JPH04322119A - Digital current differential protective relay - Google Patents

Abstract

PURPOSE:To detect so-called blind point fault, occurring between current transformers and disconnectors at each terminal of a multi-terminal transmission line having a pi branch, positively. CONSTITUTION:Digital current differential relays 11, 21, 31 are provided for each terminal of a multi-terminal transmission line including pi branch terminals. The current differential relay takes in current value information and open/close information of disconnector at its terminal. The information is then transmitted/ received mutually and decision is made between fault section and interrupted section based on the current value information and open/close information of disconnector at all terminals thus protecting a system. The current differential relay 31 corresponding to the pi branch terminal is provided with a transmission selecting means 51 for transmitting current value information only of the closed one of the disconnectors 33A, 33B. The current differential relays 11, 21, 31 corresponding to respective terminals are provided with reception processing means 52 for processing the open circuit command of circuit breaker at its terminal while considering that there is no current value information at the other terminal of an opened circuit breaker being inserted.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is provided for each terminal of a multi-terminal power transmission line including π-type branch terminals, and transmits current value information and disconnector opening/closing information between these current differential relay devices. This invention relates to a digital current differential protection relay device that transmits and receives signals to protect the system.

0002

2. Description of the Related Art A conventional protection relay device of this type applied to a three-terminal power transmission line with a π-shaped branch is shown in FIG.

In the figure, in a three-terminal power transmission line consisting of an A terminal, a B terminal, and a C terminal, the C terminal has a π-shaped branch configuration. Of these, a disconnector 13 and a circuit breaker 15 are connected in series to the A terminal, and a disconnector 23 is connected to the B terminal.
and a circuit breaker 25 are connected in series. On the other hand, the C terminal has a disconnector 33A on the A end side and a disconnector 33B on the B end side.
A transformer 36 and a circuit breaker 35 are connected in series at the mutual junction point. In addition, digital current differential relay devices 11 and 21 are provided corresponding to the A terminal, B terminal, and C terminal.
, 31 are provided.

Here, the A terminal current differential relay device 11
The secondary circuit current of the current transformer 10 that detects the current passing through the disconnector 13 is introduced into the auxiliary contact (
(not shown) is captured. Similarly, the secondary circuit current of the current transformer 20 that detects the current passing through the disconnector 23 is introduced into the current differential relay device 21 of the B terminal, and the auxiliary contact (not shown) of the disconnector 23 is introduced. Opening/closing information is imported. Furthermore, the secondary circuit currents of current transformers 30A and 30B that detect the current passing through the disconnectors 33A and 33B are introduced into the current differential relay device 31 of the C terminal, and the
Each opening/closing information is captured by an auxiliary contact (not shown).

Further, the current differential relay devices 11, 21 and 31 mutually transmit and receive current value information and disconnector opening/closing information via communication devices 12, 22 and 32, respectively. Then, based on the current value information of all the terminals and the opening/closing information of the disconnector, the fault section and the cut-off section are determined between all the terminals, and based on the result of this discrimination, the circuit breaker 15 at the own end is
, 25, 35 are opened.

[0006] In this case, as a specific method for determining the fault section and the cut-off section, each current transformer 10, 20, 30
The secondary circuit currents of A and 30B are respectively I10 and I2
0, I30A, I30B, follow the calculations in the table below.

[0007]

[Table 1] On the other hand, there is currently no protective relay device applicable to transmission lines with 4 or more terminals that have π-type branches.
The configuration shown in FIG. 6 can be considered as a configuration that can be applied to a terminal power transmission line. Here, the C terminal and the D terminal are π-shaped branches.

[0008] At the D terminal, a transformer 46 and a circuit breaker 45 are connected in series at the mutual junction of the A-end side disconnector 43A and the B-end side disconnector 43B. Further, secondary circuit currents of current transformers 40A and 40B that detect the currents flowing through the disconnectors 43A and 43B are introduced into the current differential relay device 41 provided corresponding to the D terminal, and Each opening/closing information is captured by auxiliary contacts 43A and 43B (not shown). Furthermore, the current differential relay device 41 transmits and receives current value information and disconnector opening/closing information to and from other current differential relay devices via the communication device 42, and similarly to other current differential relay devices, it transmits and receives current value information and disconnector opening/closing information. Determine the cutoff section.

[0009]

[Problems to be Solved by the Invention] In each of the above-mentioned protective relay devices, depending on the opening/closing conditions of the disconnector, each terminal
Although it is possible to determine the so-called fault section, which is inside or outside the protection system, there is a problem in that it is not possible to determine the so-called cut-off section, which is necessary to determine which terminals the fault is occurring between and to perform appropriate shutoff. be. This will be explained below using FIG. 5.

In FIG. 5, it is assumed that the disconnector 33A is in an open state. In this state, if a fault occurs at the point f1 between the current transformer 10 and the current transformer 30A, a fault current will flow from the A terminal to the fault point f1. Therefore, a current corresponding to this fault current flows through the secondary circuit of the current transformer 10, and this current is introduced into the current differential relay device 11. Also,
The current transformer 20 at the B terminal and the current transformer 30B at the C terminal are:
By opening the respective disconnectors 33A, normal secondary circuit current is introduced into the current differential relay device 21 and the current differential relay device 31 without being affected by the accident. On the other hand, due to the disconnection of the disconnector 33A, no current flows into the current transformer 30A at the C terminal from the C terminal, and the secondary circuit current also becomes zero.

Based on the above information, the current differential relay device 1
1, 21, and 31 are determined to be an accident between the A terminal and the C terminal, and among these, the current differential relay device 11 of the A terminal outputs an opening command to open the circuit breaker 15. However, since the current differential relay device 21 of the B terminal and the current differential relay device 31 of the C terminal do not output the circuit breaker opening command, both the circuit breaker 25 and the circuit breaker 35 maintain a closed state. Note that even if an accident occurs at the point f2 between the current transformer 20 and the current transformer 30B, the fault section and cut-off section are determined in the same manner.

However, when the disconnector 33A is in an open state, f3 between the current transformer 30A and the disconnector 33A
If an accident occurs at this point, the current differential relay device malfunctions, unlike the operation described above. That is, f3
If an accident occurs at point f3, the current flowing from the A terminal to point f3 is detected by the current transformer 10, and the secondary circuit current is introduced into the current differential relay device 11. C terminal current transformer 3
0A also detects this fault current and introduces the secondary circuit current into the current differential relay device 31. At this time, the current differential relay device 31 processes this current as an increased current in the secondary circuit of the current transformer 30B because of the condition that the disconnector 33A is in an open state. On the other hand, the current transformer 20 at the B terminal is not affected by the accident because the disconnector 33A is open.

Based on the above information, the current differential relay device 1
1 outputs an opening command to the circuit breaker 15 to open the circuit breaker 15. Furthermore, under the condition that the disconnector 33A is open, the current values flowing through the current transformer 20 and the current transformer 30B are different, so it is determined that a section fault has occurred, and the current differential relay device 31 is also connected to the circuit breaker 35. The circuit breaker 35 is opened by outputting an opening command to the circuit breaker 35 . That is, even though the C terminal is not affected by the accident and can supply power normally, the circuit breaker 35 malfunctions.

This means that current transformer 10 and disconnector 13
The same applies when an accident occurs between the current transformer 20 and the disconnector 23, or between the current transformer 30B and the disconnector 33B. Hereinafter, this accident will be referred to as a blind spot accident.

However, in the conventional protection relay device shown in FIG. 5, it is impossible to determine the cutoff section in case of a blind spot accident, and the protection corresponding to the 4-terminal π-type branch power transmission line shown in FIG. Exactly the same situation occurred in relay devices.

The present invention has been made to solve the above problems, and even if an accident occurs between the current transformer and the disconnector of each terminal, the disconnection section can be reliably determined. The purpose is to obtain a protective relay device.

[0017]

[Means for Solving the Problems] The present invention provides a digital current differential relay device corresponding to each terminal of a multi-terminal power transmission line including π-type branch terminals, and each of the current differential relay devices In addition to capturing the current value information of the own end and the opening/closing information of the disconnector, this information is mutually sent and received,
Further, in the protective relay device that protects the system by determining a fault section and a cutoff section based on current value information of all terminals and opening/closing information of disconnectors, the The current differential relay device includes a transmission selection means for transmitting only the current value information on the side where the disconnector is closed out of the two sets of current value information, and the current differential relay device is provided with the current differential relay device provided corresponding to each terminal. The relay device includes a reception processing means that outputs a command to open the circuit breaker of its own terminal on the assumption that there is no information on the current value of the other terminal in which the interposed disconnector is open.

[0018]

[Operation] In this invention, the current differential relay device provided corresponding to the π-type branch terminal transmits only current value information on the side where the disconnector is closed, and is provided corresponding to each terminal. A current differential relay device outputs a command to open the circuit breaker of its own terminal, assuming that there is no information on the current value of other open terminals in which the disconnector is installed. It is also possible to determine the cut-off section in the event of an accident.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention together with its application target. In the same figure, Figure 5
Items with the same reference numerals indicate the same elements. Here, a detailed configuration of the current differential relay device 31 is shown, and a new function is added thereto.

That is, the current differential relay device 31 includes input converters 1 and 2, filters 3A and 3B, and A-D converter 4.
A, 4B, a digital arithmetic processing section 5, and an optical interface 6. A secondary circuit of a current transformer 30A is connected to the primary side of the input converter 1, and the secondary circuit of the input converter 1 is connected to the input end of the A-D converter 4A via a filter 3A. There is. In addition, input converter 2
A secondary circuit of a current transformer 30B is connected to the primary side of the input converter 2, and the secondary side of the input converter 2 is connected to the input end of an AD converter 4B via a filter 3B. A-D converter 4A
, 4B are connected to a digital arithmetic processing section 5 and an optical interface 6. Also connected to the digital arithmetic processing unit 5 are disconnector auxiliary contacts 34A and 34B that detect the states of the disconnectors 33A and 33B, respectively. On the other hand, the digital arithmetic processing unit 5 has a transmission selection means 51 that transmits only the current value information of the side where the disconnector is closed, and a transmission selection means 51 that transmits only the current value information of the side where the disconnector is connected, and the transmission selection means 51 that transmits the current value information of the other terminal where the interposed disconnector is open. A reception processing means 52 is provided for outputting an opening command for the circuit breaker of its own terminal. In addition,
The transmission selection means 51 is provided only in the current differential relay device provided corresponding to the π-type branch terminal, and the reception processing means 52
are provided in current differential relay devices provided corresponding to each terminal.

The operation of this embodiment configured as described above will be explained below.

First, the current transformer 3 at the C terminal of the π-type branch
The secondary circuit current of 0 A is converted by the input converter 1 into a voltage suitable for processing. The output of this input converter 1 is
After the harmonic components are removed by filter 3A, A-
The signal is digitized by the D converter 4A and applied to the digital processing section 5 and the optical interface 6. Similarly, the secondary circuit current of current transformer 30B is converted by input converter 2 to a voltage suitable for processing. The output of this input converter 2 has harmonic components removed by a filter 3B, and then is digitized by an AD converter 4B and applied to a digital arithmetic processing section 5 and an optical interface 6.

Further, in order to determine the cutoff section, a disconnector auxiliary contact 34 is provided which responds to the opening and closing of the disconnectors 33A and 33B.
The opening/closing information of A and 34B is also taken into the digital arithmetic processing section 5.

Here, the digital arithmetic processing unit 5 transmits the opening/closing information of the disconnector and the current value information of the line where the disconnector is closed to the current differential relay device at the other end, and receive similar information from the current differential relay device.

Next, the current differential relay device 31 discriminates between a fault section and a cutoff section based on the current value information of all terminals and the disconnector opening/closing information, and transmits the discrimination result to the current differential relay device at the other end. At the same time, a similar determination result is received from the current differential relay device at the other end.

Of the two sets of current value information from the current transformers 30A and 30B, the transmission selection means 51 constituting the digital arithmetic processing section 5 transmits only the current value information on the side where the disconnector is closed to the other end. Send. In addition, the reception processing means 52
The interposed disconnector outputs a command to open the circuit breaker of its own terminal without information on the current value of other terminals that are open.

FIG. 2 is a flowchart showing an example of the processing procedure of the digital arithmetic processing unit 5 corresponding to the transmission selection means 51. In this case, in step (hereinafter abbreviated as S) 10, it is determined whether or not the disconnector 33A is closed, and if it is closed, it is determined in step S11 whether or not the disconnector 33B is closed. do. And disconnector 33B
If the current transformer 30A is not closed, the secondary circuit current information of the current transformer 30A is transmitted in S12. If the disconnector 33B is also closed, information on the sum of the secondary circuit currents of both the disconnectors 33A and 33B is transmitted in S13. On the other hand, S10
Even if it is determined that the disconnector 33B is not closed, it is determined in S11 whether the disconnector 33B is closed. If the disconnector 33B is closed, S
14, only the secondary circuit current information of the current transformer 30B is transmitted. Also, if the disconnector 33B is not closed, S1
In step 5, the current is set to zero and the information is transmitted.

FIG. 3 shows an example of the processing procedure of the digital arithmetic processing unit corresponding to the reception processing means 52, and particularly shows a case where the current differential relay device 11 receives current value information of the C terminal. Here, in S20, it is determined whether the disconnector 33A is closed, and if it is closed, in S21, it is determined that the current information of the C terminal is introduced, and output processing is executed to open the circuit breaker at its own end, and When the circuit is not closed, C is set in S22.
Executes output processing of the opening command for the circuit breaker at its own end without introducing terminal current value information.

FIG. 4 shows an example of the processing procedure of the digital arithmetic processing section corresponding to the reception processing means 52, and particularly shows a case where the current differential relay device 11 receives current value information of the B terminal. That is, it is determined in S30 whether or not the disconnector 33A is closed, and if it is closed, the disconnector 33A is closed in S31.
Determine whether B is closed or not, and if it is closed, S
At step 32, it is determined that the current value information of the B terminal has been introduced. If either one of the disconnectors 33A and 33B is not closed, processing is performed in S33 on the assumption that there is no current value information from the B terminal. This is a disconnector 33A interposed between the terminal A and the B terminal.
, 33B is open, it is treated as if there is no current value information of the B terminal.

[0030] Through the above processing, for example, the disconnector 33A
If an accident occurs at point f3 in FIG. 5 under the condition that is open, the current differential relay device 11 will not introduce current value information to both the C terminal and B terminal information. As a result, output processing of an opening command for the circuit breaker at the own end is performed, so accidents that could not be determined as blind spot accidents in the past can be reliably detected.

[0031] Although the above embodiment has been described as being applied to a three-terminal power transmission line that includes only one π-type branch, the present invention is not limited thereto;
It is clear that the present invention can also be applied to multi-terminal power transmission lines containing two or more shaped terminals.

[0032]

[Effects of the Invention] As is clear from the above description, according to the present invention, the current differential relay device provided corresponding to the π-type branch terminal only transmits current value information on the side where the disconnector is closed. The current differential relay device provided corresponding to each terminal outputs a command to open the circuit breaker of its own terminal without information on the current value of other terminals that are open. Therefore, even if an accident occurs between the current transformer and the disconnector of each terminal, the disconnection section can be reliably determined.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention together with its application target.

FIG. 2 is a flowchart showing the processing procedure of main elements of an embodiment of the present invention.

FIG. 3 is a flowchart showing the processing procedure of main elements of an embodiment of the present invention.

FIG. 4 is a flowchart showing the processing procedure of main elements of an embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of a conventional protection relay device together with its application target.

FIG. 6 is a block diagram showing the configuration of another conventional protection relay device together with its application target.

[Explanation of symbols]

5 Digital calculation processing section 10 Current transformer 11 Current differential relay device 13 Disconnector 15　Breaker 20 Current transformer 21 Current differential relay device 23 Disconnector 25　Breaker 30A current transformer 20B Current transformer 31 Current differential relay device 33A Disconnector 33B Disconnector 35 Breaker 51 Transmission selection means 52 Reception processing means

Claims (1)

[Claims] Claim 1: Provided at each terminal of a multi-terminal power transmission line including a π-type branch terminal, each terminal receives current value information and disconnector opening/closing information, and transmits and receives this information to and from each terminal. In a digital current differential protection relay device that operates by distinguishing between a fault section and a cut-off section based on current value information and disconnecting switch information, the disconnecting switch is closed among the two sets of current value information. a transmission selection means for transmitting only the current value information of the terminal, and a reception processing means for outputting a command to open the circuit breaker of the own terminal assuming that there is no current value information of the other terminal in which the interposed disconnector is open. A digital current differential protection relay device comprising: