Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-10-29
2004-02-17
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C700S022000
Reexamination Certificate
active
06694271
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
The present invention relates to distribution systems (such as electrical power distribution systems), more particularly to methods and apparatuses for identifying or isolating faults (such as electrical faults) pertaining to such systems.
Electrical power distribution systems, such as found in the electrical utility industry and aboard U.S. Naval ships, are subject to developing faults (e.g., failures and defects). The isolation and identification of massive electrical faults serves to minimize the adverse consequences thereof, both electrically and environmentally. For instance, electrical faults can result in burning electrical components which tend to release noxious fumes. Also, electrical faults can create large disturbances in generator fuel efficiencies, leading to incomplete combustion and the concomitant release of hydrocarbons and carbon monoxide into the atmosphere; such happenstance would be especially dire in a shipboard or similarly self-contained environment.
In military contexts, it may be desirable to quickly identify and isolate electrical faults due to combat-induced damage, thus allowing for prolonged operation of combat and other critical shipboard electrical systems. Further, the loss of critical electrical systems may translate to a loss of mission capability of a Navy ship; indeed, the cost of mission failure is potentially incalculable. In civilian contexts, it may be desirable to ensure the continuity of power to vital public facilities and interests such as hospitals, police stations and utilities, especially under exigent circumstances such as when an electrical power system is confronted with natural or other disasters.
Notable is the electrical fault protection technology previously implemented aboard U.S. Naval ships. In the past, the U.S. Navy developed an autonomous coordination logic and incorporated this logic in the “Multi-Function Monitor I” (“MFM I”). This coordination logic was necessary to allow selective coordination among the main distribution circuit breakers in the “AC Zonal Electric Distribution System” (“AC ZEDS”), regardless of plant configuration.
The MFM I unit is an autonomous device that imports line-to-line voltages and line currents, calculates fault current levels and directions, and sends a shunt trip signal to an adjacent circuit breaker if overcurrent thresholds are exceeded for a given time delay. Two time delays are incorporated in the MFM I logic, viz., one for reverse over-currents and another for forward over-currents. Since the shunt trip logic of the MFM I is autonomous, the shunt trip time delays are set to allow selective coordination among other distribution circuit breakers such as the 1600-frame AQB-type switchboard circuit breakers. Selective coordination must also be achieved in a variety of plant configurations, including split plant, single ring and double ring configurations. Consequently, the shunt trip time delays are set at 95 ms for reverse over-currents and 400 ms for forward over-currents. Additionally, the ACB-type breakers may take as long as 55 ms to open once shunt tripped, extending total shunt trip times to 150 ms and 455 ms. Several combinations of shunt trips may be necessary for the isolation of a bus-tie fault, and total fault isolation times vary from 175 ms to over 650 ms.
While the MFM I logic provides selective coordination among the AC ZEDS ACB circuit breakers, the fault isolation times required for autonomous selective coordination are too great for certain purposes; in particular, these fault isolation times are not conducive to maintaining critical combat equipment on-line, thereby allowing fight-through during combat casualty situations.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to enable expeditious identification and isolation of electrical failures in electrical power distribution systems.
It is a further object of the present invention to enable same so as to maintain the operational condition of such systems, especially when such systems are essential or critical in nature.
It is another object of the present invention to provide method, apparatus, computer, computer memory and computer program product for effecting the foregoing and other objects of the present invention.
Typical apparatus embodiments of the present invention are intended for use in association with an electrical distribution system having a plurality of circuit breakers. The inventive apparatus comprises a plurality of devices, and further comprises networking means for the devices. Each device includes an electrical sensor and a computer. Each device is paired with a corresponding circuit breaker. Each computer is capable of: (a) receiving sensory information from the corresponding electrical sensor, wherein the sensory information pertains to at least one location proximate the corresponding circuit breaker; (b) processing the corresponding sensory information into processed electrical current direction information; and, (c) receiving the corresponding processed current direction information which is generated by the remaining devices. Usually, the sensory information which is received by a computer from the computer's corresponding electrical sensor (i.e., from the electrical sensor included in the same device) pertains to at least two locations proximate the device's corresponding circuit breaker (i.e., proximate the circuit breaker with which the device is paired), wherein at least two such locations are on opposite sides of the corresponding circuit breaker. Frequently according to inventive practice, each device's computer has a memory and includes an embodiment of the present invention's software which resides in the memory; usually, each device's computer is individually equipped with identical or similar inventive software.
According to typical embodiments of this invention, the inventive apparatus is further capable of processing the cumulative processed electrical current direction information (i.e., the sum total of the device's own processed electrical current direction information together with all of the electrical current direction information respectively processed by the other networked devices) into processed fault identification information. Moreover, according to many inventive apparatus embodiments, the device's computer is further capable of regulating (controlling) the corresponding circuit breaker, based on the fault identification information. Furthermore, the devices of the inventive apparatus are preferably networked in a “self-corrective” fashion. For example, the present invention's networking means will typically include a plurality of network links, wherein each network link connects two inventive devices. Upon failure of any network link, each computer is capable of circumventing the failure so as to nevertheless effectuate the receiving of the corresponding processed current direction information which is generated by the remaining devices.
Some inventive embodiments provide computer means having a memory and including a computer program product (e.g., computer software) resident in the memory, while other inventive embodiments provide a memory having a computer program product resident therein, while still other inventive embodiments provide a computer program product which is capable of being resident in a memory or a memory of a computer means. According to usual inventive practice, the same or similar computer program product is resident in the memory of each of plural computer means. Generally in inventive practice, the computer program product comprises a computer useable medium having computer program logic recorded thereon for enabling a plurality of computer means to identify and to choose to isolate a state of def
Hoff Marc S.
Kaiser Howard
Raymond Edward
The United States of America as represented by the Secretary of
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