Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific quantity comparison means
Reexamination Certificate
1999-04-20
2001-04-24
Sherry, Michael J. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific quantity comparison means
C361S087000
Reexamination Certificate
active
06222711
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a bus-bar protection relay equipment for an electrical power system.
DESCRIPTION OF THE RELATED ART
The protective regions of the bus-bar in electrical power systems are protected by tripping the output based on a combination of outputs described below.
That is, one is an output from a check zone protection relay with a current transformer (hereinafter referred as CT) saturation countermeasure element which judges an internal and an external fault in the protective zone, and the other is an output from a discriminating zone protection relay by CT saturation measure, which is set in accordance with all protective regions, which judges the internal and an external faults in all protective regions.
To begin with, a protective region with a fault is judged in the protective zone based on the above outputs, then the tripping output is sent out to protective regions to separate the protective region with fault from the other protective regions without fault.
However, the above mentioned bus-bar protection equipment needs two or more sets of the bus-bar protection relays with CT saturation measurement equipment to protect the bus-bar having a plurality of protective regions.
In connection with it, the structure of the whole equipment becomes complicated, the reliability reduces while the cost increases.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a bus-bar protection relay equipment which simplifies the structure of the bus-bar protection relay equipment.
It is a further object of the present invention to provide a bus-bar protection relay equipment with improved reliability.
It is still a further object of the present invention to provide a simpler and more cost effective bus-bar protection relay equipment.
According to one embodiment of this present invention, a bus-bar protection relay equipment for judging a protective region having a fault, among a protective zone that includes a plurality of protective regions, based on status of a power system, comprises: a first judging unit configured to judge whether an internal fault or an external fault exists in the protective zone by performing a percentage differential protection calculation based on an operating quantity Id and a restrained quantity Ir of the protective zone; a first calculating unit configured to calculate an operating quantity Idi of each protective region, where i is equal to an integer from 1 to n; a second judging unit configured to judge a protective region having the internal fault when an absolute value of a Idi is larger than a coefficient multiplied by an absolute value of a Id; and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit.
A bus-bar protection relay equipment for judging a protective region having a fault, among a protective zone that includes a plurality of protective regions, based on status of a power system, comprises: a first judging unit configured to judge whether an internal fault or an external fault exists in the protective zone by performing a percentage differential protection calculation based on an operating quantity Id and a restrained quantity Ir of the protective zone; a first calculating unit configured to calculate an operating quantity Idi of each protective region, where i is equal to an integer from 1 to n; a second judging unit configured to judge a protective region having the internal fault when a difference between an absolute value of the Idi and an absolute value of the Id is smaller than a coefficient multiplied by an absolute value of the Id; and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge the protective region having the internal fault when following equations are satisfied: (1) an absolute value of the Idi is more than the coefficient multiplied with an absolute value of the Id, (2) a phase difference between a phase of the Idi and a phase of the Id is more than a designated phase of the Idi to satisfy the equation (1); and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge a protective region having the internal fault when following equations are satisfied: (1) an absolute value of the Idi is a coefficient (less than 1) multiplied with an absolute value of the Id; (2) an absolute value of the Idi is a coefficient (more than 1) multiplied with an absolute value of the Id; (3) a phase difference between a phase of the Idi and a phase of the Id is more than designated phase of the Idi to satisfy the equations (1l) and (2); and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge a protective region having the internal fault when following equations are satisfied: an absolute value of the Idi is more than a coefficient (less than 1) multiplied with an absolute value of max {the Id, prescribed value}; and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge a protective region having the internal fault when following equations are satisfied: (1) an absolute value of the Idi is more than a coefficient (less than 1) multiplied with an absolute value of max {the Id, a prescribed value}; (2) a phase difference between a phase of the Idi and a phase of Id is less than a designated phase of the Idi to satisfy the equation (1); and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge a protective region having the internal fault when following equations are satisfied: (1) an absolute value of the Idi is more than a coefficient (less than 1) multiplied with an absolute value of max{the Id, a prescribed value}; (2) an absolute value of the Idi is less than a coefficient multiplied (more than 1) an absolute value of the Id; an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault based on the result of the first judging unit and the second judging unit. Furthermore, the bus-bar protection relay equipment comprises: wherein the second judging unit configured to judge a protective region having the internal fault when following equations are satisfied: (1) an absolute value of the Idi is more than a value which a coefficient (less than 1) multiplied with a sum of an absolute value of the Id and a prescribed value; (2) an absolute value of the Idi is less than a value which a coefficient (more than 1) multiplied with the sum of an absolute value of the Id and a prescribed value; (3) a phase difference between a phase of the Idi and phase of the Id is more than a designated phase among the Idi to satisfy the equations (1) and (2); and an output unit configured to output a signal to separate non-fault protective regions from a protective region with the fault
Hori Masao
Imamura Kuniyasu
Nisida Hirosi
Okazaki Masato
Suga Noriyosi
Foley & Lardner
Kabushiki Kaisha Toshiba
Sherry Michael J.
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