5th International Colloquium On Transformer Research And Asset Management (lecture Notes In Electrical Engineering (671))

This book presents the proceedings of the 5th International Colloquium "Transformer Research and Asset Management," held in Opatija, Croatia, on October 9-12, 2019. The papers chiefly focus on three groups of topics: 1. Numerical Modeling: Electromagnetic fields--Coupled fields--Transients--Numerical modeling in design 2. Materials, Components and New Technologies: Insulating materials--Magnetic materials and transformer noise--Transformer components--New transformer technologies 3. Transformer Lifecycle Management: Diagnostics and monitoring--Failure--Asset management--In-service experiences. The Colloquium was organized by the Croatian National Committee of CIGRE together with the Faculty of Electrical Engineering and Computing in Zagreb and the Centre of Excellence for Transformers About This Book 6 Contents 7 About the Authors 10 Relative Permittivity Assessment of Oil-Impregnated Cellulose Insulation 12 1 Introduction 12 2 Relative Permittivity of Oil-Impregnated Material 13 3 Electrochemical Impedance Spectroscopy 17 4 Measurement Procedure 18 5 Measurement Results 19 6 Analysis 19 7 Conclusion 21 References 21 Difference Between 50 and 60 Hz Transformer No-Load Noise Levels 22 1 Introduction 22 2 Predictable Effects on Sound Power Levels 23 3 Sum of Predictable Effects on Sound Power Levels 25 4 Additional Noise Measurements at Different Supply Frequencies 26 5 Unpredictable Effects on Sound Power Levels 27 6 Conclusions 29 References 29 Reproducibility Estimation of Sound Power Level of Large Power Transformers 30 1 Introduction 30 2 Total Standard Measurement Uncertainty Versus Total Standard Deviation of Reproducibility 31 3 Measurement Uncertainty of Sound Pressure Level, Point-to-Point Procedure 32 4 Measurement Uncertainty of Sound Pressure Level, Walk-Around Procedure 36 5 Measurement Uncertainty of Sound Intensity Level, Point-to-Point Procedure 36 6 Measurement Uncertainty of Sound Intensity Level, Walk-Around Procedure 37 7 Total Standard Deviation of Reproducibility of Sound Power Level 37 8 Total Standard Deviation of Reproducibility of Sound Power Level in Short-Circuit Condition at It ≠ In 38 9 Measurement Uncertainty or Reproducibility in Decision-Making and Conformity Assessment 38 10 Results and Discussion 38 11 Conclusion 42 References 42 Stressed Oil Volume Theory in Transformer Winding Corner Stress Analysis 44 1 Introduction 44 2 Combined Stress Research 46 3 Electric Field Distribution Calculations and Stressed Oil Volume Definition 48 4 Analysis of Radial Electric Field Influence on Withstand LI Voltage 52 5 Conclusion 53 References 54 Synthetic Ester Impact on Power Transformer Design, Manufacturing and Testing 55 1 Introduction 55 2 Insulation Design 56 3 Thermal Design Impact 59 4 Fire Safety and Environmental Recommendations for Ester Filled Transformers 60 5 Built in Material and Components Compatibility 61 6 Process and Manufacture 62 7 Conclusion 62 References 62 Future Trends in Transformer Online Monitoring 64 1 Introduction 65 2 Development Trends 71 3 Future of Transformer Monitoring 73 4 Conclusion 74 References 75 Optimal Cooling and Life Time Management for Power Transformers 76 1 Introduction 76 2 Transformer Modeling 77 2.1 Thermal Modelling Based on Standards 77 2.2 Cooling Regulation and Effect on Top Oil and Hot-Spot Rise 77 2.3 Losses Modeling 79 2.4 Ageing Rate Modelling 79 3 Ambient Air Temperature Modeling 80 3.1 Annual Temperature Evolution/Ombrothermic Diagrams and Modeling 80 3.2 Daily Temperatures Evolutions Modeling 82 4 Transient Moisture Modeling 82 5 Case Study 84 5.1 Calculation Cases and Main Findings 84 5.2 Hysteresis Bandwidth Adjustment 86 5.3 Moisture Content for Two Different Settings and Evolution During Transformer’s Lifespan 88 6 Conclusion 90 References 91 Analysis of Overvoltages on Power Transformer Recorded by Transient Overvoltage Monitoring System 93 1 Introduction 93 2 On-line Transient Overvoltage Monitoring System 95 3 Lightning Location System 96 4 Transient Overvoltages Recorded on Power Transformers 97 4.1 Case 1—Lightning Strike to 220 kV Transmission Line Connecting Substations 2 and 3 Causing Insulator Flashover in Two Phases 97 4.2 Case 2—Lightning Strike to 220 kV Transmission Line Connecting Substations 1 and 2 Causing Insulator Flashover in Two Phases 100 4.3 Case 3—Multiple Lightning Strike to 220 kV Transmission Line Connecting Substations 1 and 2 Causing Insulator Flashover in Three Phases 102 5 Discussion and Future Work 106 6 Conclusions 109 References 109 Power Transformer Efficiency—Survey Results and Assessment of Efficiency Implementation 111 1 Introduction 111 2 Capitalisation 112 3 Survey Results 113 4 Regulation Impact 119 5 Conclusion 120 References 120 Reliable Power Transformer Efficiency Tests 121 1 Introduction 121 2 Power Transformer Loss Measurement Systems 122 3 LMS Calibration Aspects 124 3.1 LMS Accuracy Requirements 124 3.2 LMS Calibration, Adjustment, and Verification 126 3.3 Traceability 127 4 Reference Setups for On-Site Lms Calibration 128 4.1 LMS Component Calibration 128 4.2 LMS System Calibration 130 5 Conclusion 132 References 133 Verification of Maintenance Intervals for Vacuum On-load Tap-changers 134 1 Introduction 134 2 Tap-changer Design 135 3 Verification of Maintenance Intervals 136 3.1 Mechanic Endurance Testing 136 3.2 Capacitive Breaking Capacity 137 3.3 Service Duty Test 138 3.4 Electric Aging of Contacts 139 3.5 Dielectric Aging of Insulating Material 139 3.6 Summary 140 4 Maintenance 140 5 Conclusions 141 References 141 Prediction Model for the Distribution Transformer Failure Using Correlation of Weather Data 142 1 Introduction 142 2 Problem Formulation 144 3 Data Source 144 4 Prediction Model 146 5 Evaluation 147 6 Results 149 7 Conclusion 151 References 151 On Site Measurement and Simulation of Transferred Lightning Overvoltages Through Power Transformers 152 1 Introduction 153 2 Wideband Transformer Modelling 154 3 Transient Monitoring System 159 4 Application: Comparison Between in Situ Lightning Overvoltage Measurements and Emtp Simulations 160 5 Conclusions 164 References 167 Calculation of Circuit Parameters of High Frequency Models for Power Transformers Using FEM 170 1 Introduction 170 2 Calculation Procedure 172 3 Complex Permeability Principle 174 4 Homogenization Process 175 5 Modelling of Core Influence 176 6 Calculation of Transformer Inductive Impedances in Function of Frequency 177 7 Time Domain Inductive Equivalent Circuit 179 8 Determination of Inductive Equivalent Circuit Parameters 181 9 Calculation of Transformer Capacitive Impedances 183 10 Inclusion of Capacitances in the Inductive Equivalent Circuit 184 11 Solving the Equivalent Circuit in Time Domain 185 12 Comparison Between Calculations and Measurements 185 13 Conclusions 187 References 188 Small Signal Internal Voltage Transfer Measurements and White-Box Transient Calculations for Non-standard Test Conditions of a Shell-Form Power Transformer 190 1 Introduction 190 2 Shell-Form Transformer 191 2.1 Transformer Main Data 191 2.2 Transformer Winding Layout 191 2.3 Specifics of Shell-Form Versus Core-Form Effect on Voltage Distribution 192 3 Voltage Transfer Measurements 193 3.1 Procedure 193 3.2 Measurement Setup 193 3.3 Measurement Conditions 194 3.4 Conversion from Frequency Domain to Time Domain 195 4 White-Box Calculations Versus Measurements 196 4.1 Outline of the Simulation Procedure 196 4.2 Leads’ Connections 197 4.3 Measurements Versus Simulations 198 5 Observations on Measurement Accuracy 202 6 Discussion 202 7 Conclusion 203 References 203 Internal Fault Performance of Instrument Transformers with Sectioned Active Part 204 1 Introduction and Background 204 2 Basic Theory of Units with Sectioned Active Part 207 3 Numerical Modelling of Internal Fault Scenarios 209 4 Experimental Verification 212 5 Conclusions 215 References 216 Simulation of Long-Term Transformer Operation with a Dynamic Thermal, Moisture and Aging Model 217 1 Introduction 217 2 Overview of Thermo-Hydraulic Aging Model (THAM) 218 2.1 General 218 2.2 Moisture Model 220 2.3 Aging Model 222 3 Aging Simulation Study 225 3.1 Overview 225 3.2 Example for DP Value Distribution 226 3.3 Comparison of IEC and Siemens Aging 227 3.4 Influence of Initial Moisture Content and Tank Tightness 228 3.5 Influence of Non-Upgraded and Thermally Upgraded Paper 228 3.6 Influence of Initial DP Value 230 4 Conclusion 231 References 232 Line Discharge Capability of Inductive Voltage and Combined Transformers 233 1 Introduction 233 2 Thermal Capability Analysis 235 3 Mechanical Capability Analysis 243 4 Conclusion 244 References 246 Influence of Conductor Transposition on Transformer Winding RLC Parameters 247 1 Introduction 247 2 Model Development 248 2.1 Description of CTC 248 2.2 Finite Element Modeling 249 3 Simulation Results 251 4 Conclusion 252 References 255 Appropriate Modelling of Transformer High Current Leads in 3D FEM 256 1 Introduction 256 2 FEM Modelling 257 3 Result Discussion 260 4 Conclusion 264 References 266 Calculation of Eddy Current Losses in Iron Core of Transformer 268 1 Introduction 268 2 Problem Definition 269 3 Homogenization 271 4 Low-Frequency Approximation of Eddy Currents "0245Jxt 272 5 Calculation of Losses Due to Narrow Eddy Current Loops 274 6 Numerical Example 275 6.1 Results 276 7 Conclusion 277 References 278 Front Matter ....Pages i-xii Relative Permittivity Assessment of Oil-Impregnated Cellulose Insulation (Mladen Marković, Marijana Majić Renjo)....Pages 1-10 Difference Between 50 and 60 Hz Transformer No-Load Noise Levels (Miha Pirnat)....Pages 11-18 Reproducibility Estimation of Sound Power Level of Large Power Transformers (Zdenko Godec, Filip Razum, Davor Švarc)....Pages 19-32 Stressed Oil Volume Theory in Transformer Winding Corner Stress Analysis (Petar Gabrić, Ana Orešković, Vjenceslav Kuprešanin, Antun Mikulecky, Vladimir Podobnik)....Pages 33-43 Synthetic Ester Impact on Power Transformer Design, Manufacturing and Testing (Dario Šegović, Ana Orešković, Žarko Janić)....Pages 45-53 Future Trends in Transformer Online Monitoring (Teemu Auronen, Ivan Murat, Teemu Hanninen, Samir Keitoue)....Pages 55-66 Optimal Cooling and Life Time Management for Power Transformers (Luc Paulhiac, Johannes Raith)....Pages 67-83 Analysis of Overvoltages on Power Transformer Recorded by Transient Overvoltage Monitoring System (Bozidar Filipovic-Grcic, Bruno Jurišić, Samir Keitoue, Ivan Murat, Dalibor Filipovic-Grcic, Alan Zupan)....Pages 85-102 Power Transformer Efficiency—Survey Results and Assessment of Efficiency Implementation (Žarko Janić, Anthony Walsh, Adesh Singh, Yordan Botev)....Pages 103-112 Reliable Power Transformer Efficiency Tests (Gert Rietveld, Ernest Houtzager, Dennis Hoogenboom, Gu Ye)....Pages 113-125 Verification of Maintenance Intervals for Vacuum On-load Tap-changers (Niklas Gustavsson)....Pages 127-134 Prediction Model for the Distribution Transformer Failure Using Correlation of Weather Data (Eun Hui Ko, Tatjana Dokic, Mladen Kezunovic)....Pages 135-144 On Site Measurement and Simulation of Transferred Lightning Overvoltages Through Power Transformers (Bruno Jurišić, Tomislav Župan, Goran Plišić, Božidar Filipović-Grčić, Goran Levačić, Alain Xemard)....Pages 145-162 Calculation of Circuit Parameters of High Frequency Models for Power Transformers Using FEM (Álvaro Portillo, Luiz Fernando de Oliveira, Federico Portillo)....Pages 163-182 Small Signal Internal Voltage Transfer Measurements and White-Box Transient Calculations for Non-standard Test Conditions of a Shell-Form Power Transformer (Bjørn Gustavsen, Ariana Martins, Carlos A. Sá, Luis Braña, Ricardo Castro Lopes, Pedro Lima et al.)....Pages 183-196 Internal Fault Performance of Instrument Transformers with Sectioned Active Part (Igor Žiger, Danijel Krajtner, Boris Bojanić)....Pages 197-209 Simulation of Long-Term Transformer Operation with a Dynamic Thermal, Moisture and Aging Model (Johannes Raith, Christian Bonini, Mario Scala)....Pages 211-226 Line Discharge Capability of Inductive Voltage and Combined Transformers (Ivan Konta, Dijana Papić, Dalibor Filipović-Grčić, Danijel Brezak)....Pages 227-240 Influence of Conductor Transposition on Transformer Winding RLC Parameters (Ana Drandić, Bojan Trkulja, Željko Štih)....Pages 241-249 Appropriate Modelling of Transformer High Current Leads in 3D FEM (Karlo Petrović, Bruno Jurišić, Tomislav Župan)....Pages 251-262 Calculation of Eddy Current Losses in Iron Core of Transformer (Stjepan Frljić, Bojan Trkulja, Željko Štih)....Pages 263-273