Method and Control System for Fault Direction Detection

Content Provider	The Lens
Abstract	A method for detecting fault direction of a transmission line of an AC power system and a control system using the same. The method includes sampling current values and voltage values at one end of the transmission line for a series of time points; computing instantaneous voltage values at compensated point on the transmission line from the current value samples and the voltage value samples based on a time domain lumped parameter differential equation for the transmission line for the series of time points; recording the current value samples and the computed instantaneous voltage values at the compensated point; computing at least one voltage fault component each using the recorded computed instantaneous voltage values for at least the at least two of the series of time points; identifying the fault direction in consideration of the at least one computed voltage fault component and the at least one computed current fault component; and generating a fault direction signal indicating the identified fault direction. Where a fault directional element is designed using the voltage fault components at the compensated point, it will work well for the AC power system with strong power source.
Related Links	https://www.lens.org/lens/patent/009-287-574-983-762/frontpage
Language	English
Publisher Date	2019-09-05
Access Restriction	Open
Content Type	Text
Resource Type	Patent
Jurisdiction	United States of America
Date Applied	2019-05-21
Applicant	Abb Schweiz Ag
Application No.	201916418105
Claim	A method for detecting fault direction of transmission line of an AC power system, including: sampling current values and voltage values at one end of the transmission line for a series of time points; computing instantaneous voltage values at compensated point on the transmission line from the current value samples and the voltage value samples based on a time domain lumped parameter differential equation for the transmission line for the series of time points; recording the current value samples and the computed instantaneous voltage values at the compensated point; computing at least one voltage fault component each using the recorded computed instantaneous voltage values for at least two of the series of time points; computing at least one current fault component each using the recorded current value samples for the at least two of the series of time points; identifying the fault direction in consideration of the at least one computed voltage fault component and the at least one computed current fault component; and generating a fault direction signal indicating the identified fault direction. The method according to claim 1 , wherein: the fault direction is identified as forward where signs of the computed voltage fault component and the computed current fault component are opposite to each other; and the fault direction is identified as reverse where signs of the computed voltage fault component and the computed current fault component are the same. The method according to claim 1 , wherein: the fault direction is identified as forward where an energy directional element involving the computed voltage fault component and the computed current fault component is negative under a predetermined time period; and the fault direction is identified as reverse where an energy directional element involving the computed voltage fault component and the computed current fault component is positive under a predetermined time period. The method according to claim 3 , further including: computing a multiple of energy directional elements involving different electrical loops; the fault direction is identified as forward where sign of sum of the computed energy directional elements is negative under predetermined time period; and the fault direction is identified as reverse where sign of sum of the computed energy directional elements is positive under predetermined time period. The method according to claim 1 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line. The method according to claim 1 , further including: the generation of the fault direction signal is triggered by an absolute value of the computed energy directional elements being above a predetermined threshold. The method according to claim 1 , wherein: the computed instantaneous voltage values indicate one of three-phase voltages at the compensated point on the transmission line; and the current value samples indicate corresponding one of three-phase currents measured at the end of the transmission line. A control system for detecting fault direction of transmission line of an AC power system, including: a sampling circuit, for sampling current values and voltage values at one end of the transmission line for a series of time points; a controller for computing instantaneous voltage values at compensated point on the transmission line from the current value samples and the voltage value samples based on a time domain lumped parameter differential equation for the transmission line for the series of time points; and a storage circuit, for recording the current value samples and the computed instantaneous voltage values at the compensated point; wherein the controller is operational for: computing at least one voltage fault component each using the recorded computed instantaneous voltage values for at least two of the series of time points; computing at least one current fault component each using the recorded current value samples for the at least two of the series of time points; identifying the fault direction in consideration of the at least one computed voltage fault component and the at least one computed current fault component; and generating a fault direction signal indicating the identified fault direction. The control system according to claim 8 , wherein: the fault direction is identified as forward where signs of the computed voltage fault component and the computed current fault component are opposite to each other; and the fault direction is identified as reverse where signs of the computed voltage fault component and the computed current fault component are the same. The control system according to claim 8 , wherein: the fault direction is identified as forward where an energy directional element involving the computed voltage fault component and the computed current fault component is negative under a predetermined time period; and the fault direction is identified as reverse where an energy directional element involving the computed voltage fault component and the computed current fault component is positive under a predetermined time period. The control system according to claim 10 , wherein: the controller is operational for a multiple of energy directional elements involving different electrical loops; the fault direction is identified as forward where sign of sum of the computed energy directional elements is negative under predetermined time period; and the fault direction is identified as reverse where sign of sum of the computed energy directional elements is positive under predetermined time period. The control system according to claim 8 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line. The control system according to claim 8 , wherein: the generation of the fault direction signal is triggered by an absolute value of the computed energy directional elements being above a predetermined threshold. The control system according to claim 8 , wherein: the computed instantaneous voltage values indicate one of three-phase voltages at the compensated point on the transmission line; and the current value samples indicate corresponding one of three-phase currents measured at the end of the transmission line. The method according to claim 4 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line. The method according to claim 2 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line. The method according to claim 5 , further including: the generation of the fault direction signal is triggered by an absolute value of the computed energy directional elements being above a predetermined threshold. The control system according to claim 11 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line. The control system according to claim 9 , wherein: the generation of the fault direction signal is triggered by an absolute value of the computed energy directional elements being above a predetermined threshold. The control system according to claim 9 , wherein: the identified fault direction is related to the fault occurring in an electrical loop of the transmission line; and the current value samples and the voltage value samples are measurements concerning the electrical loop of the transmission line.
CPC Classification	EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS Measuring Electric Variables;Measuring Magnetic Variables
Extended Family	009-287-574-983-762 150-751-603-363-684 013-418-858-863-369 185-774-165-936-21X 095-649-815-799-056 092-104-288-660-466 181-848-363-758-243 077-433-257-379-296
Patent ID	20190271730
Inventor/Author	Liu Kai Wang Jianping Li Youyi
IPC	G01R31/02 H02H1/00 H02H7/26
Status	Active
Owner	Hitachi Energy Ltd Abb Schweiz Ag Hitachi Energy Switzerland Ag
Simple Family	009-287-574-983-762 150-751-603-363-684 185-774-165-936-21X 181-848-363-758-243 095-649-815-799-056 092-104-288-660-466 013-418-858-863-369 077-433-257-379-296
CPC (with Group)	H02H3/165 G01R31/085 H02H3/081 H02H3/385 H02H7/26 G01R19/2513 H02H1/0007
Issuing Authority	United States Patent and Trademark Office (USPTO)
Kind	Patent Application Publication