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1
Melnikova, O. S. "Impact of distribution of impurity particles on electric strength of transformer oil." Vestnik IGEU, no. 6 (2019): 41–49. http://dx.doi.org/10.17588/2072-2672.2019.6.041-049.
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To extend the service life and ensure the operability of oil-filled transformer equipment, the attention is paid to the development of methods for monitoring the state of oil-barrier insulation. When monitoring the technical condition of transformer oil, the class of liquid purity is determined depending on the rated voltage of the equipment. However, the influence of the parameters of mechanical impurities on the breakdown voltage is not taken into account, thereby lowering the requirements for the quality of oil barrier insulation. This makes it relevant to study the influence of the size distribution of impurity particles on the electric strength of the internal insulation of power transformers and determine the parameters of particles of mechanical impurities to justify the underestimation of the quality indicators of transformer oil in operation. Methods of mathematical statistics were employed using the Gnedenko-Weibull distribution based on the standard values of liquid purity classes. To determine the maximum and minimum voltages, the standard values of the average breakdown voltages and the results of operational tests of transformer oil in a standard spark gap were used. The relation between the particle size of mechanical impurities and the breakdown voltage of transformer oil has been established. The particle size distribution of impurities has been obtained for 12 and 13 classes of liquid purity for power transformers with a voltage of 110–750 kV. The particle size range that defines the maximum and minimum breakdown voltages has been determined, and the values of limit concentrations of mechanical particles have been established. The obtained parameters of impurity particles which determine the maximum and minimum breakdown voltages of the operating oils can be used to evaluate the technical condition when diagnosing the internal insulation of power transformers in order to increase their operational reliability, as well as to adjust the regulatory requirements for the quality of operational transformer oil according to the content of mechanical impurities.
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Fursanov, M. I., and A. A. Zalotoy. "Improvement of the Method of Calculation of Steady-State Modes of Urban Electric Networks Taking into Account Consumer Energy Sources." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 6 (November 29, 2019): 514–27. http://dx.doi.org/10.21122/1029-7448-2019-62-6-514-527.
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The method of calculation of the steady-state mode of the open city distribution electric network with small generation sources is offered. It is shown that the city electric network consists of passive and active physical elements. Passive elements include power transformers and linear regulators, overhead and cable power lines, current-limiting reactors, etc. Active elements of networks are power sources (transformer inputs of low voltage of feeding substations and distributed small generation sources) and loads, mathematical models of which can be various. Power sources in urban distribution networks of 10 kV and below are classified by type and power and can be of two kinds, viz. power feeding centers of the network and small generation sources. Consumer loads are modeled by current sources connected to network nodes. The parameters of the current sources are usually graphs of the change of the module of the actual current value and the power factor in time. The values of these parameters in single-line substitution schemes of 6–10 kV distribution networks with isolated neutral are assumed to be average for three phases. The power centers are transformer inputs of low voltage power substations of the main electric networks of 35 kV and above, equipped with digital devices of the account of the electric power connected to the automated system of control and accounting of power resources. The developed technique allows receiving the refined balanced calculation model of the steady mode of the open city network for the set time of the daily schedule. It includes the sequential distribution of the specified power of each network power supply between its loads, followed by clarification of flows and power losses in the sections, as well as voltages and actual loads in the nodes of the scheme by the overlay method.
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Kutin, V. M., M. V. Nikitchuk, V. M. Svitko, and O. O. Shpachuk. "AUTOMATION OF THE HEAT STATE ANALYSIS PROCESS HIGH-VOLTAGE CURRENT TRANSFORMERS." METHODS AND DEVICES OF QUALITY CONTROL, no. 2(43) (December 24, 2019): 96–110. http://dx.doi.org/10.31471/1993-9981-2019-2(43)-96-110.
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Thermographic control of electrical equipment allows you to draw preliminary conclusions about the technical condition of insulation, contact joints, windings, structural elements and cooling systems of electrical equipment of voltage classes 0.4 ÷ 750 kV. However, it should be borne in mind that the results of temperature measurement and assessment of the thermal state of electrical equipment are influenced by such factors as: environmental conditions, qualifications of personnel performing thermographic control and data interpretation, the need to improve regulatory documents for assessing the thermal state of electrical equipment and develop unified algorithms analysis of the results of thermographic examinations and gradation of the development of defects in electrical equipment.
Modern research in the field of thermographic control of electrical equipment is developing in several directions, namely: the use of automated (stationary or mobile) systems for collecting thermographic data; development of algorithms for processing thermal images that reduce the influence of extraneous noise on the values of the measured temperatures, select the image of the object being examined, select the optimal level of contrast of the thermal image to detect thermal anomalies; using statistical processing of thermal fields of thermal monitoring objects and making decisions about the thermal state of equipment using neural networks, machine learning and expert knowledge. Automation of the analysis of thermographic control data is an urgent scientific and practical task, the solution of which will improve the quality of maintenance, repairs, extension of the operating life and operational management of electrical equipment in conditions of a significant level of aging of the main production assets of electric companies and change of generations of staff.
Measuring current transformers of voltage classes 330 ÷ 750 kV are critical elements in the distribution schemes of electric power and in electric networks, and their technical condition directly affects the reliability of electric networks and power supply to consumers. The paper considers the reasons for the development of defects in current transformers of voltage classes 330 ÷ 750 kV, and also proposes relationships to take into account the influence of the air flow rate and the actual value of the emissivity of the structural element of the current transformers, as well as elements of the algorithms for analyzing data from thermal imaging surveys to reduce the influence of environmental factors and qualification level of the personnel performing the analysis, diagnostic results.
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Nakadomari, Akito, Ryuto Shigenobu, Takeyoshi Kato, Narayanan Krishnan, Ashraf Mohamed Hemeida, Hiroshi Takahashi, and Tomonobu Senjyu. "Unbalanced Voltage Compensation with Optimal Voltage Controlled Regulators and Load Ratio Control Transformer." Energies 14, no. 11 (May 21, 2021): 2997. http://dx.doi.org/10.3390/en14112997.
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Penetration of equipment such as photovoltaic power generations (PV), heat pump water heaters (HP), and electric vehicles (EV) introduces voltage unbalance issues in distribution systems. Controlling PV and energy storage system (ESS) outputs or coordinated EV charging are investigated for voltage unbalance compensation. However, some issues exist, such as dependency on installed capacity and fairness among consumers. Therefore, the ideal way to mitigate unbalanced voltages is to use grid-side equipment mainly. This paper proposes a voltage unbalance compensation based on optimal tap operation scheduling of three-phase individual controlled step voltage regulators (3ϕSVR) and load ratio control transformer (LRT). In the formulation of the optimization problem, multiple voltage unbalance metrics are comprehensively included. In addition, voltage deviations, network losses, and coordinated tap operations, which are typical issues in distribution systems, are considered. In order to investigate the mutual influence among voltage unbalance and other typical issues, various optimization problems are formulated, and then they are compared by numerical simulations. The results show that the proper operation of 3ϕSVRs and LRT effectively mitigates voltage unbalance. Furthermore, the results also show that voltage unbalances and other typical issues can be improved simultaneously with appropriate formulations.
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Vukolov, V. Yu, A. A. Petrov, S. N. Yurtaev, and R. Sh Bedretdinov. "Development of universal algorithm of voltage circuits detecting faults of microprocessor protection and automation devices." Vestnik IGEU, no. 3 (June 30, 2021): 33–41. http://dx.doi.org/10.17588/2072-2672.2021.3.033-041.
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Reliability, along with response speed, sensitivity, and selectivity, is the key requirement for relay protection (RP) devices. The reliability of modern RP digital terminals is understood as protection operation for all estimated failure modes and failure of protection equipment to operate in all other modes, in which this protection is not provided. Analysis of the secondary voltage schemes and algorithms of detecting faults in these circuits reveals several disadvantages of the implementation of blocking in case of faults in voltage circuits. All existing algorithms and blocking schemes in case of faults in voltage circuits suffer from several disadvantages. In this regard, it is relevant to develop a universal relay protection terminal, which can be used with any types of voltage transformers. The MatLAB Simulink is used to simulate the primary failure of secondary circuits for the connection schemes of the voltage transformer load on phase and electric line voltages. The authors propose the algorithm that allows us to create a typical universal RP terminal, which can be used with any type of voltage transformers. To detect the neutral conductor interruption of the «star» circuits, it is proposed to create an artificial asymmetry at the input voltage circuits of the relay protection and automation (RPA) terminal and develop a group of fault detectors that analyze the position of the offset neutral on the voltage complex plane. Using a simulation model of various types of failure of voltage transformer secondary circuits and the logic diagram of the unit that implements the proposed algorithm, the authors graphically show that the detection of a break in the neutral wire is possible due to monitoring the zero-sequence voltage spike (triggering of the pulsed dU0 fault detector) with neutral displacement to the complex plane area, which is set by the setpoints. The results obtained allow us to implement a universal scheme of blocking faults in voltage circuits. This scheme does not depend on the voltage transformer secondary load connection method and exclude the disadvantages of existing solutions discussed in the article. This algorithm allows us to develop a typical universal RPA terminal. Due to its connection scheme and functional and logical implementation, this terminal can be used with any types of voltage transformer without reprogramming. Also, the proposed algorithm fully complies with the requirements of the current regulatory and legal documents.
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Severo, Lucas Compassi, and Wilhelmus Adrianus Maria Van Noije. "A Generic Test Board for the Electrical Characterization of ULP and ULV Fully-Differential Integrated Analog Circuits." Journal of Integrated Circuits and Systems 14, no. 3 (December 27, 2019): 1–7. http://dx.doi.org/10.29292/jics.v14i3.90.
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The characterization of ultra-low power (ULP) fully-differential/balanced amplifiers and active filters is challenging due to the incompatibility with the classical single-ended (SE) and 50 Ω impedance equipment. Interface circuits between the device under test (DUT) and the equipment are needed to perform the signal conversion and to work as voltage buffers. In this work, we propose a generic test circuits to be used in the characterization of ULP and ultra-low voltage (ULV) analog circuits. The test board includes balun transformers to the signal conversion, a high input impedance and low capacitance output driver and voltage regulators to provide the target DUT supply voltage. The characterization of the proposed PCB demonstrates a bandwidth of 30 MHz, output driver input impedance of 5 MΩ with 2.5 pF capacitance and low input-referred noise. The proposed circuit was applied to the electrical characterization of two fully-differential ULV and ULP analog integrated circuits.
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Attia, Hussain. "Novel 9-Steps Automatic AC Voltage Regulator based on Two Step-down Transformers." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 2 (April 1, 2017): 576. http://dx.doi.org/10.11591/ijece.v7i2.pp576-583.
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<p class="IEEEAbtract">A novel design and simulation results of 9-steps automatic AC voltage regulator based on one step-down transformer is presented in this paper. Avoiding the problem of surge at the AC load during controlling jump steps is done through the proposed design. Accurate and smooth controlling function is achieved as well. Instead of the necessity of increasing the number of taps of the used multi tap transformer for wide controlling range of fluctuated AC supply voltage, the proposed designed adopts using only two step down transformers with 10 Vrms, and 30 Vrms secondary voltages respectively. Through the controlling of the proposed design of AV voltage regulator, the resultant load voltage is equal the AC supply voltage as well as the suitable voltage step which may one of the following voltages; +40V, +30V, +20V, +10V, 0V, -10V, -20V, -30V, -40V. The electronic design is done Multisim software while the electrical circuit connection of step down transformers and relays contacts that is made by using PSIM software for power circuit design.</p>
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Noskov, M. Yu, M. M. Ginshparg, and N. S. Nesterov. "Results of tests on the indicator of external noise of electric locomotives in the standing time." Vestnik of the Railway Research Institute 76, no. 5 (October 28, 2017): 301–5. http://dx.doi.org/10.21780/2223-9731-2017-76-5-301-305.
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The authors of the Test Loop of the JSC “VNIIZhT” had conducted tests of mainline electric locomotives intended for handling freight trains on sections of the road electrified with alternating current at a voltage of 25 kV (electric locomotives of an alternating current). Tests were conducted in terms of the level of external noise at the standing time. The results of tests of AC electric locomotive, which was in a stationary mode, are presented in terms of the external noise index, and a methodology for performing these tests is described. As a result of the conducted researches, the article establish the main sources of external noise in the operation of AC electric locomotives (fans intended for cooling electrical equipment and traction motors, air compressors, traction transformers, etc.), its actual values, as well as the nature of the sound field around electric locomotives. The analysis of the obtained sound field made it possible to identify the points where the excess of the standard noise values (more than 65 dBA) is observed. It is proposed to bring the technical condition of the equipment, such as traction transformer, converter and cooling module of the traction engine of the power compartment of an electric locomotive in accordance with the normative documentation. The repeated measurements of the external noise level after technical completion did not reveal the excess of its normative values in accordance with the regulatory documentation. In order to provide a normative margin in terms of the external noise of an electric locomotive, it is proposed to use sound-absorbing material in the construction of its body. It is recommended to perform an experimental study of the spectral composition of the noise of the equipment of an electric locomotive operating at the standing time and the resulting external noise at points located outside and around the locomotive in order to calculate the acoustic characteristics of sound-absorbing materials. Sound absorbing material is expedient to be selected depending on the frequency range in which the greatest excess is observed above the maximum permissible values using known empirical and semi-empirical dependences, on the basis of which it is possible to preliminary determine its sound-absorbing properties in the frequency range established by regulatory documents. After equipping the power compartment of the locomotive with soundproof materials, tests on the evaluation of the external noise of an electric locomotive at standing should be repeated.
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Obaid, Waleed, Abdul-Kadir Hamid, and Chaouki Ghenai. "Hybrid solar/wind/diesel water pumping system in Dubai, United Arab Emirates." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 3 (June 1, 2021): 2062. http://dx.doi.org/10.11591/ijece.v11i3.pp2062-2067.
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This paper proposes a hybrid power system design for water pumping system in Dubai (Latitude 25.25 °N and Longitude 55 °E), United Arab Emirates using solar photovoltaic (PV) panels, wind turbines, and diesel generator. The proposed design considers the changes in weather conditions (humidity percentage, temperature in celsius, and wind speed in m/s) that directly affect solar irradiance values which alter the performance of the hybrid system. The proposed design deals with the problem of rare rainy days in Dubai between December and March and the high temperature throughout the year since that makes providing water to rural and isolated zones essential. The proposed system uses voltage regulator to maintain stable DC voltage from the solar power system, battery bank to store the voltage from solar PV panels, three-phase rectifier to convert the AC voltage from wind power system to DC, three-phase step-down transformers to reduce the AC voltage of the wind turbine and diesel generator, and DC electric motor for water pumping output. The system used neural network for solar irradiance forecasting over an interval of 10 years (from 2009 to 2019). The proposed system will be demonstrated using Simulink to show the stability and performance under different weather conditions.
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Hanley, Patrick, Thomas Healy, and Nancy Shannon. "Con Edison's Success in Reducing Risk: Applying Real-World Lessons Learned to Broaden Spill Planning and Response Programs and Build Personnel Competencies." International Oil Spill Conference Proceedings 2014, no. 1 (May 1, 2014): 1910–21. http://dx.doi.org/10.7901/2169-3358-2014.1.1910.
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ABSTRACT Con Edison's service territory covers more than 1,000 miles of inland and coastal shoreline in one of the most heavily regulated and scrutinized areas of the Unites States: New York City. In November 2009, the company experienced a catastrophic failure of a large transformer at a high-voltage electric substation, resulting in approximately 200 gallons of dielectric oil impacting the Bronx River. While the volume of oil was relatively small, the duration of the cleanup lasted nearly one month with costs of approximately $1.75 million, plus a nearly $1 million compliance order issued by New York State for violation of state regulations. Following this event, and through a study of all historical spill incidents, it was clear that the primary risk of spills to the environment came from the more than 30 million gallons of oil contained in the company's high-voltage transformers and oil-filled electric transmission and distribution system, which were not covered by existing Facility Response Plans developed as part of implementing OPA 90. Given these results, the company sought to refine existing spill response program elements to further reduce risks and enhance environmental stewardship. Using the existing Spill Management Team (SMT) model in the OPA 90 program, a company-wide SMT approach was created to better prepare for and reduce the risks associated with potential spills from all company sources. The team consists of more than 50 personnel from the various business units of the company, providing direct access to a wide spectrum of skill-sets and specialties. In addition, the company has developed Oil Spill Contingency Plans (OSCP)—also covered under OPA 90—with detailed response tactics for over 300 locations. On the heels of the program implementation, a large spill of dielectric oil from an underground high-voltage electric distribution line resulted in more than 2,000 gallons impacting the Hutchinson River. While the impact to the waterway was greater than in the 2009 event, the response duration was only 6 days with clean-up costs just over $300,000 with no state issued compliance order, a significant improvement. This result was due, in large part, to implementation of the OSCP and SMT programs. Through these experiences, the many benefits of establishing a company-wide SMT and the OSCP's were realized, including developing spill response and Incident Command System expertise, refined coordination, and improved cost management. These efforts have significantly reduced the company's spill risk exposure by improving response capabilities.
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Cavallo, Alberto, Beniamino Guida, and Luigi Rubino. "Boost Full Bridge Bidirectional DC/DC Converter for Supervised Aeronautical Applications." International Journal of Aerospace Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/808374.
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The More Electrical Aircraft concept requires electronic devices able to efficiently and safely convert electrical power between different voltage levels. The entire realization of a bidirectional DC/DC converter, from design to validation phase, is here discussed in detail. First, a boost full bridge electrical structure is selected, adopting a Parallel Input Parallel Output (PIPO) interleaving technique and an optimal turns ratio selection for the transformers in order to reduce both weight and size of the equipment. Next, modulation schemes in both step-down and step-up modes are discussed. Successively ad hoc PI regulators for both operative modes are presented. A key idea of the paper is that the converter behavior must be related not only to the control strategy but also to a global supervision logic able to safely conduct the converter operations and to react from external stimuli. Thus, a finite state machine (FSM) approach is employed. An innovative strategy called buffer mode is presented, defined as an intelligent combination of buck and boost modes. Extensive simulations and experimental results are shown, in order to confirm the effectiveness of the proposed approach.
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Nazarov, Serdar, Gurbangulych Kelov, and Berdimyrat Gochyev. "The influence of changing resistance on the determination accuracy of short circuits in power lines." E3S Web of Conferences 288 (2021): 01091. http://dx.doi.org/10.1051/e3sconf/202128801091.
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In high-voltage electrical networks, the occurrence of short circuits leads to forced interruptions in the power supply of large consumers and disruptions in intersystem communications. More than 65% of all types of occurring short circuits are single-phase short circuits [1]. In a single-phase short circuits (SPSC), a change in the zero sequence resistance (ZSR) especially significantly affects the inaccuracy in detection of damage sites (DDS). When choosing DDS methods, preference is given to remote methods according to the parameters of the emergency conditions (PEC), which are recorded by special instruments or determined from the oscillograms of emergency conditions. The use of modern microprocessor-based relay protection and automation devices (RPA) [26] or emergency event recorders allow viewing the oscillograms of emergency events. In a branched 110 kV network with a complex configuration, the DDS accuracy is influenced by a change in the ZSR. Averaging of specific parameters often leads to erroneous results. The choice of one value from the oscillograms puts the maintenance personnel in difficulty. In the scientific work, the influence of changes in the ZSR on the accuracy of the DDS is considered. The changes in the ZSR are influenced by the position of the on-load voltage regulator (OLTC) switches of transformers with a grounded neutral. In the work, for a more accurate record of the specific parameters of the network, a calculation program has been compiled, which allows making changes in the calculated specific parameters of the network. To determine the short-circuit current from the oscillograms, it is proposed to determine the stable state of accidents in which the current value will be approximately the same. The analysis of the oscillograms of SPSC in 110-220 kV networks in the southern part of the electric power system of Turkmenistan has been carried out.
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Radwan, Ali A., Ahmed A. Zaki Diab, Abo-Hashima M. Elsayed, Hassan Haes Alhelou, and Pierluigi Siano. "Active Distribution Network Modeling for Enhancing Sustainable Power System Performance; a Case Study in Egypt." Sustainability 12, no. 21 (October 29, 2020): 8991. http://dx.doi.org/10.3390/su12218991.
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The remarkable growth of distributed generation (DG) penetration inside electrical power systems turns the familiar passive distribution networks (PDNs) into active distribution networks (ADNs). Based on the backward/forward sweep method (BFS), a new power-flow algorithm was developed in this paper. The algorithm is flexible to handle the bidirectional flow of power that characterizes the modern ADNs. Models of the commonly used distribution network components were integrated with the developed algorithm to form a comprehensive tool. This tool is valid for modeling either balanced or unbalanced ADNs with an unlimited number of nodes or laterals. The integrated models involve modeling of distribution lines, losses inside distribution transformers, automatic voltage regulators (AVRs), DG units, shunt capacitor banks (SCBs) and different load models. To verify its validity, the presented algorithm was first applied to the unbalanced IEEE 37-node standard feeder in both passive and active states. Moreover, the algorithm was then applied to a balanced 22 kV real distribution network as a case study. The selected network is located in a remote area in the western desert of Upper Egypt, far away from the Egyptian unified national grid. Accordingly, the paper examines the current and future situation of the Egyptian electricity market. Comparison studies between the performance of the proposed ADNs and the classical PDNs are discussed. Simulation results are presented to demonstrate the effectiveness of the proposed ADNs in preserving the network assets, improving the system performance and minimizing the power losses.
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Sosnina, Elena, Aleksandr Sevostyanov, Evgeny Kryukov, and Rustam Bedretdinov. "Thyristor Voltage Regulator Experimental Research." E3S Web of Conferences 209 (2020): 07020. http://dx.doi.org/10.1051/e3sconf/202020907020.
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The article is devoted to the thyristor voltage regulator (TVR) development. The TVR purpose is to control power flows and regulate voltage in 6-20 kV distribution electrical networks (DEN). The principle of TVR operation is based on the plus EMF (or minus EMF) introduction into power line when the shared use of longitudinal (change of magnitude) and transverse (change of phase) voltage regulation. The description of the TVR prototype is given. The TVR prototype consists of a 0.4 kV thyristor switches, power transformers (shunt and serial) and a 6 kV switchgear. The TVR has a two-level control system (CS). The TVR prototype experimental research was conducted in four stages: check of power equipment, first level CS research, second level CS research, prototype tests as a whole. The connection diagrams (thyristor switches unit, transformer and measuring equipment) and contact connections reliability were checked when the power part was tested. A qualitative characteristic of the input and output signals was obtained when testing the first level CS. It is found that the thyristor control pulses are formed according to the developed algorithm. The correctness of control system algorithms, executed and transmitted commands, passed and received data was confirmed as a result of the second level CS tests. The TVR research results indicate that the prototype provides the smoothness and specified accuracy of voltage regulation in all modes. The control range of the output voltage relative to the input was ±10%. The discreteness of regulation did not exceed 1.5%. The range of change in the shift angle of the output voltage relative to the input was ±5°. Research confirmed the TVR ES operability and its readiness for trial operation.
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Pieters, Willem D., and Raynitchka Tzoneva. "Investigation of an IEC 61850 standard-based process bus implementation of a protection and control scheme for parallelly connected transformers." Journal of Engineering, Design and Technology 19, no. 4 (February 26, 2021): 850–75. http://dx.doi.org/10.1108/jedt-01-2020-0023.
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Purpose This paper aims to focus on the implementation of the International Electrotechnical Commission (IEC) 61850–9-2 standard based process bus with merging units (MUs) and sampled values (SV) to improve the protection and control systems. The digital process interface is important to be included on the process bus level. Design/methodology/approach The IEC 61850–9-2 process bus standard is not extensively used in regard to SV when the IEC 61850 standard is implemented by power utilities. Many protection and control intelligent electronic devices (IEDs) are connected to a substation communication network, routers and switches using fibre-optic linked Ethernet. However, inductive current transformers (CTs) and voltage transformers (VTs) secondary circuits are still hardwired to the IEDs. The paper highlight issues with the copper wires for currents signals and how these issues can be eliminated by using the MUs and the SV protocol. The voltage regulator control IED of each transformer is required to regulate the voltage level of the secondary side bus bar it is connected to. All the regulating IEDs of parallel-connected transformers are required to communicate with each other to share information. They collectively control the bus bar voltage depending on the switching configuration of the parallel transformers. Findings It is shown that process bus information such as the high voltage switchgear status information of primary plant in the yard, can be used to improve the substation protection and control systems. The power transformer protection and voltage regulator control are focused on. Research limitations/implications The deliverables of the research work can be applied in: The Centre for Substation Automation and Energy Management systems of the Department of Electrical Engineering, power utilities and other establishments using power systems and digital substations in the electrical supply industry. The research work on the thesis led to the development of a laboratory test-bench where students can learn and understand the basics of the IEC 61850–9-2 SVs principles. The test-bench components such as the IEDs, real-time digital simulator, standalone MUs and Ethernet equipment can be used for future research applications. The test-bench can be used to demonstrate during course work for students at the University, the basics of digital substations using a process bus network with IEDs, MUs and Ethernet equipment. Practical implications The research work showed where lab equipment is getting outdated and future equipment will be required for research work in IEC 61850–9-2 process bus. Originality/value Power utilities can benefit from implementing the IEC 61850 part 9–2 of the standard and by using MUs and other process interface information in substations. A cost reduction in high voltage equipment, substation installation and commissioning costs and better performance of protection and control system can be achieved.
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Sharma, Jitendra. "A-CAT’S health: operational parameters." Emerald Emerging Markets Case Studies 6, no. 1 (April 29, 2016): 1–10. http://dx.doi.org/10.1108/eemcs-12-2014-0283.
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Subject area Operations management. Study level/applicability This case can be used in a core course in production and operation management; process management and courses like design and planning of operations at the graduate level, preferably during or after the basic operations module of the course. The case focuses on the use of a process analysis that decomposes the problem into a number of easily solvable sub-problems, each of which could be distinctly analyzed and solved. The case can also be effectively utilized in elective courses on process reengineering, concurrent engineering/management, process management, capacity planning, etc. Ideally, this case can be discussed for 75 to 90 minutes. Case overview The case describes the situation facing the operations supervisor, Sunil Mehta, of A-CAT Corp. in Vidarbha Region, Maharashtra, India. A-CAT Corp. was a mid-sized manufacturer and distributor of domestic electrical appliances, largely catering to the price-sensitive rural population. The firm operated two medium-sized facilities in one of the remote districts in Vidarbha, and these manufacturing units had been in operation since 1986. A-CAT manufactured a relatively wide range of electrical appliances for household use. Typical products from its stable included TV signal boosters, transformers, FM radio kits, electronic ballasts, battery chargers, voltage regulators, etc. The voltage regulators manufactured by A-CAT were used for many different purposes, although the focus was on its flagship product, VR500. The issue at hand for Sunil Mehta, operations supervisor at A-CAT, was to get data and act right; more often than not, this boiled down to critical information which everyone in the firm kept collecting but were too busy to use and utilize. The challenge was to select the right kind of data needed from the data-deluge that the company had in their databases. The eluding objective was to use it for the betterment of the firm. The challenge was to utilize the data that the workers and other operators kept logging in and, in the process of doing so, came up with some solutions to the problems faced on the operational front. Expected learning outcomes The case teaching and learning objectives are as following: to grasp the basics of process and process parameters; to understand the interrelationship between capacity, utilization, efficiency and productivity of a process; and to carry out process capacity analysis in assessing the performance of the firm on different metric drivers. The case also provides a very good foundation for understanding process parameters in a simple and lucid manner. To make right computations and not to use the terms and terminology in “cook book” or “strait jacketed” manner, students need to realize the parameters and their understanding changes from situation to situation. Supplementary materials Teaching notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes. Subject code CSS 9: Operations and Logistics.
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Li, Gu, Zi Ming Fu, Jie Feng Yan, Bing Wen Li, and Zhi Rong Cen. "Research the Test Method of the Voltage Transformer Secondary Load in the Three-Phase Three-Wire Electric Energy Metering Device." Applied Mechanics and Materials 687-691 (November 2014): 3110–15. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.3110.
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This paper analyzes and studies the definition of the voltage transformer secondary load, examines the practical purposes of the measured values of the voltage transformer secondary load, and presents a variety of testing methods to analyze and compare the differences. This paper gives the test methods of the voltage transformer secondary load when the connection of the voltage transformer is the Y / Y in a three-phase three-wire power supply system, filling the blank of this type of test method in the industry. When other units within the industry carry out such work, the conclusions of this paper are available for reference, and the conclusions of this paper can be referred when drafting relevant regulations in the future.
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Majchrzak, Virginie, Guillaume Parent, Jean-François Brudny, Valentin Costan, and Philippe Guuinic. "Influence of the electrical circuit configurations of a DVR coupling transformer with a magnetic bypass." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, no. 3 (May 2, 2017): 804–10. http://dx.doi.org/10.1108/compel-09-2016-0402.
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Purpose For the proposed coupling transformer, a magnetic bypass based on the virtual air gap principle is realized by inserting auxiliary windings in a return leg added to a standard transformer. With such a setup, it is able to act as a voltage regulator as well as protect the power electronics of the dynamic voltage restorer from electrical grid fault currents. This paper focuses on the electrical design part of the coupling transformer. It aims to explain how the behavior of the auxiliary windings electrical circuit of the magnetic bypass impacts the performances of the device. Design/methodology/approach The influence of the electrical auxiliary windings circuit configurations on the operation of the coupling transformer is studied by finite element analyses with nonlinear and isotropic magnetic materials. Findings A configuration for the realization of the electrical circuit of the auxiliary windings is determined according to the finite element simulation results to achieve the design of the coupling transformer whose magnetic core was previously designed. Originality/value By studying the operation of a special coupling transformer with nonlinear saturation phenomenon by finite element analyses, a to-do list of the electrical circuit parameters is described to design this device well.
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Nesterov, Nikita, and Aleksei Bykov. "Locomotive Noise Reduction." MATEC Web of Conferences 320 (2020): 00013. http://dx.doi.org/10.1051/matecconf/202032000013.
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This paper presents the results of the investigation of the noise characteristics of the dual-voltage mainline electric locomotive. The study identified noise levels generated by the locomotive equipment that violate regulations. The analysis of points, where the noise is above regulations, indicated the primary source of the elevated noise is the operation of the traction transformer. We proposed installing a noise barrier below the locomotive body to reduce noise and bring the locomotive in compliance with the noise regulations. This solution allowed reducing the locomotive noise and ensure its compliance with regulations.
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ÖZÜPAK, Yıldırım. "Medium Frequency Electric Field Analysis of Power Transformers in High Voltage System." BEN Vol:2 Issue:3 2021 2, no. 3 (February 8, 2021): 1–5. http://dx.doi.org/10.36937/ben.2021.003.001.
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Electronic power transformers (EPT) are transformers that are smaller in size and volume compared to conventional 50 Hz frequency transformers. Medium frequency transformers (MFT) have begun to become important components in high voltage and high power energy conversion systems such as EPTs. In this study, the electric field distribution of these transformers is discussed. The electric field distributions in the transformer have been obtained using the two-dimensional finite element method (FEM). Besides, maximum electric field intensities were obtained in the study. ANSYS@Maxwell simulation program, which realizes a solution based on FEM, was used for these analyzes. Electromagnetic field analyzes of the same transformer under normal conditions were also performed to compare the analyzes. Besides, the values obtained from the high-frequency analysis, the values obtained from the study below 50 Hz frequency, and the values obtained experimentally were compared. In this way, the stress in the insulation material of the transformer and the weak parts of the insulation material were detected. It is expected that the method used will contribute to future studies to examine the results of the electric field distribution analysis of transformers.
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Kulesz, Barbara. "RECTIFIER TRANSFORMERS IN ELECTRIC TRACTION SUBSTATIONS ‐ DIFFERENT DESIGNS." TRANSPORT 20, no. 2 (April 20, 2005): 66–72. http://dx.doi.org/10.3846/16484142.2005.9637998.
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Electric traction in Poland is supplied with dc voltage which is obtained from the power grid via traction substations equipped with transformers and rectifiers. The paper gives the results of the investigation of different designs of these transformer‐rectfier sets ‐ namely, 12‐ and 24‐pulse systems. The comparison of electrical quantities such as ripple content, harmonic content of supply current and output voltage and utilisation of transformer secondary windings is provided.
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Vladimir, Vladimir S., and Tatiana V. Gerasimenko. "DESIGNING PHASE TRANSFORMERS AND QUALITY REGULATORS OF ELECTRIC POWER ON THE BASIS OF FREQUENCY TRANSFORMERS." Scholarly Notes of Komsomolsk-na-Amure State Technical University 1, no. 2 (June 30, 2010): 21–23. http://dx.doi.org/10.17084/2010.ii-1(2).4.
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Hanus, Oleksii, and Kostiantyn Starkov. "STUDY OF THE NATURE OF OVERVOLTAGES IN THE ELECTRICAL NETWORK ARISING FROM VOLTAGE TRANSFORMERS." Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency, no. 1 (2) (July 2, 2021): 28–36. http://dx.doi.org/10.20998/2224-0349.2021.01.05.
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A non-linear dynamic mathematical model of voltage transformer has been considered and overvoltages arising on the elements of voltage transformer equivalent circuit during transient processes have been investigated. The influence of voltage transformer secondary circuit capacitance on overvoltage multiplicity in the primary circuits and the duration of transients has been determined. The advantages of approximation of nonlinearity of voltage transformers by hyperbolic sine are used. Mathematical expressions determining the nature of changes in the forced and free components of the transient process in an electrical network with a voltage transformer have been obtained. It is shown that with the increase of the electric network capacitance the duration of the transition process damping increases and the frequency of the forced oscillations and the level of overvoltage decrease. It is proved that even small, in comparison with the primary nominal sinusoidal voltage, aperiodic components of the voltage transient process can lead to significant overvoltages during voltage transformer outages. It has been substantiated that both the secondary resistance and the switching torque influence the overvoltage multiplicity arising in the primary winding of voltage transformers. It is shown that the closed secondary winding worsens the disconnection process of non-linear inductance of voltage transformers. The values to which overvoltages increase in this case are determined. According to the results of calculations it is determined that with open secondary winding of voltage transformers the duration of transient process significantly increases. It has been found that the decrease of frequency of forced oscillations, which occurs in this case, is accompanied by an increase of currents in the primary winding of the voltage transformer, which is dangerous in terms of thermal stability of the winding insulation. It is shown, that closing the secondary winding of voltage transformers leads to significant reduction of transient damping time. It is suggested that this algorithm can be used to provide a rapid breakdown (suppression) of ferroresonant processes. The effectiveness of such a measure of stopping of ferroresonance processes as short-term shunting of secondary winding of voltage transformers has been investigated. The correlation of parameters of electric networks (capacity of busbar sections, nonlinearity of characteristics of voltage transformers, disconnection torque, etc.) at which ferroresonance process may occur and consideration of which may allow, in terms of prevention of ferroresonance processes, to identify substations (electric networks) that require more detailed research has been determined. The results of analytical studies were tested in the electric networks of JSC "Kharkivoblenergo" and used in the electricity distribution system for the selection of specific voltage transformers for certain configurations of electrical networks.
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Brito, M. E. C., L. R. Limongi, M. C. Cavalcanti, F. A. S. Neves, and G. M. S. Azevedo. "A step-dynamic voltage regulator based on cascaded reduced-power series transformers." Electric Power Systems Research 108 (March 2014): 245–53. http://dx.doi.org/10.1016/j.epsr.2013.11.024.
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Alyunov, A. N., O. S. Vyatkina, I. G. Akhmetova, R. D. Pentiuc, and K. E. Sakipov. "Issues on optimization of operating modes of power transformers." E3S Web of Conferences 124 (2019): 02015. http://dx.doi.org/10.1051/e3sconf/201912402015.
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The article presents measure to optimize the operating modes of power transformers in order to minimize losses of electrical energy. The influence of actual voltage and service life of power transformers on electric power losses is shown. It was proposed to determine the economic capacity of power transformers taking into account the indicated factors, as well as taking into account the time of transformer switching on into the electric network and the form of the load schedule.
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Gotovkina, Elena, Vladimir Tyutikov, Nikolay Smirnov, Vladimir Lebedev, and Evgeniy Bushuev. "Influence of insolation and ambient temperature on operation of digital voltage transformers in Russia." MATEC Web of Conferences 178 (2018): 09005. http://dx.doi.org/10.1051/matecconf/201817809005.
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The present study is devoted to questions connected with influence of solar radiation and high values of ambient air temperatures on work of digital voltage transformers. The developed designs of digital voltage transformers are included in smart grid system of technical and commercial metering of electric energy consumption. The analysis of the unfavorable conditions for work of digital voltage transformers for the conditions of Russia in summer is carried out. The results of mathematical simulation for thermal state of transformers, obtained with the help of COMSOL Multiphysics program based on the finite element method, are presented. Experimental research regarding the thermal field of resistive voltage divider transformer was conducted on a verified mathematical model in order to determine the position of resistive elements where their self-heating is minimal.
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Lee, Sang-Hyun, and Choong-Koo Chang. "Separation of Transformers for Class 1E Systems in Nuclear Power Plants." Science and Technology of Nuclear Installations 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/3976049.
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In order to supply electric power to the safety related loads, safety and reliability of onsite power have to be ensured for the safety function performance in nuclear power plants. Even though the existing electric power system of APR1400 meets the requirements of codes regarding Class 1E system, there is a room for improvement in the design margin against the voltage drop and short circuit current. This paper discusses the amount that the voltage drop and short circuit current occur in the existing electric power system of APR1400. Additionally, this paper studies with regard to the improved model that has the extra margin against the high voltage drop and short circuit current by separation of unit auxiliary transformer (UAT) and standby auxiliary transformer (SAT) for the Class 1E loads. The improved model of the electric power system by separation of UAT and SAT has been suggested through this paper. Additionally, effects of reliability and cost caused by the electric power system modification are considered.
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Fetisov, L. V., N. V. Rozhencova, and O. A. Bulatov. "IMPROVING THE QUALITY OF ELECTRIC POWER IN LOW VOLTAGE NETWORKS." Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS 20, no. 11-12 (February 27, 2019): 99–106. http://dx.doi.org/10.30724/1998-9903-2018-20-11-12-99-106.
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This article is devoted to development of actions for improvement of quality of the electric power in low voltage networks, by installation of booster transformers (BT), and to calculation of economic effect in comparison with alternative versions of the solution of tasks of ensuring reliable, high-quality and available power supply of consumers.
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Melnikova, O. S., and V. S. Kuznetsov. "Method of calculating the electric strength of oil channels of the main insulation of power transformers." Vestnik IGEU, no. 5 (December 30, 2020): 48–55. http://dx.doi.org/10.17588/2072-2672.2020.5.048-055.
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The most damage-sensitive unit of power transformers is the main insulation of the oil barrier type. The breakdown of such insulation occurs as a result of the breakdown of the oil channel near the high voltage winding. In accordance with traditional methods of calculating the dielectric strength of insulation, the value of the breakdown strength is determined by empirical formulas depending on the selected width of the oil channel. The existing methods do not consider the influence of the oil channel volume, of the electric strength the statistical characteristics of the oil, the design features of the insulation of power transformers, and do not contain recommendations for creating design models. Thus, to improve the calculation accuracy, it is relevant to develop the evaluation method of dielectric strength of the main insulation of power transformers taking into account the volume and parameters of the breakdown voltage distribution of transformer oil, design features. The research results of the breakdown tension in oil channels with different volumes of transformer oil were used. To improve the accuracy of the calculation and taking into account the design features, the model of the main insulation of power transformers was made in the ANSYS program. Boundary data and assumption of linear stress distribution of transformer coils were considered. A method for calculating the dielectric strength of oil channels of the main insulation of power transformers, considering the volume and parameters of the breakdown voltage distribution of transformer oil was proposed. Unlike the existing methods, when calculating the minimum breakdown strength in the model of the main insulation, the design features of power transformers are taken into account and assumptions are justified to improve the accuracy of the calculation. In accordance with the methodology, the parameters of the dielectric strength of the transformer oil in the oil channel of the high voltage winding of the transformer were calculated. It was concluded that with increase of relative value of breakdown tension, dielectric strength of oil channel is decreasing, and it corresponds to physical sense of breakdown. The method for calculating the dielectric strength of transformer oil can be used when choosing the main insulation of power transformers in design.
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Li, Jian Wen, Bing Xin Zhang, and Jian Ping Xing. "An Improved Compensation Alternating Voltage Regulator Using Bidirectional-Thyristor Bridge." Applied Mechanics and Materials 148-149 (December 2011): 556–60. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.556.
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High power alternating voltage regulators commonly use few isolation transformers to compensate the variation of the input voltage or output load, and use a bidirectional-thyistor bridge with multiple arms to adjust the direction and magnitude of the compensation voltage . This kind of voltage regulator has been widely used for its simplicity, low cost, and high efficiency. But its compensation voltage adjustment process often accompanies with deep output voltage sags or high input current overshoots. An improved topology is proposed---adding one more circuit unit to help the adjustment of compensation voltage. The improved topology can adjust the compensation voltage smoothly---having neither output voltage sags nor input current overshoots.
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Ziemelis, Imants, Arnolds Šķēle, Henriks Putāns, Uldis Iljins, and Aldis Putāns. "VOLTAGE REGULATORS FOR LOCAL HEATING OF PIGLETS." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 1 (June 20, 2001): 229. http://dx.doi.org/10.17770/etr2001vol1.1967.
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The optimum air temperature in a pigsty for sows is 16-18 °C, but during the first days o f new born piglets life the temperature in their lairs ought to be 32...34 °C. Therefore the local warming for piglets is installed. The goal of the investigation was to measure the intensity o f heat irradiation under different kinds o f infra-red heaters, more often used on Latvia farms. An autonomous infra-red piglet warming systems have been developed. The experiment has showed, that during the first days o f piglets life the heater should be kept at the high, so that the irradiated area 0.3- 0.4 m2 has been. Gradually heaters have to be lifted up 3-4 times while.the warming area is 0.6-0.7 m2 in 40-45 days, when piglets are weaned. The temperature in a lair has to be regulated by change o f electric power of the heater. Several constructions of voltage regulators are worked out, which are able to ensure the temperature on the warmed surface automatically or manually, depending on the temperature in a pigsty and live mass of piglets. The automatic power regulation of the heaters decreases the consumption of electric energy more than 2 times.
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Tikhonov, V. A. "On the effect of the periodicity of diagnostic measurements on improving the reliability of high-voltage transformers." Safety and Reliability of Power Industry 12, no. 1 (April 10, 2019): 18–21. http://dx.doi.org/10.24223/1999-5555-2019-12-1-18-21.
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The influence of the periodicity of diagnostic measurements on the operational state of high-voltage transformers is considered. Examples of defects of switching devices of converter transformers and methods for their detection are given. The rationale for the importance of recognition of defects at an early stage of their occurrence is given. The influence of the multiplicity of overvoltages on the service life of converter transformers in the aluminum industry is investigated. Based on the analysis of the service life of converter transformers of one of the powerful aluminum plants, where 83% of converter transformers have exhausted their standard service life, it is shown that in 40% of cases it would be possible to avoid their failures, with timely detection and elimination of emerging defects. Examples of defects of OLR (on-load regulators) of converter transformers and methods for their detection are given. The importance of recognition of defects at an early stage of their occurrence is substantiated. A method for chromatographic analysis of dissolved gases in transformer oil has been developed for the qualitative determination of defects and ways to eliminate them. Examples of diagnostics of converter transformers at operating voltage and working load are given, providing the best quality operational characteristics of converter transformers. The periodicity of diagnostic measurements and the reduction of defects and failures has been substantiated. The question of diagnosing the state of the converter transformer TDNP-40000/10 at an enterprise of the aluminum industry is investigated. Currently, diagnostic methods are being developed based on chromatographic analysis of dissolved gases in transformer oil. The presented method of evaluating the operating parameters of transformers allows for the safe operation of high-voltage transformers and enables to increase the reliability of the power supply scheme of aluminum industry plants.
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Hassani, Mahdi, Seyed Siavash Karimi Madahi, Hassan Feshki Farahani, and Hossein Sarabadani. "A New Method to Improve the Voltage Distribution and Electric Field Control for Conceder Bushing." Applied Mechanics and Materials 110-116 (October 2011): 5184–88. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.5184.
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Capacitor bushings are one of the key components in power transformers. Although their price is a negligible part of the total price of the power transformer, their quality has a significant effect on performance and reliability of power transformers. In high voltage capacitor bushings, the intensity of voltage and electric field on bushing abacus is very high. This high intensity is also observed in flange parts. The amount of multi layer insulator among the electrodes or floating plates in capacitor bushing make equi-potential surfaces and reduction of electric field in these areas can greatly improve the capacitor bushing performance. In this paper, we investigate the reduction of field intensity and electrical tension and also improvement in voltage control by displacing floating plates which are in the form of aluminum foils stick to impregnated paper. To calculate the field intensity, we used the MAXWELL software using FEM (Finite element method). Using this new method of placing capacitor core its effect on voltage profile reduction and field electrical tension is shown. Over voltage and pollution effects are also investigate on power transformer bushings.
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Akhmetshin, Azat, George Marin, and Dmitrii Mendeleev. "Modeling of asynchronous motor operation modes for the correct selection of voltage regulation devices." E3S Web of Conferences 178 (2020): 01015. http://dx.doi.org/10.1051/e3sconf/202017801015.
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Many electrical appliances are used in production and in everyday life, which include elements that are extremely sensitive to voltage deviations from acceptable values. Failure in their work can cause equipment failure or a breakdown in technological processes. There are a number of technical solutions to solve this problem, one of which is the using of voltage control devices such as boost transformers. The principle of operation of booster transformers is the introduction of a longitudinal EMF into the electric circuit, which provides booster. The choice of voltage regulation devices consists in determining its power and the required transformation ratio. The latter needs some justification, because it cannot be formally accepted: if it is necessary to increase the voltage, for example by 5%, it is enough to introduce a longitudinal EMF of 5% of the nominal voltage into the electric circuit. This is due to the fact that with increasing voltage from the load side, the power consumption also increases, which causes an increase in voltage drop compared to modes in the absence of voltage regulation devices. Thus, the load will receive a slightly lower voltage level in comparison with the desired one.
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Okunev, Alexander V., Anastasia A. Ivanova, and Alexander A. Philipiev. "Assessment of performance reliability of transformers." Innotrans, no. 3 (2020): 50–53. http://dx.doi.org/10.20291/2311-164x-2020-3-50-53.
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Increase of freight traffic resulted in increased loads on traction substations and, respectively, in increase of their equipment failure risks. In the context of maintaining the required voltage level and power quality, which determine appropriate values in reliability for traction substation transformers, the article looks upon solving the problem of determination of reliability essential parameters. A proposed calculation model makes it possible to simplify the choice of electrical apparatus for uninterrupted power supply of electric rolling stock traction.
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Жорняк, Людмила Борисівна, Олексій Іванович Афанасьєв, Віталій Миколайович Щусь, Юліанна Володимирівна Азорська, Олексій Володимирович Коляда, and Дмитро Олександрович Грінівецький. "Feattures of regulation of electric field along external isolation of high-voltage gas-insulated voltage transformers." Bulletin of NTU "KhPI". Series: Problems of Electrical Machines and Apparatus Perfection. The Theory and Practice, no. 2 (December 18, 2019): 13–18. http://dx.doi.org/10.20998/2079-3944.2019.2.03.
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Bolshanin, G. A., and E. G. Skulina. "USE OF TRANSFORMERS AS PAIRING DEVICES FOR MEASURING SYSTEMS." EurasianUnionScientists 1, no. 7(76) (August 20, 2020): 66–70. http://dx.doi.org/10.31618/esu.2413-9335.2020.1.76.895.
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The execution of devices of interface of means of control of indicators of quality of electric energy with the electric power system in the form of measuring transformers of voltage and shunt of alternating current is shown. This is most preferable due to the lack of non-linearity in the working area of magnetic characteristics. A transformer substitution scheme is shown, as well as experiment execution schemes, as a result of which the necessary parameters are determined.
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Ba, Ji Lun, Hai Ming Wang, Meng Yao, Xiao Lei Deng, Xiang Fang, and Gen Yong Chen. "Study on Electric Energy Metering Program under the Impact of Distorted Waveform." Advanced Materials Research 732-733 (August 2013): 948–53. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.948.
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Many factors affect the precision of electric energy metering in measuring process, and distorted waveform is one of them. Based on maths principle and equivalent circuit model, the metering error related to electronic energy meter algorithm (metering principle), current transformers and voltage transformers is analyzed. Corresponding improvement metering scheme is put forward. Finally, taking the common nonlinear load-AC EFA (electric arc furnace) as an example, it is simulated in the MATLAB/Simulink simulation platform. The results validate the conclusions of the error analysis and some methods proposed to improve the rationality of actual metering operation significantly.
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Cherepanov, Aleksandr, Vasily Zakaryukin, and Andrey Kryukov. "Modeling of traction power supply systems for movement of high-speed trains." MATEC Web of Conferences 216 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201821602006.
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Upgrading of traction power supply systems will be required to transfer electrified railway lines to high-speed traffic. Coaxial cables and balancing transformers can be used as technical upgrading means. The article presents the results of computer simulation in the Fazonord software complex of the traditional 2x25 kV traction system, as well as systems with coaxial cables and Woodbridge symmetric transformers. Simulation results showed that the use of cables contributes to a significant increase in the level of voltage on current collectors of electric rolling stock. Use of modified Woodbridge transformers makes it possible to reduce the imbalance coefficient by the reverse sequence on high voltage buses of traction substations. However, the reduction is insignificant and depends on the modes of movement of trains in adjacent inter-station zones. The biggest positive effects occur in the integrated application of balancing transformers and coaxial cables.
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Malažinskas, Vilius, Renaldas Raišutis, Alfonsas Morkvėnas, Saulius Gudžius, Audrius Jonaitis, Jonas Vaičys, and Gediminas Daukšys. "EVALUATION OF THE INSULATION CONDITION OF HIGH-VOLTAGE TRANSFORMERS BY DETECTING PARTIAL DISCHARGES USING THE ELECTROMAGNETIC WAVE RADIATION METHOD." Materiali in tehnologije 55, no. 2 (April 15, 2021): 253–61. http://dx.doi.org/10.17222/mit.2020.175.
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High-voltage transformers are among the most important elements in an electric-power system. Each one of them is affected by various external factors: overvoltage, partial discharge (PD), overheating, vibrations, etc., which are created by a strong electric field, thermal effect, humidity, impurities, factory defects, dissolved water and gas in oil-type-transformer insulation. These and other factors, caused by the environment, reduce the life of a device. Thus, the evaluation of the device condition is one of the most important factors for a system-safety evaluation, which ensures a reliable and economical electrical-network operation. This work reviews different contact and non-contact methods, used to evaluate the conditions of transformers by measuring the level of PD. The selected method, i.e., the non-contact measurement of electromagnetic-wave radiation was used to evaluate the voltage-transformer status. The experiment was performed at a 110 kV substation. The authors discuss the efficiency of the selected method to evaluate the voltage-transformer insulation condition.
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Khlebnikov, Vladimir, Nicholay Tsygulev, Kirill Smagin, Razmik Galstyan, and Dmitriy Zhirovov. "Control of Digitalized Distribution Electric Network According to the Criterion of Minimum Loss of Electric Power Transmission." Известия высших учебных заведений. Электромеханика 64, no. 2 (2021): 71–77. http://dx.doi.org/10.17213/0136-3360-2021-2-71-77.
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At present, the world energy industry is focused on creating intelligent distribution electric networks with management on the energy Internet platform. To solve this problem, a model circuit of an intelligent distribution radial electric network was developed, for controlling parameters in normal and post-accident modes of which, it is proposed to use regulators of transformation coefficients of network transformers and fastacting compensating devices for smooth control of reactive load power. Mathematical model of proposed network and target function are formed, minimization of which ensures minimum losses of electric power transport. Algorithms for control of parameters of operating modes in normal and post-accident modes have been developed. The implementation of the proposed algorithms ensures the operation of the network with minimal losses of electricity transport
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Černelič, Jernej, Robert Brezovnik, Primož Sukič, and Martin Petrun. "Eliminating short switching cycles when using hysteresis control of resistance spot welding systems." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, no. 3 (May 2, 2017): 791–803. http://dx.doi.org/10.1108/compel-09-2016-0429.
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Purpose This paper aims to present two hysteresis-control algorithms designed for medium-frequency, direct-current, resistance-spot-welding (MFDC RSW) systems. The first proposed control algorithm (MSCHC) eliminates the short switching cycles that can occur when using the existing hysteresis-control algorithms. This control minimises the number of switching cycles that are needed to generate the selected welding current. The welding-current ripple can be high when using this control algorithm. Therefore, a second algorithm (HCRR) is presented that reduces the welding-current ripple by half. Design/methodology/approach The proposed hysteresis controllers consist of the transformer’s magnetic-flux-density hysteresis regulator and a welding-current hysteresis regulator. Therefore, the welding current must be measured and the saturation of the iron core must be detected. The proposed hysteresis controller supplies the inverter with the signals needed to generate the supply voltage for the RSW transformer, which then generates the selected welding current. Findings The proposed MSCHC algorithm produces the smallest possible number of switching cycles needed to generate the selected welding current. The high welding-current ripple can be reduced if the number of switching cycles is increased. The observed number of switching cycles and the welding-current ripple change if the welding resistance and/or inductance change. Originality/value The number of switching cycles can be minimised when using the first proposed control algorithm (MSCHC), and so the switching power losses can be minimised. If the welding-current ripple produced by the first control algorithm is unacceptable, the second control algorithm (HCRR) can reduce it by increasing the number of switching cycles.
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de Andrade Reis, Raphael Leite, Washington Luiz Araujo Neves, Felipe V. Lopes, and Damasio Fernandes. "Coupling Capacitor Voltage Transformers Models and Impacts on Electric Power Systems: A Review." IEEE Transactions on Power Delivery 34, no. 5 (October 2019): 1874–84. http://dx.doi.org/10.1109/tpwrd.2019.2908390.
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Berg, Heinz-Peter, and Nicole Fritze. "Risk and Consequences of Transformer Explosions and Fires in Nuclear Power Plants / Ryzyko I Konsekwencje Wybuchów Transformatora I Pożarów W Elektrowniach Jądrowych." Journal of KONBiN 23, no. 1 (September 1, 2012): 5–16. http://dx.doi.org/10.2478/jok-2013-0034.
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Abstract The high failure frequency and the resultant reliability and safety implications in recent years of transformers, in particular at nuclear power plants (NPP), required an in-depth assessment. Fires of main transformers are considered as critical because of the large quantity of oil in contact with high voltage elements. Therefore, these phenomena have been investigated in more detail using the information from the OECD FIRE database for NPP. 12.8 % of all fires and, thus, the most frequent fire source in this database are transformer fires, mainly fires of high voltage oil-filled transformers. Thus, possible diagnostic measures to avoid such events and enhance the reliability currently discussed in Germany are shortly described. Moreover, consequences of transformer failures with respect to a reliable electric power supply are addressed.
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Kurniawan, Teguh, Craig A. Baguley, Udaya K. Madawala, Suwarno Suwarno, Nanang Hariyanto, and Yuana Adianto. "An Electric Vehicle Charge Scheduling Approach Suited to Local and Supplying Distribution Transformers." Energies 13, no. 13 (July 6, 2020): 3486. http://dx.doi.org/10.3390/en13133486.
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Distribution networks with high electric vehicle (EV) penetration levels can experience transformer overloading and voltage instability issues. A charge scheduling approach is proposed to mitigate against these issues that suits smart home settings in residential areas. It comprises measurement systems located at distribution transformers that communicate directly with fuzzy logic controller (FLC) systems embedded within EV supply equipment (EVSE). This realizes a reduction in data processing requirements compared to more centralized control approaches, which is advantageous for distribution networks with large numbers of transformers and EV scheduling requests. A case study employing the proposed approach is presented. Realistic driver behavior patterns, EV types, and multivariate probabilistic modeling were used to estimate EV charging demands, daily travel mileage, and plug-in times. A Monte Carlo simulation approach was developed to obtain EV charging loads. The effectiveness of mitigation in terms of reducing distribution transformer peak load levels and losses, as well as improving voltage stability is demonstrated for a distribution network in Jakarta, Indonesia.
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Eminoglu, Ulas, and M. Hakan Hocaoglu. "Three-Phase Transformer and Voltage Regulator Modelling for Forward/Backward Sweep-Based Distribution System Power Flow Algorithms." International Journal of Electrical Engineering & Education 46, no. 1 (January 2009): 30–46. http://dx.doi.org/10.7227/ijeee.46.1.3.
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Bignucolo, Fabio, and Manuele Bertoluzzo. "Application of Solid-State Transformers in a Novel Architecture of Hybrid AC/DC House Power Systems." Energies 13, no. 13 (July 3, 2020): 3432. http://dx.doi.org/10.3390/en13133432.
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The ongoing diffusion of solid-state DC/DC converters makes possible a partial migration of electric power systems from the present AC paradigm to a future DC scenario. In addition, the power demand in the domestic environment is expected to grow considerably, for example, due to the progressive diffusion of electric vehicles, induction cooking and heat pumps. To face this evolution, the paper introduces a novel electric topology for a hybrid AC/DC smart house, based on the solid-state transformer technology. The electric scheme, voltage levels and converters types are thoroughly discussed to better integrate the spread of electric appliances, which are frequently based on internal DC buses, within the present AC distribution networks. Voltage levels are determined to guarantee high safety zones with negligible electric risk in the most exposed areas of the house. At the same time, the developed control schemes assure high power quality (voltage stability in the case of both load variations and network perturbations), manage power flows and local resources according to ancillary services requirements and increase the domestic network overall efficiency. Dynamic simulations are performed, making use of DIgSILENT PowerFactory software, to demonstrate the feasibility of the proposed distribution scheme for next-generation smart houses under different operating conditions.
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Shagiev, Rinat Ildarovich, Arkadi Vasilyevich Karpov, and Sergei Aleksandrovich Kalabanov. "The Diagnostics System for Power Transmission Lines of 6/10 kV." Applied Mechanics and Materials 666 (October 2014): 138–43. http://dx.doi.org/10.4028/www.scientific.net/amm.666.138.
Full textAbstract:
The article describes the diagnostics system of the power transmission lines of 6/10 kVolts on the basis of smart electric modems. It shows the description of the smart electric modem and the creation principle of the diagnostics system. The main feature here is the use of power transformers as coupling devices with a high-voltage power line.
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Obaid, Waleed, Abdul-Kadir Hamid, and Chaouki Ghenai. "Solar/wind pumping system with forecasting in Sharjah, United Arab Emirates." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 4 (August 1, 2021): 2752. http://dx.doi.org/10.11591/ijece.v11i4.pp2752-2759.
Full textAbstract:
This paper demonstrates a water pumping hybrid power system design. The proposed system was designed for water related applications in Sharjah (Latitude 25.29 °N and Longitude 55 °E), United Arab Emirates. The proposed water hybrid system has two primary renewable power systems: solar PV panels and wind turbines. The proposed hybrid system considers the changes in weather conditions (humidity, wind speed, and temperature) since wind speed affects the performance of the wind turbines and solar panels are affected by solar irradiance. The following components are involved in the proposed design: battery (to store the power from solar panels), voltage regulator circuit (for getting stable DC voltage), three-phase rectifier (to convert the reduced AC voltage to DC), three-phase transformer (for reducing the obtained AC voltage), and DC electric motor (the main output of the proposed water pumping system). The proposed water pumping system relies on neural network blocks to achieve weather forecasting by obtaining solar irradiance values from the input temperature, wind speed, and humidity in a span of five years. Both MATLAB and Simulink are used simulate the performance of the proposed system under different weather conditions by changing the values according to the measured weather conditions values over five years.
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Gracheva, E. I., A. N. Gorlov, and Z. M. Shakurova. "Calculation of the economy of electric energy in industrial electrical supply systems." Power engineering: research, equipment, technology 22, no. 2 (May 15, 2020): 65–74. http://dx.doi.org/10.30724/1998-9903-2020-22-2-65-74.
Full textAbstract:
The article examines the main features of the layout of electrical equipment for shop networks of internal power supply with the definition of indicators for a group of shop customers connected to a single power center, affecting the choice of the structure of schemes for shop network sites. The parameters characterizing the circuit topology are revealed. A study is presented of the influence of the load factor of workshop transformers on their reactive power factor, it is proved by calculation by technical and economic criteria the feasibility of replacing a workshop transformer with two with a lower total power. The calculation of energy savings in the in-plant power supply systems. The type of dependences tgφ of transformers ТМ and ТСЗ with various rated powers in the function of loading transformers is established. The most significant factors of the growth of idle power losses during operation are presented. With determination of losses of active and reactive power and electricity in transformers and losses of active power in a high voltage distribution network A feasibility study was carried out on the options for internal power supply schemes with two transformers of lower power installed instead of one, and the feasibility of such a replacement to increase the efficiency of the equipment was proved and the estimated payback period for the investment capital was determined. A comparative analysis of the studied power supply schemes of industrial enterprises with the identification of their advantages and disadvantages.