This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Development and InDevelopment and In--Grid Demonstration of a Transmission Grid Demonstration of a Transmission Voltage Voltage SuperLimiterSuperLimiterTMTM
Fault Current LimiterFault Current Limiter
funded by the U.S. Department of Energy funded by the U.S. Department of Energy --
National Energy National Energy Technology LaboratoryTechnology Laboratory
American Superconductor Corporation: A. Otto, E. Podtburg, J. Maguire, J. Yuan, P. Winn, W. Romanosky, B. Gamble, D. Madura.
M. Ross, D. Folts,
H. Cai, J. McNamara, T. MacDonald and A. P. Malozemoff,Siemens AG Corporate Technology:
H.-P. Kraemer, P. La Seta, W. Schmidt, M. Wohlfart, and H.-W. Neumueller,
Nexans: N. Lallouet
and F. Schmidt. Los Alamos National Laboratory:
S. Ashworth and J.O. Willis.Southern California Edison:
The Need for Current Limiting Devices in Power Grids
“The most important near term energy and utility markets appear to be fault current limiters
and synchronous condensers.”
High Temperature Superconductors (HTS) Peer Presentation Document –
July 25, 2006 Navigant Consulting, Inc.
Citation from Navigant Consulting (2006):"Increasing loads on the existing power transmission system, coupled with lack of investment, lead to a growing demand for current limiting devices.
The perfect fault current limiting device features an instantaneous, self triggered transition from near zero impedance to above grid impedance in case of a fault.
→ Superconducting Fault Current Limiters (SFCL) can provide the solution. "
The fault current levels rise due toincreasing power consumption interconnection of grids to improve reliability and voltage stability
additional feeding by IPPsConventional solutions
reactors pyroelectric
limiters
no limitation, but switching off by breakers, while designing all components to carry the full fault current until the breaker opens
however, fault currents are often close to or even higher than rated breaking current of installed breakers
Wish for a current limiting device, which is …self-acting, self-restoring, fail-safe, compact, inexpensiveThe resistive HTS-FCL can meet most of these requirementsefficient use of existing grids at increased load
Temperature: 77.5 K 76.1 K 74.9 K 73.1 K 72.2 K 70.5 K 69.2 K
U [m
V]
I [A]
Functional Principal of Resistive SFCL
Very
sharp
current
–
voltage
characteristic
of YBCO thin
filmsvery low R in normal operation, high dR/dI above Icvery fast 'switching' to the resistive state when thecritical current is exceededself-actingvery effective currentlimitationself-restoring afterfault current interruption
But, warming
up during
limitation:fast switch-off after a fault is mandatorywait for recoverybefore re-activation
Proposed Test Sites for the Transmission Voltage SFCL
Two test sites in Southern California Edison's grid have been analyzed using time domain grid planning tools.
Valley Substation Devers Substation
Located near Riverside, CA in a desert climate
Located very near Palm Springs, CA in a desert climate
115 kV bus tie application 115 kV line application
SFCL provides an 18% reduction in fault current at one of the tied buses
SFCL provides a 33% reduction of fault current on the out-going line
The design voltage of 30.7 kV across the SFCL module had to be fixed before finalization of grid integration studies. Therefore, the impedance of the parallel reactor was adjusted to the grid impedance. This causes the site dependent fault current reduction.
Bifilar coils, the basic switching elements, are arranged as horizontal stack Support legs are resting on the cryostat inside wallCorona rings and end plates are attached for electric field controlComplete module for one electrical phase has been assembled
Modular concept allows simple, expandable, and robust mechanical
79 bifilar coils have been wound and tested, 63 coils have been selected for the moduleThorough testing has been applied to each coil: R(295K), Ic, 32 switching tests,..
Coil design characteristics•Bifilar winding
for low inductance and low AC loss•two-in-hand winding and 1.2 cm wide tape
for higher compactness•back-to-back tape orientation
for reduced AC loss•spacer tape between winding turns
for high LN2
transparency•wire insulation
for increased electrical strength
Basic module design provides ultra low line impedance in normal operation
A subscale switching module has been equipped with corona rings and end plates for conducting lightning impulse voltage withstand measurements at the University of Braunschweig.
No breakdown at 220 kV in air at 1 bar (15 pulses with both polarities).Specification of 650 kV in nitrogen at 5 bar can be met (by scaling plus margin).
Project phase 1a successfully finishedDesign of bifilar coils as switching elements under HV aspectsSubscale module made of 6 full size coils fabricated
and successfully tested at IPH Berlin, 8.4 kV ×
425 A = 3.5 MVA
Project phase 1b mostly finished:One complete phase of the FCL manufacturedRated apparent power: 30.9 kV ×
1.35 kA = 42 MVA (74 K)
Power tests at PowerTech
labs. (Surrrey) passed successfullyHigh voltage tests to be repeated in June 2011