Epoxy-based Spacers for Gas Insulated Power Apparatus

494 Pages·2022·22.385 MB·English

by  Boxue Du, Hucheng Liang

Boxue Du
Hucheng Liang
Epoxy-based
Spacers for Gas
Insulated Power
Apparatus
Epoxy-based Spacers for Gas Insulated Power
Apparatus
·
Boxue Du Hucheng Liang
Epoxy-based Spacers for Gas
Insulated Power Apparatus
Boxue Du Hucheng Liang
School of Electrical and Information School of Electrical and Information
Engineering Engineering
Tianjin University Tianjin University
Tianjin, China Tianjin, China
ISBN 978-981-19-7110-5 ISBN 978-981-19-7111-2 (eBook)
https://doi.org/10.1007/978-981-19-7111-2
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Preface
High-voltage gas-insulated apparatuses, including Gas-Insulated Substations (GIS)
and Transmission Lines (GIL), play an important role in the global power transmis-
sion systems. GIS has been widely used in the transformer substation attributed to its
advantages of less land occupation and superior insulation performance. GIL is an
advanced medium for high-capacity and long-distance power transmission due to its
advantages of large capacity, low loss, and strong environment adaptability. GIS and
GIL have a similar structure with the conductor and the metal enclosed enclosure
coaxially installed, using SF gas as the insulating medium and epoxy-based spacers
6
for mechanical support. Because the epoxy-based spacers and SF gas have different
6
electrical properties (permittivity, conductivity, etc.), the electric field distribution
in GIS/GIL is extremely non-uniform, easily triggering partial discharges and even
insulation breakdowns. Moreover, GIS/GIL are subjected to complex conditions
during operation, the thermo-electro-structural coupled field makes the insulation
failure process more complicated to be understood and suppressed.
This book is a collection of our previous researches on epoxy-based spacers for
gas-insulated apparatuses. Three topics make up this book, with 7–9 chapters in each
topic. The first topic is “Electric field, Surface Charge and Discharge”, consisting of
nine chapters. We have paid attention to the surface charging and discharging behav-
iors of the epoxy-based spacers in GIS/GIL and found that the insulation break-
down of the epoxy-based spacers is closely related to the electric field distortion
under variable voltage waveforms (AC, DC, impulse, etc.) and temperature gradi-
ents. The second topic is “Surface Functionally Graded Materials for GIL/GIS”,
consisting of seven chapters. We provided an original study on the electric field
relaxation of epoxy-based spacers by surface functionally graded materials (SFGM).
Several optimization methods and fabrication technologies for SFGM spacers were
introduced and discussed. The last topic is “Electric Field Adaptive Materials for
GIL/GIS”, consisting of nine chapters. Nonlinear conductivity materials (NCM),
such as epoxy/SiC and epoxy/ZnO composites, were applied as coatings to adap-
tively regulate the electric field distribution around DC-GIL/GIS spacers. Besides,
the concept of the multidimensional functionally graded materials was proposed to
v
vi Preface
control the electric field distribution of DC-GIL/GIS spacers under stationary and
transient conditions, exhibiting great potential in the future application.
Pursuing the Research and Development of Advanced Dielectric Materials for
Polymer Insulation started for me when I worked as the leader of the high voltage
lab of Tianjin University, China. This book includes our recent progresses on
epoxy-based insulating materials for GIL/GIS, some of which are original and
quite promising. It is really a team effort to finish this book. It is my pleasure to
acknowledge the numerous contributions made by my team.
Tianjin, China Boxue Du
Contents
Part I Electric Field, Surface Charge, and Discharge
1 Electric Field Distribution Around Basin-Type Spacer
in DC-GIS .................................................... 3
1.1 Introduction ............................................. 3
1.2 Mathematical Model ...................................... 4
1.2.1 Geometric Model ................................. 4
1.2.2 Corona Discharge in SF /N Mixture ................ 5
6 2
1.2.3 Charge Transport in Epoxy Spacer .................. 8
1.3 Poisson Equation ......................................... 10
1.4 Heat Transfer in GIS ...................................... 10
1.5 Results and Discussion .................................... 12
1.5.1 Effects of Surface Charge .......................... 12
1.5.2 Effects of Temperature ............................ 16
1.5.3 Effects of Shielding Electrode ...................... 18
1.6 Conclusion .............................................. 21
References .................................................... 22
2 Gas Convection Affecting Surface Charge and Electric Field
Distribution Around Tri-Post Insulators in DC-GIL .............. 25
2.1 Introduction ............................................. 25
2.2 Simulation and Parameters ................................. 26
2.2.1 Geometry Models ................................. 26
2.2.2 Temperature Calculation ........................... 27
2.2.3 Surface Charge and Electric Field ................... 28
2.2.4 Simulation Parameters ............................. 29
2.3 Results and Discussion .................................... 29
2.3.1 Temperature and Dielectric Strength ................. 29
2.3.2 Surface Charge and Electric Field ................... 32
vii
viii Contents
2.3.3 Flashover Voltage ................................. 36
2.4 Conclusion .............................................. 39
References .................................................... 39
3 Polarity Reversal and Over Voltage Affecting Discharge
Inception of Tri-Post Insulator in DC-GIL ....................... 41
3.1 Introduction ............................................. 41
3.2 Simulation and Parameters ................................. 42
3.2.1 Geometry Model ................................. 42
3.2.2 Surface Charge and Electric Field ................... 42
3.2.3 Overvoltage ...................................... 43
3.2.4 Polarity Reversal ................................. 43
3.2.5 Micro Discharge .................................. 44
3.2.6 Theoretical Discharge Inception Voltage ............. 44
3.3 Results and Discussion .................................... 45
3.3.1 Overvoltage ...................................... 45
3.3.2 Polarity Reversal ................................. 47
3.3.3 Micro Discharge .................................. 51
3.4 Conclusion .............................................. 54
References .................................................... 55
4 Simulation on Surface Charge Accumulation of Epoxy Resin
Under Needle-Plane Corona Discharge in Air .................... 57
4.1 Introduction ............................................. 57
4.2 Simulation Model ........................................ 58
4.2.1 Geometric Model ................................. 58
4.2.2 Corona Discharge in Air ........................... 58
4.2.3 Charge Trapping and De-Trapping Process
in the Epoxy Insulation ............................ 62
4.2.4 Poisson Equation ................................. 64
4.2.5 Surface Potential Measurement ..................... 65
4.3 Results and Discussion .................................... 66
4.4 Conclusion .............................................. 73
References .................................................... 74
5 Surface Charge Dynamic Behaviors of Epoxy Resin Under
Combined Effects of DC and Pulse Voltages ..................... 77
5.1 Introduction ............................................. 77
5.2 Experimental Arrangement ................................ 78
5.2.1 Sample Preparation ............................... 78
5.2.2 Test Procedure ................................... 78
5.3 Results and Discussion .................................... 80
5.3.1 Effect on Initial Surface Potential ................... 80
5.3.2 Effect on Surface Potential Distribution .............. 83
5.3.3 Effect on Surface Potential Decay ................... 85
Contents ix
5.3.4 Trap Energy Distributions .......................... 89
5.4 Conclusion .............................................. 91
References .................................................... 92
6 Surface Charge Accumulation and Decay Behaviors of Epoxy
Resin Under Combined Effects of AC and Pulse Voltages ......... 95
6.1 Introduction ............................................. 95
6.2 Experimental Arrangement ................................ 96
6.2.1 Sample Preparation ............................... 96
6.2.2 Test Procedure ................................... 96
6.3 Results and Discussion .................................... 98
6.3.1 Effects of Voltage Amplitudes ...................... 98
6.3.2 Effects of Pulse Numbers .......................... 104
6.3.3 Trap Energy Distributions .......................... 105
6.4 Conclusion .............................................. 108
References .................................................... 110
7 Effects of Surface Charge on DC Flashover Characteristics
of Epoxy/BN Nanocomposites .................................. 113
7.1 Introduction ............................................. 113
7.2 Experimental Arrangement ................................ 114
7.2.1 Sample Preparation ............................... 114
7.2.2 Test Procedure ................................... 114
7.3 Results and Discussion .................................... 118
7.3.1 Surface Charge Characteristics ...................... 118
7.3.2 Flashover Test .................................... 119
7.3.3 Discussion ....................................... 123
7.4 Conclusion .............................................. 126
References .................................................... 126
8 Temperature Dependent Surface Charge and Discharge
Behavior of Epoxy/AIN Nanocomposites ........................ 129
8.1 Introduction ............................................. 129
8.2 Experimental Arrangement ................................ 130
8.2.1 Specimen Preparation ............................. 130
8.2.2 Measurement of Conductivity ...................... 130
8.2.3 Measurement of Surface Charge .................... 131
8.2.4 Measurement of Surface Discharge .................. 131
8.3 Results and Discussion .................................... 132
8.3.1 Properties of Test Specimens ....................... 132
8.3.2 Effects of Ambient Temperature .................... 134
8.3.3 Effects of Adding Nanoparticles .................... 137
8.4 Conclusion .............................................. 142
References .................................................... 143
x Contents
9 Surface Charging and Discharging Behaviors of Epoxy-Based
Spacer in DC-GIL ............................................. 145
9.1 Introduction ............................................. 145
9.2 Experimental Arrangement ................................ 146
9.2.1 Downsized DC-GIL Structure and Test Samples ....... 146
9.2.2 Surface Charging System .......................... 147
9.2.3 Surface Charge Measurement System ................ 149
9.2.4 Flashover Test Platform ............................ 151
9.3 Surface Charge and Flashover Characteristics Under DC
Stress ................................................... 152
9.3.1 Transient Process of Surface Charge Accumulation .... 152
9.3.2 Surface Charge Characteristics Under Different
Voltage Levels ................................... 157
9.3.3 Flashover Characteristics and Analyses .............. 162
9.3.4 Insulation Performances Under Different Testing
Conditions ....................................... 168
9.4 Conclusion .............................................. 176
References .................................................... 178
Part II Surface Functionally Graded Materials for GIL/GIS
10 Surface Functionally Graded Insulator for Electric Field
Grading in AC Gas Insulated Power Apparatus .................. 183
10.1 Introduction ............................................. 183
10.2 Concept of SFGM ........................................ 184
10.3 Fabrication of SFGM Insulator ............................. 187
10.3.1 Magnetron Sputtering ............................. 187
10.3.2 Surface Morphology .............................. 187
10.3.3 Dielectric Parameters Measurement ................. 188
10.4 Electric Field Simulation .................................. 189
10.4.1 Simulation Model ................................. 189
10.4.2 Effects of Sputtering Layer Permittivity .............. 190
10.4.3 Effects of Sputtering Layer Thickness ............... 192
10.4.4 Application of Prepared Insulators .................. 193
10.5 Flashover Test Results .................................... 195
10.6 Conclusions ............................................. 196
References .................................................... 197
11 Epoxy-Based Insulator with Permittivity-Graded Surface
Layer by Magnetron Sputtering for Gas Insulated Lines .......... 199
11.1 Introduction ............................................. 199
11.2 BaTiO Layer Deposition ................................. 201
3
11.2.1 Magnetron Sputtering ............................. 201
11.2.2 Characterization of BaTiO Layer ................... 201
3
11.3 Simulation and Optimization ............................... 203