Proceedings, Electrical engineering institute "Nikola Tesla"
type: channel
description: ZBORNIK RADOVA, ELEKTROTEHIČKI INSTITUT NIKOLA TESLA je periodična i stručna publikacija koja sadrži naučne i stručne radove iz oblasti elektrotehnike. Njegov osnovni cilj je da upozna naučnu javnost sa najnovijim torijskim I praktičnim rezultatima istraživanja iz oblasti elektroenergetskih sistema, energetske elektronike, automatike, regulacije, elektroenergetskih objekata i električnih merenja. Svi radovi su recenzirani od strane afirmisanih istraživača iz oblasti elektroenergetike i prvi put se publikuju.
publisher: Elektrotehnički institut Nikola Tesla Akcionarsko društvo Beograd
language: en
publication name: Proceedings, Electrical engineering institute "Nikola Tesla"
issn: 0350-8528
items: Technical specifications for the procurement of power transformers
items: https://asistent.ceon.rs/index.php/zeint/en/article/view/62902
items: Determination of the Efficiency of the Turbogenerator B3 Rated 412 MVA at Thermal Power Plant “Kostolac B”
items: Srpski
items: Conceptual solution for enhancing the electrolyser power supply system and hydrogen production
items: Kinetics of the reaction between elemental sulfur and silver in synthetic esters and comparison with mineral oils
items: Estimation of the moment of inertia of a unit in a thermal power plant
items: Electricity Consumption Forecasting using ARIMA and LSTM
items: Remote Control Implementation of the Hydraulic Turbine Governor on the Test Field
items: Methodology for Assessing Voltage–Reactive Power Capability of Synchronous Units under Modified Transformer Impedance
items: Concept and Application of Digital Twins for Oil-Immersed Power Transformers
items: A Three-Phase Current Source Inverter With Third Harmonic Injection For Grid-Connected Renewable Power Sources
items: Application of dispersion and regression analysis to optimize the efficiency of the technological procedure of dechlorination of PCB-contaminated insulating oils
items: Results of the GreenCleanS Project Funded by the Science Fund of the Republic of Serbia
items: Examples of ultrasonic detection of partial discharges in case of 110kV instrument transformers
items: Modification of the implementation of the underexcitation limiter within the generator excitation system of unit B1 at TPP “Nikola Tesla B”
items: A Comparative Analysis of Deep Neural Networks and Gradient Boosting Algorithms in Long-Term Wind Power Forecasting
items: Blind Equalization of Partial Discharge Channels
items: Investigation of ferroresonance phenomena in isolated 6 kV power network
items: Frequency controlled drive of vibrating screens with unbalanced exciters: practical implementation and experimental results
items: Parameter Selection and Analysis of Dynamic Characteristics of a Under-Excitation Limiter Using a Computer Model
items: Examples of power transformers testing after outages and bad results of the chemical analysis of the oil sample
items: Declaration of Conformity of Excitation System of Synchronous Machines
items: Hybrid Uninterruptible Power Supply System for Irrigation of Vegetable Crops
items: Algorithm of reactive power dispatching “per generator” realization on TPP Nikola Tesla A
items: Nikola Tesla as a phenomenon in the world of science
items: The Reliability of Serial Data Communication Using Uart-Usb converter
items: ESTIMATION OF HYDROGENERATOR ROTOR DYNAMIC THERMAL MARGINE
items: Analysis of the possibility of a parallel resonant circuit in RHPP Bajina Bašta
items: Application of measures for reduction of magnetic flux density levels in the apartment located above the 10/0.4 kV transformer station

Technical specifications for the procurement of power transformers
type: item
description: The paper presents a comprehensive and complex project of the Internal Standard, IS2 Technical specifications for the procurement of power transformers, for the needs of Elektroprivreda Srbije ad (EPS ad), according to contract no. 2.5.0.012.01 - 39646/4-2022 and 02/04/5076-22 dated 29.12.2022. The project deals with 21 chapters, according to the program task and includes 209 pages. Considering the complexity of the project, it also contains 6 shemas and 25 table views. The project was adopted by the Expert Council of EPS ad.
subject: Professional Paper
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creator: Mihajlo Ristić
creator: Slobodan Maksimović
creator: Branko Pejović
creator: Djordje Jovanovic
creator: Dragan Teslić
creator: Miroslav Radojčić
creator: Vesna Radin
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-30
publication date: 2025-12-30
starting page: 147
ending page: 167
doi: 10.5937/zeint35-55545

https://asistent.ceon.rs/index.php/zeint/en/article/view/62902
type: item
title: Measurements of power transformers winding frequency response using the SFRA (Sweep Frequency Response Analysis) method - examples after failures in power transformers and factors that have influence on the recorded frequency responses
description: Sweep Frequency Response Analysis (SFRA) represents an unconventional method used in case of recording the frequency response of transformer windings. The method has found application in the analysis of geometry of power transformer windings in order to determine integrity of the core and winding geometry. Recently, this method has become an almost indispensable part of factory acceptance tests of transformers. Frequency responses recorded in factory or first time in transformer life are used as „fingerprint“ for all future comparisons. The method is applied in on-site tests when mechanical failures are suspected due to the action of dynamic forces during operation, as well as during the transport of transformers. In addition, it can also indicate certain electrical failures. The paper will present examples of recorded frequency responses on transformers that had some failures during their operation. Also it will be shown some examples of various influences on the frequency responses which can be misinterpreted and lead to an error in the assessment of the state of the winding geometry.
subject: Professional Practice
  topic: section
subject: Array
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creator: Momčilo Milić
creator: Djordje Jovanovic
creator: Marko Dimitrijevic
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 87
ending page: 104
doi: 10.5937/zeint35-62902

Determination of the Efficiency of the Turbogenerator B3 Rated 412 MVA at Thermal Power Plant “Kostolac B”
type: item
description: In modern power systems, which are rapidly transforming toward a sustainable future, the role of conventional generation units — synchronous generators — remains of fundamental importance. During the ongoing energy transition, the increasing share of renewable energy sources connected to the grid through power electronic converters poses a challenge, as their generation does not inherently contribute to the system’s inertial stability. For this reason, the construction of the new unit B3 at thermal power plant Kostolac B, equipped with a synchronous turbogenerator, has particular significance for the Serbian power system. It ensures the preservation of system reliability and operational security while enabling further integration of renewable energy sources. This paper presents the results of the performance tests of the B3 turbogenerator, rated 412 MVA (350 MW), at thermal power plant Kostolac B, with a focus on determining the generator efficiency — one of the guaranteed parameters defined in the contract between the supplier and the customer. In the context of achieving green agenda objectives, where maximum reliability and optimal utilization of existing resources are required, precise determination of generator efficiency is of great importance. The tests were carried out on-site, following a methodology agreed upon between the supplier and the customer, and in accordance with the IEC 60034 standard for rotating electrical machines. The generator efficiency was determined using the calorimetric method, selected as the reference approach due to its highest accuracy and minimal measurement uncertainty. The obtained results confirm that the achieved efficiency of the B3 turbogenerator exceeds the guaranteed value, thereby validating the high quality of the delivered equipment.
subject: Professional Paper
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creator: Ilija G Klasnić
creator: Miroslav Dragićević
creator: Dušan Joksimović
creator: Darko Šarić
creator: Željko Lazović
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 21
ending page: 32
doi: 10.5937/zeint35-62727

Srpski
type: item
description: Uninterruptible Power Supply (UPS) systems are of vital importance for many consumers in complex facilities such as a thermal power plant. This paper presents a solution for the parallel operation of two inverters with nominal powers of 60 kVA, based on controlling the nature of the inverters. All challenges and technical details of parallelizing the two inverters are presented, from uniform load sharing and communication to establishing a "master-slave" relationship, and even the transient phenomena during the failure of one of the inverters. Detailed simulations of all relevant events and phenomena are simulated using the Plecs software tool. In accordance with the calculations, the inverters were developed, and experimental results of the operation of these inverters under simulated operational conditions are also included.
subject: Professional Paper
  topic: section
subject: Array
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creator: Nikola Mirković
creator: Blagota Jovanović
creator: Srpski
creator: Anđelka Mirković
creator: Zlatko Simeunović
creator: Dejan Žukovski
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 33
ending page: 47
doi: 10.5937/zeint35-63145

Conceptual solution for enhancing the electrolyser power supply system and hydrogen production
type: item
description: The paper presents a realized solution for powering an alkaline electrolyser for hydrogen production and offers a proposal for its improvement. By connecting photovoltaic panels, via a DC-DC converter, directly to the DC side of the existing twelve-pulse rectifier, it is possible to achieve savings in electrical energy necessary for hydrogen production through the alkaline electrolysis process. Measurements of electrical quantities for the existing power supply system are provided, along with a simulation of the improved system's operation and a proposal for its more efficient control. Hydrogen obtained using energy from renewable sources in the electrolysis process is green hydrogen, which will be a significant energy carrier in the future and the backbone of the energy transition.
subject: Original Scientific Paper
  topic: section
creator: Nikola Kovačević
creator: Kristina Lazović
creator: Milorad Igić
creator: Sava Dobričić
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 105
ending page: 126
doi: 10.5937/zeint35-63000

Kinetics of the reaction between elemental sulfur and silver in synthetic esters and comparison with mineral oils
type: item
description: For decades, the problem of corrosive sulfur was considered to be exclusively associated with mineral oils. However, recent cases from industry have disproved this assumption. The presence of elemental sulfur in insulating oil causes corrosion of silver contacts and consequently leads to power transformer failures. The aim of this study is to determine the kinetics of the reaction between elemental sulfur and silver in synthetic ester within the temperature range of 120–180 °C. The elemental sulfur content in the oil during the reaction is determined using gas chromatography with an electron capture detector (GC-ECD). The results show that the reaction between silver and elemental sulfur follows the first-order law. A comparative analysis of the examined reaction in synthetic ester and mineral oil shows that the reaction proceeds faster in synthetic ester.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Milica Djukic
creator: Jelena Lukic
creator: Jelena Jankovic
creator: Dejan Kolarski
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 127
ending page: 147
doi: 10.5937/zeint35-63582

Estimation of the moment of inertia of a unit in a thermal power plant
type: item
description: Increasing integration of renewable energy sources and the withdrawal of fossil-fuel generators reduce overall power-system inertia, making the grid more vulnerable to disturbances and threatening transient and frequency stability. Low inertia can lead to large frequency deviations, equipment damage, and financial losses, which highlights the need for accurate assessment of inertia contributions from remaining generation units and determination of the minimum inertia required for stable operation. While synchronous generator inertia constants are usually provided by manufacturers, corresponding data for steam turbines are often unavailable. Since post-fault transient stability depends on the true inertia of the combined generator–turbine assembly, this gap complicates stability studies. This paper proposes a method for estimating the inertia of turbogenerators using coast-down measurements from thermal unit B1 of the "Nikola Tesla B" power plant. The method is based on Newton’s rotational motion equation and enables more accurate evaluation of inertia in large thermal units.
subject: Original Scientific Paper
  topic: section
subject: Array
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subject: Array
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creator: Anita Mijajlović
creator: Jasna Dragosavac
creator: Ilija Klasnić
creator: Milan Đorđević
creator: Igor Damjanac
creator: Miloš Brdarević
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 49
ending page: 59
doi: 10.5937/zeint35-63014

Electricity Consumption Forecasting using ARIMA and LSTM
type: item
description: Accurate load forecasting is essential for the reliable and efficient operation of modern power systems. This study presents a comparative analysis of two prominent forecasting models—Autoregressive Integrated Moving Average (ARIMA) and Long Short-Term Memory (LSTM)—to assess their effectiveness in predicting electricity consumption. Both models were developed and fine-tuned through hyperparameter optimization to ensure fair and optimal performance. The evaluation considered predictive accuracy, computational efficiency, and resource usage. While ARIMA demonstrated advantages in inference speed and model simplicity, the LSTM model consistently outperformed it in terms of forecasting accuracy and its ability to capture complex temporal dependencies. These findings underscore the importance of selecting appropriate models and tuning strategies for specific forecasting scenarios. The study highlights LSTM as a more suitable approach for applications that demand high accuracy and adaptability, and it provides a foundation for future research involving advanced or hybrid methods.
subject: Original Scientific Paper
  topic: section
subject: Array
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creator: Živko Sokolović
creator: Sasa Milic
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-06-26
publication date: 2025-06-26
starting page: 1
ending page: 20
doi: 10.5937/zeint0-58547

Remote Control Implementation of the Hydraulic Turbine Governor on the Test Field
type: item
description: This paper presents the enhancement of the turbine governor test field of a hydraulic turbine through the implementation of a modern SCADA system based on an integrated PLC web server and OPC UA communication with a Simulink environment simulator and turbine governor. The system enables realistic simulation of turbine governor operation under laboratory conditions, with the capability of remote monitoring and parameter adjustment via a standard web browser. Within the research, a web server SCADA system was developed on the Siemens S7-1500 PLC, connecting the physical controller and the simulation model into a unified hardware-in-the-loop (HIL) environment. The obtained results demonstrate a significant improvement in the flexibility, transparency, and efficiency of the turbine governor testing process.
subject: Original Scientific Paper
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creator: Jovan Stevanović
creator: Goran Kvaščev
creator: Miroslav Dragićević
creator: Jelena Pavlović
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 61
ending page: 71
doi: 10.5937/zeint35-63093

Methodology for Assessing Voltage–Reactive Power Capability of Synchronous Units under Modified Transformer Impedance
type: item
description: This paper presents a methodology for evaluating the voltage–reactive power capability of synchronous generators following changes in transformer impedance. The framework integrates per-unit calculations, an equivalent generator–transformer model, and numerical simulations across multiple grid-voltage scenarios. The SIM-Operating Map application provides analytical and graphical verification of reactive margins, limiting factors, and grid-code compliance, supporting operational decision-making and enhancing system security after transformer replacement.
subject: Original Scientific Paper
  topic: section
subject: Array
  topic: keywords
subject: Array
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subject: Array
  topic: keywords
creator: Anita Mijajlovic
creator: Jasna Dragosavac
creator: Žarko Janda
creator: Ilija Klasnić
rights: Copyright (c) 2025 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2025-12-29
publication date: 2025-12-29
starting page: 73
ending page: 86
doi: 10.5937/zeint35-63149

Concept and Application of Digital Twins for Oil-Immersed Power Transformers
type: item
description: This paper provides a literature review and establishes the state-of-the-art in the concept and application of Digital Twin (DT) technology to power transformers. The introductory sections focus on the evolving definition and universal concepts of DT, independent of specific fields of application, as well as the goals of Industry 4.0 and the technologies that enable digital transformation in industry. Special attention is given to the particularities of the power industry, with an emphasis on the unique requirements posed by the nature and importance of oil-filled power transformers, which serve as the foundation for the development of systems based on DT technologies.
subject: Review Paper
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creator: Uros Radoman
creator: Filip Kilibarda
creator: Nenad Kartalovic
creator: Nikola Miladinović
creator: Vladimir Poluzanski
creator: Valentina Vasovic
creator: Branko Pejovic
creator: Aleksandar Zigic
creator: Jelena Lukic
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-26
publication date: 2024-12-26
starting page: 61
ending page: 82
doi: 10.5937/zeint34-54654

A Three-Phase Current Source Inverter With Third Harmonic Injection For Grid-Connected Renewable Power Sources
type: item
description: <!-- [if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--><!-- [if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:EnableOpenTypeKerning/> <w:DontFlipMirrorIndents/> <w:OverrideTableStyleHps/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--><!-- [if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true" DefSemiHidden="true" DefQFormat="false" DefPriority="99" LatentStyleCount="267"> <w:LsdException Locked="false" Priority="0" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="Normal"/> <w:LsdException Locked="false" Priority="9" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="heading 1"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/> <w:LsdException Locked="false" Priority="9" Q…
subject: Original Scientific Paper
  topic: section
subject: Array
  topic: keywords
creator: Žarko S. Janda
creator: Predrag Ninković
creator: Predrag Pejović
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-26
publication date: 2024-12-26
starting page: 109
ending page: 127
doi: 10.5937/zeint34-55462

Application of dispersion and regression analysis to optimize the efficiency of the technological procedure of dechlorination of PCB-contaminated insulating oils
type: item
description: Abstract. Modern experimental research theory includes plans for statistical multifactorial analysis. The advantage of this theory is that all factors are changed simultaneously so that a minimum number of experimental points distributed in the experimental hyperspace is obtained, which results in much lower costs and shorter time of experimental tests. The process of decontamination of polychlorinated biphenyls (PCB) from transformer oils is based on a dechlorination reaction using a reagent mixture (KPEG) consisting of potassium hydroxide (KOH) and polyethylene glycol (PEG), whereby the PCB molecule is chemically decomposed. Using 23 orthogonal plans, the influence of the mass percent of KPEG/oil, KOH/PEG molar ratio and temperature on the dechlorination reaction were investigated to optimize this process. The success of the reaction was evaluated by determining the efficiency of chemical degradation of PCBs (DRE) from transformer oil. The DRE values ​​were from 81.81% to 99.81%. Using dispersion analysis, the significance and degree of interactivity of the examined factors on DRE were determined, and using regression analysis, a multi-linear regression model was set up.
subject: Original Scientific Paper
  topic: section
subject: Array
  topic: keywords
creator: Savo Marinković
creator: Draginja Mihajlović
creator: Jelena Lukić
creator: Ana Marinković
creator: Dragana Naumović Vuković
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-26
publication date: 2024-12-26
starting page: 95
ending page: 108
doi: 10.5937/zeint34-55173

Results of the GreenCleanS Project Funded by the Science Fund of the Republic of Serbia
type: item
description: The project funded by the Science Fund of the Republic of Serbia, Development of Green Technology to Mitigate Power Transformer Failures Induced by Elemental Sulphur and Change Current Hazardous Practice in Transformer Oil Regeneration, under the acronym GreenCleanS focuses on developing a new technology for removing elemental sulphur molecule (S₈) from mineral insulating oils used in power transformers (PT) utilization an innovative low-temperature desulfurization process. The technology development includes experimental work at the laboratory scale and pilot scale level (technology readiness level, TRL 4), as well as the demonstration of the technology in an operational environment, involving the treatment of 3 tons of oil in a mobile desulfurization unit to achieve TRL 7. The implementation of this innovative technology will contribute to reducing the number of transformer failures caused by mineral oils containing S₈, a highly corrosive compound.
subject: Professional Paper
  topic: section
creator: Dejan Kolarski
creator: Jelena Lukic
creator: Valentina Vasovic
creator: Jelena Janković
creator: Draginja Mihajlovic
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-26
publication date: 2024-12-26
starting page: 83
ending page: 93
doi: 10.5937/zeint34-54867

Examples of ultrasonic detection of partial discharges in case of 110kV instrument transformers
type: item
description: Instrument transformers represent an important part in case of power plants where they are widely distributed because they play a significant role in measuring and protecting the entire power system. Taking into account the continuous exposure of instrument transformers to ambient and electrical stresses, as well as the fact that their explosions often occur, which directly endangers the operation of electric power facilities and disrupts the stability and continuity of the supply of consumers, there is a need for electrical tests of instrument transformers in order to determine their condition and to be sure they are capable or risky for further operation. One of the methods for testing instrument transformers, whose advantage is that it does not require their disconnection from operation, but the measurements are performed while the tested object is loaded is an acoustic (ultrasound) method and involves placing an acoustic piezo-sensor on the wall of the transformer tank that is grounded and at a safe distance from high voltage, short-term acquisition and subsequent analysis. This is exactly what makes the mentioned method simple to apply in the power plant because it does not require any special interventions or protection. Acoustic detection of partial discharges is generally performed in cooperation with gas chromatographic analysis of insulating oil, which confirms the expressed suspicion of the activity of partial discharges in the insulation of the instrument transformers. The paper will first of all present examples of ultrasonic detection of partial discharges on 110kV instrument transformers where the chemical analysis of the oil sample confirmed the existence of partial discharges.
subject: Professional Paper
  topic: section
creator: Momčilo Milić
creator: Ђорђе Јовановић
creator: Весна Радин
creator: Марко Димитријевић
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-26
publication date: 2024-12-26
starting page: 49
ending page: 60
doi: 10.5937/zeint34-54558

Modification of the implementation of the underexcitation limiter within the generator excitation system of unit B1 at TPP “Nikola Tesla B”
type: item
description: The paper describes the event of the outage of the unit B1 at TPP "Nikola Tesla B" from the grid which, as well as the modification of the implementation of the underexcitation limiter within the excitation system, which is the result of a detailed analysis of the excitation system response immediately before and during the event itself. The structure of the underexcitation multiple-segment straight-line characteristic and the method of its realization are described. The modification of the implementation of the limiter was carried out based on the recordings of unit B1 outage from the grid and in-depth analysis of the event and the response of the excitation system, Additionally, the measurements that enter the limiter implementation algorithm are filtered: stator voltage measurement and generator active power measurement. The limiter also has a variable gain depending on the range of reactive power or active segment. Lastly, the results of testing the response of the underexcitation limiter during the operation of the generator B1 on the grid are presented, which indicate a stable response with damped oscillations.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Ilija G Klasnić
creator: Slavko Veinović
creator: Dušan Joksimović
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-12-25
publication date: 2024-12-25
starting page: 37
ending page: 47
doi: 10.5937/zeint34-54005

A Comparative Analysis of Deep Neural Networks and Gradient Boosting Algorithms in Long-Term Wind Power Forecasting
type: item
description: A vital step toward a sustainable future is the power grid's incorporation of renewable energy sources. Wind energy is significant because of its broad availability and minimal environmental impact. The paper presents a comparative analysis of recurrent neural network (RNN) algorithms and gradient boosting algorithms (GBMs) applied to time series data for the regression issue of estimating the active power generated by a wind farm (WF). GBM algorithms combine the advantages of a few machine learning models (decision trees, random forests, etc.) to produce a powerful prediction model. In addition to existing conventional RNN, the article deals with long short-term memory LSTM (LSTM) and gate ruccerrent unit (GRU) as cut of the edge models for time series prediction. In addition to conventional RNNs, the article deals with long short-term memory LSTM (LSTM) and gated recurrent unit (GRU) as cutting-edge models for time series analysis and predictions. A comprehensive analysis was carried out on a large wind power generation data set.
subject: Original Scientific Paper
  topic: section
subject: Array
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subject: Array
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subject: Array
  topic: keywords
creator: Luka Ivanovic
creator: Saša Milić
creator: Živko Sokolović
creator: Aleksandar Rakić
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-10-17
publication date: 2024-10-17
starting page: 15
ending page: 36
doi: 10.5937/zeint34-51258

Blind Equalization of Partial Discharge Channels
type: item
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subject: Professional Paper
  topic: section
subject: Array
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creator: Aleksandar Žigić
creator: Nenad Kartalovic
creator: Uros Radoman
creator: Uros Kovačevic
rights: Copyright (c) 2024 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2024-04-04
publication date: 2024-04-04
starting page: 1
ending page: 13
doi: 10.5937/zeint34-49112

Investigation of ferroresonance phenomena in isolated 6 kV power network
type: item
description: Ferroresonance is a complex nonlinear electrical phenomenon that can cause significant dielectric and thermal stresses in power equipment, leading to potential faults, equipment damage, power supply interruptions, etc. Three-phase networks with isolated neutral point and single-phase isolated inductive voltage transformers are susceptible to ferroresonance, caused by the interaction of the transformer's nonlinear inductances and zero sequence capacitance of power network. The paper analyzes the possibility of ferroresonance occurrence in a real 6 kV power network, with an isolated neutral point, using the electromagnetic transients program ATP/EMTP. A detailed network model is developed, taking into account the nonlinearity of voltage and power transformers, which is utilized to analyze various configurations, switching operations, and faults in the network that could trigger ferroresonance. It is shown that, under certain circumstances, ferroresonance can occur, with faults clearing being the most common initiators of ferroresonance. The efficiency of different measures to suppress ferroresonance is also analyzed. The impact of the resistance values of voltage transformer’s open delta winding dumping resistor on the suppression of ferroresonance occurrence, is considered.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Ranko Jasika
creator: Katarina Maksić
creator: Jovan Mrvić
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 1
ending page: 13
doi: 10.5937/zeint33-47844

Frequency controlled drive of vibrating screens with unbalanced exciters: practical implementation and experimental results
type: item
description: The paper presents a practically realized technical solution for frequency control of the AC power drive of vibrating sieves based on unbalanced vibration exciters. The operation of vibrating screen used in the industry for sieving and separating material fractions of different granulations is determined to a significant extent by the tilting angle of the vibrating sieve, its amplitude, the angle of attack of the excitation force and the frequency of oscillation. The frequency control of the vibrating sieves drive in this particular case made it possible to obtain the amplitude-frequency (AF) characteristic of the vibrating screen and based on it, the optimal operating frequency, which ensures the best separation of individual material fractions was determined. The solution was applied to two process lines in silos for de-ashing in the system of transport and separation of boiler slag from ash at the Thermal Power Plant "Nikola Tesla" B (TPP-B) in Obrenovac. The paper presents the key experimental results that were obtained during exploitation and testing of two implemented systems of regulated vibrating sieves.
subject: Professional Paper
  topic: section
subject: Array
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subject: Array
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subject: Array
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subject: Array
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subject: Array
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subject: Array
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creator: Željko V Despotović
creator: Aleksandar I. Pavlović
creator: Jovana Vujić
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 59
ending page: 73
doi: 10.5937/zeint33-48149

Parameter Selection and Analysis of Dynamic Characteristics of a Under-Excitation Limiter Using a Computer Model
type: item
description: <!-- [if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:DontVertAlignCellWithSp/> <w:DontBreakConstrainedForcedTables/> <w:DontVertAlignInTxbx/> <w:Word11KerningPairs/> <w:CachedColBalance/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--><!-- [if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true" DefSemiHidden="true" DefQFormat="false" DefPriority="99" LatentStyleCount="267"> <w:LsdException Locked="false" Priority="0" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="Normal"/> <w:LsdException Locked="false" Priority="9" SemiHidden="false" UnhideWhenUsed="false" QFormat="true" Name="heading 1"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/> <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 6"/> <w:LsdException Locked="false" Priorit…
subject: Professional Paper
  topic: section
creator: Dušan
creator: Ilija Klasnic
creator: Djordje Stojic
creator: Luka Ivanovic
creator: Nemanja Milojcic
creator: Slavko Veinovic
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 75
ending page: 89
doi: 10.5937/zeint33-48352

Examples of power transformers testing after outages and bad results of the chemical analysis of the oil sample
type: item
description: Power transformers represent one of the most important components in terms of production, transmission and distribution of electricity. Precisely for this reason, it is necessary to pay some attention in terms of preventive electrical measurements that should be done in order to have an adequate insight into their condition, avoid unwanted breakdowns and thus ensure stable and reliable operation of the entire power system. However, there are situations when power transformers fail due to various factors. In such cases, depending on which protection has reacted and preemptively switched off the observed transformer, and especially in the case of an outage due to the differential protection of the transformer, it is necessary to carry out certain tests before possible reconnection in order to assess the reason for the outage and the continued ability of the transformer itself to work. Electrical tests should be preceded by sampling oil from the transformer (and/or gas and oil from the Buchholz relay) for chemical analysis by the gas chromatography method. The results of the chemical analysis of the oil sample can express doubts about possible irregularities that may be a problem for further normal operation of the transformer and such situations are followed by certain electrical tests whose results in most cases will give a better insight into the state of the transformer itself. This paper will give examples of the results of electrical measurements made after power transformers were out of operation and measurements after bad results of chemical analysis of oil samples.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Momčilo Milić
creator: Djordje Jovanovic
creator: Marko Dimitrijević
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 15
ending page: 31
doi: 10.5937/zeint33-47927

Declaration of Conformity of Excitation System of Synchronous Machines
type: item
description: The paper presents a comprehensive complex model for the Declaration of Conformity of the Excitation System. The necessary projects for conformity assessment, standardization, accreditation and metrology are given. Some testing and compliance modules are listed. A part of the test according to the CB scheme of Low-voltage switchgear and controlgear assemblies for the excitation system Tesla ES 7000A is presented, which is according to valid standards, and for nominal currents up to 7000 A. A part of the test according to the CB scheme of electromagnetic compatibility for the Tesla ES excitation regulator is presented. The Declaration of Conformity of the Tesla ES 1600 excitation system is presented
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Zoran Ćirić
creator: Mihajlo Ristić
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 33
ending page: 48
doi: 10.5937/zeint33-48333

Hybrid Uninterruptible Power Supply System for Irrigation of Vegetable Crops
type: item
description: The paper presents the realization of a hybrid and uninterruptible power supply system based on green or renewable energy sources (solar and wind) which is used for irrigation of vegetable crops on the "smart land" at the location of the town Belegiš, which is located in the immediate vicinity of Belgrade and on the side of the Danube River. Within the power system are realized the photovoltaic power plant with an output AC power of 8 kW, the wind generator with a power of 0.5 kW and battery bank 48Vdc/720Ah. This three of power supplies are as primary power sources, while a diesel electric generator (DEG) with a power of 7.5 kW, is one auxiliary power source. In addition to this hybrid and uninterruptible power supply, a system for smart management for irrigation has been implemented. At the end of the paper will be present the experimental results obtained during the exploitation.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
subject: Array
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subject: Array
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subject: Array
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subject: Array
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subject: Array
  topic: keywords
creator: Željko V Despotović
creator: Ilija R. Stevanović
creator: Aleksandar Rodić
rights: Copyright (c) 2023 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2023-12-28
publication date: 2023-12-28
starting page: 49
ending page: 58
doi: 10.5937/zeint33-48022

Algorithm of reactive power dispatching “per generator” realization on TPP Nikola Tesla A
type: item
description: The algorithm of reactive power dispatching “per generator” realization is presented in the paper. Dispatching “per generator” and “per grid” are two modes of reactive power dispatching used by coordinated reactive power and voltage regulator (GRRS). Reactive power dispatching “per generator” ensures equal heating of the generators, while dispatching “per grid” ensures maximal reactive power reserve when generated reactive power either increases, or decreases. Reactive power dispatching “per generator” is more complex for realization because the dispatching criterion may have wider generator’s reactive power operation area than the working capability curve. In these cases, the additional limiting of the generator reactive power is necessary, while other generators take over the remaining reactive power, still considering the reactive power dispatching criteria “per generator” and the limits of the remaining generators. Both reactive power dispatching modes are presented in two examples, while operating near and far from the limit area. Eventually, as the verification of the algorithm and its realization, the operating results of GRRS while dispatching “per generator” is active, are presented.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Jelena Pavlović
creator: Bojan Radojičić
creator: Lazar Stančić
creator: Jasna Dragosavac
creator: Sava Dobričić
creator: Žarko Janda
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 113
ending page: 123
doi: 10.5937/zeint32-41760

Nikola Tesla as a phenomenon in the world of science
type: item
description: This article is dedicated to Nikola Tesla, who created a technically and intellectually highly developed civilization and who is a true companion to humanity in the historical process. The significance of its motives is a need, which drives to the activity towards a specific goal in favour of technical achievements applicable in practice. Of particular importance for understanding Tesla's actions is a moral awareness that represents the adopted principles of his thoughts that are logical and impeccably clear, and they are the proof that on their basis he made arguments and achieved new results.
subject: Biographical Item
  topic: section
subject: Array
  topic: keywords
creator: Vukan R Slavković
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 125
ending page: 135
doi: 10.5937/zeint32-39893

The Reliability of Serial Data Communication Using Uart-Usb converter
type: item
description: During the design of the device that is based on a central microcontroller for measurements and an additional computer for graphical presentation and storage of measurement results, it often happens that there is not enough available USB ports. Therefore the need for using particular serial converters arises. This paper presents the results of reliability testing of serial UART-USB communication using UM232R converter. The development environment Tiva TM4C1294XL microcontroller Launchpad sends temperature measurement results using UART communication to UM232R converter which is connected to ROCK PI 4 single board computer via USB interface. The user application is based on Java programming language and jSerialComm library. The communication is tested using packets of 100, 1 000 i 10 000 arrays of 50 characters. Time intervals used for tests are 10mS, 100mS, 500mS, 1s. Each test is repeated 10 times to improve test validity. The average data loss is 50%, while the proposed algorithm reduced the loss up to 30%.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Nikola S Cakić
creator: Aleksandar Žigić
creator: Srđan Milosavljević
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 95
ending page: 100
doi: 10.5937/zeint32-41677

ESTIMATION OF HYDROGENERATOR ROTOR DYNAMIC THERMAL MARGINE
type: item
description: Field winding temperature of the synchronous generator is one of the operating limits indicated in the generator PQ diagram. Therefore as accurate as possible information about its value is of great importance. It can be measured directly using built-in temperature sensors or determined indirectly. With the increasing penetration of renewable energy sources into the high-voltage transmission system, there are fundamental changes in the way conventional units work, including hydrogenerators. They are facing operating modes characterized by rapid load changes and an increased number of start-stop cycles. This mode of operation causes additional thermal stress on parts of the hydrogenerator, including the rotor. In order to be able to respond to new demands that they are facing, it is necessary to know the thermal capacity of the rotor and its influence on the dynamic hydrogenerator PQ diagram.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Ilija G Klasnić
creator: Dragan Belonić
creator: Žarko Janda
creator: Jasna Dragosavac
creator: Zoran Ćirić
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 101
ending page: 111
doi: 10.5937/zeint32-41740

Analysis of the possibility of a parallel resonant circuit in RHPP Bajina Bašta
type: item
description: The pumps in RHPP Bajina Bašta are started via a static frequency converter (SFC). This resulted in increased level of higher harmonics within the RHPP. However, it was not known whether the operation of this SFP could endanger the consumers supplied from the mentioned RHPP via the distribution transformer. For this purpose, it is necessary to check the possibilities of the existence of a parallel resonant circuit, both in the RHPP itself, and in the part of the distribution network that was of interest. Analyzes were performed in the linear simulation model created in the DIgSILENT PowerFactory software package. The simulation model was created so that it corresponds to the state of minimum load of the distribution area supplied by TS Metaljka. Also, several variants were analyzed in TS Đurići (depending on the number of motor engines in operation). The results show the existence of parallel resonant circuit in the vicinity of the 13th harmonic at the level of 10 kV busbars in TS Metaljka, while its existence was not identified at the transmission system busbar, which is in accordance with the measurements.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Milica Dilparic Cakić
creator: Branka Kovačević
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 85
ending page: 93
doi: 10.5937/zeint32-41656

Application of measures for reduction of magnetic flux density levels in the apartment located above the 10/0.4 kV transformer station
type: item
description: The paper analyzes the levels of magnetic flux density in the apartment located above the 10/0.4 kV distribution transformer station. During the first magnetic field testing, it was concluded that in the case of the rated load of the transformers, increased values of magnetic flux density would occur in the apartment. The main sources of magnetic field in the apartment were the busbars and cable lines connecting the transformers and the 0.4 kV distribution cabinets. For that reason it is proposed to apply measures to reduce the levels of magnetic flux density, which are described in detail in the paper. After implementing the proposed measures, magnetic field testing in the apartment was repeated. The paper presents magnetic field testing results before and after the application of the measures and gives a conclusion regarding the effectiveness of the applied measures as well as regarding the compliance of the levels of magnetic flux density with the exposure limit prescribed by the current national regulations.
subject: Professional Paper
  topic: section
subject: Array
  topic: keywords
creator: Maja Grbić
creator: Aleksandar Pavlović
creator: Dejan Hrvić
rights: Copyright (c) 2022 Proceedings, Electrical engineering institute "Nikola Tesla"
date: 2022-12-30
publication date: 2022-12-30
starting page: 73
ending page: 84
doi: 10.5937/zeint32-41601