Preface xix
Acknowledgments xxiii
I THEORY, CONSTRUCTION, AND OPERATION
1 Principles of Operation of Synchronous Machines 3
1.1 Introduction to Basic Notions on Electric Power 3
1.1.1 Magnetism and Electromagnetism 3
1.1.2 Electricity 6
1.2 Electrical–Mechanical Equivalence 7
1.3 Alternating Current (ac) 8
1.4 Three-Phase Circuits 15
1.5 Basic Principles of Machine Operation 16
1.5.1 Faraday’s Law of Electromagnetic Induction 18
1.5.2 Ampere–Biot–Savart’s Law of Electromagnetic 18
1.5.3 Lenz’s Law of Action and Reaction 18
1.5.4 Electromechanical Energy Conversion 20
1.6 The Synchronous Machine 21
1.6.1 Background 21
1.6.2 Principles of Construction 24
1.6.3 Rotor Windings 26
1.6.4 Stator Windings 28
1.7 Basic Operation of the Synchronous Machine 30
1.7.1 No-Load Operation 32
1.7.2 Motor Operation 34
1.7.3 Generator Operation 35
1.7.4 Equivalent Circuit 35
1.7.5 Machine Losses 36
Additional Reading 38
2 Generator Design and Construction 39
2.1 Stator Core 41
2.2 Stator Frame 46
2.3 Flux and Armature Reaction 48
2.4 Electromagnetics 51
2.5 End-Region Effects and Flux Shielding 56
2.6 Stator Core and Frame Forces 62
2.7 Stator Windings 63
2.8 Stator Winding Wedges 73
2.9 End-Winding Support Systems 76
2.10 Stator Winding Configurations 77
2.11 Stator Terminal Connections 80
2.12 Rotor Forging 81
2.13 Rotor Winding 89
2.14 Rotor Winding Slot Wedges 95
2.15 Amortisseur Winding 96
2.16 Retaining Rings 97
2.17 Bore Copper and Terminal Connectors 105
2.18 Slip-Collector Rings and Brush Gear 106
2.19 Rotor Shrink Coupling 107
2.20 Rotor Turning Gear 108
2.21 Bearings 109
2.22 Air and Hydrogen Cooling 111
2.23 Rotor Fans 112
2.24 Hydrogen Containment 113
2.25 Hydrogen Coolers 118
References 118
3 Generator Auxiliary Systems 121
3.1 Lube-Oil System 122
3.2 Hydrogen Cooling System 122
3.3 Seal-Oil System 125
3.4 Stator Cooling Water System 128
3.4.1 System Components 128
3.4.2 Stator Cooling Water Chemistry 132
3.4.3 Stator Cooling Water System Conditions 134
3.5 Exciter Systems 136
3.5.1 Types of Excitation Systems 137
3.5.2 Excitation System Performance Characteristics 139
3.5.3 Voltage Regulators 141
4 Operation and Control 143
4.1 Basic Operating Parameters 143
4.1.1 Machine Rating 144
4.1.2 Apparent Power 145
4.1.3 Power Factor 146
4.1.4 Real Power 149
4.1.5 Terminal Voltage 149
4.1.6 Stator Current 149
4.1.7 Field Voltage 150
4.1.8 Field Current 150
4.1.9 Speed 150
4.1.10 Hydrogen Pressure 152
4.1.11 Hydrogen Temperature 152
4.1.12 Short-Circuit Ratio 153
4.1.13 Volts per Hertz and Overfluxing Events 153
4.2 Operating Modes 160
4.2.1 Shutdown 160
4.2.2 Turning Gear 160
4.2.3 Run-up and Run-Down 162
4.2.4 Field Applied Offline (Open Circuit) 163
4.2.5 Synchronized and Loaded (Online) 163
4.2.6 Start-up Operation 163
4.2.7 Online Operation 163
4.2.8 Shutdown Operation 165
4.3 Machine Curves 165
4.3.1 Open-Circuit Saturation Characteristic 165
4.3.2 Short-Circuit Characteristic 165
4.3.3 Capability Curves 167
4.3.4 V-Curves 169
4.4 Special Operating Conditions 170
4.4.1 Unexcited Operation (“Loss-of-Field” Condition) 170
4.4.2 Negative-Sequence Currents 174
4.4.3 Off-Frequency Currents 175
4.4.4 Load Cycling and Repetitive Starts 177
4.4.5 Overloading 178
4.4.6 Extended Turning-Gear Operation 178
4.4.7 Loss of Cooling 181
4.4.8 Overfluxing 182
4.4.9 Overspeed 190
4.4.10 Loss of Lubrication Oil 190
4.4.11 Out-of-Step Synchronization and “Near” Short Circuits 191
4.4.12 Ingression of Cooling Water and Lubricating Oil 192
4.4.13 Under- and Overfrequency Operation (U/F and O/F) 193
4.5 Basic Operation Concepts 193
4.5.1 Steady-State Operation 193
4.5.2 Equivalent Circuit and Vector Diagram 196
4.5.3 Power Transfer Equation between Alternator and 196
4.5.4 Working with the Fundamental Circuit Equation 198
4.5.5 Parallel Operation of Generators 203
4.5.6 Stability 206
4.5.7 Sudden Short Circuits 211
4.6 System Considerations 213
4.6.1 Voltage and Frequency Variation 214
4.6.2 Negative-Sequence Current 214
4.6.3 Overcurrent 224
4.6.4 Current Transients 224
4.6.5 Overspeed 224
4.7 Grid-Induced Torsional Vibrations 224
4.7.1 Basic Principles of Shaft Torsional Vibration 224
4.7.2 Spring Model of a Turbo-Generator Shaft Train 226
4.7.3 Determination of Shaft Torque and Shaft Torsional Stress 229
4.7.4 Material Changes due to Torsional Vibrations 229
4.7.5 Types of Grid-Induced Events 229
4.7.6 Monitoring of Torsional Vibration Events 234
4.7.7 Industry Experience and Alleviation Techniques 236
4.8 Excitation and Voltage Regulation 237
4.8.1 The Exciter 237
4.8.2 Excitation Control 238
4.9 Performance Curves 238
4.9.1 Losses Curves 238
4.9.2 Efficiency Curve 239
4.10 Sample of Generator Operating Instructions 239
References 250
5 Monitoring and Diagnostics 251
5.1 Generator Monitoring Philosophies 252
5.2 Simple Monitoring with Static High-Level Alarm Limits 253
5.3 Dynamic Monitoring with Load-Varying Alarm Limits 254
5.4 Artificial Intelligence Diagnostic Systems 257
5.5 Monitored Parameters 260
5.5.1 Generator Electrical Parameters 261
5.5.2 Stator Core and Frame 265
5.5.3 Stator Winding 276
5.5.4 Rotor 293
5.5.5 Excitation System 313
5.5.6 Hydrogen Cooling System 315
5.5.7 Lube-Oil System 319
5.5.8 Seal-Oil System 321
5.5.9 Stator Cooling Water System 324
References 330
6 Generator Protection 333
6.1 Basic Protection Philosophy 333
6.2 Generator Protective Functions 334
6.3 Brief Description of Protective Functions 337
6.3.1 Synchronizer and Sync-Check Relays (Functions 15 339 and 25)
6.3.2 Short-Circuit Protection (Functions 21, 50, 51,51V, 339 and 87)
6.3.3 Volts/Hertz Protection (Function 24) 341
6.3.4 Over- and Undervoltage Protection (Functions 59 342 and 27)
6.3.5 Reverse Power Protection (Function32) 343
6.3.6 Loss-of-Field Protection (Function 40) 345
6.3.7 Stator Unbalanced Current Protection (Function 46) 345
6.3.8 Stator and Rotor Thermal Protection (Function 49) 347
6.3.9 Voltage Balance Protection (Function 60) 348
6.3.10 Time Overcurrent Protection for Detection of 349
6.3.11 Breaker Failure Protection (Function 62B) 350
6.3.12 Rotor Ground-Fault Protection (Function 64F) 351
6.3.13 Over-/Underfrequency Protection (Function 81) 352
6.3.14 Out-of-Step Operation (Loss of Synchronism) 353
6.4 Specialized Protection Schemes 355
6.4.1 Protection Against Accidental Energization 355
6.4.2 dc Field Ground Discrimination 357
6.4.3 Vibration Considerations 360
6.4.4 Operation of the Isolated-Phase Bus (IPB) at Reduced 362
Cooling and Risks from H2 Leaks into the IPB
6.4.5 Calculation of the H2 Mix in the IPB for a Given H2 364
6.5 Tripping and Alarming Methods 367
References 372
II INSPECTION, MAINTENANCE, AND TESTING
7 Inspection Practices and Methodology 375
7.1 Site Preparation 375
7.1.1 Foreign Material Exclusion 375
7.1.2 Foreign Material Exclusion - Procedures 383
7.2 Experience and Training 384
7.3 Safety Procedures—Electrical Clearances 384
7.4 Inspection Frequency 387
7.5 Generator Accessibility 388
7.6 Inspection Tools 389
7.7 Inspection Forms 394
References 409
8 Stator Inspection 411
8.1 Stator Frame and Casing 412
8.1.1 External Components 412
8.1.2 Internal Components 423
8.1.3 Caged Stator Cores—Inspection and Removal 435
8.2 Stator Core 438
8.2.1 Stator Bore Contamination 438
8.2.2 Blocked Cooling Vent Ducts 440
8.2.3 Iron Oxide Deposits 440
8.2.4 Loose Core Iron/Fretting and Interlaminar Failures 443
8.2.5 Bent/Broken Laminations in the Bore 455
8.2.6 Space Block Support and Migration 460
8.2.7 Migration of Broken Core Plate and Space Block 461
8.2.8 Laminations Bulging into Air Vents 461
8.2.9 Greasing/Oxide Deposits on Core Bolts 462
8.2.10 Core-Compression Plates 464
8.2.11 Core-End Flux Screens and Flux Shunts 465
8.2.12 Frame-to-Core Compression (Belly) Bands 467
8.2.13 Back-of-Core Burning 467
8.2.14 Core-End Overheating 470
8.3 Stator Windings 473
8.3.1 Stator Bar/Coil Contamination (Cleanliness) 473
8.3.2 End-Winding Blocking and Roving 474
8.3.3 Surge-Rings 478
8.3.4 Surge-Ring Insulation Condition 480
8.3.5 End-Winding Support Structures 481
8.3.6 Ancillary End-Winding Support Hardware 484
8.3.7 Asphalt Bleeding/Soft Spots 487
8.3.8 Tape Separation/Girth Cracking 489
8.3.9 Insulation Galling/Necking beyond the Slot 492
8.3.10 Insulation Bulging into Air Ducts 492
8.3.11 Insulation Condition, Overheating, and Electrical Aging 493
8.3.12 Corona Activity 496
8.3.13 Stator Wedges 504
8.3.14 End-Wedge Migration Out of Slot 507
8.3.15 Side-Packing Fillers 508
8.3.16 Leaks in Water-Cooled Stator Windings 509
8.3.17 Magnetic Termites 512
8.3.18 Flow Restriction in Water-Cooled Stator Windings 515
8.3.19 Hoses, Gaskets, and O-Rings in Water-Cooled 518
Stator Windings
8.4 Phase Connectors and Terminals 520
8.4.1 Circumferential Bus Insulation 520
8.4.2 Phase Droppers 523
8.4.3 High-Voltage Bushings 525
8.4.4 Standoff Insulators 526
8.4.5 Bushing Vents 527
8.4.6 Bushing-Well lnsulators and Hydrogen Sealant Condition 528
8.4.7 Generator Current Transformers (CTs) 529
8.5 Hydrogen Coolers 532
References 534
Additional Reading 535
9 Rotor Inspection 537
9.1 Rotor Cleanliness 538
9.2 Retaining Rings 539
9.2.1 Nonmagnetic 18–5 and 18–18 Retaining Rings 545
9.2.2 Removal of Retaining Rings 546
9.3 Fretting/Movement at Interference Fit Surfaces of Wedges and Rings 554
9.3.1 Tooth Cracking 554
9.4 Centering (Balance) Rings 563
9.5 Fan Rings or Hubs 563
9.6 Fan Blades 565
9.7 Bearings and Journals 567
9.8 Balance Weights and Bolts 570
9.9 End Wedges and Damper Windings 571
9.10 Other Wedges 576
9.11 Windings—General 577
9.11.1 Conductor Material 578
9.12 Rotor Windings—Slot Region 580
9.12.1 Slot Liner 580
9.12.2 Turn Insulation 583
9.12.3 Creepage Block and Top Channel 587
9.12.4 C-Channel Subslot 589
9.13 End Windings and Main Leads 589
9.13.1 Retaining Ring Liners 592
9.13.2 End Turns and Blocking 594
9.13.3 Shorted Turns 600
9.13.4 Top-Tooth Cracking 603
9.13.5 dc Main Leads 603
9.13.6 Coil and Pole Connections 607
9.14 Collector Rings 613
9.15 Collector Ring Insulation 619
9.16 Bore Copper and Radial (Vertical) Terminal Stud Connectors 621
9.17 Brush-Spring Pressure and General Condition 624
9.18 Brush Rigging 626
9.19 Shaft Voltage Discharge (Grounding) Brushes 629
9.20 Rotor Winding Main Lead Hydrogen Sealing—Inner and Outer 630
9.21 Circumferential Pole Slots (Body Flex Slots) 633
9.22 Blocked Rotor Radial Vent Holes—Shifting of Winding and/or 635
9.23 Couplings and Coupling Bolts 636
9.24 Bearing Insulation 638
9.25 Hydrogen Seals 640
9.25.1 Journal Seals 641
9.25.2 Thrust-Collar Seals 642
9.25.3 Carbon Seals 645
9.26 Rotor-Body Zone Rings 646
9.27 Rotor Removal 648
References 657
10 Auxiliaries Inspection 659
10.1 Lube-Oil System 659
10.2 Hydrogen Cooling System 660
10.2.1 Hydrogen Desiccant/Dryer 661
10.3 Seal-Oil System 662
10.4 Stator Cooling Water System 663
10.5 Exciters 666
10.5.1 Rotating Systems Inspection 666
10.5.2 Static Systems Inspection 666
10.5.3 Brushless Systems Inspection 667
10.5.4 Specific Inspection Items 667
11 Generator Maintenance Testing 673
11.1 Stator Core Mechanical Tests 673
11.1.1 Core Tightness 673
11.1.2 Core and Frame Vibration Testing 674
11.2 Stator Core Electrical Tests 676
11.2.1 EL CID Testing 676
11.2.2 Rated Flux Test with Infrared Scan 684
11.2.3 Core Loss Test 695
11.2.4 Through-Bolt Insulation Resistance 696
11.2.5 Insulation Resistance of Flux Screens 696
11.3 Stator Winding Mechanical Tests 696
11.3.1 Wedge Tightness 696
11.3.2 Stator End-Winding Vibration 700
11.4 Water-Cooled Stator Winding Tests 700
11.4.1 Air Pressure Decay 700
11.4.2 Tracer Gases 701
11.4.3 Vacuum Decay 701
11.4.4 Pressure Drop 702
11.4.5 Flow Testing 702
11.4.6 Capacitance Mapping 702
11.5 Stator Winding Electrical Tests 702
11.5.1 Pretesting Requirements 703
11.5.2 Series Winding Resistance 704
11.5.3 Insulation Resistance (IR) 704
11.5.4 Polarization Index (PI) 706
11.5.5 Dielectric Absorption during dc Voltage Application 708
11.5.6 dc Leakage or Ramped Voltage 708
11.5.7 dc Hi-Pot 710
11.5.8 ac Hi-Pot 710
11.5.9 Partial Discharge (PD) Off-line Testing 714
11.5.10 Capacitance Measurements 717
11.5.11 Dissipation/Power Factor Testing 717
11.5.12 Dissipation/Power Factor Tip-up Test 717
11.6 Rotor Mechanical Testing 718
11.6.1 Rotor Vibration 718
11.6.2 Rotor Nondestructive Examination Inspection 719
11.6.3 Some Additional Rotor NDE Specifics 727
11.6.4 Air Pressure Test of Rotor Bore 731
11.7 Rotor Electrical Testing 733
11.7.1 Winding Resistance 733
11.7.2 Insulation Resistance (IR) 733
11.7.3 Polarization Index (PI) 733
11.7.4 dc Hi-Pot 734
11.7.5 ac Hi-Pot 734
11.7.6 Shorted Turns Detection—General 734
11.7.7 Shorted Turns Detection by Recurrent Surge Oscillation 736
(RSO)
11.7.8 Shorted Turns Detection by Open-Circuit Test 737
11.7.9 Shorted Turns Detection by Winding Impedance 741
11.7.10 Shorted Turns Detection by Low-Voltage dc or Volt 742
Drop
11.7.11 Shorted Turns Detection by Low-Voltage ac or “C” 743
Core Test
11.7.12 Shorted Turns Detection by Shorted Turns Detector 744
(Flux Probe)
11.7.13 Field-Winding Ground Detection by the Split-Voltage 762
Test
11.7.14 Field Ground Detection by the Current-through-Forging 762
Test
11.7.15 Shaft Voltage and Grounding 765
11.8 Hydrogen Seals 765
11.8.1 NDE 765
11.8.2 Insulation Resistance 766
11.9 Bearings 766
11.9.1 NDE 766
11.9.2 Insulation Resistance 766
11.10 Thermal Sensitivity Testing and Analysis 767
11.10.1 Background 767
11.10.2 Typical Thermal Sensitivity Test 769
11.11 Heat-Run Testing 771
11.11.1 Test Procedure 771
11.11.2 Acceptance Parameters 772
11.12 Hydrogen Leak Detection 773
11.12.1 Pressure Drop 774
11.12.2 SF6 776
11.12.3 Helium 777
11.12.4 Snoop 777
11.12.5 Ultrasonic 777
References 777
12 Maintenance 779
12.1 General Maintenance Philosophies 779
12.1.1 Breakdown Maintenance 780
12.1.2 Planned Maintenance 781
12.1.3 Predictive Maintenance 782
12.1.4 Condition-Based Maintenance (CBM) 782
12.2 Operational and Maintenance History 783
12.3 Maintenance Intervals/Frequency 783
12.4 Type of Maintenance 784
12.4.1 Extent of Maintenance 784
12.4.2 Repair or Replacement 786
12.4.3 Rehabilitation/Upgrading/Uprating 787
12.4.4 Obsolescence 789
12.5 Work Site Location 791
12.5.1 Transportation 791
12.6 Workforce 792
12.7 Spare Parts 795
12.8 Uprating 796
12.8.1 Drivers for Uprating 796
12.8.2 Uprating Considerations 798
12.8.3 Component Evaluations 800
12.8.4 Reliability and Effect of Uprating on Generator Life 804
12.8.5 Required Inspection and Tests Prior to Uprating 806
12.8.6 Required Maintenance Prior to Uprating 807
12.8.7 Heat-Run Testing After Uprating 808
12.8.8 Maintenance Schedule After Uprating 810
12.9 Long-Term Storage and Mothballing 810
12.9.1 Reasons for Storage of Generator Equipment 810
12.9.2 General Requirements 811
12.9.3 Storage Requirements 812
12.9.4 Monitoring and Maintenance During Storage 818
12.9.5 Restoration from Storage 820
12.9.6 Long Term Storage Maintenance Procedures and 822
Testing
12.10 Life Cycle Management (LCM) 825
12.11 Single Point Vulnerability (SPV) Analysis 827
References 828
Index 829
0 comments:
Post a Comment