Electromagnetic Analysis and Condition Monitoring of Synchronous Generators

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

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.