JP2004080894A - Protective system for in-loop system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the laying of a transmission line of an optical fiber or the like, in protecting an in-loop relay based on a current differential relay method. <P>SOLUTION: Terminal units 18 to 21 provided in each consumer position prepare current pattern information, which have the presence of an accident current and an accident current direction detected by a pair of current transformers CT, provided in both ends of an own device, and carrier-transmit the prepared current pattern information through a power line. An external accident and an internal accident incurred at the consumer, and the accident direction are determined by send/receive of the current pattern information. This determination indicates both trips of the pair of circuit breakers, provided in both ends of the each consumer position, the trip of one circuit breaker, accident current passage, and an accident current passage trailing end in the right direction or the left direction. When the determination of the accident current passage indicates that the right side or left side of the own device is located at the current passage trailing end, backup of a main protection is performed by opening the current breaker on the trailing end side after a specified time elapses. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a protection system for a ring system in which a power line from a power substation to a customer position is connected to a ring.
[0002]
[Prior art]
Conventionally, a current differential relay system has been adopted for protection of the ring system, and current information from an instrument current transformer (CT) installed at each customer location away from a power substation is transmitted through an optical fiber or the like. The data is collected at the central unit of the power substation through the road, and the protective relay operation is performed by the central unit.
[0003]
FIG. 10 shows an example of the configuration of a ring system protection device equipped with two terminals. A ring-shaped power line is laid from two power substations 1 and 2 to two customers 3 and 4, and in a ring system for distributing power to the respective customers 3 and 4, a central device 5 provided at the power substation is provided. The customer terminal devices 6 and 7 are communicatively connected by an optical fiber transmission line 8 having a loop configuration.
[0004]
The central unit 5 collects the current detection information of the pair of right and left current transformers (CT) at each customer position through the optical fiber transmission line 8, and further detects the current detection information of the current transformers at the power supply substations 1 and 2. From the pair of left and right current transformers at the customer location, determine whether the customer has an internal accident or an external accident, and in the case of an external accident, determine which power substation caused the accident, and the accident section The protection relay calculation for separating the power failure section from the system by performing the determination of (1) is performed.
[0005]
[Problems to be solved by the invention]
In the conventional protection method, it is necessary to lay a high-speed transmission line with a large information transmission amount, such as an optical fiber transmission line, in order to transmit the detected current information of the current transformer from each customer location to the power substation. There is a problem that it becomes equipment and involves large equipment costs.
[0006]
Furthermore, there is a case where there is no communication transmission facility between the power substation and the customer depending on the plan situation of the facility, and in this case, the protection of the customer section becomes impossible.
[0007]
An object of the present invention is to provide a ring system protection system that solves the above problems.
[0008]
[Means for Solving the Problems]
The present invention focuses on the fact that a power line is always laid to a customer position, and performs carrier wave transmission using a power line for information transmission from a terminal device at each customer position. Since the carrier wave transmission is slower than the optical fiber transmission line, if current information having a very large data amount is transmitted as it is, a delay occurs in protection. Therefore, as the fault current information detected by the current transformer, the presence / absence of fault current corresponding to the difference in fault point and the current pattern information having fault current direction are transmitted and received. And the direction of the accident are determined, and processing such as opening a circuit breaker appropriate for system protection is performed. This current pattern information requires only the presence / absence of a fault current of a pair of current transformers, the direction of the fault current, and the position (or number) of the terminal device. The amount is extremely small, and transmission can be performed at a speed sufficient for protection even by carrier wave transmission. From the above, the present invention has the following features.
[0009]
(1) A ring system protection system in which a power line from a power substation to a customer position is connected to a ring system,
The terminal devices provided at each customer location are:
Means for generating a current pattern information having the presence and absence of a fault current and a fault current direction detected by a pair of current transformers provided at both ends of the own device and transmitting a carrier wave through the power line,
Means for determining the external accident and internal accident of the customer by transmitting and receiving the current pattern information and determining the accident direction,
From the determination, the trip of both the pair of circuit breakers provided at both ends of each customer position, the trip of one circuit breaker, the fault current passing, the fault current passing termination of the adjacent customer on the right or left side of the own device is determined. And a means for obtaining.
[0010]
(2) In the above-mentioned fault current passage determination, when the adjacent customer on the right or left side of the own device obtains the determination of the termination of the passing current, the circuit breaker on the terminal side is opened after a certain period of time to back up the main protection. Means are provided.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram of a ring system and a protection device according to an embodiment of the present invention, which is applied to a distribution system that connects two power supply substations 11 and 12 to four customers 13 to 16 by a ring. This is the case.
[0012]
A central device 17 for system protection based on the current differential relay system is provided at the power substation position, and system protection information is transmitted to each of the customer terminal devices 18 to 21 by carrier wave transmission using power lines.
[0013]
The terminal devices 18 to 21 are based on the presence / absence of a fault current and a fault current direction of a pair of left and right current transformers (CT) at the position of the own customer when a fault occurs, as shown by functional blocks as representative of the terminal device 18. Sequencer 22 that generates a circuit breaker trip signal at the time of generating current pattern information and determining an internal accident, and transmitting the current pattern information from this sequencer 22 to the ring system by carrier wave transmission using a power line and receiving from another terminal device. A carrier transmission / reception unit 23 and a circuit breaker trip unit 24 that performs open control of one of a pair of circuit breakers at the customer's position, open control of both, or no control by a trip signal from the sequencer 22 are provided.
[0014]
FIG. 2 shows the difference in the current direction (current pattern) of the pair of left and right current transformers depending on the accident situation at each customer position. (A) to (c) of the figure show the direction of the fault current at the time of a customer internal fault. In (a), when a power source is present at both ends and an internal fault occurs, it is detected by a pair of right and left current transformers. The current direction (the current direction flowing through the circuit breakers O1 and O2 at both ends) is the customer bus direction (inward). In (b), when the power supply is on the left side of the drawing and an internal fault occurs, an inward fault current is detected in one of the current transformers (the circuit breaker O2 side), and the other current transformer has a fault. No current flows. In (c), when an internal fault occurs when there is a power supply on the right side of the drawing, an inward fault current is detected in one of the current transformers (the circuit breaker O1 side), and the fault is detected in the other current transformers. No current flows. 2 (d) and 2 (e) show the direction of the fault current at the time of a customer external fault. In FIG. 2 (d), the current directions of a pair of current transformers when the fault occurs on the left side of the drawing are shown. Both are on the left side, and in (e), the current directions of the pair of current transformers are both on the right side when an accident occurs on the right side in the drawing. One of these current directions is inward with respect to the customer bus, and the other is outward with respect to the customer bus.
[0015]
Each of the current pattern information shown in FIG. 2 is determined and generated from the detected current direction of the current transformer and the power supply configuration in each terminal device, and each terminal device determines the current pattern information generated by its own terminal device and the left and right current pattern information. The internal circuit determines the internal fault and the external fault and the direction of the fault from the current pattern information transmitted by the carrier from another terminal device installed in the terminal device, and determines the circuit breaker (CB) to be opened. Hereinafter, the protection sequence processing will be specifically described.
[0016]
First, FIG. 3 shows an example of a pattern name for distinguishing a difference in a current pattern. Patterns A, B, and C are for a customer internal accident, pattern D is an accident at a power substation, and pattern R , L are at the time of an external accident of the customer, and there are six types of current patterns in total.
[0017]
FIG. 4 shows an example of transmission of a current pattern in the case of a system line fault. (A) of FIG. 1 and No. No. 2 shows a case where a line accident occurred between the customers. The terminal device of No. 1 transmits the pattern R by carrier wave transmission, and The second terminal device transmits the pattern L. By transmitting and receiving these pattern information to each other, the No. The sequencer of the terminal device on the first side opens the circuit breaker on the O1 side. The sequencer of the two-side terminal device can disconnect the accident section from the system by opening the O2-side circuit breaker.
[0018]
FIG. 4B shows a case of a line fault in a single-ended power supply configuration. The terminal device of No. 1 transmits the pattern R, and The terminal device 2 does not transmit a pattern because no fault current flows. From these pattern information, No. The sequencer of the terminal device on the side 1 is set to the fault current passing terminal R, and the circuit breaker No. 1 is opened by opening the circuit breaker on the O1 side. The accident section including the two sides can be separated from the system.
[0019]
FIG. 5 shows a transmission example of a current pattern in the case of a customer bus accident. (A) of FIG. No. 1 shows a case where an accident occurred on the customer bus. The terminal device of No. 1 transmits pattern A, and The second terminal device transmits the pattern L. By transmitting and receiving these pattern information to each other, the No. The sequencer of the first terminal device opens both the O1 and O2 circuit breakers and disconnects them from the system. No. The sequencer of the two-side terminal determines the transition to the single-ended power supply without opening the circuit breaker.
[0020]
FIG. 5B shows a single-ended power supply configuration. No. 1 shows a case where an accident occurred on the customer bus. The terminal device of No. 1 transmits the pattern B, and The terminal device 2 does not transmit a pattern because no fault current flows. From these pattern information, No. The sequencer of the terminal device on the side 1 is set to the fault current passing terminal L and the circuit breaker No. 2 is opened by opening the circuit breaker on the O2 side. The accident section including the two sides can be separated from the system.
[0021]
As described above, in the case of a customer bus accident, the system can be disconnected from the system by opening one of the pair of circuit breakers at both ends of the bus. However, a blind spot failure as shown in FIG. 6 (a failure of the customer circuit breaker) In this case, it is preferable to open both circuit breakers.
[0022]
FIG. 7 shows a sequence logical configuration of the sequencer 22 of the terminal device. The determination J ₁ through J ₅ based on a pair of fault detection current status of the current transformer of the apparatus, on-delay, the determination continues a continuation operation due to the off-delay T, the current pattern A, B, C, One of L and R is transmitted by a carrier wave. Also generates a trip signal of its own both breaker O1, O2 in a logical G ₁ is either in the determination of the pattern A~C become consumers bus accident.
[0023]
The determination condition of the pattern L, a pattern A from the neighboring device of the breaker O1 side by the reception judgment J ₆ of (B, C as well), a combination inconceivable from NG (accident modal a logical G _2, G ₃ And it is regarded as some kind of device abnormality). Further, the reception determination J ₇ of pattern A from an adjacent device breaker O2 side (B, C as well), for generating a trip signal from the O2 side breaker of the self apparatus in a logical G _4, G _5.
[0024]
In similar manner, the reception determination J ₈ through J ₁₃ of the pattern L, R, D, determination of the trip or fault current passage end L of O1 side circuit breaker to obtain a determination of the fault current passes. For example, the device itself determines the pattern L obtained, logic G in the case of the reception determination J ₉ is no pattern L from the adjacent device reception determination J ₈ and O2 side of the pattern L from O1 side of the neighboring device ₆ . G ₇ determines that the adjacent device on the left side is the fault current passage termination L. In addition, a determination of the pattern L is obtained in the own device, and the reception determination J ₈ of the pattern L from the adjacent device on the O1 side, the reception determination J ₉ of the pattern L from the adjacent device on the O2 side, or the adjacent device on the O1 side. If the reception determination J ₁₂ pattern D from determines that the fault current passes.
[0025]
These processes are the same although there is a difference in the circuit breaker to be tripped on the O1 side and the determination on the end R side even in the determination state of the pattern R.
[0026]
Here, the determination of the passage of the fault current in the own device is obtained, and in the case where the fault current also passes through the adjacent customers on either the left or right side, basically, the own device expects the device operation at both ends of the fault section, Nothing is performed as the sequence processing. However, if the information from the other party is erroneous or interrupted for some reason, the main protection is deactivated and the protection is provided afterwards, resulting in a power outage of the entire system. To cope with this inconvenience, when it is determined that the own device is located at the passing current terminals R and L, the main protection is backed up by opening the circuit breaker at the terminal side after a certain period of time.
[0027]
This example will be described with reference to FIGS. FIG. 8 shows a case where the partner device is unresponsive in a track accident. When an accident occurs on the line between the terminal device of No. 1 and the central device and the central device does not respond and no pattern signal comes, One device cannot determine whether the passing current stops on the left side of the own device or passes through the adjacent device and goes to the left side device.
[0028]
Therefore, as shown in FIG. 9, the main part of the additional backup sequence logic, in the configuration of FIG. When one terminal device determines its own pattern L, it receives the O1-side adjacent device pattern L (or pattern D) according to the logic of FIG. Judge as the end.
[0029]
Here, in FIG. 9, if at the end, the O2 side adjacent device pattern R should be received within a certain time period at the time of an accident, but if the pattern R is not received after the certain time period, some trouble occurs. Therefore, the logic of tripping the O2 circuit breaker of the own device is assumed, and the entire power failure is prevented. Similarly, in the case of the determination of the own device pattern R, the own device O1 side circuit breaker is tripped.
[0030]
【The invention's effect】
As described above, according to the present invention, the terminal device at each customer position transmits / receives current pattern information having presence / absence of fault current and fault current direction detected by a pair of current transformers to / from each other by carrier wave transmission using a power line. From this current pattern information, each terminal device determines external and internal accidents and the direction of the accident, and performs processing such as opening a circuit breaker appropriate for system protection. This eliminates the need for an optical fiber transmission line for transmitting the signal, thereby achieving a simple and low-cost operation, and a high-speed protection operation.
[0031]
In addition, even when there is no communication transmission equipment between the power substation and the customer, the customer section can be protected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a ring system and a protection device according to an embodiment of the present invention.
FIG. 2 is an example of a direction (current pattern) of a fault current in the embodiment.
FIG. 3 is an example of names of current patterns in the embodiment.
FIG. 4 is an example of a line fault and pattern transmission in the embodiment.
FIG. 5 is an example of a customer bus accident and pattern transmission in the embodiment.
FIG. 6 is an example of blind spot failure and pattern transmission in the embodiment.
FIG. 7 shows an example of a sequence logical configuration in the embodiment.
FIG. 8 is a diagram illustrating an example of a case where a partner device is unresponsive in a track accident according to the embodiment.
FIG. 9 is a main configuration of a backup sequence logic in the embodiment.
FIG. 10 is a configuration example of a ring system (a case corresponding to two terminals).
[Explanation of symbols]
11, 12 Power supply substations 13 to 16 Customer 17 Central device 18 to 21 Terminal device 22 Sequencer 23 Carrier transmitting / receiving unit 24 Circuit breaker trip unit No. 1, No. 2. Terminal device

Claims (2)

A protection system for a ring system in which a power line from a power substation to a customer position is connected to a ring system,
The terminal devices provided at each customer location are:
Means for generating a current pattern information having the presence and absence of a fault current and a fault current direction detected by a pair of current transformers provided at both ends of the own device and transmitting a carrier wave through the power line,
Means for determining the external accident and internal accident of the customer by transmitting and receiving the current pattern information and determining the accident direction,
From the determination, the trip of both the pair of circuit breakers provided at both ends of each customer position, the trip of one circuit breaker, the fault current passing, the fault current passing termination of the adjacent customer on the right or left side of the own device is determined. A ring system protection method characterized by comprising means for obtaining. In the accident current passage judgment, when the adjacent customer on the right side or left side of the own device has obtained the judgment of the end of the passing current, after a certain period of time, there is provided a means for opening the circuit breaker on the end side to back up the main protection. The protection system for a ring system according to claim 1, wherein:

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