals From a technical point of view, it is necessary to take into account the regime parameters: indicators of the quality of electricity at the point of connection, voltage levels at load nodes, operating modes of energy storage devices. To assess the operating parameters of an isolated power supply system with renewable energy sources, this paper proposes to use the wavelet transform method. The Haar wavelet was used as a basic function in the paper. A mathematical model is presented that makes it possible to obtain a low-frequency (trend) component and a high-frequency component using the wavelet transform. The model allows for the optimal choice of a hybrid energy storage device for a renewable energy source - a battery and a supercapacitor.

The necessity to develop analysis and calculation methods of nonsinusoidal modes in electric power networks is conditioned by the increasing number of electrical receivers parental to non-linear distortions (variable-frequency electric drive, LED-based lightning and so on). Higher harmonic components increase power and efficiency loss in current carrying parts, result in overheating of conductors and intense insulation deterioration, can cause resonance overvoltage and automation equipment malfunctions. Due to digitalization of the electric power industry it is necessary to develop methods of receiving, processing and digital communication on system state variables (currents, voltage, power), including nonsinusoidal modes. Wavelet transform is wider applied to analyze complex harmonic processes in electric power industry in conditions of transient modes. The paper introduces calculation methods of integrated indexes of electric power system modes – currents, voltage and power in the presence of electrical receivers with non-linear current-voltage characteristics. The method is based on Parseval equality and allows calculating via wavelet coefficients received by transformation of the initial stream of transient values of currents and voltages. Herewith the issue of data compressing is solved when transmitting digital information. The method allows determining the variables of every frequency component, interpreting the data in the three-dimensional scale (peak values, frequency and time) which will be used in choosing activities for higher harmonics filtration to reduce the loss in current carring parts.

In a number of EU countries medium voltage networks operate in the compensated neutral mode. In that case an arc suppression coil is commonly shunted with a resistor. The most common type of damage to such networks is a single phase-to-ground fault. The paper presents the method for two stage identification of a line where the fault has occured. The first stage is based on the analysis of high frequency components arising under transients. At the first stage a continuous wavelet transform is used to find frequencies. The second stage involves an analysis of the steady-state mode of a single phase-to-ground fault. Based on the energy spectrum of higher harmonics a damaged line is detected. To determine the energy spectrum at the second stage of the work a wavelet packet transform is applied. Wavelet transform has a number of advantages compared with short-time Fourier transform (STFT), particularly when analyzing non-stationary modes. The proposed method can be implemented to organize digital protection against ground faults.

One of the key indicators of the energy efficiency of electrical power systems should include the level of electric power losses. In a market economy, the significance of losses increases, since the cost of losses is an essential component of the tariff. One of the effective measures to reduce power network losses is reactive power compensation. However, the cost of compensating devices used for this purpose disagree with the task of reducing electric energy losses. The paper describes the effect of changing the capacity of static capacitor banks on the value of losses in the network with variation in the number of sections and the type of annual reactive load curves. The effect of the number of capacitor bank sections on the maximum reduction of annual reactive power losses in the network is analyzed. For the linearized load graphs, the relations for the values of natural losses in the capacitor banks are obtained, as well as expressions applicable to estimate the reduction of losses in the network. The conclusion is drawn that full reactive power compensation is impractical in most cases. The dependence of loss reduction on the power of capacitor banks reaches the maximum at the point where the battery power is less than the load power. It is proved that significant reduction of the loss in reactive power transmission in the electrical network requires no more than 3-4 sections (the reduction is close to 100 percent), and a 90 percent reduction in a wide range of load curves can be achieved with two sections..

The paper presents an algorithm for frequency decomposition of daily load graphs based on a discrete wavelet transform. This algorithm makes it possible to choose the optimal type of wavelet function, optimal level and wavelet decomposition tree. The inverse wavelet transform (recovery) along a single branch of the approximating coefficient allows obtaining the lowfrequency component of the power graph for selecting the optimal mode of the hybrid energy storage battery. The detailing branch of the wavelet coefficients determines the operating mode of the supercapacitor. A numerical experiment is built on the basis of data obtained using certified equipment

This paper presents the calculation of non-stationary non-sinusoidal mode of the power supply system (PSS) under the condition of current resonance (parallel resonance). Evaluation of the need for higher harmonics (HH) filtering was carried out. To achieve this, measurements of the actual level of HH and other unified power quality indexes were conducted, and oscillograms of the network mode parameters and HH spectrum were constructed. The measurement of unified power quality indexes was carried out with certified and calibrated power quality analyzers Metrel 2792A. These instruments satisfy the effective world standards on power quality and other reference documentation. Resonance frequencies where resonance modes emergence is possible were determined by calculation. Maximum overvoltage ratios for different points of the examined PSS were also determined.

Долгих с.А. гороВой В. е. поплАВсКАя Омский государственный технический университет, г.Омск АнАлиз Дополнительных потерь от Высших гАрмониК В сетях 380 В с помощьЮ АлгоритмоВ пАКетного ВейВлет-преоБрАзоВАния в работе представлена методика анализа нестационарных несинусоидальных режимов систем электроснабжения на основе пакетного вейвлет-преобразования. вейвлет-преобразование, в отличие от оконного преобразования фурье, позволяет производить анализ высших гармоник в трехмерной плоскости (амплитуда, частота, время).Отсутствие необходимости выбора ширины окна при реализации вейвлет-преобразования позволяет избежать негативного эффекта растекания спектра.Применение вейвлет-преобразования для расчета высших гармоник позволит повысить точность

In this article the method of automatic setup of the adjustable arc-suppressing reactor using a surge characteristic of a circuit of the zero sequence of a distributive network for determination of natural frequency and parameters of a circuit is considered. In this method it is used wavelet conversion and the nonparametric analysis for determination of natural frequency of a circuit of the zero sequence. In the article results of operation of a method of automatic setup of the arc-suppressing reactor when using different algorithms of the nonparametric analysis in case of determination of natural frequency are provided.