Skip to main content

Banery wysuwane

na ciemnogranatowym tle cztery kolorowe rysunki i zdjęcia
High Frequency Methods for Condition Assessment of Transformers and Electrical Machines

Product category
Nauki techniczne » Elektrotechnika
ISBN
978-83-7464-614-7
Publication type
monografia
Format
B5
Binding
twarda
Number of pages
222
Publication date
2013
Edition
1
Description

The monograph deals with the issues of the impact of operational exposures on the transformers' internal structures and electrical machines. It also focuses on the possibility of assessing their condition using high-frequency methods. It presents, with reference to the literature on the subject, original results of the authors' own research, including: analyses of high-frequency and resonance phenomena occurring in the windings of transformers and electrical machines subjected to fast-changing voltage surges arising in electrical networks, experimental studies using high-frequency methods and computer simulation studies.


Monografia dotyczy zagadnień oddziaływania narażeń eksploatacyjnych na struktury wewnętrzne transformatorów i maszyn elektrycznych oraz możliwości oceny ich stanu metodami wysokoczęstotliwościowymi. Przedstawione zostały w niej, z uwzględnieniem literatury przedmiotu, oryginalne wyniki badań własnych autorów, w tym: analizy zjawisk wysokoczęstotliwościowych i rezonansowych występujących w uzwojeniach transformatorów i maszyn elektrycznych poddawanych działaniu szybkozmiennych udarów napięciowych powstających w sieciach elektrycznych, badania eksperymentalne z zastosowaniem metod wysokoczęstotliwościowych oraz komputerowe badania symulacyjne.

Contents

Summary  7
Streszczenie  8
Symbols and abbreviations  9
1. Modern condition assessment techniques  13
1.1. Exploitation stresses  14
1.2. Diagnostics methods of electrical equipment  15
1.2.1. Transformer diagnostics methods  16
1.2.2. Electrical machines diagnostics methods  18
2. Diagnostics based on high frequency analysis  20
2.1. High frequency analysis of transformers  21
2.2. High frequency analysis of machine windings  25
3. Modelling and simulations of windings for high frequency analysis  28
3.1. Introduction  28
3.2. General characteristic of digital models of windings  29
3.3. Model with distributed parameters of windings  33
3.3.1. Transients in time domain  33
3.3.2. Transients in frequency domain  35
3.4. Lumped parameters model  36
3.5. Multiconductor transmission line model  42
3.6. Parameters of equivalent circuit of windings  49
4. Transfer function based fault discrimination criteria  54
4.1. Introduction  54 
4.2. Transfer function based analysis  58
4.3. Transfer function for the deformed transformer windings  61
4.4. Transfer function-based fault discrimination criteria  68
4.4.1. Theoretical basis  68
4.4.1.1. Experimental setup  75
4.4.1.2. Measurement results  77
4.5. Application of high frequency method to assessment of electrical machine winding failures  85
4.5.1. Asynchronous motor  86
4.5.2. Windmill generator winding  91
4.5.3. Results of numerical modelling  95
5. Very fast voltage stresses of transformers insulating systems  98
5.1. Very fast transients  99
5.2. Lightning impulse  100
5.3. Impact of vacuum circuit breakers  102
5.4. Steep frontwave mitigation methods  103
5.4.1. Traditional methods preventing fast transients impact on transformers  103
5.4.2. SmartChoke based transient suppression  104
5.5. Impact of impulse voltage steep-front  111
5.6. Impact of winding patterns  115
6. Analysis of transient voltage distributions in transformer windings at different voltage stimuli  122
6.1. Introduction  122
6.2. Transients in time domain  124
6.2.1. Initial distributions in transformer windings  124
6.2.2. Influence of oil temperature on voltage distributions in transformer windings  126
6.2.3. Initial voltage distributions in transformer windings at different voltage stimulus  127
6.2.3.1. Influence of winding construction on transients  134
6.2.3.2. Initial voltage distributions in windings of power transformer at ultra fast stresses  138
6.2.4. Influence of surge magnitude on transient voltages in windings  143 
6.3. Frequency characteristics of voltages in windings at different insulation conditions  144
6.3.1. Model windings and measurement setup  144
6.3.2. Influence of oil temperature on frequency characteristics of transformer windings of different constructions  145
7. Impact of resonance overvoltages in transformers on internal insulation systems  152
7.1. Introduction  152
7.2. Investigations of internal overvoltages in the winding of 110 kV 153
7.3. Investigations of frequency dependences of overvoltages inside the winding  159
7.4. Internal overvoltages in the winding of 15 kV generated by selected stimulus  165
7.5. Simulation of resonance overvoltages in the transformer windings  167
7.6. Spatial resonances in windings  169
7.7. Analysis of selected damages of transformers caused by resonance overvoltages  172
8. Application of transfer function to recognition of resonance overvoltages in transformer winding  175
8.1. Introduction  175
8.2. Transfer based recognition of resonance overvoltage prone zones  176
8.3. Investigations of frequency dependences of overvoltages inside the windings  177
8.4. Transfer function based recognition of resonance overvoltage sensitive zones  179
8.5. Simulation of resonance overvoltages in the transformer windings  181
9. Transfer overvoltages and frequency signatures of windings for transformers with steel and amorphous core  184
9.1. Introduction  184
9.2. Characteristic of experimental transformers  185
9.3. Measurement results  188
9.3.1. The 20 kVA transformer with silicon steel core  188
9.3.2. The 160 kVA transformer with silicon steel core  191
9.3.3. The 33 kVA transformer with amorphous magnetic core  193 
10. Assessment of manufacturing processes based on FRA  198
10.1. Introduction  198
10.2. Theory and measuring technique 198
10.3. Results of investigations  200
Literature  207
Index  221

Fragments
Contents
Price
0.00
In order to arrange international shipping details and cost please contact wydawnictwa@agh.edu.pl