Preface |
|
xiii | |
Authors |
|
xv | |
1 Introduction |
|
1 | (20) |
|
1.1 Historical Background |
|
|
1 | (1) |
|
1.2 Uses in Power Systems |
|
|
2 | (5) |
|
1.3 Core-Form and Shell-Form Transformers |
|
|
7 | (1) |
|
1.4 Stacked and Wound Core Construction |
|
|
8 | (2) |
|
|
10 | (1) |
|
|
11 | (2) |
|
1.7 Insulation Structures |
|
|
13 | (3) |
|
|
16 | (3) |
|
|
19 | (2) |
2 Magnetism and Related Core Issues |
|
21 | (22) |
|
|
21 | (1) |
|
|
22 | (3) |
|
|
25 | (2) |
|
|
27 | (5) |
|
|
32 | (2) |
|
2.6 Fault Current Waveform and Peak Amplitude |
|
|
34 | (5) |
|
2.7 Optimal Core Stacking |
|
|
39 | (4) |
3 Circuit Model of a 2-Winding Transformer with Core |
|
43 | (16) |
|
|
43 | (1) |
|
3.2 Circuit Model of the Core |
|
|
43 | (3) |
|
3.3 2-Winding Transformer Circuit Model with Core |
|
|
46 | (4) |
|
3.4 Approximate 2-Winding Transformer Circuit Model without Core |
|
|
50 | (3) |
|
3.5 Vector Diagram of a Loaded Transformer with Core |
|
|
53 | (1) |
|
|
54 | (2) |
|
|
56 | (3) |
4 Reactance and Leakage Reactance Calculations |
|
59 | (30) |
|
|
59 | (1) |
|
4.2 General Method for Determining Inductances and Mutual Inductances |
|
|
60 | (5) |
|
4.2.1 Energy by Magnetic Field Methods |
|
|
61 | (2) |
|
4.2.2 Energy from Electric Circuit Methods |
|
|
63 | (2) |
|
4.3 2-Winding Leakage Reactance Formula |
|
|
65 | (4) |
|
4.4 Ideal 2-, 3-, and Multi-Winding Transformers |
|
|
69 | (4) |
|
4.4.1 Ideal Autotransformer |
|
|
72 | (1) |
|
4.5 Leakage Reactance for 2-Winding Transformers Based on Circuit Parameters |
|
|
73 | (4) |
|
4.5.1 Leakage Reactance for a 2-Winding Autotransformer |
|
|
76 | (1) |
|
4.6 Leakage Reactances for 3-Winding Transformers |
|
|
77 | (12) |
|
4.6.1 Leakage Reactance for an Autotransformer with a Tertiary Winding |
|
|
81 | (4) |
|
4.6.2 Leakage Reactance between 2 Windings Connected in Series and a Third Winding |
|
|
85 | (1) |
|
4.6.3 Leakage Reactance of a 2-Winding Autotransformer with X-Line Taps |
|
|
86 | (3) |
5 Phasors, 3-Phase Connections, and Symmetrical Components |
|
89 | (18) |
|
|
89 | (3) |
|
5.2 Y and Delta 3-Phase Connections |
|
|
92 | (5) |
|
|
97 | (1) |
|
|
98 | (3) |
|
5.5 Symmetrical Components |
|
|
101 | (6) |
6 Fault Current Analysis |
|
107 | (28) |
|
|
107 | (1) |
|
6.2 Fault Current Analysis on 3-Phase Systems |
|
|
108 | (5) |
|
6.2.1 3-Phase Line-to-Ground Fault |
|
|
110 | (1) |
|
6.2.2 Single-Phase Line-to-Ground Fault |
|
|
111 | (1) |
|
|
112 | (1) |
|
6.2.4 Double Line-to-Ground Fault |
|
|
112 | (1) |
|
6.3 Fault Currents for Transformers with Two Terminals per Phase |
|
|
113 | (7) |
|
6.3.1 3-Phase Line-to-Ground Fault |
|
|
116 | (1) |
|
6.3.2 Single-Phase Line-to-Ground Fault |
|
|
116 | (1) |
|
|
117 | (1) |
|
6.3.4 Double Line-to-Ground Fault |
|
|
118 | (1) |
|
6.3.5 Zero-Sequence Circuits |
|
|
119 | (1) |
|
6.3.6 Numerical Example for a Single Line-to-Ground Fault |
|
|
120 | (1) |
|
6.4 Fault Currents for Transformers with Three Terminals per Phase |
|
|
120 | (14) |
|
6.4.1 3-Phase Line-to-Ground Fault |
|
|
123 | (1) |
|
6.4.2 Single-Phase Line-to-Ground Fault |
|
|
124 | (2) |
|
|
126 | (2) |
|
6.4.4 Double Line-to-Ground Fault |
|
|
128 | (2) |
|
6.4.5 Zero-Sequence Circuits |
|
|
130 | (1) |
|
|
131 | (3) |
|
|
134 | (1) |
7 Phase-Shifting and Zigzag Transformers |
|
135 | (34) |
|
|
135 | (1) |
|
|
136 | (3) |
|
7.3 Squashed Delta-Phase-Shifting Transformer |
|
|
139 | (5) |
|
7.3.1 Zero Sequence Circuit Model |
|
|
142 | (2) |
|
7.4 Standard Delta-Phase-Shifting Transformer |
|
|
144 | (4) |
|
7.4.1 Zero Sequence Circuit Model |
|
|
147 | (1) |
|
7.5 2-Core Phase-Shifting Transformer |
|
|
148 | (5) |
|
7.5.1 Zero Sequence Circuit Model |
|
|
152 | (1) |
|
|
153 | (1) |
|
7.7 Fault Current Analysis |
|
|
154 | (6) |
|
7.7.1 Squashed Delta Fault Currents |
|
|
156 | (1) |
|
7.7.2 Standard Delta Fault Currents |
|
|
157 | (2) |
|
7.7.3 2-Core Phase-Shifting Transformer Fault Currents |
|
|
159 | (1) |
|
|
160 | (9) |
|
7.8.1 Calculation of Electrical Characteristics |
|
|
161 | (3) |
|
|
164 | (2) |
|
7.8.3 Zero Sequence Impedance |
|
|
166 | (1) |
|
7.8.4 Fault Current Analysis |
|
|
167 | (2) |
8 Multiterminal 3-Phase Transformer Model |
|
169 | (44) |
|
|
169 | (1) |
|
|
170 | (4) |
|
8.2.1 Two-Winding Leakage Inductance |
|
|
170 | (1) |
|
8.2.2 Multi-Winding Transformer |
|
|
171 | (3) |
|
8.2.3 Transformer Loading |
|
|
174 | (1) |
|
8.3 Transformers with Winding Connections within a Phase |
|
|
174 | (4) |
|
8.3.1 Two Secondary Windings in Series |
|
|
174 | (1) |
|
8.3.2 Primary Winding in Series with a Secondary Winding |
|
|
175 | (1) |
|
|
176 | (2) |
|
8.4 Multiphase Transformers |
|
|
178 | (5) |
|
|
180 | (1) |
|
|
181 | (2) |
|
8.5 Generalizing the Model |
|
|
183 | (2) |
|
8.6 Regulation and Terminal Impedances |
|
|
185 | (2) |
|
8.7 Multiterminal Transformer Model for Balanced and Unbalanced Load Conditions |
|
|
187 | (19) |
|
|
188 | (2) |
|
8.7.2 Admittance Representation |
|
|
190 | (3) |
|
8.7.2.1 Delta Winding Connection |
|
|
191 | (2) |
|
8.7.3 Impedance Representation |
|
|
193 | (6) |
|
8.7.3.1 Ungrounded Y Connection |
|
|
194 | (2) |
|
8.7.3.2 Series-Connected Windings from the Same Phase |
|
|
196 | (1) |
|
8.7.3.3 Zigzag Connection |
|
|
197 | (1) |
|
|
198 | (1) |
|
8.7.3.5 Three Windings Joined |
|
|
199 | (1) |
|
|
199 | (1) |
|
|
200 | (1) |
|
8.7.5.1 Terminal Currents and Voltages |
|
|
200 | (1) |
|
8.7.5.2 Winding Currents and Voltages |
|
|
201 | (1) |
|
8.7.6 Unbalanced Loading Examples |
|
|
201 | (3) |
|
8.7.6.1 Autotransformer with Buried Delta Tertiary and Fault on LV Terminal |
|
|
201 | (1) |
|
8.7.6.2 Power Transformer with Fault on Delta Tertiary |
|
|
202 | (1) |
|
8.7.6.3 Power Transformer with Fault on Ungrounded Y Secondary |
|
|
203 | (1) |
|
8.7.7 Balanced Loading Example |
|
|
204 | (1) |
|
8.7.7.1 Standard Delta Phase Shifting Transformer |
|
|
204 | (1) |
|
|
205 | (1) |
|
|
206 | (7) |
|
8.8.1 2-Core Parallel Connection |
|
|
207 | (1) |
|
8.8.2 2-Core Series Connection |
|
|
208 | (1) |
|
|
209 | (1) |
|
8.8.4 Example of a 2-Core Phase Shifting Transformer |
|
|
209 | (3) |
|
|
210 | (1) |
|
8.8.4.2 Single Line-to-Ground Fault |
|
|
211 | (1) |
|
|
212 | (1) |
9 Rabins' Method for Calculating Leakage Fields, Inductances, and Forces in Iron Core Transformers, Including Air Core Methods |
|
213 | (30) |
|
|
213 | (1) |
|
|
214 | (12) |
|
9.3 Rabins' Formula for Leakage Reactance |
|
|
226 | (6) |
|
9.3.1 Rabins' Method Applied to Calculate the Leakage Reactance between Two Windings Which Occupy Different Radial Positions |
|
|
226 | (3) |
|
9.3.2 Rabins' Method Applied to Calculate the Leakage Reactance between Two Axially Stacked Windings |
|
|
229 | (2) |
|
9.3.3 Rabins' Method Applied to Calculate the Leakage Reactance for a Collection of Windings |
|
|
231 | (1) |
|
9.4 Rabins' Method Applied to Calculate the Self-Inductance of and Mutual Inductance between Coil Sections |
|
|
232 | (2) |
|
9.5 Determining the B-field |
|
|
234 | (2) |
|
9.6 Determining the Winding Forces |
|
|
236 | (2) |
|
9.7 Numerical Considerations |
|
|
238 | (1) |
|
|
238 | (5) |
10 Mechanical Design |
|
243 | (40) |
|
|
243 | (2) |
|
|
245 | (1) |
|
|
246 | (21) |
|
10.3.1 Compressive Stress in the Key Spacers |
|
|
248 | (1) |
|
10.3.2 Axial Bending Stress per Strand |
|
|
249 | (3) |
|
|
252 | (3) |
|
10.3.4 Stress in the Tie Bars |
|
|
255 | (4) |
|
10.3.5 Stress in the Pressure Ring |
|
|
259 | (1) |
|
|
260 | (1) |
|
10.3.7 Radial Bending Stress |
|
|
261 | (6) |
|
10.4 Radial Buckling Strength |
|
|
267 | (9) |
|
10.4.1 Free Unsupported Buckling |
|
|
268 | (2) |
|
10.4.2 Constrained Buckling |
|
|
270 | (2) |
|
10.4.3 Experiment to Determine Buckling Strength |
|
|
272 | (4) |
|
10.5 Stress Distribution in a Composite Wire-Paper Winding Section |
|
|
276 | (3) |
|
10.6 Additional Mechanical Considerations |
|
|
279 | (4) |
11 Electric Field Calculations |
|
283 | (42) |
|
|
283 | (12) |
|
|
283 | (3) |
|
11.1.2 Cylindrical Geometry |
|
|
286 | (2) |
|
11.1.3 Spherical Geometry |
|
|
288 | (1) |
|
11.1.4 Cylinder-Plane Geometry |
|
|
289 | (6) |
|
11.2 Electric Field Calculations Using Conformal Mapping |
|
|
295 | (23) |
|
11.2.1 Mathematical Basis |
|
|
295 | (1) |
|
|
296 | (3) |
|
11.2.3 Schwarz-Christoffel Transformation |
|
|
299 | (1) |
|
11.2.4 Conformal Map for the Electrostatic Field Problem |
|
|
300 | (31) |
|
11.2.4.1 Electric Potential and Field Values |
|
|
305 | (8) |
|
11.2.4.2 Calculations and Comparison with a Finite Element Solution |
|
|
313 | (1) |
|
11.2.4.3 Estimating Enhancement Factors |
|
|
314 | (4) |
|
11.3 Finite Element Electric Field Calculations |
|
|
318 | (7) |
12 Capacitance Calculations |
|
325 | (38) |
|
|
325 | (1) |
|
12.2 Distributive Capacitance along a Winding or Disk |
|
|
325 | (6) |
|
12.3 Stein's Disk Capacitance Formula |
|
|
331 | (7) |
|
12.3.1 Determining Practical Values for the Series and Shunt Capacitances, Cs and Cdd |
|
|
334 | (4) |
|
12.4 General Disk Capacitance Formula |
|
|
338 | (1) |
|
12.5 Coil Grounded at One End with Grounded Cylinders on Either Side |
|
|
339 | (2) |
|
12.6 Static Ring on One Side of a Disk |
|
|
341 | (1) |
|
12.7 Terminal Disk without a Static Ring |
|
|
342 | (1) |
|
|
343 | (2) |
|
12.9 Two End Static Rings |
|
|
345 | (3) |
|
12.10 Static Ring between the First Two Disks |
|
|
348 | (1) |
|
12.11 Winding Disk Capacitances with Wound-in-Shields |
|
|
349 | (12) |
|
|
349 | (3) |
|
|
352 | (5) |
|
12.11.3 Experimental Methods |
|
|
357 | (1) |
|
|
358 | (3) |
|
12.12 Multi-Start Winding Capacitance |
|
|
361 | (2) |
13 Voltage Breakdown Theory and Practice |
|
363 | (30) |
|
|
363 | (1) |
|
13.2 Principles of Voltage Breakdown |
|
|
364 | (8) |
|
13.2.1 Breakdown in Solid Insulation |
|
|
368 | (1) |
|
13.2.2 Breakdown in Transformer Oil |
|
|
369 | (3) |
|
13.3 Geometric Dependence of Transformer Oil Breakdown |
|
|
372 | (14) |
|
|
373 | (1) |
|
|
374 | (2) |
|
13.3.3 Cylindrical Geometry |
|
|
376 | (2) |
|
13.3.4 Spherical Geometry |
|
|
378 | (1) |
|
13.3.5 Comparison with Experiment |
|
|
379 | (1) |
|
|
380 | (5) |
|
13.3.6.1 Breakdown for the Cylinder-Plane Geometry |
|
|
381 | (1) |
|
13.3.6.2 Breakdown for the Disk-Disk-to-Ground Plane Geometry |
|
|
382 | (3) |
|
|
385 | (1) |
|
13.4 Insulation Coordination |
|
|
386 | (3) |
|
13.5 Continuum Model of Winding Used to Obtain the Impulse Voltage Distribution |
|
|
389 | (4) |
|
13.5.1 Uniform Capacitance Model |
|
|
389 | (3) |
|
13.5.2 Traveling Wave Theory |
|
|
392 | (1) |
14 High-Voltage Impulse Analysis and Testing |
|
393 | (22) |
|
|
393 | (1) |
|
14.2 Lumped Parameter Model for Transient Voltage Distribution |
|
|
393 | (9) |
|
14.2.1 Circuit Description |
|
|
393 | (3) |
|
14.2.2 Mutual and Self-Inductance Calculations |
|
|
396 | (1) |
|
14.2.3 Capacitance Calculations |
|
|
396 | (1) |
|
14.2.4 Impulse Voltage Calculations and Experimental Comparisons |
|
|
397 | (4) |
|
14.2.5 Sensitivity Studies |
|
|
401 | (1) |
|
14.3 Setting the Impulse Test Generator to Achieve Close-to-Ideal Waveshapes |
|
|
402 | (13) |
|
14.3.1 Impulse Generator Circuit Model |
|
|
404 | (3) |
|
14.3.2 Transformer Circuit Model |
|
|
407 | (1) |
|
14.3.3 Determining the Generator Settings for Approximating the Ideal Waveform |
|
|
408 | (4) |
|
14.3.4 Practical Implementation |
|
|
412 | (3) |
15 No-Load and Load Losses |
|
415 | (48) |
|
|
415 | (1) |
|
15.2 No-Load or Core Losses |
|
|
416 | (6) |
|
|
418 | (1) |
|
15.2.2 Interlaminar Losses |
|
|
419 | (3) |
|
|
422 | (26) |
|
|
422 | (2) |
|
|
424 | (24) |
|
15.3.2.1 Eddy Current Losses in the Coils |
|
|
426 | (3) |
|
15.3.2.2 Tie Plate Losses |
|
|
429 | (7) |
|
15.3.2.3 Tie Plate and Core Losses due to Unbalanced Currents |
|
|
436 | (5) |
|
15.3.2.4 Tank and Clamp Losses |
|
|
441 | (7) |
|
15.4 Tank and Shield Losses due to Nearby Busbars |
|
|
448 | (8) |
|
15.4.1 Losses Obtained with 2D Finite Element Study |
|
|
448 | (1) |
|
15.4.2 Losses Obtained Analytically |
|
|
449 | (7) |
|
|
449 | (1) |
|
15.4.2.2 Delta Function Current |
|
|
450 | (2) |
|
15.4.2.3 Collection of Delta Function Currents |
|
|
452 | (3) |
|
|
455 | (1) |
|
15.5 Tank Losses Associated with the Bushings |
|
|
456 | (7) |
|
15.5.1 Comparison with a 3D Finite Element Calculation |
|
|
460 | (3) |
16 Stray Losses from 3D Finite Element Analysis |
|
463 | (18) |
|
|
463 | (1) |
|
16.2 Stray Losses on Tank Walls and Clamps |
|
|
463 | (8) |
|
16.2.1 Shunts on the Clamps |
|
|
464 | (2) |
|
16.2.2 Shunts on the Tank Wall |
|
|
466 | (3) |
|
16.2.3 Effects of 3-Phase Currents on Losses |
|
|
469 | (1) |
|
16.2.4 Stray Losses from 3D Analysis versus Analytical and Test Losses |
|
|
469 | (2) |
|
16.3 Nonlinear Impedance Boundary Correction for the Stray Losses |
|
|
471 | (10) |
|
16.3.1 Linear Loss Calculation for an Infinite Slab |
|
|
471 | (2) |
|
16.3.2 Nonlinear Loss Calculation for a Finite Slab |
|
|
473 | (2) |
|
16.3.3 Application to Finite Element Loss Calculations |
|
|
475 | (7) |
|
16.3.3.1 Comparison with Test Losses |
|
|
477 | (1) |
|
|
478 | (3) |
17 Thermal Design |
|
481 | (48) |
|
|
481 | (1) |
|
17.2 Thermal Model of a Disk Coil with Directed Oil Flow |
|
|
482 | (16) |
|
17.2.1 Governing Equations and Solution Process |
|
|
482 | (5) |
|
17.2.2 Oil Pressures and Velocities |
|
|
487 | (3) |
|
|
490 | (3) |
|
17.2.4 Nodal Temperatures and Duct Temperature Rises |
|
|
493 | (3) |
|
17.2.5 Comparison with Test Data |
|
|
496 | (2) |
|
17.3 Thermal Model for Coils without Directed Oil Flow |
|
|
498 | (2) |
|
17.4 Radiator Thermal Model |
|
|
500 | (3) |
|
|
503 | (1) |
|
17.6 Oil Mixing in the Tank |
|
|
504 | (2) |
|
|
506 | (2) |
|
|
508 | (1) |
|
17.9 Comparison with Test Results |
|
|
508 | (4) |
|
17.10 Determining m and n Exponents |
|
|
512 | (2) |
|
17.11 Loss of Life Calculation |
|
|
514 | (3) |
|
17.12 Cable and Lead Temperature Calculation |
|
|
517 | (5) |
|
17.13 Tank Wall Temperature Calculation |
|
|
522 | (1) |
|
17.14 Tie plate Temperature Calculation |
|
|
523 | (2) |
|
17.15 Core Steel Temperature Calculation |
|
|
525 | (4) |
18 Load Tap Changers |
|
529 | (16) |
|
|
529 | (1) |
|
18.2 General Description of LTC |
|
|
529 | (1) |
|
|
530 | (1) |
|
18.4 Principle of Operation |
|
|
531 | (3) |
|
18.4.1 Resistive Switching |
|
|
531 | (2) |
|
18.4.2 Reactive Switching with Preventative Autotransformer |
|
|
533 | (1) |
|
|
534 | (7) |
|
18.5.1 Power Transformers |
|
|
534 | (2) |
|
18.5.1.1 Fixed Volts/Turn |
|
|
534 | (1) |
|
18.5.1.2 Variable Volts/Turn |
|
|
535 | (1) |
|
|
536 | (4) |
|
18.5.3 Use of Auxiliary Transformer |
|
|
540 | (1) |
|
18.5.4 Phase Shifting Transformers |
|
|
540 | (1) |
|
18.5.5 Reduced versus Full-Rated Taps |
|
|
541 | (1) |
|
|
541 | (4) |
19 Constrained Nonlinear Optimization with Application to Transformer Design |
|
545 | (32) |
|
|
545 | (1) |
|
19.2 Geometric Programming |
|
|
546 | (6) |
|
19.3 Nonlinear Constrained Optimization |
|
|
552 | (14) |
|
19.3.1 Characterization of the Minimum |
|
|
552 | (9) |
|
19.3.2 Solution Search Strategy |
|
|
561 | (4) |
|
19.3.3 Practical Considerations |
|
|
565 | (1) |
|
19.4 Application to Transformer Design |
|
|
566 | (11) |
|
|
566 | (1) |
|
|
567 | (2) |
|
19.4.3 Equality Constraints |
|
|
569 | (3) |
|
19.4.4 Inequality Constraints |
|
|
572 | (1) |
|
19.4.5 Optimization Strategy |
|
|
573 | (4) |
References |
|
577 | (6) |
Index |
|
583 | |