JP2009005565A - Distribution line accident zone selecting and blocking device and distribution line accident zone selecting and blocking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a distribution line accident zone selecting and blocking device for selectively blocking a distribution line accident zone which enables the discrimination of an earth fault accident zone and blocking only the accident zone without measuring both a zero-phase current and a zero-phase voltage in each zone of a distribution line, and accordingly for reducing measuring cost, and a distribution line accident zone selecting and blocking method. <P>SOLUTION: The distribution line 5 is sectioned by zone switches 4 in the number of n, while CTs (current transformers) 2 in the number of n are provided corresponding to the individual zone switches 4. A switch blocking instruction preparing part 1 receives a measured value of a phase current from each CT 2 via a communication circuit 3 and calculates a difference in the zero-phase current between the adjacent CTs 2. In the case that some of absolute values of the differences exceed a threshold value, a blocking instruction is transmitted to the zone switch 4 of the concerned zone. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for detecting an occurrence section of a ground fault occurring in a distribution line of an electric power system, and selecting and blocking this accident section.

  Conventionally, when a ground fault occurs in a distribution line of a power system, a breaker in a substation is opened to cause a power failure in the entire distribution line to eliminate the failure. However, the distribution line is provided with a plurality of section switches in the middle of the track. By opening the section switch corresponding to the section where the ground fault occurred, the accident can be eliminated by causing only the accident section to power out. Is possible. Such a device is called a distribution line fault section detection / separation device or the like (see Patent Documents 1 and 2).

  When a ground fault occurs in a distribution line, a weak zero-phase current or zero-phase voltage is generated in the distribution line. In the conventional distribution line fault section detection and disconnection device, each section switch is provided with a ground fault direction relay (relay) and a communication function, and the zero phase current and zero phase voltage generated due to the ground fault are displayed in the direction of each fault. Measured with a relay, detects the ground fault occurrence direction for each division switch from the relationship between zero-phase current and zero-phase voltage, and further identifies the accident section by using the communication function to narrow down the accident section. ing.

Japanese Patent Publication No. 07-1980 Japanese Patent Publication No. 07-4048

  However, the conventional technique has the following problems. That is, in the conventional techniques described in Patent Documents 1 and 2, a ground fault direction relay is used to determine the ground fault accident section, but the ground fault direction relay measures both zero-phase current and zero-phase voltage. Therefore, there is a problem that the cost becomes high. In particular, the measurement of the zero-phase voltage is more expensive than the measurement of the zero-phase current, and thus the cost of the measuring device is high.

  The present invention has been made in view of the above, and does not measure both the zero-phase current and the zero-phase voltage in each section of the distribution line. An object of the present invention is to obtain a distribution line accident section selective blocking device and a distribution line accident section selective blocking method capable of determining and blocking only the accident section.

  In order to solve the above-described problems and achieve the object, the distribution line accident section selective interruption device according to the present invention detects a section of occurrence of a ground fault in the distribution line of the power system, and selects and blocks the accident section. A distribution line fault section selective interruption device, comprising: a plurality of division switches provided on the distribution line; and a plurality of current transformers provided on the distribution line corresponding to each of the division switches. Determining a section in which a ground fault has occurred, a switch break command generation unit for generating a break command for the segment switch corresponding to the accident section, the plurality of segment switches, and the plurality of switches. And a communication line that provides a communication function by mutually connecting the switch and the switch breaker command creation unit, and the switch breaker command creation unit includes the plurality of switches obtained via the communication line. Based on the measured value of the phase current of the current transformer. The absolute value of the difference in the zero-phase current between the current transformers adjacent to each other is calculated, and when there is a value exceeding a predetermined threshold among the absolute values, A cut-off command is transmitted via the communication line to a section switch corresponding to a section that gives the absolute value that is greater than.

  According to the present invention, the phase current of each phase is measured by a plurality of current transformers, and these measured values are transmitted to the switch breaker command creating unit using a communication line. Based on the zero-phase current alone, the ground fault occurrence accident section is determined. Therefore, it is not necessary to measure both the zero-phase current and the zero-phase voltage as in the prior art, and in particular, it is not necessary to measure the zero-phase voltage, so that the installation cost of the measuring device is greatly reduced. Thus, it is possible to greatly reduce the measurement cost, determine the ground fault accident section, and select and block only the accident section.

  DESCRIPTION OF EMBODIMENTS Embodiments of a distribution line accident section selective interruption device and a selective interruption method according to the present invention will be described below in detail based on the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a power distribution system including a distribution line accident section selection / blocking device according to the present embodiment. FIG. 2 is a flowchart showing the flow of processing when the present embodiment is applied to determine a section in which a ground fault has occurred, select the section, and issue a shutoff command.

  As shown in FIG. 1, a distribution line 5 is wired from a substation 10, and a breaker 7 is provided in the substation 10. The circuit breaker 7 can block the electric power transmitted from the substation 10 via the distribution line 5.

  The distribution line 5 is provided with n section switches 4 (1) to 4 (n), and the distribution line 5 is divided into a plurality of sections by each section switch 4. The subscript (i) of the section switch 4 (i) indicates that the section switch is installed i-th from the substation 10 in the power transmission direction. FIG. 1 shows a case where a one-line ground fault has occurred between the section switch 4 (2) and the section switch 4 (3), for example.

  The distribution line 5 is provided with n CTs (current transformers) 2 (1) to 2 (n) corresponding to the respective section switches 4 respectively. The subscript (i) of CT2 (i) indicates that the current transformer is installed i-th from the substation 10 in the power transmission direction, as in the case of the section switch 4 (i). ing. CT2 (1) -2 (n) measures the phase current which is flowing through the distribution line 5 in each installation location.

  The switch breaker command creation unit 1 is a device that creates a break command for controlling the switching of each of the segment switches 4 (1) to 4 (n) to shut off the ground fault occurrence section. The switch breaker command creation unit 1, CT 2 (1) to 2 (n), and the section switches 4 (1) to 4 (n) are connected to each other via the communication line 3. The measured value of the phase current measured at each CT 2 (1) to 2 (n) by the communication line 3 is transmitted to the switch breaker command creation unit 1 and created by the switch breaker command creation unit 1. The shut-off command thus transmitted is transmitted to each of the segment switches 4 (1) to 4 (n). As described above, various data can be communicated via the communication line 3. Note that the communication function is not limited to the communication line 3, and the communication function between the switch breaker command generation unit 1, CT2 (1) to 2 (n), and the section switches 4 (1) to 4 (n) is realized. For example, other communication means can be used. The distribution line fault section selective interruption device according to the present embodiment includes a switch breaker instruction creation unit 1, CT2 (1) to 2 (n), section switches 4 (1) to 4 (n), and communication. The communication line 3 for realizing the function is provided, an accident section where a ground fault has occurred is determined, and this section is selected and blocked.

  Next, the operation of the present embodiment, that is, the distribution line accident section selective blocking method will be described with reference to FIG.

  First, in step S <b> 1, the switch breaker command creation unit 1 receives the measured values of the phase current measured by the CT <b> 2 (1) to 2 (n) via the communication line 3.

  In step S2, the switch breaker instruction creation unit 1 calculates the difference in zero-phase current between adjacent CT2. That is, ΔI0 (1) = zero-phase current of CT2 (1) −zero-phase current of CT2 (2), ΔI0 (2) = zero-phase current of CT2 (2) −zero-phase current of CT2 (3), ΔI0 ( 3) = zero phase current of CT2 (3) −zero phase current of CT2 (4),..., ΔI0 (n−1) = zero phase current of CT2 (n−1) −zero phase of CT2 (n) Each current is calculated. The zero-phase current of each CT2 is measured or calculated as the sum of the phase currents of each phase measured by each CT2.

  Subsequently, in step S3, the switch breaker command creation unit 1 uses the absolute value of the difference value of the zero-phase current, that is, | ΔI0 (1) |, | ΔI0 (2) |,. n-1) | is calculated, and each absolute value is compared with a threshold value for determining whether or not a ground fault has occurred. If there is any of | ΔI0 (1) |, | ΔI0 (2) |,..., | ΔI0 (n−1) | that exceeds the threshold value, the process proceeds to step S4. On the other hand, when there is no object exceeding the threshold, the process returns to step S1 and the same processing is repeated.

  In step S <b> 4, the switch breaker instruction creation unit 1 transmits a breaker instruction to the sorting switch 4 corresponding to the section exceeding the threshold value via the communication line 3. In the case of FIG. 1, since a one-line ground fault has occurred between the section switches 4 (2) and 4 (3), for example, the value of | ΔI0 (3) | exceeds the threshold value. . Therefore, when it is determined in step S3 that the value of | ΔI0 (3) | has exceeded the threshold value, the switch breaker command generation unit 1 performs, for example, the section switches 4 (2) and 4 (3). Send a shutdown command to both. When this disconnection command is received and the section switch 4 (2) is opened, the power transmission from the substation 10 is not supplied to the section where the ground fault occurs, and the section where the ground fault occurs is interrupted. Further, the section switch 4 (3) is opened, and further, for example, the distribution line 5 in the range of the section switches 4 (3) to 4 (n) from a substation (not shown) different from the substation 10 is provided. By performing reverse power transmission, power can be supplied except for the section where the ground fault occurred.

  Note that the opening of the section switch 4 and the disconnection of the ground fault accident section after receiving the disconnection command are performed before the circuit breaker 7 of the substation 10 is operated and the entire distribution line is interrupted.

  In the present embodiment, the phase current is measured by CT2 (1) to 2 (n), and the zero-phase current is calculated by taking the sum of each phase of these phase currents. As another form, instead of CT2 (1) to 2 (n), n ZCTs (zero phase current transformers) for measuring the zero phase current are provided, and the difference is obtained by directly measuring the zero phase current. Also good.

  According to the present embodiment, the phase current is measured by CT2 (1) to 2 (n), and using the communication function, these measured values are transmitted to the switch breaker command creation unit 1, and the switch breaker command The preparation unit 1 narrows down and determines the ground fault occurrence accident section based on the zero-phase current obtained from these measured values. Therefore, it is not necessary to measure both the zero-phase current and the zero-phase voltage as in the prior art, and in particular, it is not necessary to measure the zero-phase voltage, so that the installation cost of the measuring device is greatly reduced. In this way, it is possible to greatly reduce the measurement cost, discriminate the ground fault accident section, select only the accident section and shut off, so that the normal section where the ground fault accident has not occurred can be cut off Therefore, stable operation of the entire system can be ensured.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing a configuration of a power distribution system including a distribution line accident section selection / cutoff device according to the present embodiment. FIG. 4 is a flowchart showing the flow of processing when the present embodiment is applied to determine a section in which a ground fault has occurred, select that section, and issue a shutoff command.

  In the first embodiment, the ground fault occurrence section is determined based only on the zero-phase current of the adjacent CT2. However, since the magnitude of the ground fault current in the distribution system is small, there are problems in detection sensitivity and detection accuracy. Further, the distribution line 5 (own line) connected to the substation 10 in FIG. 1 is generally further connected to a distribution line (other line) (not shown) to constitute a distribution system. In such a configuration, the switch breaker instruction creation unit 1 may detect a ground fault that has occurred in a line other than its own line, and may command an unnecessary malfunction. Therefore, in the present embodiment, the accuracy of the determination result according to the first embodiment is obtained by using the existing ground fault direction relay (relay) installed in the substation and using the ground fault occurrence direction information obtained therefrom. To prevent the occurrence of unnecessary operations due to incorrect discrimination.

  As shown in FIG. 3, the configuration of the present embodiment is the same as the configuration of the first embodiment shown in FIG. 1 except that a ground fault direction relay (relay) 26 is provided. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  The ground fault direction relay 26 is connected via the communication line 3 to the switch breaker command generation unit 1, CT2 (1) to 2 (n), and the section switches 4 (1) to 4 (n). . The ground fault direction relay 26 detects the ground fault occurrence direction in the distribution line 5 and transmits the result to the switch breaker command generation unit 1 via the communication line 3.

  Next, the operation of the present embodiment, that is, the distribution line accident section selection blocking method will be described with reference to FIG.

  First, in step S <b> 11, the switch breaker instruction creation unit 1 receives the measured values of the phase current measured by the CT <b> 2 (1) to 2 (n) via the communication line 3.

  In step S12, the switch breaker instruction creation unit 1 calculates the difference in zero-phase current between adjacent CT2. That is, ΔI0 (1) = zero phase current of CT2 (1) −zero phase current of CT2 (2), ΔI0 (2) = zero phase current of CT2 (2) −zero phase current of CT2 (3), ΔI0 ( 3) = zero phase current of CT2 (3) −zero phase current of CT2 (4),..., ΔI0 (n−1) = zero phase current of CT2 (n−1) −zero phase of CT2 (n) Each current is calculated. The zero-phase current of each CT2 is measured or calculated as the sum of the phase currents of each phase measured by each CT2.

  In step S <b> 13, the switch breaker instruction creating unit 1 receives the ground fault occurrence direction from the ground fault direction relay 26.

  Subsequently, in step S14, the switch breaker command generation unit 1 uses the absolute value of the difference value of the zero-phase current, that is, | ΔI0 (1) |, | ΔI0 (2) |,. n-1) | is calculated, and each absolute value is compared with a threshold value for determining whether or not a ground fault has occurred. This threshold value is the same as the threshold value in the first embodiment. And | ΔI0 (1) |, | ΔI0 (2) |,..., | ΔI0 (n−1) | If the ground fault occurrence direction of the ground fault direction relay 26 is the distribution line 5 that is the own line, the process proceeds to step 15. On the other hand, if there is nothing exceeding the threshold value, or the ground fault generation direction is not the own line, the process returns to step S11 and the same processing is repeated.

  In step S <b> 15, the switch breaker instruction creation unit 1 transmits a breaker instruction to the section switch 4 in the section that exceeds the threshold value via the communication line 3. This operation is the same as in the first embodiment.

  According to the present embodiment, by using the ground fault occurrence direction information of the existing ground fault direction relay 26, it is possible to improve the determination accuracy of the ground fault occurrence accident section according to the first embodiment. Therefore, the measurement cost can be greatly reduced and the discrimination accuracy can be increased. Other operations, effects, and the like of the present embodiment are the same as those of the first embodiment.

Embodiment 3 FIG.
FIG. 5 is a flowchart showing the flow of processing when the present embodiment is applied to determine a section where a ground fault has occurred, select that section, and issue a shutoff command.

  In the first and second embodiments, the ground fault occurrence zone is determined based on the zero-phase current of the adjacent CT2. However, if a short-circuit failure or a different-phase ground fault occurs (when a ground fault occurs in two different points at the same time and in different phases), a large current may flow and cause serious damage to the equipment. Yes, in this case, the accident should be removed by the circuit breaker 7 of the substation 10 without operating the section switch 4.

  Therefore, in the present embodiment, when the current measured by CT2 is large in the switch breaker command generation unit 1, unnecessary operation is prevented by not operating the segment switch 4. In other words, the present embodiment has a function of locking the operation with respect to “different-point ground fault”, “contact accident of two or more wires”, and the like.

  The configuration of the present embodiment is the same as that of the first embodiment shown in FIG.

  Next, the operation of the present embodiment, that is, the distribution line accident section selective blocking method will be described with reference to FIG.

  First, in step S <b> 21, the switch breaker command generation unit 1 receives the measured values of the phase current measured by the CT <b> 2 (1) to 2 (n) via the communication line 3.

  In step S22, the switch breaker instruction creation unit 1 calculates the difference in zero-phase current between adjacent CT2. That is, ΔI0 (1) = zero phase current of CT2 (1) −zero phase current of CT2 (2), ΔI0 (2) = zero phase current of CT2 (2) −zero phase current of CT2 (3), ΔI0 ( 3) = zero phase current of CT2 (3) −zero phase current of CT2 (4),..., ΔI0 (n−1) = zero phase current of CT2 (n−1) −zero phase of CT2 (n) Each current is calculated. The zero-phase current of each CT2 is measured or calculated as the sum of the phase currents of each phase measured by each CT2.

  Subsequently, in step S23, the switch breaker command generation unit 1 uses the absolute value of the difference value of the zero-phase current, that is, | ΔI0 (1) |, | ΔI0 (2) |,. n-1) | is calculated, and each absolute value is compared with a threshold value 1 for determining whether or not a ground fault has occurred. The threshold value 1 is the same as the threshold value in the first embodiment. Among the | ΔI0 (1) |, | ΔI0 (2) |,... | ΔI0 (n−1) |, there are those exceeding the threshold 1, and the absolute value of each phase current. When all values | CT2 (1) |, | CT2 (2) |,..., | CT2 (n) | are smaller than the threshold value 2, the process proceeds to step S24. The threshold value 2 is a threshold value for determining whether or not a large current due to the above-described short circuit failure or the like flows in each phase current. On the other hand, all of | ΔI0 (1) | to | ΔI0 (n−1) | are smaller than threshold value 1, or any of | CT2 (1) | to | CT2 (n) | When the threshold value 2 is exceeded, the switch breaker command creation unit 1 does not transmit a break command to the segment switch 4, and branches to step S21 again.

  In step S <b> 24, the switch breaker instruction creation unit 1 transmits a breaker instruction to the section switch 4 in the section that exceeds the threshold 1 via the communication line 3. This operation is the same as in the first embodiment.

  According to the present embodiment, when any one of | CT2 (1) | to | CT2 (n) | In this case, when a short circuit failure or an out-of-phase ground fault has occurred, the switch breaker 7 of the substation 10 is not operated without operating the segment switch 4. Accidents can be dealt with by operations. Other operations, effects, and the like of the present embodiment are the same as those of the first embodiment.

  As described above, the distribution line accident section selective interruption device and the selective interruption method according to the present invention can detect the ground fault by reducing the cost of the measuring instrument, and thus can be widely applied to the power system. it can.

It is a block diagram which shows the structure of the power distribution system containing the distribution line accident area selection interruption | blocking apparatus concerning Embodiment 1. FIG. It is a flowchart which shows the flow of the process at the time of applying Embodiment 1 and discriminating the section where a ground-fault accident occurs, selecting the section, and issuing a cutoff command. It is a block diagram which shows the structure of the power distribution system containing the distribution line accident area selection interruption | blocking apparatus concerning Embodiment 2. FIG. It is a flowchart which shows the flow of the process at the time of discriminating the section where a ground fault accident is applied by applying Embodiment 2 and selecting the section. It is a flowchart which shows the flow of a process at the time of discriminating the section where a ground fault accident is applied by applying Embodiment 3 and selecting the section.

Explanation of symbols

1 Switch breaker command generation part 2 (1)-2 (n) Current transformer (CT)
3 Communication line 4 (1) to 4 (n) Division switch 5 Distribution line 7 Breaker 10 Substation 26 Ground fault direction relay (relay)

Claims (5)

A distribution line accident section selection interruption device that detects an occurrence section of a ground fault in a distribution line of an electric power system, and selects and blocks the accident section,
A plurality of section switches provided on the distribution line;
A plurality of current transformers provided in the distribution line corresponding to the respective section switches;
A switch breaker command generation unit that determines the occurrence section of the ground fault accident and creates a shutoff command for the section switch corresponding to the accident section;
A communication line for providing a communication function by mutually connecting the plurality of section switches, the plurality of current transformers, and the switch breaker command generation unit;
With
The switch breaker command creation unit is configured to use the current transformers adjacent to each other for the plurality of current transformers based on the measured values of the phase currents of the current transformers obtained through the communication line. The absolute value of the difference between the zero-phase currents between them is calculated, and if there is an absolute value that exceeds a predetermined threshold value, it corresponds to a section that gives the absolute value larger than the threshold value A distribution line fault section selective blocking device, wherein a blocking command is transmitted to the sorting switch through the communication line. Further comprising a ground fault direction relay connected to the switch breaker command creation unit via the communication line,
In addition to the determination of the accident section based on the threshold value, the switch breaker instruction creation unit indicates that the ground fault occurrence direction by the detection of the ground fault direction relay obtained through the communication line indicates the own line. The distribution line accident section selective interruption apparatus according to claim 1, wherein the interruption instruction is transmitted only in the case.   In addition to determining the fault section based on a first threshold value that is a threshold value that is compared with the absolute value of the difference between the zero-phase currents, the switch breaker command generation unit includes a plurality of current transformers. The distribution line fault section selective interruption device according to claim 1, wherein the interruption instruction is transmitted only when all of the absolute values of the measured phase currents are smaller than the second threshold value. A distribution line accident section selection interruption device that detects an occurrence section of a ground fault in a distribution line of an electric power system, and selects and blocks the accident section,
A plurality of section switches provided on the distribution line;
A plurality of zero-phase current transformers provided in the distribution line corresponding to the respective section switches;
A switch breaker command generation unit that determines the occurrence section of the ground fault accident and creates a shutoff command for the section switch corresponding to the accident section;
A plurality of section switches, a plurality of zero-phase current transformers, and the switch breaker command creation unit connected to each other, a communication line providing a communication function;
With
The switch breaker command generation unit is configured to mutually connect the plurality of zero-phase current transformers based on the measured values of the zero-phase currents of the plurality of zero-phase current transformers obtained through the communication line. Calculate the absolute value of the difference of the zero-phase current between adjacent zero-phase current transformers, and when there is a value exceeding a predetermined threshold in the absolute value, the absolute value greater than the threshold A distribution line accident section selective cutoff device, wherein a cutoff command is transmitted via the communication line to a section switch corresponding to a section giving an absolute value. A plurality of section switches provided on the distribution line, a plurality of current transformers provided on the distribution line corresponding to each of the section switches, and a section in which a ground fault has occurred are determined. The switch breaker command creation unit for creating a break command for the segment switch corresponding to the above, the plurality of segment switches, the plurality of current transformers, and the switch breaker command creation unit are connected to each other And a communication line providing a communication function, and a distribution line accident section selective blocking method of a distribution line accident section selective blocking device comprising:
The switch breaker command creation unit receives a phase current measurement value from the plurality of current transformers via the communication line;
Obtaining a zero-phase current from the measured value of the phase current, and for the plurality of current transformers, calculating a difference value of the zero-phase current between mutually adjacent current transformers;
The absolute value of the difference of the zero-phase current is compared with a predetermined threshold value, and when the absolute value of the difference of the zero-phase current exceeds the threshold value, Determining that a ground fault has occurred in the section that gives the absolute value that is greater, and transmitting a shut-off command to the section switch corresponding to the section via the communication line;
A distribution line accident section selective blocking method characterized by comprising:

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