Electromagnetic Analysis and Condition Monitoring of Synchronous Generators
, by Ehya, Hossein; Faiz, Jawad- ISBN: 9781119636076 | 1119636078
- Cover: Hardcover
- Copyright: 12/28/2022
Discover an insightful and complete overview of electromagnetic analysis and fault diagnosis in large synchronous generators
In Electromagnetic Analysis and Condition Monitoring of Synchronous Generators, a team of distinguished engineers delivers a comprehensive review of the electromagnetic analysis and fault diagnosis of synchronous generators. Beginning with an introduction to several types of synchronous machine structures, the authors move on to the most common faults found in synchronous generators and their impacts on performance.
The book includes coverage of different modeling tools, including the finite element method, winding function, and magnetic equivalent circuit, as well as various types of health monitoring systems focusing on the magnetic field, voltage, current, shaft flux, and vibration. Finally, Electromagnetic Analysis and Condition Monitoring of Synchronous Generators covers signal processing tools that can help identify hidden patterns caused by faults and machine learning tools enabling automated condition monitoring.
The book also includes:
- A thorough introduction to condition monitoring in electric machines and its importance to synchronous generators
- Comprehensive explorations of the classification of synchronous generators, including armature arrangement, machine construction, and applications
- Practical discussions of different types of electrical and mechanical faults in synchronous generators, including short circuit faults, eccentricity faults, misalignment, core-related faults, and broken damper bar faults
- In-depth examinations of the modeling of healthy and faulty synchronous generators, including analytical and numerical methods
Perfect for engineers working in electrical machine analysis, maintenance, and fault detection, Electromagnetic Analysis and Condition Monitoring of Synchronous Generators is also an indispensable resource for professors and students in electrical power engineering.
Jawad Faiz, PhD, is Professor at the School of Electrical and Computer Engineering at the University of Tehran. He is a senior member of the IEEE, a member of the Iran Academy of Sciences, and the Scientific Committee of the Iranian Conference of Electrical Engineering.
Hossein Ehya, PhD, is a Research Fellow in the Department of Electrical Power Engineering at the Norwegian University of Science and Technology. He has designed over 30 industrial and home induction motors for the Electrogen Company.
Author Biographies
Preface
Chapter 1
Introduction
1.1. Introduction to Condition Monitoring of Electric Machines
1.2. Importance of Synchronous Generators
1.3. Economic Aspects and Advantages
1.4. Intention of the Book
References
Chapter 2
Operation Principles, Structure, and Design of Synchronous Generators
2.1. Introduction 2
2.1.1. Rotating Magnetic Field of a Three-Phase Synchronous Machine 2
2.2. History of Synchronous Generators 3
2.2.1. Advancement History of Synchronous Generators 4
2.2.1.1. Up to the year 1970 4
2.2.1.2. Changes in the 1970s 6
2.2.1.3. Developments in the 1980s 6
2.2.1.4. Developments in the 1990s 7
2.2.1.5. Developments after 2000 8
2.3. Types and Constructions of Synchronous Machines 9
2.3.1. Non-salient or Round Rotor 9
2.3.2. Salient-Pole Rotor 11
2.3.3. Synchronous Generators with Different Field Locations 13
2.3.4. Different Schemes of Excitation Systems for Synchronous Generators 14
2.3.4.1. DC Excitation 14
2.3.4.2. Static Excitation System 14
2.3.4.3. Brushless Excitation System 15
2.4. Voltage Equation and Rated Power of the Synchronous Generator 16
2.5. Synchronous Generator Model Parameters 17
2.6. Different Operating Modes of Synchronous Machines 17
2.7. Damper Bars in Synchronous Generators 18
2.8. Losses and Efficiency in Synchronous Generators 18
2.9. High-Voltage Synchronous Generators 19
2.10. Preliminary Design Considerations 21
2.10.1. Output Equations 21
2.10.2. Selecting Specific Magnetic Loading 22
2.10.3. Selecting Specific Electric Loading 22
2.10.4. Relationship between L and D 23
2.10.4.1. Salient-Pole Generators 23
2.10.4.2. Turbo-generators 23
2.10.4.3. Short Circuit Ratio 23
2.10.5. Air Gap Length 24
2.11. Stator Design Considerations 24
2.11.1. Stator Core Outer Diameter 25
2.11.2. Leakage Reactance 25
2.11.3. Stator Winding 26
2.11.3.1. Double-Layer Winding 26
2.11.3.2. Stator Winding Resistance 26
2.11.3.3. Eddy Current Losses in Conductors 27
2.11.3.4. Eddy Current Loss Estimation 27
2.11.3.5. Number of Slots 28
2.11.3.6. Number of Turns per Phase 28
2.11.3.7. Conductor Cross-section 29
2.11.3.8. Single-turn Bar Winding 29
2.11.3.9. Multi-turn Windings 29
2.11.3.10. Stator Winding Type Comparison 30
2.11.3.11. Winding and Slot Insulation 30
2.11.3.12. Stator Slot Dimensions 31
2.11.4. Rotor Design of a Salient Pole Synchronous Generator 32
2.11.4.1. Pole Shape 32
2.11.4.2. Pole Dimensions 32
2.11.4.3. Copper Losses of Field Windings 33
2.11.4.4. Rotor Core Depth 34
2.11.4.5. Ampere-Turns of the No-Load Field 34
2.11.5. Design of the Rotor of Round-Rotor Synchronous Generators 35
2.11.6. Rotor Winding Design 35
2.11.7. Synchronous Generator Excitation System Design Issues 36
2.12. Summary……………………………………………………………………………….. 37
References
Chapter 3. Transformed Models and Parameter Identification of Synchronous Generators
3.1. Introduction……………………………………………………………………. 2
3.2. Multi-Phase Synchronous Generator Modeling Based on Park Equations…… 3
3.2.1. Two-Phase Synchronous Generators 6
3.2.2. Three-Phase Synchronous Generators 11
3.2.3. Six-Phase Synchronous Generators 14
3.3. Mathematical Modeling 16
3.3.1. Optimal Observer with Kalman Filters 20
3.4. Parameter Estimation Algorithms 20
3.4.1. Offline Parameter Estimation Techniques 21
3.4.1.1. Frequency Domain-Based Methods 21
3.4.1.2. Time Domain-Based Methods 22
3.4.1.3. Finite Element Methods 23
3.4.1.4. An Example of Offline Parameter Estimation Using the DC Standstill Test 23
3.4.2. Online Parameter Estimation Techniques 25
3.4.2.1. Numerical Methods 25
3.4.2.2. Observer-Based Methods 27
3.4.2.3. Artificial Intelligence (AI)-Based Methods 27
3.4.2.4. An Example of Online Parameter Estimation Using the Affine Projection Algorithm
3.5. Parameter Accuracy Increments by Considering Saturation
3.6. Fault Detection Based on Parameter Deviation 31
3.6.1. Principle of the Method 31
3.7. Summary…………………………….…………………………………………….. 33
References…………………………………………………………………………… 33
Chapter 4. Introduction to Different Types of Faults in Synchronous Generators
4.1. Reasons for Condition Monitoring of Synchronous Generators 2
4.2. Different Faults in Synchronous Generators 2
4.3. Main Factors Leading to Electrical Machine Damage 4
4.4. Major Destruction Factors of Stator Winding 6
4.4.1. Thermal Stress 6
4.4.2. Electrical Stress 8
4.4.3. Mechanical Stresses 9
4.4.4. Ambient Stress 9
4.5. Common Faults in Stator Winding 10
4.6. Rotor Field Winding Fault 12
4.7. Eccentricity Faults 13
4.8. Misalignment Faults 15
4.9. Damper Winding Fault 16
4.10. Summary 18
References
Chapter 5. Laboratory Scale Implementation
5.1. Introduction 1
5.2. Salient Pole Synchronous Generator 2
5.3. Induction Motor 5
5.4. Gearbox 6
5.5. Converter 7
5.6. Rotor Magnetization Unit 8
5.7. DC Power Supply 9
5.8. Local Passive Load 10
5.9. Sensors 13
5.9.1. Hall-Effect Sensors 13
5.9.2. Search Coil 17
5.9.3. Accelerometer 19
5.9.4. Voltage Transformer 21
5.9.5. Current Transformer 22
5.10. Data Acquisition 24
5.11. Fault Implementation 26
5.11.1. Stator Short Circuit Fault 27
5.11.2. Inter-Turn Short Circuit Fault in Rotor Field Winding 28
5.11.3. Eccentricity Fault 29
5.11.4. Misalignment Fault 31
5.11.5. Broken Damper Bar Fault 32
5.12. Noise Considerations……………………………………………………………………. 33
5.13. Summary…………………………………………………………………………………... 33
References
Chapter 6. Analytical Modeling Based on Wave and Permeance Method
6.1. Introduction,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1
6.2. Eccentricity Fault Definition…………………………………………………… 2
6.3. The Air Gap Magnetic Field……………………………………………………. 4
6.4. The Electromotive Force in Stator Terminals………………………………….. 8
6.5. The Stator Current……………………………………………………….... 10
6.6. Force Density and Unbalanced Magnetic Pull…………………………….. 13
6.7. Stator Slotting Effects …………………………………………………………..16
6.8. Magnetic Saturation Effects ………………………………………………….17
6.9. The Mixed Eccentricity Fault………………………………………….. 18
6.10. The Air Gap Magnetic Field ………………………………………….20
6.11. Induced Electromotive Force in Stator Terminals,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
6.12. Force Density and Unbalanced Magnetic Pull…………………….. 23
6.13. Short Circuit Modeling …………………………………………………..32
6.14. Air Gap Permeance Under a Short Circuit Fault……………………….. 34x
6.15. Force Density and Unbalanced Magnetic Pull under a Rotor Inter-turn Short Circuit Fault…………………… 36
6.16.Summary………………………………………………………………………36
References…………………………………………………………………………………….....37
Chapter 7. Analytical Modeling Based on Winding Function Methods
7.1. Introduction 2
7.2. History and Usage of the WFM 3
7.3. Winding Function Modeling of a Synchronous Generator 3
7.4. Mutual Inductance Calculation Between the Stator Phases 7
7.4.1. Turn Function of Winding Phase 8
7.4.2. The Modified Winding Function of Phase , 8
7.4.3. The Inverse Air Gap Function 8
7.5. The Mutual Inductance Between the Stator and Rotor 13
7.5.1. The Mutual Inductance Between the Stator Phase Winding and Rotor Field Winding 13
7.5.2. The Mutual Inductance of the Stator Phase Winding and Rotor Damper Winding 15
7.6. The Self Inductance of the Rotor 21
7.6.1. The Self Inductance of the Rotor Field Winding 21
7.6.2. The Self Inductance of the Rotor Damper Winding 21
7.6.3. The Mutual Inductance Between the Rotor Field Winding and Damper Winding in the Axis 25
7.6.4. The Mutual Inductance Between the Rotor Field Winding and Damper Winding in the Axis 26
7.7. Derivative Forms of Synchronous Generator Inductances 26
7.7.1. Derivative Form of Stator Mutual Inductance 26
7.7.2. Derivative Form of Stator and Rotor Mutual Inductance 26
7.7.1. Dynamic Equations Governing the Synchronous Machines 28
7.8. A Practical Case study 31
7.8.1. Parameter Identification 32
7.8.1.1. Resistance of the Stator Phase Winding 32
7.8.1.2. Rotor Field Winding Resistance 33
7.8.1.3. The Direct Axis (d) Reactance 33
7.8.1.4. Sub-transient Reactance of the Direct Axis 34
7.8.1.5. Number of Turns of Rotor Field Windings 35
7.8.1.6. Transient Direct Axis Reactance 35
7.8.1.7. Number of d-Axis Damper Winding Turns 35
7.9. Healthy Case Simulation 36
7.9.1. Stator and Rotor Winding Function 36
7.9.2. Stator Phase Windings Mutual Inductances 39
7.9.3. Mutual Inductance Between Stator and Rotor Windings 40
7.9.3.1. Mutual Inductance Between Stator Phase Windings and Rotor Field Winding 40
7.9.3.2. Mutual Inductance Between Stator Phase Windings and Damper Winding 41
7.9.4. Dynamic Model Simulation in the Healthy Case 44
7.10. Faulty Case Simulation 48
7.10.1. Turn Functions and Inductances 48
7.10.2. Dynamic Model Simulation in the Faulty Case 58
7.11. Algorithm for Determination of the Magnetic Saturation Factor 62
7.11.1. Algorithm 62
7.11.2. Excitation Field Factors Plot 63
7.11.3. Magnetic Equivalent Circuit Modeling Under the No-Load Condition 68
7.12. Eccentricity Fault Modeling Considering Magnetic Saturation Under Load Variations 71
7.12.1. Calculation of Inverse Air Gap Length by Considering the Saturation Effect 71
7.12.2. The Air Gap Length Calculation in the Presence of the Eccentricity Fault 77
7.12.3. Mutual and Self Inductance Calculations Under an Eccentricity Fault 80
7.12.4. Comparison with Finite Element Results 88
7.13. Dynamic Modeling under an Eccentricity Fault 89
7.14. Summary ……………………………………………………………………………….. 93
References …………………………………………………………….………………………,,,…93
Chapter 8. Finite Element Modeling of a Synchronous Generator
8.1. Introduction 1
8.2. Electromagnetic Field Computation 3
8.3. Eddy Current and Core Loss Considerations 4
8.4. Material Modeling 6
8.5. Band Object, Motion Setup, and Boundary Conditions 7
8.6. Mesh Consideration 7
8.7. Time Steps and Simulation Run Time 9
8.8. Transient and Steady-State Modeling 10
8.9. No-Load and On-Load Modeling 11
8.10. 2D and 3D FEM 12
8.11. 3D-FE Equations of the Synchronous Generator 14
8.12. Modeling of the Stator and Rotor Windings of the Generator and Its Load 15
8.12.1. Modeling Movement of Movable Parts and Electromechanical Connections 18
8.13. Air Gap Magnetic Field Measurements 18
8.14. Stray Flux Measurements 19
8.15. Eccentricity Fault Modeling 20
8.16. Stator and Rotor Short Circuit Fault 25
8.16.1. Phase-to-Earth Fault 27
8.16.2. Phase-to-Phase Fault 27
8.16.3. Inter-turn Fault 29
8.16.4. Inter-turn Fault in Field Windings of the Synchronous Generator 30
8.17. Broken Damper Bar Modeling 31
8.18. Summary 32
References
Chapter 9. Thermal Analysis of Synchronous Generators9.1. Introduction 1
9.2. Overview of Thermal Modeling and Analysis 2
9.3. Thermal Modeling and Analyzing Synchronous Generators 3
9.3.1 Analytical Method 3
9.3.1.1 Heat Conduction 5
9.3.1.2 Heat Convection 6
9.3.1.3 Heat Radiation 7
9.3.2 Synchronous Generator Loss Calculation 8
9.3.3 Numerical Methods 10
9.4. Modeling and Analysis of Faulty Synchronous Generators 13
9.4.1. Reasons for Faults in Synchronous Generators 13
9.4.1.1 Different Types of Synchronous Generators…………………… …...13
9.4.1.2 Single-Phase Open-Circuit Fault 13
9.4.1.3 Conversion of Three-Phase to Two-Phase 14
9.4.1.4 Three-Phase Short Circuit Fault 16
9.5. Summary ………………………………………………………………………………….. 18
References
Chapter 10. Signal Processing
10.1. Introduction 2
10.2. Signals 2
10.3. Fast Fourier Transform 4
10.4. Fast Fourier Transform with an Adjusted Sampling Frequency 5
10.5. Short-Time Fourier Transform 9
10.6. Continuous Wavelet Transform 12
10.7. Discrete Wavelet Transform 17
10.7.1. Wavelet Energies 19
10.7.2. Wavelet Entropy 20
10.8. Hilbert-Huang Transform 20
10.8.1. Hilbert Transform 20
10.8.2. Empirical Mode Decomposition 23
10.9. Time Series Data Mining 24
10.10. Spectral Kurtosis and Kurtogram 25
10.10.1. Kurtosis 25
10.10.2. Spectral Kurtosis 27
10.10.3. Kurtogram 28
10.11. Noise 30
10.11.1. Various Types of Noise 30
10.11.2. Sources of Noise in Industry 33
10.11.3. Noise Recognition 34
10.11.4. Noise Effect on FFT 35
10.11.5. Noise Effect on STFT 37
10.11.6. Noise Effect on CWT 39
10.11.7. Noise Effect on DWT 41
10.11.8. Noise Effect on TSDM 42
10.12. Summary
References
Chapter 11. Electromagnetic Signature Analysis of Electrical Faults
11.1. Introduction………………………………………………………………………. 3
11.2. General Introduction to Short Circuit Fault Detection Methods in Synchronous Machines 4
11.3. Stator Short Circuit Fault Types……………………………………………………. 6
11.3.1. Stator Unbalanced Phases 6
11.3.2. Single-Phase Fault to Ground 6
11.3.3. Phase-to-Phase Fault 7
11.3.4. Turn-to-Turn Short Circuit Fault 7
11.4. Synchronous Generator Stator Fault Effects ………………………………......................7
11.5. Fault Diagnosis Methods in the Stator Winding……………………………………………8
11.5.1. Invasive Methods 8
11.5.1.1. Thermal Analysis 8
11.5.1.2. Vibration Analysis 10
11.5.1.3. Acoustic Noise Analysis 10
11.5.1.4. Partial Discharge Analysis 11
11.5.1.5. Output Gas Analysis 11
11.5.1.6. Impulse Test 11
11.5.1.7. Air Gap Magnetic Field Monitoring 11
11.5.2. Non-invasive Methods 12
11.5.2.1. Field Current Signature Analysis 13
11.5.2.2. Stator Winding Currents 14
11.5.2.3. Current Park Vector 17
11.5.2.4. Rotor Current 21
11.5.2.5. Using the Negative Sequence Current of the Stator 22
11.5.2.6. The Injected Negative Sequence Current 23
11.5.2.7. Second Component of Current in the q-Axis 24
11.5.2.8. Using the Stator Terminal Voltage 24
11.5.2.9. Using Voltage Sequences 25
11.5.2.10. Using the Impedance Sequence 26
11.5.2.11. Instantaneous Power Index 28
11.5.2.12. Analysis of Transient Operation of the Salient Pole Synchronous Generator 30
11.5.2.13. Stray Magnetic Field 31
11.5.2.14. Axial Leakage Flux 31
11.6. Stator Short Circuit Fault Detection of Brushless Synchronous Machines 32
11.7. Stator Short Circuit Fault Detection of Powerformers 34
11.8. Stator Short Circuit Fault Detection of Turbo-generators 36
11.8.1. The Inter-turn Fault Detection Algorithm of the Stator Winding 36
11.8.1.1. Circuit Analysis 36
11.8.1.2. Turn-to-Turn Fault 36
11.8.1.3. Factors Affecting the Proposed Index 39
11.8.1.4. External Phase-to-Phase Fault 40
11.8.1.5. Internal Phase-to-Phase Fault 43
11.8.1.6. Turn-to-Turn Fault Detection Algorithm 44
11.8.1.7. Increasing the Gradient of the Current 45
11.8.1.8. Current Category Determination 46
11.8.1.9. Calculating the Difference Between Two Currents 48
11.8.2. Algorithm Applications 49
11.8.2.1. Single-Phase to Ground Fault 49
11.8.2.2. Inter-turn Fault 49
11.8.2.3. Internal Phase-to-Phase Fault 54
11.8.2.4. External Phase-to-Phase Fault 58
11.8.2.5. Transformer Inrush Current 59
11.8.2.6. Performance of the Proposed Algorithm in the Face of Various Types of Faults.... 60
11.9. Inter-turn Short Circuit Fault in Rotor Field Winding 62
11.9.1. Introduction 62
11.9.2. Invasive Method 63
11.9.2.1. Airgap Magnetic Field 63
11.9.2.2. Polar Diagram 68
11.9.2.3. Application of the Frequency Spectrum in the Inter-turns Short Circuit Fault Using the Air Gap Magnetic Field 75
11.9.2.4. Differential Magnetic Field 80
11.9.3. Non-invasive Methods 85
11.9.3.1. The Stator and Rotor Current 85
11.9.3.2. Stator Voltage 89
11.9.3.3. Rotor Coil Impedance Index 93
11.9.3.4. Electromagnetic Power Index 94
11.9.3.5. Generator Capability Curve 96
11.9.3.6. Shaft Flux 98
11.9.3.7. Stray Magnetic Field 99
11.10 Summary ……………………………………………………………………………..111
References ……………………………………………………………………………..111
Chapter 12. Electromagnetic Signature Analysis of Mechanical Faults
12.1. Introduction 1
12.2. Eccentricity Faults 2
12.2.1. Invasive Detection Methods 2
12.2.1.1. Air Gap Magnetic Field 2
12.2.1.2. Frequency Analysis of the Air Gap Magnetic Field 6
12.2.1.3. Differential Air Gap Magnetic Field 10
12.2.1.4. Spectral Kurtosis 14
12.2.2. Non-invasive Detection Methods 16
12.2.2.1. Inductance Variation Index 16
12.2.2.2. Harmonics of the Stator Current 16
12.2.2.3. Harmonics of the Open-Circuit Voltage of the Stator Winding 18
12.2.2.4. Analysis of the Space Vector Loci of the Electromotive Force 22
12.2.2.5. The Harmonic Component in the Current of the Rotor Field Winding 22
12.2.2.6. Stator Split-Phase Current 23
12.2.2.7. Stator Voltage Subharmonics Index 24
12.2.2.8. Shaft Voltage 25
12.2.2.9. Stray Magnetic Field 28
12.3. Stator Core Fault 50
12.3.1... Introduction 50
12.3.2. Core Loss 51
12.3.3. Rated Flux 52
12.3.4. EL-CID Method 53
12.4. Broken Damper Bar Fault 55
12.4.1. Introduction 55
12.4.2. Single-Phase Rotation Test 56
12.4.3. Air Gap Magnetic Field 57
12.4.4. Stray Magnetic Field Monitoring 60
12.4.5. Stator Current 67
12.4.6. Rotor Field Winding Voltage 71
12.5. Summary 74
References
Chapter 13. Vibration Monitoring
13.1. Introduction ………………………………………………………………………….2
13.2. Condition Monitoring Using Vibration……………………………………….. 2
13.3. Vibration in Salient-Pole Synchronous Generators…………………………… 3
13.4. Introduction to Utilized Terms in Vibration Analysis…………………………. 4
13.4.1. Time Harmonics 4
13.4.2. Spatial Harmonics 6
13.4.3. Mode Number and Deformation 8
13.4.4. Resonance 10
13.5. Force and Vibration Analysis 10
13.5.1. Modal Analysis 11
13.5.2. Analysis of a Healthy Generator 12
13.5.2.1. Time-Domain Distributions of the Magnetic Field 12
13.5.2.2. Spatial-Domain Distributions of the Magnetic Field 17
13.5.2.3. Mechanical Analysis 25
13.5.3. Analysis of a Synchronous Generator under an Inter-turn Short Circuit Fault 28
13.5.3.1. Time-Domain Distributions of the Magnetic Field 28
13.5.3.2. Spatial-Domain Distributions of the Magnetic Field 31
13.5.3.3. Mechanical Analysis 35
13.5.4. Analysis of a Synchronous Generator under Static Eccentricity 38
13.5.4.1. Time-Domain Distributions of a Magnetic Field 38
13.5.4.2. Spatial-Domain Distributions of the Magnetic Field 42
13.5.4.3. Mechanical Analysis 47
13.5.5. Load Effect 49
13.5.6. Comparison of Fault Impacts on the Magnetic and Vibration Signatures 49
13.6. Summary 52
References
Chapter 14. Application of Machine Learning in Fault Detection
14.1. Introduction 2
14.2. Supervised Learning 2
14.2.1. Feature Extraction and Selection 3
14.2.1.1. Time Series Feature Extraction Based on Scalable Hypothesis Tests (TSFRESH) 3
14.2.2. Data Set Balancing 4
14.2.3. Training and Testing 5
14.2.4. Evaluation Metrics 6
14.3. Ensemble Learners 8
14.4. Logistic Regression 9
14.5. K-Nearest Neighbors 9
14.6. Support Vector Machine 10
14.7. Decision Tree Learning 11
14.8. Random Forest 12
14.9. Boosted Trees 12
14.10. Gradient Boost Decision Trees 13
14.11. Artificial Neural Network 13
14.11.1. Perceptron 13
14.11.2. Multi-Layer Perceptron 13
14.11.3. Activation Function 14
14.11.4. Training 14
14.12. Other Artificial Neural Networks 15
14.13. Real Case Application 15
14.13.1. Data Pre-processing 15
14.13.2. Feature Extraction 16
14.13.2.1. Fast Fourier Transform 16
14.13.2.2. DWT Wavelet Energies 16
14.13.2.3. TSFRESH 17
14.13.3. Exploratory Data Analysis 17
21
14.13.4. Random Forest Feature Selection 21
14.13.4.1. Time Series Feature Extraction Based on Scalable Hypothesis Tests (TSFRESH) 21
14.13.4.2. Summary 22
14.13.5. Fault Detection 22
14.13.5.1. Initial Hyper-parameter Choices 23
14.13.5.2. Metrics 23
14.13.5.3. Cross-Validation 24
14.13.5.4. Standardization 24
14.13.5.5. Results 24
14.13.6. Feature Selection and Reduction Performance 24
14.13.7. Hyper-parameter Optimization and Selection 26
14.13.8. Stacking Classifiers 28
14.13.9. Final Classifier 29
14.13.9.1. Feature Usefulness 30
14.13.9.2. Fault Severity Assessment 30
14.13.10. Data Management and Pre-processing 33
14.13.11. Feature Extraction and Importance 33
14.13.12. Feature Selection and Target Leakage 34
14.13.13. Classifier Selection 34
14.13.14. Performance 35
14.13.15. Real-World Validity 35
14.13.16. Real-World Applicability 35
14.13.17. Anomaly Detection 35
14.13.18. Simulated Data Generation 36
14.14. Summary 36
References
Chapter 15. Insulation Defect Monitoring
15.1. Introduction 3
15.2. History and Advantages of Using Partial Discharge Techniques 3
15.3. Electrical Machine Fault Generation Factors 4
15.4. Rotating Machine Insulation System 5
15.4.1. Rotor Insulation System 5
15.4.2. Stator Insulation System 6
15.5 PD Types in Rotating Machines 6
15.5.1. Internal Discharge 7
15.5.1.1. Internal Void
15.5.1.2. Internal Delamination 8
15.5.1.3. Delamination Between the Conductor and Insulation 8
15.5.1.4. Electrical Treeing 9
15.5.2. Slot Discharges 9
15.5.3. Discharges in the End Winding 9
15.5.3.1. Surface Discharge 9
15.5.3.2. Conductive Particles 9
15.5.3.3. Phase-to-Phase Discharge 9
15.5.4. Arcing and Sparking 10
15.5.4.1. Arcing at Broken Conductors 10
15.5.4.2. Vibration Sparking 10
15.6. Risk Assessment of Different Partial Discharge Faults 11
15.7. Frequency Characteristics of Current Pulses 12
15.8. Measurement of PD Signals 12
15.9. Online Measurements of PD in Rotating Electrical Machines 20
15.9.1. Electrical Measurement of Partial Discharge 21
15.9.1.1. Capacitive Coupling Method 23
15.9.1.2. Implement Capacitive Coupler Method 25
15.9.1.3. Current Transformer 29
15.9.1.4. Antenna Monitoring Method 33
15.9.2. Acoustic Measurement of PD 45
15.9.3. Chemical Measurement of PD 46
15.9.4. Visual Inspection and Optical Measurement of PD 46
15.10. Summary
References
Chapter 16. Noise Rejection Methods and Data Interpretation
16.1. Introduction 1
16.2. Noise Rejection in Online Measurement 2
16.3. Noise Sources in Generators 3
16.4. Different Methods for Denoising 3
16.4.1. Restricting the Frequency Range 3
16.4.2. Pulse Shape Analysis 4
16.4.3. Noise Rejection by Propagation Time 5
16.4.4. Residue of Two Channel Signals 6
16.4.5. Gating 6
16.4.6. Three-Phase Amplitude Relation Diagram (3PARD) 9
16.4.7. Current Signal Features 10
16.4.8. Noise Rejection Using Fourier Transform 15
16.4.8.1. Principles of Noise Rejection Using Fourier Transform 15
16.4.9. Denoising Using Wavelet Transform 17
16.5. Data Interpretation 19
16.5.1. Data Interpretation in the Low-Frequency Range 19
16.5.2. Data Interpretation in VHF and UHF Measurement 22
16.5.3. Data Interpretation Based on Artificial Intelligence 25
16.6. Separating PD sources 26
16.7. Summary 29
References 30
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