US 12,348,036 B2 · Adaptive arc suppression method for ground faults in a combined active and passive distribution network

Abstract

This application presents an adaptive arc suppression method for ground faults in distribution networks, merging active and passive relay protection strategies. The method proceeds as follows: based on collected ground parameters, the fault phase is identified; compensation current is calculated from the fault's electromotive force, ground leakage resistance, and ground capacitance; current is injected at the neutral point according to the compensation current; finally, the arc suppression scheme is executed based on the zero-sequence voltage of the network's busbars. This approach incorporates both voltage- and current-based methods, addressing the limitation of fixed operation scenarios in traditional arc suppression methods. By quickly adapting to various fault situations, this method ensures an efficient and prompt response tailored to specific scenario requirements.

An Adaptive Arc Suppression Method for Ground Faults in a combined Active-Passive Distribution Network, characterized in that the method includes:

determining the target fault phase based on ground parameters collected from the distribution network;
calculating a compensation current based on a target electromotive force of the power source, the target ground leakage resistance, and the target ground capacitance of the identified fault phase;
injecting current into the neutral point of the distribution network based on the compensation current;
determining and executing an arc suppression scheme based on a zero-sequence voltage of busbars in the distribution network, which includes both voltage-based and current-based arc suppression methods, wherein:
steps for determining the compensation current based on the target electromotive force of a faulted phase, target ground leakage resistance, and target ground capacitance include:
when the ground parameters of three phases in the distribution network are symmetrical, determining a first product of the target electromotive force and the target ground leakage resistance;
determining a second product of the target electromotive force and the target ground capacitance;
determining the compensation current based on the first product and the second product;
wherein the compensation current equation is as follows:
I
.
in
=
(
U
.
N
+
E
.
A
)
⁢
(
1
R
A
+
j
⁢
ω
⁢
C
A
+
1
R
f
)
+
(
U
.
N
+
E
.
B
)
⁢
(
1
R
B
+
j
⁢
ω
⁢
C
B
)
+
(
U
.
N
+
E
.
C
)
⁢
(
1
R
C
+
j
⁢
ω
⁢
C
C
)
+
U
.
N
⁢
1
j
⁢
ω
⁢
L
+
U
.
o
⁢
h
(
j
⁢
ω
⁡
(
C
A
+
C
B
+
C
C
)
+
1
R
A
+
1
R
B
+
1
R
C
+
1
j
⁢
ω
n
⁢
L
)
Simplified as:
I
˙
in
=
-
E
˙
A
(
3
R
0
+
3
⁢
j
⁢
ω
⁢
C
0
+
1
j
⁢
ω
⁢
L
)
+
∑
n
=
3
,
4
∞
U
.
0
⁢
h
(
3
⁢
j
⁢
ω
⁢
C
0
+
3
R
0
+
1
j
⁢
ω
n
⁢
L
)
;
where, ω represents an angular frequency, ωn denotes the angular frequency under the n-th harmonic, j is the imaginary unit, {dot over (U)}N refers to a neutral point voltage, R0 is a relative ground leakage resistance, C0 is a relative ground capacitance, L signifies an inductance of an arc suppression coil, Uoh indicates the neutral point voltage of the harmonic, and ĖA, ĖB, ĖC are the electromotive forces of the three-phase power supply in the distribution network. {dot over (U)}N represents the neutral point voltage in the distribution network, while RA, RB, RC are the ground leakage resistances for the three phases in the distribution network, additionally, CA, CB, CC are the ground capacitances for the three phases in the distribution network, and Rf denotes the transitional resistance for grounding faults;
steps for determining and executing the arc suppression scheme based on the zero-sequence voltage of the busbars in the distribution network include:
when the zero-sequence voltage is greater than or equal to a boundary setting value, wherein:
a second neutral point voltage after initial compensation is determined based on the target source electromotive force and the three-phase ground leakage resistances and capacitances of the distribution network;
a first neutral point voltage prior to initial compensation is determined based on historical ground parameters;
a corrective current is determined based on the first neutral point voltage, the second neutral point voltage, and the compensation current;
current suppression at the neutral point is executed based on the corrective current;
taking into account the effect of unbalanced voltage, an injected current is defined as:
İ0=ĖA(YA+αYB+α2YC);
therefore, the current that needs to be injected after a single-phase grounding fault occurs is:
İi=İin+İ0;
and
upon detection of a single-phase grounding fault, the current neutral point voltage at that moment, namely the first neutral point voltage, is:
U
.
N
⁢
1
=
-
E
.
A
(
Y
A
+
α
⁢
Y
B
+
α
2
⁢
Y
C
)
-
E
.
A
/
R
f
-
U
.
o
⁢
h
(
Y
A
+
Y
B
+
Y
C
+
1
j
⁢
ω
n
⁢
L
)
Y
A
+
Y
B
+
Y
C
+
1
/
R
f
+
Y
0
;
after injecting a small current İin, the voltage at the second neutral point is:
U
.
N2
=
-
E
.
A
⁢
(
Y
A
+
α
⁢
Y
B
+
α
2
⁢
Y
C
)
-
E
.
A
/
R
f
-
U
.
o
⁢
h
⁢
(
Y
A
+
Y
B
+
Y
C
+
1
j
⁢
ω
n
⁢
L
)
+
I
.
in
Y
A
+
Y
B
+
Y
C
+
1
/
R
f
+
Y
0
;
by combining {dot over (U)}N1 and {dot over (U)}N2, the corrected injected current is expressed as:
I
˙
i
=
I
˙
in
+
I
˙
0
=
-
I
˙
in
(
E
.
A
+
U
.
N
⁢
1
)
U
.
N
⁢
2
-
U
.
N
⁢
1
∘
where, YA, YB, and YC represent the ground admittances for the three phases,
Y
A
=
1
R
A
+
jw
⁢
C
A
,
Y
B
=
1
R
B
+
j
⁢
w
⁢
C
B
,
Y
C
=
1
R
C
+
jw
⁢
C
C
,
YO is the neutral point admittance to ground, given by Y0=−jwLP, w denotes the angular frequency, and α represents a phase shift of 120 degrees;
and
the steps for determining and executing the arc suppression scheme based on the zero-sequence voltage of the bus in the distribution network include:
when the zero-sequence voltage is not greater than the boundary setting value, the injection current is determined based on the electromotive force of the target power supply and the three-relative ground leakage resistance and three-relative ground capacitance of the distribution network;
and
performing voltage arc suppression at the neutral point based on the injected current.

450 more elements

Adaptive arc suppression method for ground faults in a combined active and passive distribution network

Life of this patent

Adaptive arc suppression method for ground faults in a combined active and passive distribution network

Life of this patent

Abstract

Claims7