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E-Journal N3(47) 2020



0 Efficiency Investigation of Metallized Film Capacitor Electrodes Segmentation Patterns
Authors: Ivanov I.O., Belko V.O., Glivenko D.Y., Feklistov E.G., Kulbako K.A. Peter the Great St. Petersburg Polytechnic University St. Petersburg, Russian Federation
  Abstract: The results of theoretical efficiency investigation of metallized film capacitor electrodes segmen-tation patterns are presented in this article. The aim of present investigation was the most effec-tive patterns configuration determination using by numerical simulation method. The experi-mental investigation method of metallized film capacitor electrodes electrodynamic destruction was developed to reach the needed scope. This method differs from the known methods by us-ing samples of metallized polymer film with different segmentation patterns instead of real ca-pacitors. Based on experimental results the numerical model of segmented electrodes electrody-namic destruction was developed using by COMSOL Multiphysics software. This numerical model allows to investigate different segmentation pattern’s efficiency during self-healing pro-cess (recovery of operating ability after dielectric breakdown) and to determine metallization’s electrical parameters without experimental investigations. Existing and novel types of segmented electrodes for metallized film capacitors were investigated. The dependence of electrodynamic destruction energy, i.e. energy needed to breakdown channel isolating, versus destruction time was used as a criterion of segmentation pattern efficiency. Advantages and disadvantages of in-vestigated electrodes segmentation types were determined. The most important result is the best pattern configuration determination. It was found that bridge-diamond segmentation is the most effective patterns configuration for metallized film capacitor’s application. The significance of the obtained results is practical application in capacitor’s manufacturing ability. The developed numerical model and investigation results can be used in design of new metallized film capaci-tors types with high specific characteristics.
  Keywords: metallized film capacitor, segmented electrodes, self-healing, electrodynamic destruction, numerical simulation.
DOI: 10.5281/zenodo.4018908
1 Rotor Flux Controller for Induction Machines Considering Main Inductance Saturation
Authors: Diachenko G. Dnipro University of Technology Dnipro, Ukraine
  Abstract: This paper discusses the problem of controlling electromechanical systems with maximum per-formance while maintaining accuracy and minimum power consumption. The objective of the study is to develop a law for regulating the coordinates of an electromechanical system, taking into account an energy-efficient algorithm for transferring the system from one operation point to another. An essential feature of the proposed solution is the possibility of applying the ap-proach in modern high-speed electromechanical systems operating mainly in transient modes, without providing additional requirements for the digital part. The objective is achieved through the use of the law of the rotor flux generation augmented with adaptive low-pass filtering of the flux reference at each sampling step. The proposed method is investigated in both steady-state and dynamic modes of operation using laboratory experiments with a 370-W induction machine. With appropriate control of the change rate of the magnetic flux, the losses during the full oper-ating cycle with changes in the torque can be significantly reduced compared to the conventional approach. The varying load is typical for the electromechanical systems with a variable moment of inertia and requirements for the positioning accuracy. The most critical result of the study is the reduction of the minimum possible cycle time, at which the expediency of using loss-minimizing control methods remains actual. The significance of the results obtained is in the re-duction of losses while maintaining the required torque, contributing to the more efficient opera-tion of this machine type.
  Keywords: dynamic operation, energy efficiency, induction machine, optimization, adaptive filtering.
DOI: 10.5281/zenodo.4018933
2 Research on the Impact of Distributed Generation on Slow Changes of Voltage Profiles in Low Voltage Electrical Networks
Authors: Vieru D., Institute of Power Engineering, Chisinau, Republic of Moldova
  Abstract: The article considers the issue of assessing the impact on the mode of the share of distributed generation, after connecting of low-power photovoltaic installations to the low-voltage network. The purpose of the article is to substantiate the procedure for calculating the mode in an electric network with loads and distributed generation sources to assess the change in the voltage profile in the transmission line depending on the generating power of photovoltaic installations and changes the load curve in the networks. For the analysis of the network regime it was proposed to use the loop currents method. This from the start highlights the currents in loads and the currents of the sources the network. The matrix form for presenting the voltage equilibrium equations was applied, which was also used to calculate the loop currents of the power line circuits. The object of the research was selected the low voltage power line presented in the single-wire topology with distributed loads and sources, which includes 24 consumers and 24 generation sources. A lower impact of distributed generation has been established with smaller in-line voltage deviations at low consumption, and at high consumption the voltage deviations can exceed the allowable values stipulated in the normative documents. Following the limitation of these deviations in the limit of the admissible values, the recommendation was formulated to limit the power of the distributed sources to the level of about 30% of the power consumed in the peak hours. This will maintain electricity quality indices in all load regimes.
  Keywords: loop current method, power quality, voltage deviation, power limitation of generation sources.
DOI: 10.5281/zenodo.4028507
3 Multi-Level Estimation of the Heat Transfer Processes Efficiency in the Power Plants Elements
Authors: Kuznetsov V.V. Admiral Makarov National University of Shipbuilding Мykolaiv, Ukraine
  Abstract: The increase of power plants efficiency by improving the processes of heat and mass transfer of the working fluid between their elements is a relevant problem. The influence of the heat transfer processes intensity on the values of the simple and complex cycles of power plants efficiency has been revealed. The most significant results of the work are: the dependences to determine the efficiency of heat conversion in power plants of simple and complex cycles, which take into account the thermal and hydrodynamic efficiency of the elements included in them have been proposed; to ensure the highest possible efficiency of heat transfer processes in the elements of power plants, the following levels have been proposed: heat transfer in a power plant element; heat exchange in the element of the power plant; heat transfer between the elements of the power plant. The significance of the obtained results lies in the possibility to increase the power plants efficiency at the design and modernization stages using the presented dependencies, which take into account the thermal and the hydrodynamic efficiency of heat transfer between the elements of the plants. According to the proposed dependencies, an assessment of the efficiency of heat conversion in a gas turbine plant with a heat recovery boiler operating on a steam turbine has been carried out. It has been found that due to the intensification of heat transfer along the gas side of the boiler, it is possible to increase the heat efficiency from 0.516 to 0.752.
  Keywords: efficiency, heat, intensification, element, power plant.
DOI: 10.5281/zenodo.4018947
4 Extended Schedule of Heating Regulation: Assessment of the Impact on the Efficiency of Steam Turbine CHP Plants
Authors: Pyatin A.A. Kirov branch of PJSC "T Plus", Kirov, Russian Federation Suvorov D.M. Vyatka State University, Kirov, Russian Federation
  Abstract: The aim of the work is to study the energy efficiency of using an extended schedule of heating regulation when using it for a model district heating system connected to the CHP. The extended schedule of heating regulation ensures the maximum use of the thermal potential of the heat transfer agent and the minimum energy costs for its transport. The assessment of the impact of the extended schedule on the energy efficiency of the CHPP operation was carried out by using an adequate mathematical model of the heat supply system in a generalized form. It was deter-mined that when switching to an extended schedule, the specific energy production for heat consumption in a wide range of changes in the district heating coefficient of a model CHPP in-creases by 1-2% when working on an electrical schedule and by 4-6% when working on a ther-mal schedule. The calculation of the modes of a model CHPP with a fixed design heat load of the CHPP and constant electric power showed that the transition to an extended schedule leads to fuel savings of up to 4.5% during the heating period. Calculations showed that a decrease in heat supply during the transition to new methods of regulation is unprofitable for thermal power plants; therefore, tariffing in the field of thermal energy requires changes, including the transi-tion to two-part tariffs.The results obtained are important for assessing the effectiveness of the transition of heat supply systems to modern schedules of quantitative and qualitative regulation.
  Keywords: heat supply system, heating load, heating regulation, temperature schedule, extended schedule of regulation, CHPР, specific consumption, two-part tariff.
DOI: 10.5281/zenodo.4018949
5 Organization of Low-Temperature Poor Combustion of Recycled Gas
Authors: Bachev N.L., Shilova A.A., Matyunin O.O., Bulbovich R.V. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: When developing a combustion chamber as a part of recycling micro-gas turbine plants, it is usually performed as a two-zone one. The purpose of this work is to substantiate the possibility of organizing low-temperature stable combustion of a lean mixture in a single-zone combustion chamber as a part of recycling gas turbine power plants. To achieve this goal, the issues of ex-panding the lower combustion limit due to external heating of the ballasted fuel gas before it is fed into the combustion chamber are considered for the first time. The regime and weight and size characteristics of the fuel gas recuperators included in the installation are also considered. Calculations of the operating parameters of the installation showed that with an increase in the supply temperature of the utilized gas to 600...800 K, stable combustion can be ensured at the lower limit at temperatures of 900...1200 K. The characteristics of tubular and plate recuperators along the fuel gas line were analyzed using the available statistical characteristics. It is shown that in recycling power plants with capacity of up to 200 kW, it is advisable to use plate finned recuperators with thermal power of up to 10 kW and a heat exchange surface of up to 1.7 m2. The studies carried out enables us to formulate the conclusion that organization of low-temperature stable combustion with external heating of fuel gas makes it possible to develop single-zone uncooled combustion chambers as a part of gas turbine power plants.
  Keywords: fuel gas recycling, single-zone non-cooling combustion chamber, heated fuel gas, heater, sustainable combustion at a poor limit.
DOI: 10.5281/zenodo.4018968
6 Robust Short-Term Wind Speed Forecasting Using Adaptive Shallow Neural Networks
Authors: P.V. Matrenin, V.Z. Manusov, E.A. Igumnova Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: Wind speed forecasting is necessary to integrate wind farms into power systems. In the past ten years, the forecasting models have become increasingly complex due to the development of arti-ficial intelligence methods and computing power. Simultaneously, the robustness of models has decreased since complex models have a high risk of overfitting and decline in the accuracy if working conditions change significantly. This work aims to develop a machine learning model for short-term wind speed forecasting with acceptable accuracy but high robustness and the pos-sibility of automatic online retraining. A shallow multilayer perceptron, trained only on retro-spective data on wind speed, is proposed. The most significant results are combining simple neu-ral network architecture with ReLU activation function, Adam training method developed for deep neural networks; and the automatic hyper-parameters selection using Grid search with open upper bounds. The model was trained on the data of the autumn period and tested on the winter data. A comparison was made with the simplest and most robust adaptive forecasting methods: Brown and Holt models. The significance of the obtained results is that shallow neural networks using ReLU, Adam, and Grid search are practically not inferior to adaptive models in terms of tuning speed and the risk of subsequent differences in accuracy between training data and data supplied during operation. At the same time, shallow neural networks make it possible to obtain more accurate forecasts, and due to their small size, they are trained quickly; and retraining can be performed automatically when new data arrives.
  Keywords: short-term forecasting, wind energy, adaptive methods, shallow neural network.
DOI: 10.5281/zenodo.4018960
7 Power Distribution Laws Modeling of Wind Power and Solar Stations
Authors: Manusov V. Z., Khaldarov Sh. K. Novosibirsk State Technical University (NSTU) Novosibirsk, Russian Federation
  Abstract: Despite the obvious advantages of renewable and alternative energy sources (RAES) the main unresolved problem is the issue of the variability of the generated capacity of these power plants. It is difficult for energy system operators to determine how much per unit of time RAES are ready to provide capacity and energy. It does not allow considering such sources as full-fledged participants in power and electricity market. It is a big obstacle to investment in renewable energy projects. At the same time, the generated power of these stations depends on the natural conditions at a particular geographic point, the level of wind speed and solar insolation. The patterns of these parameters depend on the time of year, locality and are purely probabilistic in nature. The research purpose is to build distribution law models that can describe not only the data of solar insolation and wind speed, but also the RAES generated power. This goal has been achieved by methods of estimating the distribution law parameters and testing statistical hypotheses. The most important result is the identification of the basic distribution laws describing the probabilities of solar insolation and wind speed. For the considering area the laws of the 3rd kind beta distributions family and their mixtures better describe these data than the widespread Weibull's law. The same laws are applicable to RAES generated power. It allows to estimate the share of renewable energy in the total energy systems more accurately and helps system operators to predict output power of RAES.
  Keywords: probability distribution laws, output power probability distribution, third kind beta distribution, renewable and alternative energy sources.
DOI: 10.5281/zenodo.401898
8 Photoelectric Water Heaters Use in Hot Climate Conditions
Authors: Frid S.E., Lisitskaya N.V., Tarasenko A.B., Frolova N.D., Suleimanov M.Zh. Joint Institute for High Temperatures of the Russian Academy of Sciences Moscow, Russian Federation
  Abstract: This paper is devoted to the hot water production using photoelectric modules. The research goal was to estimate required photovoltaic array peak power to provide necessary hot water amount for an individual residential building in Uzbekistan climate conditions. To achieve this goal, the water heater operation has been simulated with TRNSYS software using data from NASA POWER meteorology database. To verify photovoltaic water heater mathematical models three-month experiment has been conducted. Operation with and without maximum power point tracking controller was considered. The main results are approximation equations, which were constructed basing on simulation outcome to estimate the required photovoltaic array power without numerical calculations for the region. As for electric boilers, consuming energy generated by traditional thermal power plants photovoltaic water heaters have been still considered inefficient and quite expensive. However solar collectors market growth slowdown and substantial decrease of photovoltaic panels cost make the heat generation by photovoltaic panels economically justified. Such photovoltaic panels application can be proposed as alternative to thermal and optical method of solar radiation concentration in solar heaters. The main advantage is a possibility to obtain any temperature from the generated electricity without limitations concerned with the coolant presence in the system The obtained results significance is concerned with highlighting of photovoltaic heating systems technical and economic competitiveness for some applications and with simplified calculation technique to estimate system composition for different climate conditions.
  Keywords: solar water heater, photovoltaic panel, controller, maximum power point tracking, mathematical model, solar fraction, concentrator.
DOI: 10.5281/zenodo.4018982
9 Economic Incentives for the Modernization of the Electricity Distribution System Operators' Network Infrastructure
Authors: Serebrennikov В.S. Institute of Economics and Forecasting of Ukraine's National Academy of Sciences Kyiv, Ukraine Petrova K.H., Serebrennikov S.V., Savelenko I.V. Central Ukrainian National Technical University Kropyvnytskyi, Ukraine
  Abstract: The paper aimed at improving an economic mechanism for incentivizing distribution system operators to retrofit electricity networks and provide better services. The suggested approach envisages setting up operators' profitability relating to their rating scores, which were calculated considering essential criteria, in particular technical level of networks, efficiency, congestion, reliability, innovativeness, and quality of electricity. For this purpose, operators were ranked by the rating scores that allowed to elaborate methodology for distribution tariffs calculation individually. The essential findings: comprehensive assessment and ranking were based on an analysis of 20 key performance indicators of the networks' technical level; application of additive convolution considering the significance of indicators by Fishburn's weighting approach ensured their proper aggregation; using the principles of fuzzy logic, the aggregated values for the technical level of network infrastructure were calculated. The minimum tariff rates were computed for each operator according to the break-even point, with the maximum tariff rate being equal for the whole sample. A linear functional transformation provided a transition from the aggregated scores to specific tariff rates. Consequently, the best-rated operators received the maximum tariff rate, and the less-rated operators received relevantly lower rates. By varying the slope of the suggested tariff function, one can adjust the dynamics of the tariff rate change. The assessment of 24 operators allowed to verify the elaborated methodology for distribution tariff setting. The application of unbiased rating assessment by a set of designed sector-specific indicators allowed setting up adequate and efficient tariff rates aimed at incentivizing network upgrades.
  Keywords: distribution system operator, electricity network, tariff policy, ranking criteria, ranking score, tariff function.
DOI: 10.5281/zenodo.4018972
10 Reflection of Production and Energy Inter-Sectoral Relations in the Model of Analysis of Territorial Multisector Objects (ATMO)
Authors: Samkov T.L. Siberian State University of Telecommunications and Information Sciences Novosibirsk, Russian Federation
  Abstract: The aim of the work is creation of a block of intersectoral production balance as part of the Analysis of Territorial Multisector Objects model. For one branch of industry it is achieved by uniting activity of manufacturing and trading enterprises meeting regional needs, including import and export. The concept of technological coefficient is corrected and the notion of logistic coefficient is introduced. The main results are as follows: the influence of government purchases and consumption in the sphere of small business is defined; methods of using R&D funds to change resource and material consumption in production and trade are presented. Each variable in the model has three dimensions, compiled by parent and child coordinates. The variables are split into manufacturing and trading components with indices. Macroeconomic technological and investment restrictions of complete demand satisfaction for economic entities in the region are developed. The service consumption variable is an indicator of full coverage of regional needs in industrial products. It is positive when other needs of regional industry, trade and households, as well as in other regions and abroad, are satisfied. Framework conditions affecting regional economy through fuel and energy complex by decreasing energy and electrical intensity in industry and trade and by the growth of their exports are developed with reference to payment for its consumption in households. The importance of work is defined by the model implementation by simple software of object-oriented languages, using OLAP (data hypercube) to store variables, and by practical and market orientation of this software.
  Keywords: Leontief’s model, production, intersectoral, balance, industrial, trade, region, resource intensity, material intensity, fuel and energy complex (FEC).
DOI: 10.5281/zenodo.4018993
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