University of Applied Sciences of Eastern Switzerland
Jasmin Smajic, Roman Obrist, Martin Regg, Thomas Franz
Modeling, Simulation, and Experimental Verification of Fast- and Very Fast Electromagnetic Transients University of Applied Sciences of Eastern Switzerland (HSR) Institute of Energy Technology (IET) Oberseestrasse 10, CH-8640 Rapperswil, Switzerland [email protected]
University of Applied Sciences of Eastern Switzerland
Outline
2
n Introduction
n Electromagnetic transients in power system components
n HF modeling and simulation of power and distribution transformers
n Lightning impulse (LI) overvoltages and fast transients
n HF modeling and simulation of gas insulated switchgears
n Very fast transients
n Conclusions
University of Applied Sciences of Eastern Switzerland
Introduction
3
n Electromagnetic transients in power system components [1]:
n Origin: sudden change in the steady state values of voltages or currents (lightning stroke, system malfunction, normal operation switching operation, switching operation to clear a fault, etc).
n Duration, i.e. frequency range:
n LI-overvoltages: according to the IEC standard 1.2s/50s (
University of Applied Sciences of Eastern Switzerland
Introduction
4
n LI- and fast transients in power and distribution transformers [2]
n HF transformer modeling and simulation
n Experimental verification of the results
n Very fast transients in gas insulated switchgears (GIS) [3]
n Full-Maxwell modeling and simulation of VFTs in GIS
n Mitigation of VFTs in GIS
n Experimental verification of the results [2] J. Smajic, T. Steinmetz, M. Regg, Z. Tanasic, R. Obrist, J. Tepper, B. Weber, M. Carlen, Simulation and Measurement of Lightning-impulse Voltage Distributions Over Transformer Windings, IEEE Transactions on Magnetics, Vol. 50, No. 2, Article#: 7013604, February 2014. [3] J. Smajic, A. Shoory, S. Burow, W. Holaus, U. Riechert, S. Tenbohlen, Simulation Based Design of HF Resonators for Damping Very Fast Transients in GIS, IEEE Transactions on Power Delivery, Vol. 29, No. 6, pp. 2528-2533, December 2014.
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
5
1.2s / 50s impulse:
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
6
1.2s / 50s impulse: = / ()
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
7
Boundary initial value problem (BIVP): (1/ )+ 0/+ 00/(/)=0, (,,) 3 =0, (,,) 2 (1/ ) 0//( )= 20/( 0), (,,) 2 =0, =0, (,,) 3
Accurate Full-Maxwell Approach
J. Smajic et al., Transient Full-Maxwell Computation of Slow Processes, in Scientific Computing in Electrical Engineering (SCEE 2010), Mathematics in Industry, Vol. 16, Part 2, pp. 87-95, Springer Verlag, Berlin, Heidelberg, New York, 2012.
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
8
Vector Finite Element Method (FEM) is required for this analysis.
Linear vector tetrahedral element: (,,,)= (,,) ()
Accurate Full-Maxwell Approach
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
9
Accurate Full-Maxwell Approach
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
10
J. Smajic et al., Transient Full-Maxwell Computation of Slow Processes, in Scientific Computing in Electrical Engineering (SCEE 2010), Mathematics in Industry, Vol. 16, Part 2, pp. 87-95, Springer Verlag, Berlin, Heidelberg, New York, 2012.
Accurate Full-Maxwell Approach
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
11
J. Smajic et al., Transient Full-Maxwell Computation of Slow Processes, in Scientific Computing in Electrical Engineering (SCEE 2010), Mathematics in Industry, Vol. 16, Part 2, pp. 87-95, Springer Verlag, Berlin, Heidelberg, New York, 2012.
Accurate Full-Maxwell Approach
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
12
[2] J. Smajic, T. Steinmetz, M. Regg, Z. Tanasic, R. Obrist, J. Tepper, B. Weber, M. Carlen, Simulation and Measurement of Lightning-impulse Voltage Distributions Over Transformer Windings, IEEE Transactions on Magnetics, Vol. 50, No. 2, Article#: 7013604, February 2014.
A 4-turn winding model as an example:
Novel Approach: Winding Modeling in Its Full Complexity
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
13
[2] J. Smajic, T. Steinmetz, M. Regg, Z. Tanasic, R. Obrist, J. Tepper, B. Weber, M. Carlen, Simulation and Measurement of Lightning-impulse Voltage Distributions Over Transformer Windings, IEEE Transactions on Magnetics, Vol. 50, No. 2, Article#: 7013604, February 2014.
Structure of the equation system:
C-matrix (left) and L-matrix in logarithmic scale:
Novel Approach: Winding Modeling in Its Full Complexity
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
14
Example: dry-type 1600kVA VCC transformer.
University of Applied Sciences of Eastern Switzerland
LI- and Fast Transients in Power and Distribution Transformers
15
[2] J. Smajic, T. Steinmetz, M. Regg, Z. Tanasic, R. Obrist, J. Tepper, B. Weber, M. Carlen, Simulation and Measurement of Lightning-impulse Voltage Distributions Over Transformer Windings, IEEE Transactions on Magnetics, Vol. 50, No. 2, Article#: 7013604, February 2014.
Example: dry-type 1600kVA VCC transformer.
Voltage distribution E-field
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
16
1100kV AC Jingman Substation in China
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
17
Shaft
Moving contact Fixed contact
Insulator Additional shield
Circuit breakers
side
Transformers side
0 0.01 0.02 0.03 0.04 0.05 0.06
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Voltage is high enough to ignite a spark
Floating potential conductor Network voltage
Contact separation
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
18
[4] J. Smajic, W. Holaus, J. Kostovic, U. Riechert, 3D Full-Maxwell Simulations of Very Fast Transients in GIS, IEEE Transactions on Magnetics, Vol. 47, No. 5, pp. 1154-1517, May 2011.
( ) ( )( )
( )
00 0 0
00
1
2PORT
PORT
i i r ir PORT
iPORT
A AA N dV N dV N n n A dSt t t Z t
N n n E dSZ
+ + =
=
r rr rr r r r rr rr r
Weak form of the BIVP:
Linear system of equations:
[ ] { } ( ) { } { } { }2
2 ( ) [ ] [ ] ( ) [ ] ( ) ( )A A
T t R Q t S A t f tt t
+ + =
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
19
[4] J. Smajic, W. Holaus, J. Kostovic, U. Riechert, 3D Full-Maxwell Simulations of Very Fast Transients in GIS, IEEE Transactions on Magnetics, Vol. 47, No. 5, pp. 1154-1517, May 2011.
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
20
[4] J. Smajic, W. Holaus, J. Kostovic, U. Riechert, 3D Full-Maxwell Simulations of Very Fast Transients in GIS, IEEE Transactions on Magnetics, Vol. 47, No. 5, pp. 1154-1517, May 2011.
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
21
[4] J. Smajic, W. Holaus, J. Kostovic, U. Riechert, 3D Full-Maxwell Simulations of Very Fast Transients in GIS, IEEE Transactions on Magnetics, Vol. 47, No. 5, pp. 1154-1517, May 2011.
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
22
HF resonator:
J. Smajic, W. Holaus, M. Seeger, F. Greuter, A. Iordanidis, U. Riechert, Conductor Arrangement for Reducing Impact of Very Fast Transients, European Patent Office, Application/Patent No. 11174464.5 1231, Date of filing: 19.07.2011.
University of Applied Sciences of Eastern Switzerland
Very Fast Transients in Gas Insulated Switchgears
23
[3] J. Smajic, A. Shoory, S. Burow, W. Holaus, U. Riechert, S. Tenbohlen, Simulation Based Design of HF Resonators for Damping Very Fast Transients in GIS, IEEE Transactions on Power Delivery, Vol. 29, No. 6, pp. 2528-2533, December 2014.
Experimental verification:
University of Applied Sciences of Eastern Switzerland
Conclusions (Transformers)
24
The suggested method is mathematically well founded, stable, accurate and efficient.
Due to its generality the presented method can be used in case of very complex windings (transformers for 36-pulse rectifiers, for example).
The disagreement between the simulations and measurements in terms of both the oscillation frequencies and the voltage peaks stays below 20%.
Considering the complexity of the analysis this accuracy is sufficient for the daily design.
University of Applied Sciences of Eastern Switzerland
Conclusions (GIS)
25
Full-Maxwell 3-D simulation of the VFTs in GIS are feasible. The results of the 3-D VFT simulations improve our understanding of the
phenomenon.
The presented simulations reveal critical places of the given GIS design. The 3-D time-domain VFT simulations enable parameter studies and design
optimization.
Simulation based resonator design was confirmed by experiments. Efficiency of the resonator at damping the VFTs was confirmed by
measurements.
All simulation models are wrong, but some are useful!