Volume 5, Number 1 (2019)
Physical Modeling of Power Unit in Power Plant with
Auxiliary Transformer
Heorhiy Lysiak, Olena Pastukh , Bohdan Kharchyshyn
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: March 22, 2019. Revised: April 03, 2019. Accepted: May 23, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
The article shows the option of the first degree transformation scheme in auxiliary power supply systems of the power unit (PU). The power supply to the auxiliary receivers is carried out from the generator through the working and additional working auxiliary transformers (AAT). The method of switching on the latter one provides its operation in the source mode set by the PU current load. Experiments were carried out on a static physical model of the scheme fragment of the auxiliary power supply system with an AAT. It is confirmed that its natural properties, in contrast to the traditional schemes, provide during the normal modes, modes of external short circuits the level of voltage on the busbars, sufficient for the reliable operation of their electrical receivers. The possibility of effective research with the use of appropriate mathematical and digital models has been proved. The high adequacy of the results has been confirmed.
Keywords: power plant; auxiliary transformer; power unit; diagram.
Література – 12.
Construction of Empirical Models of Complex Oscillation Processes with
Non-Multiple Frequencies Based on the Principles of Genetic Algorithms
Mykhailo Horbiychuk, Olha Bila , Nataliia Lazoriv
Ivano-Frankivsk National Technical University of Oil and Gas, 15, Karpatska Str., Ivano-Frankivsk, 76019, Ukraine
Received: October 30, 2018. Revised: December 10, 2018. Accepted: February 28, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
A method for constructing the empirical models of complex processes has been developed on the basis of genetic algorithms which, compared to the inductive method of self-organization of models, significantly reduces computer time for their implementation. An approach has been used that allows a complex model to be considered as a composition of three components, i.e. a linear trend, an oscillatory component with non-multiple frequencies and a regression equation which simplifies the process of building complex models. To implement the proposed method, algorithms and software have been developed based on a specific example of the dependence of the water level in the river. The Dniester River weather conditions show that a model built on the basis of the proposed method describes the behavior of complex processes with sufficient accuracy. The resulting empirical model can be used to predict the water level depending on weather conditions.
Keywords: complex process; empirical model; unpredictable frequencies; genetic algorithm.
Література – 16.
Virtual Source of Reactive Power in Electricity Supply Systems
of Household Consumers
Mykhailo Korchak , Olha Sivakova, Yevhen Fediv
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: February 12, 2019. Revised: April 08, 2019. Accepted: April 18, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
It is proposed to include the principle of distributed generation of reactive power in the basic principles of constructing smart microgrids for non-commercial facilities. Individual reactive power compensation devices should be installed for its implementation at the points of final distribution of electricity networks of buildings and structures. As a result, in addition to the effect of reducing the losses of electricity in distribution networks from the flow of reactive component currents, it is possible to create virtual sources of reactive power as an auxiliary resource at the disposal of the distribution system operator for solving the problem of providing a balance of reactive power in normal and post-accidental transient operational modes for reliable and high-quality power supply. The article substantiates the expediency and expected effect of reactive power compensation in the electric grids of civil engineering facilities.
Keywords: power supply systems; reactive power; virtual power plant; virtual reactive power plant; reactive power compensation.
Література – 8.
Computer-Aided System for Monitoring and Planning of Actions to Increase Machine-Building Enterprises Energy Efficiency
Nataliya Stupnytska
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: April 08, 2019. Revised: April 18, 2019. Accepted: May 20, 2019.
© 2019 The Author. Published by Lviv Polytechnic National University.
Abstract
The article describes mathematical model of analyses the energy use costs efficiency (depending on the type and volume of products produced by the machine-building enterprise, the consumption of certain types of energy resources and their use in specific production processes, etc.). Methodology and mathematical model of the plan for modernization of industrial production energy-consuming processes has been developed. Estimation of energy saving actions efficiency is proposed by calculation of the ratio of energy consumption cost reduction to the cost of installation works and materials related with the implementation of these actions. The article outlines problem-oriented classification of energy-consuming machine-building production processes and actions intended to reduce the specific energy machine-building enterprise consumption. The algorithm and program realization of the computer-aided system for monitoring and planning of actions to increase machine-building enterprises energy efficiency are proposed.
Keywords: mathematical model; energy efficiency monitoring; enterprise; energy saving.
Література – 8.
Influence of Type of Solar Modules Anchorages on
Power of Solar Power Station
Olena Savchenko, Khrystyna Kozak
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: April 09, 2019. Revised: April 23, 2019. Accepted: May 29, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
Electricity generation through solar power plants is one of the ways to Ukraine’s energy independence. The amount of electricity generated by a solar power plant depends on the intensity of the solar radiation entering onto the solar module, the total area of the solar modules, and their efficiency. The intensity of solar radiation entering the solar module depends directly on the type of the solar module anchorages. In this article, the intensity of solar radiation, which enters onto the solar modules with different types of anchorages, is determined. It is established that the highest intensity of solar radiation enters onto the solar modules, which have a dynamic mount with two-axle trackers. The difference between the dynamic type of fastening with one-axis and two-axis trackers is practically absent in the warm period of the year; in the cold period of the year, a dynamic mount with a two- axis tracker allows you to increase the amount of solar radiation entering the solar module to 30 %. Compared to a stationary anchorage, the dynamic anchorage of solar modules allows you to increase the intensity of solar radiation that enters onto the solar module to 67 %.
Keywords: solar power station; stationary anchorage; dynamic anchorage; one-axis tracker; two-axis tracker.
Література – 8.
Preparation of Papers for the Journal EECS
Selection of Functional Diagram of Air Multi-Compressor Control System
Roman Kokoshko , Oleksandr Kril, Bohdan Kril
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: May 05, 2019. Revised: June 04, 2019. Accepted: June 11, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
Compressed air generation systems are a necessary facility for most enterprises; they also belong to the most energy-consuming equipment category. Study of transients of these systems’ operation is a prerequisite for creating new, more efficient algorithms of multi-compressor control systems. The paper presents the results of development and research of the operation algorithms of multi-compressor control systems. It is proposed that major solutions for the start/shutdown of specific compressors and changing their productivity should be implemented on a programmable logic controller that will function as the master for the local controllers of the individual compressors. A high-speed flow meter based on the differential pressure method for measuring the air flow-rate has been developed and implemented. The flow meter provides an auxiliary informative signal.
Keywords: multi-compressor system; compressor; compressed air; programmable logic controller; variable-frequency drive.
Література – 11.
Dynamic Modelling of Centrifugal Hydraulic Load
of Pumping Station Electric Drive
Vladyslav Lysiak , Mykhailo Oliinyk, Olha Sivakova, Myroslav Sabat
Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine
Received: January 24, 2019. Revised: February 19, 2019. Accepted: March 12, 2019.
© 2019 The Authors. Published by Lviv Polytechnic National University.
Abstract
The paper analyzes modern trends in modelling the centrifugal hydraulic load of the pumping station electric drive. It was found that a very simplified approach to the representation of one of the inextricably linked subsystems (hydraulic or electromechanical) is mostly used, which significantly reduces the possibility of a complex analysis of the processes in its individual elements. Models based on this approach can be effectively applied to solve highly specialized tasks and do not always give a clear idea of the state and modes of all the elements of the subsystems. This problem was partially solved while carrying out the simulation of the steady state modes of the pumping stations. The paper offers an advanced dynamic model of the centrifugal hydraulic load of the pumping station electric drive which enables studying the processes in the main elements of the centrifugal pump, taking into account its internal parameters and dependences of these parameters on the physical parameters of the fluid.
Keywords: electric drive; load; pumping station; centrifugal pump; hydraulic network.
Література – 16.
Вимоги до оформлення статей для подання до друку в журнал EECS
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