Granted Patent B2

US 12,401,187 · App. 17/908,859 · Granted Aug 26, 2025

Inventors: Neethu George (Karnataka, IN); Od Naidu (Karnataka, IN)

Assignee: HITACHI ENERGY LTD

H02H7/26G01R31/58

Abstract

Claims (734)

1. A method for protecting a power transmission line in response to a fault within a monitored zone in a power transmission system, the method comprising:

identifying an occurrence of a fault in at least one phase of a power transmission line;

calculating an actual rate of change of incremental current based on calculated incremental currents;

calculating a threshold for rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting for the monitored zone;

determining the fault to be in the monitored zone based on comparison of the actual rate of change of incremental current and the threshold for the rate of change of incremental current; and

generating a trip signal for controlling a switching device associated with the power transmission line, based on the comparison.

2. The method as claimed in claim 1 , wherein the calculated incremental voltages and the calculated incremental currents correspond to difference in voltages and currents, respectively, wherein the voltages and currents are measured at terminals of the power transmission line.

3. The method as claimed in claim 2 , wherein calculating the actual rate of change of incremental current further comprises:

processing, based on a moving average filter, the calculated incremental currents to provide processed incremental currents; and

calculating the actual rate of change of incremental current based on the processed incremental currents.

4. The method as claimed in claim 2 , wherein identifying the occurrence of the fault in at least one phase is based on the calculated incremental currents associated with one terminal of the power transmission line.

5. The method as claimed in claim 1 , wherein the line parameters comprise resistance and inductance of the transmission line.

6. The method as claimed in claim 1 , wherein determining the fault further comprises:

calculating a root-mean-square value of the actual rate of change of the incremental current and the threshold for the rate of change of incremental current to provide a processed actual rate of change of incremental current and a processed threshold for the rate of change of incremental current; and

comparing a processed actual rate of change of incremental current and a processed threshold for the rate of change of incremental current.

7. The method as claimed in claim 6 , wherein the fault is to have occurred when the processed actual rate of change of incremental current to be greater than the processed threshold for the rate of change of incremental current.

8. A method for protecting a power transmission line in response to a fault within a monitored zone in a power transmission system, the method comprising:

identifying an occurrence of a fault in at least one phase of a power transmission line;

calculating an actual rate of change of incremental current based on calculated incremental currents, wherein calculating the actual rate of change of incremental current comprises

processing, based on a moving average filter, the calculated incremental currents to provide processed incremental currents, and

calculating the actual rate of change of incremental current based on the processed incremental currents;

calculating a threshold for rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting for the monitored zone;

determining the fault to be in the monitored zone based on comparison of the actual rate of change of incremental current and the threshold for the rate of change of incremental current; and

generating a trip signal for controlling a switching device associated with the power transmission line, based on the comparison,

wherein a processed incremental voltage and the processed incremental currents are determined using the following equations:

Δ

⁢

v

lplma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

v

lp

(

k

-

i

)

Δ

⁢

i

lplma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpl

(

k

-

i

)

Δ

⁢

i

lprma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpr

(

k

-

i

)

v

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

v

p

⁢

r

⁢

e

(

k

-

i

)

i

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

i

p

⁢

r

⁢

e

(

k

-

i

)

wherein, Δv lpma is the processed incremental voltage;

Δi lplma is the processed incremental current across an inductive component of the transmission line;

Δi lprma is the processed incremental current across a resistive component of the transmission line;

v ma pre is a processed pre-fault loop voltage; and

i ma pre is a processed pre-fault loop current.

9. An intelligent electronic device (IED) to protect a power transmission line from a fault which is to have occurred in at least one phase of the power transmission line within a monitored zone in a power transmission system, with the IED being provided at one end of the power transmission line connecting at least two terminals with one or more power transmission line, the IED comprising:

a microprocessor;

an output interface;

a phase selection module to:

detect occurrence of a fault in at least one phase of a power transmission line;

a fault detection module to:

calculate incremental voltages and incremental currents, based on voltages and currents measured at terminals of the power transmission line;

calculate an actual rate of change of incremental current based on calculated incremental currents;

calculate a threshold for the rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting for a monitored zone;

compare the actual rate of change of incremental current and the threshold for the rate of change of incremental current to determine the fault to be in the monitored zone; and

generate a trip signal for controlling a switching device associated with the power transmission line, based on the comparison.

10. The device as claimed in claim 9 , wherein calculating the actual rate of change of incremental current comprises processing, based on a moving average filter, the incremental currents to provide processed incremental currents.

11. An intelligent electronic (IED) to protect a power transmission line from a fault which is to have occurred in at least one phase of the power transmission line within a monitored zone in a power transmission system, with the IED being provided at one end of the power transmission line connecting at least two terminals with one or more power transmission line, the IED comprising:

a microprocessor;

an output interface;

a phase selection module to:

detect occurrence of a fault in at least one phase of a power transmission line;

a fault detection module to:

calculate incremental voltages and incremental currents, based on voltages and currents measured at terminals of the power transmission line;

calculate an actual rate of change of incremental current based on calculated incremental currents, wherein calculating the actual rate of change of incremental current comprises processing, based on a moving average filter, the incremental currents to provide processed incremental currents;

calculate a threshold for the rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting for a monitored zone;

compare the actual rate of change of incremental current and the threshold for the rate of change of incremental current to determine the fault to be in the monitored zone; and

generate a trip signal for controlling a switching device associated with the power transmission line, based on the comparison,

wherein a processed incremental voltage and a processed incremental current are determined using the following equations:

Δ

⁢

v

lpma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

v

lp

(

k

-

i

)

Δ

⁢

i

lplma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpl

(

k

-

i

)

Δ

⁢

i

lprma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpr

(

k

-

i

)

v

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

v

p

⁢

r

⁢

e

(

k

-

i

)

i

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

i

p

⁢

r

⁢

e

(

k

-

i

)

wherein, Δv lpma is the processed incremental voltage; and

Δi lplma is the processed incremental current across an inductive component of the transmission line; and

Δi lprma is the processed incremental current across a resistive component of the transmission line; and

v ma pre is a processed pre-fault loop voltage; and

i ma pre is a processed pre-fault loop current.

12. The device as claimed in claim 11 , wherein the fault detection module is to calculate the actual rate of change of incremental current using the following equation:

d

⁢

Δ

⁢

i

act

(

k

)

=

(

Δ

⁢

i

lplma

(

k

)

-

Δ

⁢

i

lplma

(

k

-

1

)

)

(

Δ

⁢

t

)

wherein, Δi lpkma is the processed incremental current across an inductive component of the transmission line; and

Δt is the a interval between two consecutive samples.

13. The device as claimed in claim 11 , wherein the fault detection module is to calculate the threshold for the rate of change of incremental current using the equation:

d

⁢

Δ

⁢

i

thr

(

k

)

=

Δ

⁢

v

lpma

(

k

)

-

R

1

⋆

z

b

⋆

Δ

⁢

i

lprma

(

k

)

+

v

z

⁢

1

pre

(

k

)

L

1

*

z

b

wherein, Δv lpma is the processed incremental voltage;

Δi lprma is the processed incremental current across a resistive component of the transmission line;

z b denotes the boundary of the monitored zone;

R 1 , L 1 are positive-sequence series resistance and inductance of the transmission line; and

v z1 pre is further determined using the following equation:

v

z

⁢

1

pre

(

k

)

=

Δ

⁢

v

lpma

(

k

)

-

R

1

⋆

z

b

⋆

Δ

⁢

i

lprma

(

k

)

-

L

1

*

z

b

⋆

(

Δ

⁢

i

lplma

(

k

)

-

Δ

⁢

i

lplma

(

k

-

1

)

)

(

Δ

⁢

t

)

.

14. The device as claimed in claim 13 , wherein the processed rate of change of incremental current and the processed threshold for the rate of change of incremental current are represented as:

d

⁢

Δ

⁢

i

act

rms

=

∑

i

=

0

N

3

(

d

⁢

Δ

⁢

i

act

(

k

-

i

)

)

2

N

3

;

and

d

⁢

Δ

⁢

i

thr

rms

=

∑

i

=

0

N

/

3

(

d

⁢

Δ

⁢

i

thr

(

k

-

i

)

)

2

N

/

3

wherein dΔi act rms depicts the processed actual rate of change of incremental current; and

wherein dΔi thr rms depicts the processed threshold for the rate of change of incremental current.

15. The device as claimed in claim 14 , wherein the fault detection module determines an occurrence of the fault to be within the monitored zone when the processed rate of change of incremental current is greater than the processed threshold for the rate of change of incremental current.

16. A non-transitory computer-readable medium having instructions stored thereon, wherein the instructions when executed by a processor, cause the processor to:

identify an occurrence of a fault in at least one phase of a power transmission line;

calculate an actual rate of change of incremental current based on calculated incremental currents;

calculate a threshold for rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting for a monitored zone in a power transmission system;

determine the fault to be in the monitored zone based on comparison of the actual rate of change of incremental current and the threshold for the rate of change of incremental current; and

generate a trip signal for controlling a switching device associated with the power transmission line, based on the comparison.

17. The non-transitory computer-readable medium as claimed in claim 16 , wherein the calculated incremental voltages and the calculated incremental currents correspond to difference in voltages and currents, respectively, wherein the voltages and currents are measured at terminals of the power transmission line.

18. The non-transitory computer-readable medium as claimed in claim 17 , wherein calculating the actual rate of change of incremental current further comprises:

processing, based on a moving average filter, the calculated incremental currents to provide processed incremental currents; and

calculating the actual rate of change of incremental current based on the processed incremental currents.

19. The non-transitory computer-readable medium as claimed in claim 16 , wherein the line parameters comprise resistance and inductance of the transmission line.

20. A non-transitory computer-readable medium having instructions stored thereon, wherein the instructions when executed by a processor, cause the processor to:

identify an occurrence of a fault in at least one phase of a power transmission line;

calculate an actual rate of change of incremental current based on calculated incremental currents, wherein calculating the actual rate of change of incremental current comprises

processing, based on a moving average filter, the calculated incremental currents to provide processed incremental currents, and

calculating the actual rate of change of incremental current based on the processed incremental currents;

calculate a threshold for rate of change of incremental current based on calculated incremental voltages, the calculated incremental currents, line parameters, and a zone setting fora monitored zone in a power transmission system;

determine the fault to be in the monitored zone based on comparison of the actual rate of change of incremental current and the threshold for the rate of change of incremental current; and

generate a trip signal for controlling a switching device associated with the power transmission line, based on the comparison,

wherein a processed incremental voltage and a processed incremental current is determined using the following equations:

Δ

⁢

v

lpma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

v

lp

(

k

-

i

)

Δ

⁢

i

lplma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpl

(

k

-

i

)

Δ

⁢

i

lprma

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

Δ

⁢

i

lpr

(

k

-

i

)

v

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

v

p

⁢

r

⁢

e

(

k

-

i

)

i

m

⁢

a

p

⁢

r

⁢

e

(

k

)

=

1

3

⁢

∑

i

=

-

1

1

i

p

⁢

r

⁢

e

(

k

-

i

)

wherein, Δv lmpa is the processed incremental voltage;

Δi plma is the processed incremental current across an inductive component of the transmission line;

Δi lprma is the processed incremental current across a resistive component of the transmission line;

v ma pre is a processed pre-fault loop voltage; and

i ma pre is a processed pre-fault loop current.

Assignments (2)

Priority Claims (1)

Continuity (1)

References Cited (28)