Data processing: generic control systems or specific application – Specific application – apparatus or process – Electrical power generation or distribution system
Reexamination Certificate
2000-11-13
2004-05-25
Voeltz, Emanuel Todd (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Electrical power generation or distribution system
C700S293000, C700S297000, C700S021000, C700S022000, C700S306000, C700S020000, C702S059000, C702S187000
Reexamination Certificate
active
06741916
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an accident point locating system comprising, in combination, a digital protective control system that receives state quantities indicating a state of an electric power system, converts the state quantities into corresponding data and carries out the protective control of the electric power system, and a display system that carries out displaying and controlling operations to monitor the operation and state of the digital protective control system through a communication network.
2. Description of the Related Art
Digital protective control systems are used prevalently in the field of electric power systems. The functions of digital protective control systems have been advanced in recent years by the employment of high-performance microprocessors and large-capacity memories. More concretely, digital protective control systems include protective relay systems that detect accidents in electric power systems, accident point locating systems that locate accident point in electric power systems, and system stabilizing systems that stabilizes electric power systems. The digital protective control systems are applied prevalently to the operation of electric power systems.
A conventional digital protective control system will be described. Referring to
FIG. 9
, a digital protective control system
1
includes an A/D conversion unit
2
, a digital processing unit
3
, an I/O interface
4
connected to an external device, such as a circuit breaker, and a bus
5
. Those components are interconnected by the bus
5
.
The A/D conversion unit
2
includes analog filters
6
-
1
to
6
-n, sample-and-hold circuits
7
-
1
to
7
-n, a multiplxer
8
and an A/D converter
9
. The A/D conversion unit
2
receives n pieces of analog information A-
1
to A-n representing state data on the state of an electric power system to be protected and controlled, such as current and voltage, samples the n pieces of analog information A-
1
to A-n at predetermined sampling intervals, holds sampled analog state data and converts the analog state data into corresponding digital state data.
The digital processing unit
3
includes a CPU
10
, a RAM
11
, a ROM
12
, and an EEPROM (electrically erasable programmable read-only memory)
13
. The digital state data is transferred sequentially to the RAM
11
. The CPU
10
carries out various protective operations including a relay operation by using the digital state data stored in the RAM
11
and set values for a protection relay stored in the EEPROM
13
according to programs stored in the ROM
12
.
The I/O interface
4
receives information about external controllers including information about a circuit breaker and gives output signals including a signal requesting the operation of the protection relay, a reset signal and a trip command to external devices. The display
14
is a human interface that displays the state and operating condition of the digital protective control system.
An accident point locating system uses an accident point locating algorithm for calculating the distance between a control station and an accident point by using data provided by the A/D conversion unit in the ROM
10
and gives data on the distance between the control station and the accident point to the display
14
. Practically used accident point locating algorithms include those of an impedance calculating system that use only data available from the own control station, and those of a positive-phase loop locating system that uses electrical quantity data available from the own control station and those available through special transmission lines from other control stations. A concrete algorithm transmission line system for locating operations is described in, for example, Japanese Pat. Application No. Hei 7-64729 (JP-A No. Hei 8-233895) made by the applicant of the present patent application.
The social importance of the electric power system has increased in recent years. The electric power system requires considerable labor for maintenance and operation. For instance, when an accident occurs in a power transmission line, an accident point where the accident occurred must be located and the condition of equipment relating to the accident point must be quickly confirmed. An accident point locating system is used for calculating the distance between the relevant control station and the accident point on the basis of electric quantity data at the moment the accident occurred to reduce labor for maintenance and operation. However, the conventional accident point locating system composed of hardware equivalent to a digital protective control system is expensive. Since the display for displaying the results of accident point locating operations is able to display limited information, such as the distance between the control station and the accident point and a phase in which the accident occurred. Consequently, the output of the accident point locating system must be checked against a power transmission system map showing the layout of power transmission lines to locate the accident point.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to reduce special hardware and to reduce the cost by carrying out accident point locating operations by an display operating apparatus, such as a personal computer. A second object of the present invention is to provide a highly reliable accident point locating system capable of automatically indicating an accident point on a map by checking the results of accident point locating operations against geographic map information and power transmission line map information, of reducing load on operation and maintenance personnel and of being easily operated.
To achieve the object, according to a first aspect of the present invention, an accident point locating system is provided, which includes: a plurality of digital protective controllers that receive state data representing a state of an electric power system, convert the state data into corresponding digital state data and execute an electric power system protecting control, each of the digital protective controllers having an absolute time acquiring means for acquiring an absolute time, an A/D converting means for sampling the state data at a predetermined sampling period at absolute times acquired by the absolute time acquiring means and converting the sampled state data into corresponding digital state data, a state data processing means for deciding whether any malfunction occurred in equipment to be protected on the basis of the digital state data provided by the A/D converting means, a state decision means for executing a malfunction decision function other than the malfunction decision function of the state data processing means on the basis of the digital state data provided by the A/D converting means to decide whether or not any malfunction occurred in the equipment to be protected and in the vicinity of the equipment, a recording means for adding absolute sampling time to the digital state data provided by the A/D converting means and recording the digital state data with the absolute time when the state decision means decides that a malfunction occurred in the equipment to be controlled and protected or in the vicinity of the equipment, and a digital data sending means for reading the digital state data with the absolute time from the recording means and providing the same on a communication network; and a display operating system that is connected to the plurality of digital protective controllers by the communication network and executes displaying operations to monitor the operation and condition of the digital protective controllers, the display operating system having a digital state data receiving means connected to the communication network to receive a plurality of digital state data with the absolute time through the communication network, distance calculating means for calculating the distance between the control station and an accident point by using the
Sekiguchi Katsuhiko
Shirota Yoshihiro
Barnes Crystal J
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Todd Voeltz Emanuel
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