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Analysis of R-SFCL with Parallel Shunt Resistor in MMC-HVDC System
Xiangyu Tan, Li Ren, Siyuan Liang, Yuejin Tang, Ying Xu, Shuqiang Guo and Guilun Chen State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science & Technology, Wuhan, China
Abstract— R-SFCL has a board application prospect in MMC-HVDC system.
However, the R-SFCL will quench due to fault current, which results in temperature
rise and may damage superconducting coils. A shunt resistor in parallel can protect
the superconducting coils, but the influence has not been quantitatively calculated.
This work proposed a novel R-Q curve method to calculate quenching resistance of
R-SFCL. Using this method, the influence of shunt resistor to R-SFCL is analyzed in
terms of current-limiting effect and maximum temperature. Performance of R-SFCL
with different shunt resistance is compared, and the optimal shunt resistance value is
obtained.
Current
Pancake
Submodule
0 200 400 600 800 1000
0.00
0.01
0.02
0.03
0.04
0.05
AC 1360A DC 1460A
AC 1420A DC 1580A
AC 1580A DC 1820A
AC 1920A DC 1950A
R (
Ω/m
)
Q (J/m)
Trendline
0 2 4 6 8 10
0
2
4
6
experiment
R-Q method
FEM
Rsc (
Ω)
time (ms)
MMC1 MMC2SFCL unit
Mechanical DCCB
RSC
RSC
Rshunt
Unit 1 Unit 2
No. Rshunt Turns Tape length
1 without Rshunt24 2.64 km
2 15 Ω 28 3.53 km
3 12 Ω 30 3.89 km
4 10 Ω 36 4.49 km
0 2 4 6 8 10 12
-5
0
5
10
15
20 unlimited
#1
#2
#3
#4
I dc (
kA
)
time (ms)
0 200 400 600 800
80
100
120
140
160 #1
#2
#3
#4
T (
K)
time (ms)
0
1
2
3
4
5
#1 #2 #3 #4
Max
imum
res
ista
nce
(Ω
)
0
20
40
60
80
100
#1 #2 #3 #4
Lim
itin
g r
atio
(%
)
0
1
2
3
4
#1 #2 #3 #4
Tap
e le
ngth
(km
)
0
50
100
150
200
#1 #2 #3 #4
Max
imum
tem
per
ature
(K
)
0
100
200
300
400
Rec
over
y t
ime
(ms)
#1 #2 #3 #40.0
0.5
1.0
1.5
2.0
#1 #2 #3 #4
Rec
over
y t
ime
(s)
Basic structure of R-SFCL
Fig. Configuration of non-inductive pancake and R-SFCL
Parameter Value
Rated voltage 160kV
Critical current 2kA
No. of turns 24
No. of pancakes 16
R-Q curve method to calculate quenching resistance
Tab. Parameters of R-SFCL
Experiments show that there is a corresponding
relation between quenching resistance R and the
accumulated joule heat Q.
Fig. R-Q curve of superconducting tapes. Fig. Calculation result of R-Q method compared with experiment and FEM.
An R-Q method to calculate quenching
resistance is proposed. Result is well fitted with
finite element method (FEM) and experiments.
Analysis of R-SFCL with shunt resistor
Q = Q + q R-Q curveI
R
RSCq = I2R t *L
The R-Q method is coupled with
system simulation to calculation
quenching resistance. And FEM is
used to calculate magnetic file and
temperature.Fig. Calculation process of R-Q curve method
Fig. Structure of MMC-HVDC system with SFCL unit
Tab. Parameters of SFCL units
Four types of SFCL units with different shunt
resistance and tape length are chosen for analysis.
Fig. Fault current during DC pole-to-pole fault
Fig. Temperature of superconducting coils
(a) maximum current-limiting resistance
(b) Current-limiting ratio
(c) Tape length
(d) Maximum temperature
(e) Recovery time to 92K
(f) Recovery time to 77K
All SFCL units have the same current-limiting
ratio. The temperature is reduced by shunt resistor.
Considering the temperature and tape length, No.3
is the most economical scheme.
Fig. Comparison of SFCL units
This paper studies the performance of R-SFCL with a fixed-value shunt resistor
using R-Q method and FEM. Conclusions are as follows:
• The R-Q method is highly fitted with FEM and experiment. Combing the R-Q
method and FEM, system simulation and finite element analysis are separated. The
calculation speed is greatly improved.
• The shunt resistor can reduce the temperature and recovery time, but more tapes
are consumed. When shunt resistance is 12Ω, the maximum temperature is reduced
by 30K, which is the most economical.