Fault Location on HVDC Transmission Lines Using
Dynamic State Estimation (DSE)
上 海 科 技 大 学ShanghaiTech University
Panel Session: State Estimation for Power Electronics-Dominated
Systems: Challenges and Solutions
Presenter: Yu Liu
Power System Protection and Automation Laboratory (PSPAL)
School of Information Science and Technology
ShanghaiTech UniversityEmail: [email protected]; [email protected]
1
Power System Protection and
Automation LaboratoryP PAL电力系统保护与自动化实验室
P PAL
Personal Info
2
Education
2017 Ph.D. Electrical Engineering Georgia Institute of Technology
2013 M.S. Electrical Engineering Shanghai Jiao Tong University
2011 B.S. Electrical Engineering Shanghai Jiao Tong University
Working experiences
2017 Assistant Professor ShanghaiTech University
2012 Visiting Scholar Georgia Institute of Technology
Research Interests
• Power System Protection, Fault Location
• State and Parameter Estimation of Power Systems
• Condition Monitoring of Power Electronic Systems
P PAL
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
3
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
4
Advantages of HVDC over HVAC
• No reactive power loss
• No stability problem
• Long distance, large capacity transmission
• Flexible power control
5
IntroductionWhy HVDC transmission? Development of HVDC transmission
Point-to-Point
• LCC-HVDC transmission
• VSC-HVDC transmission
-- Two-level VSC-HVDC
-- Three-level VSC-HVDC
-- MMC-HVDC
Advantages of MMC-HVDC transmission
• Compatible with weak AC systems
• Independent control of active/reactive power
• Lower switching frequency
• Lower harmonics
compared to LCC-HVDC
compared to other VSC-
HVDC topologies
MMC 1
MMC 2
MMC 3
MMC 4
DC link 12 DC link 34
DC link 24
Line of interest
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
6
Introduction
Point-to-point MMC-HVDC
After occurrence of line faults in MMC-HVDC grids:
• Operation of DC circuit breakers, to isolate the line with fault
• Accurate fault location within the isolated line (using line terminal measurements
during faults) (focus of this presentation)
Development of HVDC transmission MMC-HVDC grids
MMC 1 MMC 2
Line of interest
us(t)is(t)
ur(t)ir(t)S R
Improve power supply
reliability of the system
lf
7
Introduction
MMC-HVDC grids
MMC 1
MMC 2
MMC 3
MMC 4
DC link 12 DC link 34
DC link 24
Line of interest
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
Accurate fault location within the isolated line
Challenges (Compared to HVAC fault location)
Power Electronics Dominated System
• Low Inertia:
-- Severe transients during faults
• Vulnerable Power Electronic Devices:
-- Short data window (several milliseconds, to prevent MMC shutdown)
• DC system:
-- Absence of fundamental frequency (50 or 60 Hz) components
lf
Fundamental frequency phasor based methods
-- Steady state assumptions at system fundamental frequency (50 or 60 Hz);
-- Not Applicable for HVDC lines
Travelling wave based methods
-- Limited wavefront detection reliability (especially high impedance faults)
-- Require very high sampling rate (100khz -> systematic error ≈ 1.5 km)
Natural frequency based methods
-- Mode mixing phenomenon (especially during single pole to ground faults)
-- Frequency extraction errors
Time domain model based methods
-- Traditional methods: utilize models with lumped parameters
-- Dynamic state estimation (DSE) based fault location method
Existing transmission line fault location methods
8
Introduction
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
9
Review of Existing DSE Based Fault Location Method
Section
1
( )1
1 ( )ai t
( )1
1 ( )v t
( )1
1 ( )bi t
( )1
2 ( )v t
Section
m
( )1( )ami t
( )1( )mv t
( )1( )bmi t
Section
1
( )2
1 ( )ai t( )2
1 ( )bi t
( )2
2 ( )v t
Section
n
( )2( )ani t
( )2( )nv t
( )2( )bni t
( )2
1 ( )nv t+
( )1
1 ( )mv t+
Rf
( )2
1 ( )v tor
( )fl t ( )fl l t−
Location
of the faultSide 1 Side 2
Parameter to be
determined
Model of section k
Left part
Model of section k
Right part
10
• Works well in HVAC systems
• Introduce the fault location as
a parameter (extended state) of
the dynamic model
• Use DSE to solve the states of
the dynamic model, including
fault location
Details of transmission line modeling :
• Multi-section π model
• Very accurate approximation of fully distributed parameter line model, with large m and n
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
Model of section k, left part
Section
k
( )1( )aki t
( )1( )kv t
( )1( )bki t
( )1
1 ( )kv t+
( )1( )aki t
( )1( )kv t
1 ( ) /fl t m R 1 ( ) /fl t mL
( )1( )Lki t
1 ( ) /fl t mG 1 ( ) /fl t mC 1 ( ) /fl t mG 1 ( ) /fl t mC
( )1( )bki t
( )1
1 ( )kv t+
Model of section k,
left side part
( )( )
( ) ( )1
1 1 11 1( )( ) ( ) ( )vk
ak vk Lk
d tt t t
m dt m= + +
yC Gi y i
( ) ( )( )
( )( ) ( )
1
11 1 11 11
( )( ) ( ) ( )
v k
bk Lkv k
d tt t t
m dt m
+
+= + −
yC Gi y i
( ) ( ) ( )( )1
1 1 11 11
( )( ) ( ) ( ) Lk
k k Lk
d tt t t
m m dt+= − + + +
yR L0 v v y
( ) ( )1 1( ) ( ) ( )vk f kt l t t= − 0 y v
( )( ) ( )1 1
11( ) ( ) ( )f kv kt l t t++
= − 0 y v
( ) ( )1 1( ) ( ) ( )Lk f Lkt l t t= − 0 y i
Review of Existing DSE Based Fault Location Method
Fault location lf(t) is
strongly coupled
with the states of the
dynamic model
High nonlinearity of
the dynamic model
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
Section
k
( )2( )aki t
( )2( )kv t
( )2( )bki t
( )2
1 ( )kv t+
Model of section k, right part
Review of Existing DSE Based Fault Location Method
Fault location lf(t) is
strongly coupled
with the states of the
dynamic model
High nonlinearity of
the dynamic model
( )2( )aki t
( )2( )kv t
( )1 ( ) /fl l t n −R ( )1 ( ) /fl l t n −L
( )2( )Lki t
( )1 ( ) /fl l t n −G ( )1 ( ) /fl l t n −C ( )1 ( ) /fl l t n −G ( )1 ( ) /fl l t n −C
( )2( )bki t
( )2
1 ( )kv t+
Model of section k,
right side part
( )( ) ( )
( ) ( ) ( )2 2
2 2 2 21 1 1 1( ) ( )( ) ( ) ( ) ( )k vk
ak k vk Lk
d t d tl lt t t t
n dt n dt n n
= − + − +
v yC C G Gi v y i
( )( )
( )( )
( )( )
( ) ( )
2212 2 2 211 1 1 1
1 1
( )( )( ) ( ) ( ) ( )
v kkbk k Lkv k
d td tl lt t t t
n dt n dt n n
+++ +
= − + − −
yvC C G Gi v y i
( ) ( ) ( ) ( )( ) ( )2 2
2 2 2 21 1 1 11
( ) ( )( ) ( ) ( ) ( ) Lk Lk
k k Lk Lk
d t d tl lt t t t
n n n dt n dt+
= − + + − + −
i yR R L L0 v v i y
( ) ( )2 2( ) ( ) ( )vk f kt l t t= − 0 y v
( )( ) ( )2 2
11( ) ( ) ( )f kv kt l t t++
= − 0 y v
( ) ( )2 2( ) ( ) ( )Lk f Lkt l t t= − 0 y i
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
Review of Existing DSE Based Fault Location Method
13
1 1 1 1
2 2 2 2
3 3
( )( ) ( ) ( )
( )( ) ( )
( ) ( ) ( ) ( ) ( ) ( )
( ) ( )
eqx eqp eqx eqc
eqx eqp eqx eqc
T i T ieqx eqp eqxx eqpp
T ieqpx
d tt t t
dt
d tt t
dt
t t t t t t
t t
= + + +
= + + +
= + + +
+
xz Y x Y p D C
x0 Y x Y p D C
0 Y x Y p x F x p F p
p F x
State vector:
Standard syntax of the dynamic model (Differential and Algebraic Equations):
Parameter vector
( )tx
( )tp
( )tz Measurement vector
Nonlinear model
(Instantaneous voltages at each node;
Instantaneous currents through each branch)
(Fault location, fault resistances)
(Instantaneous voltages and currents at
terminals of the transmission line)
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
( , ) ( ( , ))m mt t t t=z h xp
After discretization of the dynamic model (Algebraic Equation):
Dynamic state estimation (DSE) procedure (batch mode regression formulation):
1 1( , ) ( , ) ( ) ( ( ( , ) ) ( , ))T T
m m m mt t t t h t t t t + −= − −xp xp H WH H W xp z
( , ) [ ( , ), ( , )]T
m m mt t t t t t=xp x p
Solution is given with following Newton’s iterative algorithm until convergence,
where H is the Jacobian matrix ( )( ) ( ) ( ) ( ), ., ,m m
m m t t t th t t t t == xp xpH xp xp
14
Review of Existing DSE Based Fault Location Method
where the extended state vector is
( )
,min ( ) ( , ) ( ( , )) ( , ) ( ( , ))
m
T
m m m mt t
J t t t t t t t t t= − −xp
z h xp W z h xp
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
The existing method does not work in HVDC lines, due to
• Large condition number of the inverse matrix and large numerical error
• High computational burden
15
Review of Existing DSE Based Fault Location Method
Yu Liu*, Sakis Meliopoulos, Zhenyu Tan, Liangyi Sun and Rui Fan, “Dynamic State Estimation-Based Fault Locating on Transmission
Lines”, IET Generation, Transmission & Distribution, vol. 11, no. 17, pp. 4184-4192, Nov. 2017. (*: corresponding author)
Limitations when applying this method in HVDC lines:
Specific Characteristics of (1) DSE Problem and (2) HVDC system
(1) DSE Problem:
• Highly nonlinear DSE problem
• High-dimensional matrix inverse in every Newton’s iteration and
DSE time step; Matrix dimension: (16m+16n+24)×(16m+16n+24)
(2) HVDC system:
• Requires small DSE time step, to accurately track severe transients during faults
• Large section number m and n to ensure model accuracy
1
1
( , ) ( , )
( )
( ( ( , ) ) ( , ))
m m
T T
m m
t t t t
h t t t t
+
−
=
−
−
xp xp
H WH H W
xp z
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
16
17
Proposed New DSE Based Fault Location Method
The DSE formulation of the existing method:
• Highly nonlinear DSE problem
• High-dimensional matrix inverse in every Newton’s iteration and DSE time step
The DSE formulation of the proposed method:
• Linear DSE problem;
• No Newton’s iterations;
• Avoid re-calculation of matrix inverse: constant matrix in all DSE time steps
Key Idea: Reformulate the DSE problem for fault location
With given fault location lf and resistance Rf :
linear dynamic model of the line
( ) ( )( )
( )( )
1 1
2 2
eqx eqx
eqx eqx
d tt t
dt
d tt
dt
= +
= +
xz Y x D
x0 Y x D
18
Proposed New DSE Based Fault Location Method
2 2 (2 2 ) 2 (2 ) 2 (2 )
2 (2 2 ) 2 2 (2 ) 2 (2 )
1
2 (2 2 ) 2 2 (2 2 2)
2 (2 2 ) 2 (2 2 2) 2
, , ,
, , ,
/2, , ,
, /2, ,
m n m n
m n m n
eqx
l m n m n
m n r m n
+
+
+ + −
+ + −
=
−
I 0 0 0
0 I 0 0Y
G 0 I 0
0 G 0 I
2 (2 2) 2 (2 ) 2 (2 ) 2 (2 )
2 (2 2) 2 (2 ) 2 (2 ) 2 (2 )
1
2 (2 2 ) 2 (2 ) 2 (2 )
2 (2 2 ) 2 (2 ) 2 (2 )
, , ,
, , ,
/2, , ,
, /2, ,
m n m n
m n m n
eqx
l m n m n
m n r m n
+
+
+
+
=
0 0 0 0
0 0 0 0D
C 0 0 0
0 C 0 0
11 (2 2) (2 +2) 2 2 (2 2) (2 )
(2 2) (2 2) 22 (2 2) (2 2) 2 2
2 2 (2 ) (2 ) 33 (2 ) (2 )
(2 ) (2 ) 2 (2 ) (2 ) 44
51 2 (2 2 2) 53 2 (2 2)
m n m m n
n m n m n
eqx m m n m n
n m n n m
m n n
− − −
− + − + −
+ − −
=
Y 0 E 00 Y 0 E
Y E 0 Y 00 E 0 Y
Y 0 Y 0
11 (2 2) (2 2) (2 2) (2 ) (2 2) (2 )
(2 2) (2 2) 22 (2 2) (2 2) (2 2) (2 )
2 (2 ) (2 2) (2 ) (2 ) 33 (2 ) (2 )
(2 ) (2 ) (2 ) (2 2) (2 ) (2 ) 44
51 2 (2 2 -2) 2 4 2 (2 2)
m n m m m n
n m n m n n
eqx m m m n m n
n m n n n m
m n n
− + − −
− + − + −
+
+
+ −
=
D 0 0 00 D 0 0
D 0 0 D 00 0 0 D
D 0 0 0
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
the coefficient matrices are functions
of lf , Rf , and other constant parameter
matrices of the transmission line.
where
Section
1
Section
1
Section
m
Section
n
Multi section model, left part
(m sections)
Multi section model, right part
(n sections)
...
...
...
...
Fault
Fault
model
lf l-lf
( ) ( )1
lti
( ) ( )2
rti
( ) ( )1
l
L ti( ) ( )l
Lm ti( ) ( )1
r
L ti( ) ( )r
Ln ti
( ) ( )1
ltv
( ) ( )2
ltv
( ) ( )l
m tv( ) ( )1
l
m t+v( ) ( )1
rtv
( ) ( )2
rtv
( ) ( )r
n tv( ) ( )1
r
n t+v
19
Proposed New DSE Based Fault Location Method
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
( ) ( ), ,z Y x Bm eqx m eqt t t t= −
Discretization of the dynamic model,
Dynamic state estimation (DSE) procedure (batch mode regression formulation):
1ˆ ( , ) ( ) ( ( , ) )T Tm eqx eqx eqx m eqt t t t−= +x Y WY Y W z B
With given fault location lf and resistance Rf :
linear dynamic model of the line
( ) ( )( )
( )( )
1 1
2 2
eqx eqx
eqx eqx
d tt t
dt
d tt
dt
= +
= +
xz Y x D
x0 Y x D
( )( ) ( )
,min ( ) ( , ) , ( , ) ,
m
T
m eqx m eq m eqx m eqt t
J t t t t t t t t t= − + − + xz Y x B W z Y x B
Solution can be directly obtained without iterations,Constant matrix in all
DSE time steps;
No Newton’s iterations
evaluates the consistency between the measurement and the dynamic model( ) ( )ˆ, ,
ˆ ( ) ( )m mt t t t
J t J t=
=x x
20
Proposed New DSE Based Fault Location Method
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
How to determine the fault location?The best consistency corresponds to correct fault location lf and fault resistance Rf .
,min ( , )
f ff f
l Ry l R=
where function expresses the average chi-square value y as functions of lf and Rf .( )
With given fault location lf and resistance Rf :
linear dynamic model of the line
evaluates the consistency between the measurement and the dynamic model( ) ( )ˆ, ,
ˆ ( ) ( )m mt t t t
J t J t=
=x x
Solution can be obtained through Gradient Descent algorithm,
( 1) ( 1) ( ) ( ) ( ) ( ) ( )[ , ] [ , ] ( , )f f f f f fl R l R l R + + = −
Existing method
Reach last measurement?
No
No
Yes
Yes
Proposed method
Output fault location result
Newton
interation
DSE Procedure
(Highly Nonlinear)
No
No
Yes
Yes
Gradient
Decent
Initial with 1 =
Output fault location result
DSE Procedure
(Linear)
( ) ( ), ,z Y x Bm eqx m eqt t t t= −
( )Store the average chi-square value: ,f fy l R=
0Initialize with t t=0 0Initialize with ,f f f fl l R R= =
0Initialize with t t=
( ) ( ) ( )( )1
ˆ , = ,x Y WY Y W z BT T
m eqx eqx eqx m eqt t t t−
+
( ) ( ) ( )ˆ , , ,=r Y x B zm eqx m eq mt t t t t t− −
( ) ( ) ( )ˆ ˆ ˆ= , ,r WrT
m mJ t t t t t
Reach last measurement?
Generate the nonlinear line model:
( ) ( )( ), ,z h xm mt t t t=
Generate the linear dynamic model:
1 1( , ) ( , ) ( )
( ( ( , ) ) ( , ))
xp xp H WH
H W xp z
T
m m
T
m m
t t t t
h t t t t
+ −= −
−
Constant matrixduing DSE
Newton's Iteration Converges?
Updated in each iteration and each
DSE time step
Reach minimum ?y
Update
, f fl Rt t t= +
1 = +
t t t= +
Flow chart
comparison
between the
existing method
and the proposed
method
21
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
22
MMC 1
MMC 2
MMC 3
MMC 4
DC link 12 DC link 34
DC link 24
Line of interest
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
• 320 KV MMC-HVDC grid
• Line of interest: Line S-R, 200 km
• Two-pole instantaneous (sampled value) voltage and current measurements at both
terminals of the line,
• Sampling rate: 20 kilo-samples/sec
• Available time window:
5 ms after the occurrence of the fault
Existing DSE based method v.s.
proposed DSE based method
23
Numerical Experiments
• Section number: selected as m = n = 200 for
both the existing and the proposed method
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 0.01 Ω P-G fault, 50km from side S
Large
condition
number
Unreliable
fault location
results
Existing method Proposed method
24
Positive pole to ground faults (P-G)
Best
Consistency:
(lf , Rf ) =
(49.42 km,
0.0023 Ω)
Fault Location
Error = 0.29 %
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 0.01 Ω P-G fault, 50km from side S
25
Positive pole to ground faults (P-G)
2. P-G faults, through the line
Proposed method
Fault
resistance (Ω)
Average absolute
error (%)
Max absolute
error (%)
0.01 0.1827 0.3738
1 0.1877 0.3636
5 0.1747 0.3628
10 0.1595 0.4554
Accurate Fault Location Results
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 0.01 Ω P-P fault, 50km from side S
Large
condition
number
Unreliable
fault location
results
Existing method Proposed method
26
Pole to Pole faults (P-P)
Best
Consistency:
(lf , Rf ) =
(50.48 km,
0.8803 Ω)
Fault Location
Error = 0.24 %
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 0.01 Ω P-P fault, 50km from side S
27
Pole to Pole faults (P-P)
2. P-P faults, through the line
Proposed method
Fault
resistance (Ω)
Average absolute
error (%)
Max absolute
error (%)
0.01 0.1420 0.5507
1 0.1991 0.5446
5 0.1889 0.5728
10 0.1985 0.5345
Accurate Fault Location Results
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 200 Ω P-G fault, 50km from side S
Large
condition
number
Unreliable
fault location
results
Existing method Proposed method
28
High Resistance Faults
Best
Consistency:
(lf , Rf ) =
(49.36 km,
199.6725 Ω)
Fault Location
Error = 0.32 %
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
1. 200 Ω P-G fault, 50km from side S
29
High Resistance Faults
2. High resistance P-G faults, through the line
Proposed method
Fault
resistance (Ω)
Average absolute
error (%)
Max absolute
error (%)
200 0.2469 0.6966
300 0.2782 0.8249
400 0.3084 1.0679
500 0.4211 1.2898
Accurate Fault Location Results
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
Measurement
errorsParameter
errors
30
Discussions
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
• 0.01 Ω P-G faults, through the line
• Different measurement errors
• Different parameter errors
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
Proposed method
Different
section
numbers
Different
time
window
lengths
31
Discussions
MMC 1 MMC 3
Line of interests
us(t)is(t)
ur(t)ir(t)S R
B1 B2
B3 B4
• 0.01 Ω P-G faults, through the line
• Different section numbers m and n
• Different available time window length
Binglin Wang, Yu Liu*, Dayou Lu, Kang Yue and Rui Fan, “Transmission Line Fault Location in MMC-HVDC Grids Based on
Dynamic State Estimation and Gradient Descent”, IEEE Trans. Power Del., 2020, early access. (*: corresponding author)
Proposed method
01 Introduction
02 Review of Existing DSE Based Fault Location Method
03 Proposed New DSE Based Fault Location Method
04 Numerical Experiments
05 Conclusion
Outline
32
• A new dynamic state estimation based fault location method is proposed for
transmission lines in MMC-HVDC grids.
• The method solves the limitations of the existing DSE based fault location
methods, including large numerical errors and high computational burden,
especially when applied to transmission lines in MMC-HVDC grids.
• The methods present accurate fault location results, independent of fault
types, fault locations and fault resistances, and only requires a short data
window of several milliseconds.
33
Conclusions
• Power electronic dominated systems (for example HVDC
systems) bring additional challenges due to special
characteristics of electromagnetic transients in those systems.
• We need to re-examine the effectiveness of the existing
approaches when applied to power electronic dominated systems.
34
Some Observations
Thank You!
35
P PAL
Should you have any questions, please feel free to contact:
Yu Liu
Power System Protection and Automation Laboratory (PSPAL)
School of Information Science and Technology
ShanghaiTech University
Email: [email protected]; [email protected]
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