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PRZEGLĄD ELEKTROTECHNICZNY

Miesięcznik ISSN 0033-2097, e-ISSN 2449-9544 - rok powstania: 1919
Czasopismo Stowarzyszenia Elektryków Polskich (SEP)

The autonomous sources of energy supply for the liquidation of technogenic accidents
(ang. Autonomiczne źródła zasilania w energię przy likwidacji wypadków technogennych)

DOI:10.15199/48.2019.05.12
Мykhaylo ZAGIRNYAK Oleksii CHORNYI Iurii ZACHEPA Volodymyr CHENCHEVOI

Streszczenie
We have formed an approach to the creation of autonomous sources of energy supply to improve the reliability of power supply systems. We have proposed the solutions to energy supply systems enabling the decrease of influence of the unfavorable coincidence of climatic conditions or anthropogenic circumstances. The proposed solutions improve the conventional energy supply systems of the critical purpose objects. We have presented the principles of forming the local autonomous sources of energy supply, created in non-steady situations and completed with regular electric equipment that is in constant production operation at local enterprises or establishments. We have determined the limits for the stable operation of local autonomous sources of energy supply at the connection of typical consumers of electric power.
Słowa kluczowe: autonomous sources of energy supply, induction generator, dynamic loads.
Abstract
Zaproponowaliśmy podejście do tworzenia autonomicznych źródeł zaopatrzenia w energię w celu poprawy niezawodności systemów zasilania. Zaproponowaliśmy rozwiązania systemów zasilania w energię, które pozwalają na zmniejszenie wpływu niekorzystnej zbieżności warunków klimatycznych lub warunków antropogenicznych. Proponowane rozwiązania poprawiają konwencjonalne systemy zasilania energią obiektów o znaczeniu krytycznym. Zaprezentowaliśmy zasady tworzenia lokalnych autonomicznych źródeł zaopatrzenia w energię, stworzonych w niestabilnych sytuacjach i zbudowanych z klasycznego wyposażenia elektrycznego, które jest w ciągłej produkcji w lokalnych przedsiębiorstwach lub zakładach. Ustaliliśmy limity dla stabilnego funkcjonowania lokalnych autonomicznych źródeł zaopatrzenia w energię przy podłączeniu typowych odbiorców energii elektrycznej.
Keywords: autonomiczne źródła zaopatrzenia w energię, generator indukcyjny, obciążenia dynamiczne.
The problems of the improvement of the reliability of energy supply systems as a complex branched network of the generation, conversion, transmission of energy to consumers have become especially topical due to the realization of the fact that not only enterprises but also the social sphere of the society are vulnerable when the energy supply is disrupted even for a short time. The underestimation of this circumstance has already resulted in a number of big emergency situations of different nature [1, 2]. Unfavorable coincidence of climatic conditions or anthropogenic circumstances may result in creation of emergency situations caused by system disruption of energy supply to the critical-purpose objects. First of all, it is about emergency medical care facilities, heating networks and water supply and sewage systems as long absence of energy supply to them may cause serious and even tragic consequences. According to [3] (Fig.1), the number of catastrophic events in the world, of both technogenic and natural character, constantly grows. Fig. 1. Number of catastrophic events The liquidation of the consequences of accidents in energy supply systems requires great human and material resources. A guaranteed trouble-free energy supply can be practically inaccessible for most enterprises due to considerable capital expenditure at technical realization of particular solutions. A sufficiently simple solution to the problem is possible with the use of local autonomous sources of energy supply (ASE). However, technical problems have not been solved yet - the principal circuit designs, the organizational and technical measures providing ASE introduction during the minimal time. So, it is topical to create ASE based on the electric equipment and power plants of another functional purpose, to synthesize the system of their control providing energy generation for industrial and communal consumers during the elimination of anthropogeni [...]

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Bibliografia

[1] Fredrik R. Electricity Supply Reliability: Evaluation of Improvement Solutions for Existing Electricity Networks, Lund: Lund Institute of Technology, 2005.
[2] Farah P.D. "Sustainable Energy Investments and National Security: Arbitration and Negotiation Issues", Journal of world energy law and business, 2015, vol. 8, no. 6, pp. 34-49.
[3] Swiss Re Institute: Natural Catastrophes and Man-Made Disasters in 2016: A Year of Widespread Damages. Sigma no 2/2017. Zurich: Swiss Re Institute.
[4] Shokarov D., Zachepa Iu., Zachepa N., Chorna V. and Susyk D. The Control of the Traction Asynchronous Electric Drive of the Miner Electric Locomotive with Secure Dual-mode Supply // Proceedings of International IEEE Conference MEES 2017, Kremenchuk, Ukraine, pp. 132-135, ISBN: 978-1-5386-1750-2.
[5] Zagirnyak M., Zachepa Iu., Chenchevoy V. "Estimation of induction generator overload capacity under connected direct current consumers", Acta Technica, Praga: Institute of Thermomechanics AS CR, 2014, vol. 59 (2014), no 2, pp. 149- 169, ISSN 0001-7043.

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Compare of shielding effectiveness for building materials - DOI:10.15199/48.2019.05.33

Marek PAVLÍK

With the exponential growth of wireless technologies nowadays, there is an increase in the presence and use of number of mobile communications, excessive installation of mobile phone antenna masts, and broadcasting radio and TV transmitters, and even satellite systems. The mobile phone shielding device was primarily used in some special department (e.g. the army or the security). However, in recent years, the mobile phone shielding device has been widely used in the meeting room, examination room, library, cinema, hospital, court and church. Radio frequency used in mobile communication has the ability to penetrate through semi-solid substances like meat and living tissue. The researchers conducted shows that the electromagnetic wave produce by the mobile phone might cause adverse effect to human especially at place near the ear region. Table I below illustrates some typical artificial sources of electromagnetic fields with frequency and intensity. Natural sources like the magnetic field of the earth are not included [1, 2, 3]. The effects of electromagnetic field on organism have been the issue concerned by environmental, electrical, biological, medical and related subjects. From the perspective of the dielectric properties of organisms, the pulsed electromagnetic field may cause a stronger influence on organism. So since the last century, the academic and clinical medicine have shown an interest in biological effects of pulsed electromagnetic fields on organism, with the deepening of the research, many valuable results have been acquired: researches not only have established the model of cell membrane potential, but also have found the theoretical basis for the clinical application of magnetic field to treat cancer [2, 3, 4, 15, 16]. Everyone is affected by electromagnetic radiation and radio frequency radiation from all appliances, cell phones, wifi devices, cordless phones, computers, laptops, and television waves. Ele więcej »

Decrease of the thermal overloads of a variable-frequency electric drive at damages in the electric circuit of an induction motor stator - DOI:10.15199/48.2019.05.11

Mykhaylo ZAGIRNYAK Andrii KALINOV Viacheslav MELNYKOV

Damages in the stator power electric circuits stand out of the main causes of induction motors (IM) failure. Therefore, according to the research [1], the cause of 25% - 40% of IM failures consists in turn-to-turn shorting resulting from the stator winding insulation damages. The occurrence of turnto- turn shorting in the windings of IM of alternating current variable-frequency electric drives (ED) results in local overheat of particular semiconductor switches of frequency convertors (FC). A break of the whole winding or a parallel section of IM phase winding is a logical development of the turn-to-turn shorting. For IM with the number of parallel winding paths exceeding four a break of one path results in the asymmetry of the stator winding three-phase system and usually ends in the motor emergency outage. ED operation with asymmetric windings of the stator phases may also result in thermal overloads of particular FC switches and IM phases [2]. Timely detection and elimination of IM damages at the early stages of their development may increase the life span of the technological equipment and reduce the financial losses caused by unpredictable disconnection of the equipment resulting from technological faults or IM failure. Thus, fault-tolerant control systems (FTC) are of special interest as they are able to detect various types of damages at the initial stage and operatively adapt the control law in such a way that ED functionality remains for a long time till there is a possibility of IM repair or change [3]. There are two groups of the conventional methods of fault-tolerant control of IM with damages in the stator power electric circuit. The first group includes methods only allowing the detection of occurring damages and the termination of ED operation at their further development [4, 5]. This group may also include software redundancy methods based on the switch between the control algorithms from complex to simpler więcej »

Determination of a crack's size on the basis of the nondestructive testing with eddy currents using metaheuristics - DOI:10.15199/48.2019.05.07

Marko JESENIK Anton HAMLER Miloš BEKOVIĆ Mladen TRLEP

Non-destructive testing is now used more and more often for the testing of materials [1-4]. One of nondestructive methods is testing using eddy currents. In this testing case we measure the magnetic flux density within the vicinity of the tested material which has changed because of the material damage [5-9]. Our problem is a conductive plate with a crack, and is limited to a crack of rectangular geometry having a constant depth. The crack’s position, crack’s length l, crack’s depth d and crack’s width w must be found. The first part of the research was searching for the crack’s position and length. These were found by consideration of the differences between the measured magnetic flux densities and the neighbouring measurement points. Second, the more complex part of the research was searching for the crack’s depth and width. We used differential evolution [10-13] for determining the crack’s depth and width. The Finite Element Method (FEM) [1, 3] model was used for the evaluation of cost function. Measurements Measurements were carried out for two test-cases. These were two plates, the first made of aluminium and the second of austenitic stainless steel, both of 30 mm thickness and dimensions of 330 x 285 mm. The cracks of both plates were the same and had lengths of 40 mm, depths of 10 mm, and widths of 0.5 mm. The cracks were in the middle of their respective plates. The used measuring system, together with the test plate, is shown in Fig. 1. Fig.1. Measuring system The excitation coil had an inner diameter of 36.8 mm, an outer diameter of 53 mm, and a height of 56 mm. It had 566 turns and was supplied with a sinusoidal current of 1A and a frequency of 500 Hz. An axial Hall-probe HS-AGB5-4805 was placed within a bore at the centre of the coil. The Hall probe measured the z component of the magnetic flux density. When, in the continuation of the paper, we talk about the magne więcej »

Determination of salient pole synchronous machines electromagnetic parameters from the SSFR test - DOI:10.15199/48.2019.05.39

Adam GOZDOWIAK

The electromagnetic parameters of a synchronous machine are most often determined during running tests from no-load and three phase short circuit tests [1]. These tests are carried out most often at the manufacturer of electrical machines at the test station, which is equipped with a properly selected drive and a constant voltage source. Typically, such equipment is sufficient to test machines with several poles and rated power not exceeding approximately 10 MVA. The problem is encountered when the power is higher and the number of pole pairs exceeds 20-30. Then the measurement of such a machine is difficult due to its dimensions and the lack of a suitable source of DC voltage. The SSFR (Standstill Frequency Response Test) measuring method [2], which does not require a separate source of direct voltage, can be opposed to these difficulties and can be carried out on the site, eg after being built in a power plant. This method consists in forcing the voltage at a given frequency, at the right position of the rotor (direct and quadrature axis) and with the open or closed excitation circuit. Initially, it was only used to study synchronous machines with a cylindrical rotor (eg turbogenerators), but with its refinement and modification, it was also used in machines with rotor of salient pole [3-6]. Standstill Frequency Response test is used to determine the electromagnetic parameters such as the reactances and the time constants which can be utilized to compute the resistances and the inductances needed to prepare an equivalent machine circuit [1]. In this way new-created equivalent hydrogenerator model allows to predict the dynamic behaviour of the machine during the abnormal operating states. SSFR test is relatively cheaper than the preparation of no-load and sudden short circuit tests during the running test. The price of the standard test is determined by the auxiliary instruments included during the tests such as the oil więcej »

Effects of unreliability of electricity distribution systems for municipal customers in urban and rural areas - DOI:10.15199/48.2019.05.42

Kornelia BANASIK Andrzej Ł. CHOJNACKI

Electric power engineering is an indispensable component of civilization and economic infrastructure. Currently, almost all households located in the country are electrified. The increase in demand for power and electricity is a sign of the country's economic development. The problem of the reliability of the power system is such an important issue because of the requirements of the modern economy. The individual electricity recipient also has very high requirements regarding the quality and continuity of electricity supply. Possible interruptions in the supply of energy disorganize his life, expose him to material losses, and may even lead to a threat to his health or life. Such a situation forces constant development and modernization of distribution power grids. The purpose of this paper is to present the issue of losses to municipal consumers, which are the result of interruptions in the supply of electricity. As shown in the article [1], the municipal recipient incurs significant costs of failures, which constitute the sum of the costs of forced inactivity losses and the costs of damage. This issue is so important and interesting that the Authors analyzed the costs of losses to energy consumers occurring as a result of the failure of electrical power systems, classifying recipients for their place of residence: city and village. The analysis carried out in the publication [1] showed that there are quite large discrepancies between urban and rural recipients and using the average economic coefficient of forced inactivity for all municipal consumers leads to significant errors in the estimation of failures. In the conducted research, households and small farms that do not conduct business activity are considered to be municipal (individual) consumers. Although in recent years there has been development of rural areas and currently living standards in cities and villages are comparable, there is still a significant diffe więcej »

EIT detection methods of damage in landfills and flood embankments - DOI:10.15199/48.2019.05.13

Tomasz RYMARCZYK Grzegorz KŁOSOWSKI

The presented article describes a group of innovative methods enabling the identification of damage to landfills and flood embankments. These are methods based on electrical impedance tomography (EIT) [1], however, significantly improved by using original algorithms that enable reconstruction of tomographic images. In this study, three types of hybrid algorithms were considered:  generalized linear regression (GLR) [2],  generalized linear regression with stepwise regression (GLR-SR),  ElasticNET [3]. All three of the above statistical methods were used to reduce the number of predictors. In the considered EIT system, the input vector consists of 192 values of voltage drops taken due to the arrangement of 16 electrodes. The input vector reduced in this way was further used to train the artificial neural networks system (ANN) [4]. Among the tomographic methods, apart from the EIT, one can also be distinguished: electrical capacitance tomography [5-9], magnetoacoustics [10], multipath tomography [11] and others. In order to improve the imaging quality, various methods are used, mostly based on modern information techniques: fuzzy logic [12], GPU parallel computing [13], integer linear programming [14], etc. Flood is one of the most common and frequent natural disasters. Floods are the cause of many human dramas. One of the ways to protect the floodplains near landfills, rivers and water banks is to lift flood embankments. Thanks to this, you can temporarily raise the level of freshet over the main river bed and suppress the flood. However, higher water level accelerates the erosion of the top of the embankment or landfill barrier and can destroy it. In addition, given the insufficient filtration power of the embankment body, high water can lead to an increase in the number of leaks, which may lead to partial destruction of the flood bank. Despite significant achievements in the design of safe bunds więcej »

Electromagnetic field as an environmental factor affecting MCF-7 cell line in vitro - DOI:10.15199/48.2019.05.02

Anna KOZIOROWSKA Katarzyna KOZIOŁ Ewelina HAJDUGA Maria ROMEROWICZ-MISIELAK

The electromagnetic field (EMF) is defined as the energy state of the space that surrounds the electric charges in motion. The propagation of this energy takes place through electromagnetic radiation [8], which is characterized by the orderly and mutual interaction of magnetic and electric fields. The occurrence of electric charges with opposite signs results in the creation of an electric field [5], which characteristic magnitude is the intensity expressed in the SI system in newtons per coulombs. However, the intensity of the magnetic field is expressed in amperes per meter and is generated by the movement of these charges - the flow of electric current [5]. One of the main parameters describing the electromagnetic field is the frequency f, expressed in the SI system in hertz [Hz] and determining the variability of EMF over time [8]. There is a natural electromagnetic field in the environment, which is emitted by the Sun and Earth and artificial, resulting from the construction of infrastructure emitting fields of unprecedented frequencies - base stations of mobile telephony, high voltage transmission lines, transformer or radar stations, or radio navigation devices [6]. The rapid development of technology has led to an uncontrolled increase in the number of field emitters that overlap each other to create electromagnetic noise. All everyday equipment, powered from the industrial network, generates a 50 Hz field, while EMF in the radio and microwave range (100 kHz - 300 GHz) is produced, among others via TV and radio transmitters, cell phones or microwave ovens. The EMF is used in both diagnostics and therapy. The field used in medicine achieves the value of magnetic induction from picotesla to a few tesla, and the frequencies used assume values from 0 to gigahertz [9] Exposure of living organisms to EMF can cause various biological effects depending on the intensity, frequency, dose and time of exposure to EMF. It has więcej »

Further Results on Output Tracking for a Class of Uncertain High-Order Nonlinear Time-Delay Systems - DOI:10.15199/48.2019.05.22

Keylan ALIMHAN Maksat N. KALIMOLDAYEV Abilmajin A. ADAMOV Orken MAMYRBAYEV Nurbolat TASBOLATULY Andrzej SMOLARZ

The control design is one of the most relevant topics in nonlinear system theory, so a number of researchers have paid particular attention to it, for example, it can be seen in references [1-11]. The fundamental problem is to construct a feedback control law making the controlled output track a given reference signal as much as possible. The problem of global practical tracking for nonlinear state feedback systems was solved by the method of adding a power integrator [3,4] and using the idea of universal control [1,2]. However, the above results do not take into account time delays and their impact on the system as a whole. For example, in three-dimensional systems, delay is determined by the fact that the signals propagate at a finite speed and they need time to overcome distances [12]. Delay of the reaction to the signal and feedback with delay are inherent in many physical [13], chemical [14], climatic [15] and biological [16] objects and processes. In the study of systems with delay, it is important to know the values of time delays, the value of which largely determines the dynamics and properties of the system. Since time-delay exists widely in many practical systems such as electrical networks, microwave oscillator, and hydraulic systems, etc., and usually makes the considered system instable, to achieve some control objectives such as stabilization and trajectory tracking, the influence of time delay phenomenon should be considered. In view of these facts, it is meaningful and necessary to study control problems of accidental nonlinear systems with unknown parameters and time-delays. In recent years, by employing the Lyapunov-Krasovskii method to deal with the time-delay, control theory, and techniques for stabilization problem of time-delay nonlinear systems were greatly developed and advanced methods have been made; see, for instance, [17-21] and reference therein. Compared with study the stabilization problem więcej »

Gain Improvement of Dual-Band Circular Monopole Antenna for 2.45/5.5 GHz WLAN Applications - DOI:10.15199/48.2019.05.37

Suthasinee LAMULTREE Chalee JANSRI Chuwong PHONGCHAROENPANICH

With Rapid developments of modern wireless communications, various microwave technologies have been utilized for different applications, which make the microwave spectrum more crowded. Wireless fidelity has transformed in to the standard for wireless local area network (WLAN) communications in the 2.45 and 5.5 GHz ISM bands, with the frequency ranges from 2.4 to 2.485 GHz as well as 5.150-5.350 GHz, 5.470-5.725 GHz, and 5.725-5.850 GHz [1]. For system flexibility and feasibility, antennas that are capable to serve in both of the specified operation bands are highly attracted. For this reason, dualantennas are promoted to overwhelm the 2.45- and 5.5 GHz WLAN bands [2]-[10]. A dual-band antenna can be usually accomplished by utilizing two types of singlefrequency antennas for each band [8], and taking a dualfrequency antenna for two separate bands [5], [9]. For the two types of single-frequency antennas, two external feeding networks must be come up with these individual dual-band antennas, which probably entail some structural sophisticates into applications [8]-[9]. As mentioned above, an element to make up a dualband antenna is more suitable to employ a dual-frequency antenna. There are many techniques to design for WLAN dual-band, such as using quarter-wavelength resonant slots in different shapes, coplanar fed, parasitic elements, and defected ground plane [5]-[13]. Latterly, many researchers adopt an attention on printed slot antennas (PSA), since wide-slot antennas have two orthogonal resonance modes, which are combined to form a wide impedance bandwidth [14]. As reported for increasing impedance bandwidth, antennas with various shapes like circle, ellipse, and triangle were introduced [15]. In our previous work [12], we presented the design and implementation of dual band with partial ground plane (PGP); nonetheless, its gain is not high. Hence, a technique to enhance the radiation performance of a microstrip-fed ci więcej »

High speed imaging method for rotational speed calibration - DOI:10.15199/48.2019.05.43

Łukasz KĘDZIERSKI

Rotational speed calibration poses a general problem to users working with motors as there is no direct measurement standard (in a sense of a true embodiment of the unit [1]) one can rely upon like in the case of weight, length, time and so many other measurements. In such a case an indirect standard is needed. It is natural to use time as a measurement standard for rotational speed sensor calibration as the SI unit for rotational speed is radian per second [2]. However, it is common to use revolution per minute (rpm) as the unit for rotational speed (the calibration method proposed in this paper uses rpm as the preferred unit). It is an industry standard to use strobe light for the purpose of calibrating the sensors measuring rotational speed. This method is based upon the fact that when periodically moving object (such as a rotating shaft of the motor) is illuminated by a strobe light of frequency equal to the frequency of the object rotation, then the object appears to be stationary [3]. If the frequency of the strobe light can be accurately measured then the speed of rotation can be calibrated with the equal accuracy. The strobe light method suffers from two major drawbacks though. First is the aliasing - object appears to be stationary at a given frequency but it will look exactly the same when the frequency of the strobe light is doubled, tripled and so on. Second drawback is the accuracy of stroboscopes - even the top quality products when operating in rpm mode will introduce an inaccuracy of 0.02% ±1 rpm when measuring speeds above 1000 rpm [4]. High speed imaging method proposed in this paper doesn’t suffer from the aliasing and is more accurate thanks to the very precise internal clock. Test stand The test stand consists of VFD (Variable Frequency Drive) controlled asynchronous electric motor driving a shaft through a gearbox. The shaft of which the speed is measured can rotate within 500÷12000 rpm ran więcej »

Implementation of Resistorless Universal Biquad Filter with Electronic Controllability - DOI:10.15199/48.2019.05.36

Supayotin NA SONGKLA

There has been a growing interest to realize the analog active filter using active building block (ABB) [1-5]. The ABB based circuits contain minimum number of passive element. Also, the circuit can be cascaded without the using of external buffer circuit. Particularly, the universal filter which simultaneously gives several filter responses in the same circuit has been continuously proposed. This filter is significant in analog signal processing system such as in the three way crossover network, telephone decoder etc. [6-7]. The voltage-mode universal filers which provide simultaneously various filter responses in the same circuit topology have been recently proposed [8-24]. Some of the proposed filters in [9, 10, 11, 22] contain excessively number of active elements (more than two ABBs). The passive resistor is required for the proposed filter in [8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24]. In [8, 10, 11, 15, 16, 18, 19, 20, 22, 23, 24], the filter parameters, natural frequency and quality factor are not electronically controlled. Also, the quality factor is not tuned independently from the natural frequency [10, 11, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24]. The impedance at the input voltage node doesn’t exhibit high [12, 15, 16, 19, 20]. In this paper, the resistorless universal filter which simultaneously provides HP, BP, LP and BR functions is implemented. The proposed circuit is constructed from two M-CCCCTAs and two grounded capacitors. The possibility of electronically and independently adjusting of quality factor and natural frequency is achieved. Theory and Principle Basic Characteristics of M-CCCCTA The conventional CCCCTA is a five-terminal analogue active element. The names of the input and output terminal are represented as y, x, z and o terminals. The y-terminal is the voltage input port with high impedance. The x-terminal which contains controllable parasitic resistance (Rx) is więcej »

Improvement of dynamic characteristics of thermoresistive transducers with controlled heating - DOI:10.15199/48.2019.05.27

Oksana BOYKO Oleksandra HOTRA

Microprocessor sensory systems as a component of information and communication technologies are an integral attribute of human society at the present stage. The sphere of sensory systems application is constantly expanding. Special place belongs to sensors of temperature and humidity. These sensors are widely used in automated control systems at food and light industry, agriculture, oil and gas pipelines, medical and environmental monitoring systems [1-5]. Measuring the humidity and temperature of air and industrial gases is important for ensuring the quality of final products. For example, changing the temperature of gas in gas pipelines can cause condensation of water vapour, which leads to negative consequences, such as corrosion, the formation of aggressive chemicals, etc. Changing of temperature also influence the characteristics of different sensors, for example, of capacitive sensors [6]. In order to measure humidity the sensors based on polymeric or ceramic materials that are sensitive to humidity are used [7]. The measurement of low humidity (up to 20% RH) was not sufficiently investigated, and was accompanied with difficulties due to significant errors in the nonlinearity of humidity sensors. Modelling of polymer-based capacitive humidity sensors carried out in [8] allowed to explain the nature of nonlinearity and suggests a logarithmic relationship between the relative humidity and the output value of the sensor. The combination of the results of researches of humidity sensors (in particular their accuracy and calibration [9-10]) and temperature sensors (in particular linearization of the transfer function of thermoresistive transducers [11-12], cold-junction compensation in thermocouples [13]) will allow for comprehensive control of the parameters of technological processes. It is advisable to use integrated temperature and humidity sensors in which temperature compensation can improve the accuracy of humidity więcej »

Improving Efficiency of Full-Wave Electromagnetic Analysis of Grounding Systems Within Homogeneous Earth - DOI:10.15199/48.2019.05.03

Blagoja MARKOVSKI Leonid GRCEV Vesna ARNAUTOVSKI-TOSEVA Jasmina ANGELEVSKA KOSTADINOVSKA Andrijana KUHAR

The frequency dependent and transient characteristics of grounding systems are of interest in many engineering analyses related to electric power safety and lightning protection, where frequencies of interest range from dc to few MHz [1], and electromagnetic compatibility related studies, with frequencies of interest up to tens of MHz [2]. Different methods for modelling of grounding systems have been developed in the past few decades, based on electric circuit [3, 4], transmission line [5] and electromagnetic theory [6]. Among them, electromagnetic model provides most accurate results for all frequencies of interest. The most popular electromagnetic model is based on antenna theory and solution of electric field integral equations by the method of moments (MoM) [6, 7]. One difficulty in implementation of the mathematically exact solution for the electric field for semi-infinite conducting medium in practical problems is the numerical evaluation of singular, oscillatory and slow converging Sommerfeld integrals, which is numerically unstable and extremely time consuming procedure. To circumvent this problem in practical analysis, quasi-static [8, 9] or complex-images approximations [10, 11] are often employed, however, the governing approximations limit their validity to a certain upper frequency and system dimensions. Due to the lack of efficient full-wave model, the domain of applicability of these approximations as well as other approximate models has not been rigorously tested for wide range of parameters and complex configurations. Another common problem in the application of antenna theory based methods for analysis of buried conductors is that they may not provide exact solutions for low frequencies approaching 0 Hz. This is either due to improper treatment of the images of currents in conductors [9], or due to numerical instabilities often referred to as “low frequency breakdown". This paper presents efficien więcej »

IV Sympozjum "Młodzi. Technika. Przemysł."

IV Sympozjum "Młodzi. Technika. Przemysł." (MTP) odbyło się w dniach 7 - 10 marca 2019 roku w budynku Wydziału Elektrycznego Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie. Jego organizacji podjęły się: Akademickie Koło SEP przy WE ZUT oraz IEEE Student Branch Szczecin przy dużym wsparciu władz Wydziału. Wzięły w nim udział 3 środowiska: techniczne - reprezentowane przez władze i przedstawicieli akademickich, a także zaproszonych prelegentów; młodzieżowe - w skład którego wchodzili studenci i uczniowie szkół średnich oraz przemysłowe - reprezentowane przez przedstawicieli firm. Wydarzenie zostało objęte patronatem Marszałka Województwa Zachodniopomorskiego, Prezydenta Miasta Szczecin, SEP, IEEE, IEEE Young Professionals Poland, FSNT NOT Regionu Zachodniopomorskiego, Zachodniopomorskiego Uniwersytetu Technologicznego, Akademii Morskiej, Wydziału Elektrycznego ZUT, Parlamentu S więcej »

Justification of ice melting capacity on 6-10kV OPL distributing power networks based on fuzzy modeling - DOI:10.15199/48.2019.05.26

Oleksandr A. SAVCHENKO Oleksandr O. MIROSHNYK Stanislav V. DYUBKO Taras SHCHUR Paweł KOMADA Kanat MUSSABEKOV

As it is known [1], the key circuit parameters of ice melting are the value of active power losses per unit of wire length in the mode of melting deposits (melting capacity) and the time of melting deposits, which is a function of the melting capacity. When designing the ice melting schemes with using the special electric power plants of ice melting (limiting reactors, bearish autotransformers [2], iceprotected transformers [3]), which have recently used more often for harmonization of power system with the lines’ parameters. There is a problem of choosing an independent option of melting schemes (the melting capacity of deposits that must be provided by such a facility). The feasibility of mass industrial production of standardized installations for ice melting on 6-10 kV overhead power line (OPL) wires and a variety of parameters of electrical networks 6-10 kV lead to the need to solve this problem, taking into account factors of input data uncertainty. Approaches for designing of ice melting at 6-10 kV OPL electric distribution networks [1, 4] showed that the existing technical and economic models do not allow to take into account the effect of melting deposits power on cost of melting schemes characteristics and make selecting this option. In [5] we developed a single criterion technical and economic model for optimization the parameters of the ice melting schemes at 6-10 OPL using the reduced cost criterion, which takes into account the impact of melting capacity of deposits on such factors of the melting schemes as insufficient outputting of electrical energy to consumers during melting, electric power consumption for melting, the cost of electric power installations for ice melting, the cost of additional capacity of power transformer of the 110-35 / 6- 10 kV district substation. Basing on the model we carried out optimization of power ice melting, which should be provided by different electric power plants wi więcej »

Modeling and Control of multimachines System Using Fuzzy Logic - DOI:10.15199/48.2019.05.34

Taieb BESSAAD Rachid TALEB Djilali BENYOUCEF Abdelkader BELBOULA

AC machines, induction in particular have dominated the field of electric machines. Recently, researchers are interested in machines with a number of phases greater than three. These machines are often called «multiphase machines». This type of machine have large losses and to exploit these, it is possible to connect in series several machines supplied by a single static power converter with each machine in the group have an independent speed control. However, the use of multiphase converters associated with polyphase machines, generates additional degrees of freedom. Thanks to these, several polyphase machines can be connected in series in an appropriate transposition phases [1], [4]. For some applications, series connection of multiphases induction machines can be very interesting. The global system is defined as the domination of a series connected multi-machines mon-converter system (MSCS). This system consists of several machines connected in series in an appropriate transposition of phases. The whole system is supplied by a single converter via the first machine. The control of each machine must be independent of others [5], [7]. In [17], the author uses a classical PI controller to perform a speed control of series connected machines. However, PI controller parameters are highly affected by the system parameters, a temperature rise can cause a degradation of the control quality. Seen from this major drawback, our contribution is to change conventional controllers “PI" with fuzzy logic controllers and test its robustness. Modeling of Multi-machine System The drive system is composed by two induction machines. The first one is a symmetrical six-phase induction motor M(1) which its windings are series connected with that of a second three-phase induction motor M(2). The two motors are supplied by a single power converter which is a six-phase Voltage Source Inverter (VSI). Fig. 1 presents the connect więcej »

Optimization of coil geometry using Monte Carlo method with HTCondor and Microsoft Azure technologies - DOI:10.15999/48.2019.05.28

Bartosz SAWICKI Artur KRUPA

An important trend in modern computational science is certainly cloud computing. Although this term has been created by the marketing departments in early 2000’s, and a history of distributed and parallel processing in computer science is much longer, one could realize novelty in cloud computing approach. Utilization of commercially managed resources for scientific tasks has significant advantages, such as a flexibility to use different hardware, no need for infrastructure investments. On the other hand, important challenges are raised [1] and it is known that not all types the computing problems benefit from a loosely coupled architecture in the same way. Groups of problems, which could be easily transferred into the cloud infrastructure are independent simulations, sometimes called as an ’embarrassingly parallel’ problems. Sensitivity analysis [2], stochastic simulations [3] are just examples of the problems which require a large number of simulations. Another are DNA alignment in bioinformatics, 3D scene rendering in computer graphics or Monte Carlo methods, which are the main subject of this article. The Monte Carlo methods are based on probing parameters space with the use of a random generator. Applications of such simple but robust solution are wide, and they are especially compatible with the structure of the cloud services [4]. Stochastic optimization using Monte Carlo sampling is one of them [5]. In this paper, stochastic optimization technique is used to design the magnetic coil system. The developed simulation platform is constructed using HTCondor embedded in the Microsoft Azure environment as presented in Fig. 1. Finite element method solver has been constructed using FEniCS library as described later in the paper. Coil design problem is a test case, which could be also successfully solved using gradient optimization techniques. However it should be treated as a benchmarking tool to study e więcej »

Space vector modulation techniques for improved stator flux trajectory in direct torque control of induction motor - DOI:10.15199/48.2019.05.04

Goran RAFAJLOVSKI Mihail DIGALOVSKI Goga CVETKOVSKI

In direct torque vector control (DTC) systems, voltage source inverter (VSI) is describe in discrete mode as a source of constant amplitude voltage sources with strictly controlled direction, time duration and limited sample frequency. The output vector voltage vector may take up to seven different states and is altered in precisely specified time only at the command of given controlling signal. Therefore, the VSI dynamic state is discrete both in time and quantity. The stator flux space vector is used as a fundamental value in designing the control circuits of induction machine (IM). In this paper, therefore, the basic characteristics of stator flux space vector will be analysed in such a control concept for two different types of space vector modulation (SVM) techniques one is full block space vector modulation and second is called pulse edge space vector modulation.Advantages of the trajectory The selection of the switch-on and switch-off states of the power switches (Fig.1) is carried out so that the error between the real value of and the reference (assigned) value of moves within the limits of as defined by the hysteresis band of the flux controller. However, the selection of the states of the power switches not only depends on the absolute error value but also on the rotation direction of vector . For this purpose, the stationary reference domain is divided into 6 (six) equal parts (zones). Each zone has its own carrier voltage space vector. Thus, for instance, the carrier vector of the ‘0’ zone is vector . For a positive rotation direction (clockwise) the subsequent two voltage space vectors, and switch on respectively, depending on whether the upper or lower limit of the hysteresis band has been reached. For a negative rotation direction (counter clockwise) the corresponding vectors or switch on depending on whether the upper or lower limit of the hysteresis control band has been reached. The stator f więcej »

Study of the behaviour of a doubly-fed induction machine supplied with scalar open-loop control - DOI:10.15199/48.2019.05.06

Mario VUKOTIĆ Damijan MILJAVEC

Introduction Doubly-fed induction machine (DFIM) is usually used in large-power variable-speed drives with limited range of speed in the vicinity of the synchronous speed using bidirectional power converter [1-5], e. g. wind turbines, large pumps etc. Stator is connected directly to the public network (400 V and 50 Hz in Europe), whereas rotor is connected to the same network via power converter with adjustable voltage and frequency (Fig. 1). Fig.1. Power flow in the drive system with DFIM and power converter If power converter (rotor voltage source) allows only unidirectional power flow (Fig. 1), i. e. from the network to the machine (diode rectifier at the input side instead of the transistor bridge), then the operational area is limited to the supersynchronous speeds [6-7], assuming that the machine operates as a motor (Fig. 2). The power rating of the rotor voltage source is a fraction of the total power and it increases with increasing speed range [8-10]. In the steady-state motor operation, the rotor rotates in the supersynchronous area with the mechanical speed, which is defined as the sum of the rotational frequency of the stator and rotor rotating magnetic field, divided by the number of pole pairs: (1) p ω ω Ω 1 2 + = where: Ω - mechanical speed in [1/s], ω1/ω2 - angular frequency of the stator/rotor voltage in [1/s], p - number of pole pairs. Fig.2. Supersynchronous motor operation area (grey) Simulated drive system The two-dimensional finite-element-method (FEM) model (Fig. 3) with analytically calculated resistances and end-winding leakage inductances was built in order to obtain as accurate results as possible. The machine data are given in Table 1. The scalar open-loop control with variable voltage-to-frequency ratio (U/f control) has been used for the rotor voltage source in the simulations. Namely, the U/f control it is one of the simplest, easy-to-design and low-cost m więcej »

Śp. Profesor Marian Noga 1939 - 2018

Tadeusz Glinka Witold Rams

Prof. dr hab. inż. Marian Noga urodził się 2 lutego 1939 we Lwowie. W roku 1945 rodzina przeniosła się do Krakowa. Marian studia wyższe ukończył w 1961 roku na Wydziale Elektrotechniki Górniczej i Hutniczej, obecnie Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej, AGH w Krakowie. Bezpośrednio po studiach został asystentem w Katedrze Maszyn i Pomiarów Elektrycznych AGH kierowanej przez prof. Władysława Kołka. Współpracował z prof. Arkadiuszem Puchałą. W roku 1969 obronił pracę doktorską na Wydziale Elektrotechniki Górniczej i Hutniczej AGH i uzyskał stopnień naukowy doktora. Temat rozprawy doktorskiej "Zagadnienia dynamiki przetworników asynchronicznych". Promotorem przewodu był prof. Arkadiusz Puchała. Marian Noga był pierwszym doktorem wypromowanym przez Profesora. W pierwszej połowie lat 70. XX wieku, wspólnie z prof. A. Puchałą, prowadził dodatkowo zajęcia dydaktyczne i prace dyplomowe na Wydziale Elektrycznym Politechniki Częstochowskiej. W tym czasie prowadził także, wspólnie z prof. A. Puchałą, wykłady dla pracowników BOBRME Komel na temat "Dynamiki elektromechanicznych przetworników energii". Po śmierci prof. A. Pucha więcej »

The determination of the current state and the reliability indices of synchronous motors with long time between failures - DOI:10.15199/48.2019.05.17

Viacheslav PRUS Oleksandr DEHTIARENKO

One of the basic problems of electric machines (EM) operation consists in the impossibility of accurate determination of their current technical state (TS) limiting the possible conditions and modes of operation as a part of technological equipment [1]. Basically, it is explained by the fact that for the identification of EM TS it is necessary to know both electromagnetic parameters that later determine all the main indices of EM control quality and structural and operational deviations from the regulated operation characteristics (excess of the windings temperature, increased vibrations level, etc.), directly determining the ultimate operation life [2]. While it is possible to determine the required parameters of most low- and medium-power EMs during the control-diagnostic tests, practically, there is no such possibility for high-power EMs because of the absence of relevant testing equipment and load. The range of these EMs, first, includes synchronous motors (SM). They are widely applied in the drives of mills, pumps, compressors, smoke exhausters and superchargers. Due to their big mass and other technological features, their repair, as a rule, is performed at the place of their installation, which additionally reduces the possibilities for the account of their TS. As SMs are often parts of responsible mechanisms providing either direct basic technological process or the support of the necessary technological conditions, the problem of the TS prediction is important from the point of view of minimization of production losses. Thus, the purpose of the paper consisted in the solution of the problems of the determination and prediction of SM TS under the conditions of absent of incomplete information about the alteration of their basic parameters and characteristics. Theory The peculiar features of high-power SM include the individual approach to their design. First, it means that every EM of this type is unique as to więcej »

The economic feasibility analysis of generated photovoltaic energy in the USTO campus - DOI:10.15199/48.2019.05.35

Nessim Abderrahim BOURAHLA Mustapha BENGHANEM Mamadou DOUMBIA Hamid BOUZEBOUDJA

The development and use of clean renewable energy in many parts of the world in the last two decades have become vital due to the continuous decline and price fluctuation of fossil fuel resources and global concerns about climate change, air pollution and increased consumption of energy [1,2]. Advances in power electronics have also contributed more effectively and more reliably to the integration of renewable resources into power grids [3]. The cost reduction of photovoltaic (PV) technology and related components, such as inverters and batteries, and the sharp decline in the cost of large wind turbines have made these energy sources more attractive in many countries. The large-scale development of renewable energy systems and their integration to utility grid are considered as the most important challenges for the sustainable environment. The electric energy industry restructuring and the introduction of the concept of a smart grid have also led to new technologies (distributed energy resources and decentralized generation) become more and more widely adopted [3]. Since the industrial and residential sectors are among the largest consumers of electrical energy, decentralized electricity generation has now become a potential solution for satisfying the energy needs locally. In comparison to large-scale wind energy, the cost of deploying a PV system is much higher, and therefore implying that a larger financial subsidy is needed to increase the PV installation capacity by customers [4,5,6]. Microgrids are small size electrical networks built to provide a reliable electric supply and with a better quality for a small number of consumers. They consists of local power stations (micro turbines, fuel cell, small diesel generators, photovoltaic panels, etc), loads, storage batteries and a power management strategy for the supervision and dispatching power flow. They can operate either in gridconnected mode or in isolated mode. T więcej »

The incentive scheme for maintaining or improving power supply quality - DOI:10.15199/48.2019.05.20

Paweł KOMADA Iryna TRUNOVA Oleksandr MIROSHNYK Oleksandr SAVCHENKO Taras SHCHUR

Modern power systems must supply consumers with the high-quality power with the certain continuity level (that means the term «reliability of power system's work»). There are various aspects of realization of this process (objective and subjective aspects; material, technical, organizational aspects and others). All of them must be analyzed by staff of power distribution companies for improvement of service quality and ways of power supply process perfection must be defined. Employees should use precise and clear algorithm of actions for success of the task performance. They must understand consequences and an ultimate goal. An incentive scheme must be in the power distribution companies for conscientious work of employees. The implantation of an incentive scheme for maintaining or improving general continuity levels was one of recommendations the Council of European Electricity Regulators (CEER) that were submitted in 5-th benchmarking report [1] in 2011 year. The regulation of the service quality in European countries is considered in 6-th CEER benchmarking report on the quality of electricity and gas supply [2]. The systems of regulation are created on the basis of: Continuity measurement is a prerequisite for setting standards and reward/penalty regimes; Maintenance and improvement of general continuity levels as a result of the investment decisions of network operators with implementing reward/penalty for the achieved quality levels; Minimum standards for quality levels will guarantee that consumer will be compensated if the standard is not met by the network operator. The review of use of incentives systems for the distributive companies in the European countries on the basis of key reliability metrics is considered in [2]. Key reliability metrics are indicated in IEEE Std. 1366-1998 Trial-Use Guide for Electric Power Distribution Reliability Indices [3]. These must definitely be interpreted and used as re więcej »

The Influence of Infrasonic Impacts on the Crude Oil Viscosity Reduction - DOI:10.15199/48.2019.05.24

Yelena V. BLINAYEVA Waldemar WOJCIK Kanagat K. TOLUBAYEVA Saule S. SMAILOVA

Oil is a complex mixture of organic compounds based on hydrocarbons of different structure. Oils from different fields have different physical and chemical composition, contain many impurities, as well as dissolved gas, mineral salts and water. Oil is the main raw material for the production of gasoline, kerosene, diesel fuel, fuel oil, lubricating oils and other products used by various industries. Oils from different fields often differ significantly in composition, since the components of oil are a mixture of different hydrocarbons. Oil contains molecules of different structure; and the number of carbon atoms and hydrogen atoms in each molecule differs. In the process of extraction and transportation oil is exposed to various influences that can result in the concentrating of paraffins, asphaltenes and resins. This increases the density and viscosity of oil, changes its structure and characteristics; so oil gets into the category of hard-to -extract resources. Because of the active world oil production the reserves of light oils are depleted. The increasing demand for oil and products of its processing forces to look for new ways of production and processing of oil that is categorized as hardto- extract, highly viscous, and containing an increased percentage of paraffin in its composition. If oil contains more than 6% paraffin it is classified as paraffin base oil. 19,200 oil samples from various fields of the Earth were investigated in Russian Academy of Sciences. On the basis of the obtained results was compiled a database that stores information about the physical and chemical properties of oils. The study allowed to compile a scheme for the distribution of oil and gas basins whose oil contains a high percentage of paraffin. The analysis showed that the leader in the reserves of paraffin base oil is Russia, Kazakhstan occupies the second place, and China the third. Oil of newly discovered fields contains paraffin więcej »

The influence of the specifications of the elements of range of exciters voltage inverters on their spectral characteristics - DOI:10.15199/48.2019.05.21

Paweł KOMADA Oleksandr MIROSHNYK Roman M. LYSYCHENKO Taras SHCHUR

The trend of wide implementation of voltage inverters in various industries is forcing to focus on issues related to electromagnetic compatibility. For example, modern power inverters keys, especially MOSFET and IGВТ with have very high switching speed, become sources of electromagnetic interference. The range of generated interference extends from the carrier frequency of the inverter (several hundreds of KHz) to radio frequency (tens of MHz). Low-frequency interferences up to 2 kHz penetrate into the supply network, high-frequency (> 10 kHz) components create a powerful radio interference [1-4]. It is known that the PLL is generally described by nonlinear differential equations [5]. The non-linear nature of the circuit, which determined by the existence of semiconductor elements (diodes, transistors, thyristors, etc.) which are part of the inverter structure chart, is the reason for generating the higher harmonics. Therefore, we carry out a research on the effects of the non-linear nature of the drivers elements, namely the research of influence of range exciters and inventers systems of phase timing on the spectral characteristics. One of the major problems which must be solved during design and production of the voltage inverter is to eliminate adverse effect of the exciter on the technical characteristics (TС) of the inverter, in particular on electromagnetic compatibility. Thereby, the development of recommendations on the choice the optimal parameter values of the phase-locked loop (PLL) of frequency synthesizer on the basis of accurate numerical analysis occurring therein is very important. For the calculated ratios we use the method of functional expansions of Voltaire, which currently is one of the most convenient and accurate methods for analyzing non-linear dynamic systems [6, 7]. Experiment As the main circuit of direct digital synthesizers (DDS) of range exciters (which basing on the analys więcej »

The use of elastic net and neural networks in industrial process tomography - DOI:10.15199/48.2019.05.15

Tomasz RYMARCZYK Grzegorz KŁOSOWSKI

Industrial Process Tomography (IPT) is a non-invasive and non-destructive imaging [1] technique used in various industries for processes in which knowledge about the interior of the object is required [2], [3]. A common reason for using IPT is that it plays an important role in the continuous monitoring of systems, allowing better understanding and ensuring the quality of industrial processes. IPT provides fast and dynamic response, facilitates process control, including on-line, enables error detection and system failures in real time [4]. In addition, thanks to IPT, the process characteristics can be quantified, with data included in the overall process control strategy. Finally, IPT provides robust experimental means to optimize the design and operation of a process tank or pipeline by developing a model and validation. Industrial process tomography (IPT) applications are usually a challenge for obtaining spatial data from observation beyond the boundaries of the process. The wireless sensor network technology with their return loops will be the basis for production control. The decisive difference in mass production of chemicals, metals, building materials, food and other goods is that common process sensors provide only local measurements such as temperature, pressure, fill level, flow rate or species concentration. However, in most production systems, such local measurements are not representative of the overall process and therefore spatial solutions are needed. Here the future belongs to the dispersed and imaging sensors. The tomograph can be adapted to the requirements of a given company and to the specifics of a given industry. The prepared solution can effectively support the quality of products in automated production lines by identifying shapes, detecting cracks and damage, and presenting three-dimensional visualization of industrial processes. This is especially important for dairy producers, where the foami więcej »

The use of the wavelet-analysis for the research of the unsteady processes in the pipeline network of a pumping complex - DOI:10.15199/48.2019.05.09

Mykhaylo ZAGIRNYAK Roman MANKO Oleksii KRAVETS Tetyana KORENKOVA

Unsteady processes sometimes occur during the operation of pumping complexes (PC) because of frequent switching on/off of the pump units, alteration of the consumer’s operation mode, non-observance of the tempo of shutting the pipeline valves in the hydraulic network. Such unsteady processes include head pulsation, water hammer, leakage, cavitational self-oscillations, etc. Complex wave processes of different amplitude and frequency accompany their appearance and in some cases may result in the damage of the pumping and pipeline equipment. To identify PC unsteady modes there are a number of methods based on the continuous or periodical monitoring of the parameters of liquid pumping, the frequency analysis of the signals of the head or discharge, etc. [1]. Recently, engineers have often been using wavelet analysis for the diagnostics of various unsteady processes, which proved to be successful in the problems of diagnosis of damages in electric machines and gas turbine engines, the study of the properties of turbulent fields, etc [2]. In comparison with the Fourier transform, the wavelet analysis makes it possible to assess the unsteady processes by the analysis coefficients more accurately and to follow the alteration of the signal frequency properties in the time domain. In this case both a periodic and a non-periodic time function can be considered an analyzed signal. That is why the problem of the research of the wave processes in the pipeline network in unsteady operation modes of a pumping complex with the use of wavelet analysis is of interest. Research method Taking into account the above said, we propose a PC mathematical model including a frequency converter (FC); an induction motor (IM) in u,v,0-coordinates; a centrifugal pump; a block generating a moment of resistance created by the pump; a pipeline network represented by n-number of sections in the form of RLC-circuits; a consumer model with input hydraul więcej »

The ways for the improvement of the information value of the methods for the assessment of the quality of electric energy as a part of its technical accounting systems - DOI:10.15199/48.2019.05.18

Viacheslav PRUS Alyona NIKITINA

The irreversible growth of energy consumption and the increase of the index of the nonlinearity of the typical load of electrical networks at industrial enterprises, municipal service objects and household consumers, existing during the recent decades, make topical the problems of the assessment of the electric energy quality and the identification of consumers introducing various distortions into the networks [1]. The existing normative acts providing penalties regulate only the distortion of voltage. It does not give practically any idea of the real character of the energy exchange processes in electric circuits. Besides, the application of these acts in practice is opposed by the impossibility to part both the separate consumers influence on each other and their individual and (or) joint action on the mains supply. The above said is the main cause of the violation of electromagnetic compatibility manifested in the increase of energy consumption, the levels of reactive energy interchange, the distortion of electric networks currents and voltages, the disoperation of relay protection and automation devices. The principles of electric network designs in Ukraine often do not enable quick and reliable determination and localization of the sources of such distortions, which results in periodic occurrence of particular engineering problems as well as conflict situations in the relationship of the consumers and energy supplying organizations. Thus, the solution to the problem of the improvement of the information value of the method and the means of the assessment of the quality of electric energy for different types of load and operation modes of the consumers is an important research and technical task. The present paper deals with the solution to this problem. Theory The main consumers with a nonlinear character of the load include, first of all, arc steel-smelting furnaces, frequency converters and other semiconductor conv więcej »

The ways for the improvement of the information value of the thermal image control of electric machines with long mean time between fa - DOI:10.15199/48.2019.05.16

Mykhaylo ZAGIRNYAK Viacheslav PRUS Oleksandr SOMKA

To provide the reliable operation of electric machines (EM) it is necessary to have trustworthy information about their current state [1]. Its presence will enable both the assessment of their operation conditions and the forecast of the residual life for their timely withdrawal to repair or maintenance. In this case, the main problem consists in the impossibility to use many of the most accurate and advanced methods of diagnostics, as the current monitoring of EM condition is performed in most cases with operating equipment with limited access to EMs and their basic structural units [2]. The above said substantiates the use of such methods of measuring, control and diagnostics that minimize the possible preparatory procedures and even eliminate their influence on operating EM, including various distant methods [3]. According to the existing statistic data, most EM failures result from the winding or bearing units breakage preceded by the growth of their temperature. Thus, the diagnostic methods allowing additional assessment of the thermal condition of both separate units and EM on the whole are sufficiently informative [4, 5]. Their application is especially topical in the determination of the deviation of the temperature of the basic structural elements in complex dynamic operation modes and in the assessment of EM condition in the course of aging. The posed problem can be solved with the use of the methods and means of thermal image control (TC), along with the following digital processing of the obtained images. However, the problems of the accurate interpretation of separate sources of heating and the assessment of the intensity remain unsolved. The present paper settles these problems. Theory The direct application of TC to EM is a rather complicated and ambiguous problem nowadays. First, it is explained by the impossibility of the direct assessment of the state of the internal structural units as windings, cor więcej »

ViMeLa Project: An innovative concept for teaching mechatronics using virtual reality - DOI:10.15199/48.2019.05.05

Goga CVETKOVSKI Lidija PETKOVSKA Paolo Di BARBA Maria Evelina MOGNASCHI Dorota KAMIŃSKA Anna FIRYCH-NOWACKA Slawomir WIAK Mihail DIGALOVSKI Maja CELESKA Najmeh REZAEI Marcin LEFIK Grzegorz ZWOLIŃSKI Tomasz SAPIŃSKI Toomas TIKK Rain Eric HAAMER Gholamreza ANBARJAFARI

Nowadays, traditional education and teaching methods, although with significantly improved teaching techniques, can not keep enough interest of the students that grew up with Internet, mobiles and tablets. Especially sensitive to these issues are students in engineering, in particular, in mechatronics. Modern information technology is rapidly being adopted in Mechatronics Engineering education as a tool for enriching the practical experience of the students. The practical training is a vital part of Mechatronics Engineering education [1]. However, the high cost needed to implement laboratory experiments (for educational purposes) led to development of virtual facilities where physical systems can be virtually controlled via the Virtual Reality (VR) simulations. Multimedia and VR technologies offer great potential for presenting theory and laboratory experiments in an enhancing and interesting, but in an economical, way. Teaching and learning Mechatronics Mechatronics is synergy and interaction of mechanical, electrical and computer systems as seen in Fig. 1. Hence, it is an interactive combination of mechanical engineering, electronic control and computer technology, with the aim of achieving an ideal balance between mechanical structure and its overall control and performance. Fig.1. Structure and key elements of mechatronics Currently, mechatronics classes are divided into two parts: the theoretical lectures and laboratory courses with experiments following the "learning by doing" model. Expensive equipment and limited time for training do not provide sufficient educational platforms [2,3]. In some cases the students conduct based simulations and learn how mechatronic systems and devices operate in reality, despite it may seem abstract and unclear for students, and does not fully reflect the physical phenomena of particular processes. The described drawbacks of mechatronics study are greatly improved when classroom teac więcej »

Wp􀃡yw skrzy􀄪owania linii kablowych wysokiego napi􀄊cia 110 kV na ich d􀃡ugotrwa􀃡􀄅 obci􀄅􀄪alno􀄞􀃼 pr􀄅dow􀄅 - DOI:10.15199/48.2019.05.29

George J. ANDERS Maciej MRÓZ Mateusz ELLWART

m. PRZEGL􀄄D ELEKTROTECHNICZNY, ISSN 0033-2097, R. 95 NR 5/2019 120 c) Linie kablowe systemu dolnego rozsuni􀄊to osiowo na odleg􀃡o􀄞􀃼 4 m, a odleg􀃡o􀄞ci mi􀄊dzyfazowe w ka􀄪dej linii wynosz􀄅 60 cm. d) Linie kablowe systemu górnego, w miejscu skrzy􀄪owania, umieszczono w prefabrykowanych, betonowych kana􀃡ach kablowych z otworami wentylacyjnymi. Linie kablowe systemu górnego rozsuni􀄊to osiowo na odleg􀃡o􀄞􀃼 3,3 m, a odleg􀃡o􀄞ci mi􀄊dzyfazowe w ka􀄪dej linii wynosz􀄅 25 cm. e) K􀄅t skrzy􀄪owania linii kablowych systemu górnego i dolnego wynosi 90 . Przyj􀄊te rozwi􀄅zania techniczne przedstawiono na poni􀄪szych rysunkach nr 3 i nr 4. Rys.3.􀀃Widok przekroju poprzecznego rozpatrywanego skrzy􀄪owania linii kablowych Rys.4. Widok przekroju pod􀃡u􀄪nego rozpatrywanego skrzy􀄪owania linii kablowych Wybór metody obliczeniowej Wybór metody obliczeniowej, maj􀄅cej na celu wyznaczenie wielko􀄞ci wzajemnego oddzia􀃡ywania krzy􀄪uj􀄅cych si􀄊 linii kablowych, uzale􀄪niony jest od stopnia skomplikowania rozpatrywanego przypadku. Stopie􀄔 skomplikowania zale􀄪y przede wszystkim od w􀃡a􀄞ciwo􀄞ci termicznych 􀄞rodowiska pracy linii kablowych oraz od liczby krzy􀄪owanych obwodów kablowych. Kiedy dwa obwody krzy􀄪uj􀄅 si􀄊 wzajemnie, ka􀄪dy z nich zachowuje si􀄊 jak 􀄨ród􀃡o ciep􀃡a dla drugiego. Ilo􀄞􀃼 generowanego ciep􀃡a, pionowa odleg􀃡o􀄞􀃼 mi􀄊dzy obwodami i k􀄅t skrzy􀄪owania s􀄅 g􀃡ównymi parametrami maj􀄅cymi wp⣸ więcej »

Wpływ kwantowania współczynników na działanie filtru Gaussa dla realizacji bezpośredniej i ortogonalnej (rotatory Givensa) - DOI:10.15199/48.2019.05.41

Paweł POCZEKAJŁO

Powszechnie spotykane są różne systemy cyfrowego przetwarzania sygnałów (CPS) [1] mające na celu np. filtrowanie danych. Jednym z najczęściej stosowanych systemów o skończonej odpowiedzi impulsowej (FIR) jest filtr Gaussa, a kluczowe przy implementacji jest uwzględnienie skończonej precyzji zapisu współczynników [2]. Ma to bezpośrednio wpływ m.in. na charakterystykę częstotliwościową. W niniejszym artykule przedstawiono wpływ kwantowania współczynników w dwóch realizacjach jednowymiarowego (1D) filtru Gaussa. Pierwsza, wykorzystuje bezpośrednią implementację splotu. Druga, bazuje na ortogonalnym filtrze Gaussa realizowanym za pomocą rotatorów Givensa. Dla obu struktur wykonane zostały pomiary wybranych parametrów, które pozwalają określić wrażliwość na kwantowanie współczynników. Jako środowisko symulacyjne zastosowano oprogramowanie Scilab [3], umożliwiające jednocześnie precyzyjną analizę danych. Realizowane struktury Transmitancja dowolnego systemu dyskretnego 1D o skończonej odpowiedzi impulsowej może być przedstawiona następująco [1]: (1) więcej »

PRZEGLĄD ELEKTROTECHNICZNY

The autonomous sources of energy supply for the liquidation of technogenic accidents (ang. Autonomiczne źródła zasilania w energię przy likwidacji wypadków technogennych)

Prenumerata

INNE PUBLIKACJE W TYM ZESZYCIE

The autonomous sources of energy supply for the liquidation of technogenic accidents
(ang. Autonomiczne źródła zasilania w energię przy likwidacji wypadków technogennych)