JP2013093963A - Distribution automation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distribution automation system in which terminals can be protected in simple configuration and at low cost.SOLUTION: A distribution automation system comprises a control device 3 which periodically monitors current values with section switches DM1-DM4. In the case where a current value from the section switch DM1 closest to a base end side of a distribution line 100 to the section switch DM3 is changed just by a preset terminal accident current value, where there is no current change just by the terminal accident current value in the section switch DM4 at a distal end side rather than the section switch DM3, and where a short-circuiting relay 2 is not being operated, the control device 3 cuts off the section switch DM3.

Description

  The present invention relates to a power distribution automation system that automatically specifies an accident section and opens / closes a switch when a short circuit accident occurs.

  When a short-circuit accident occurs in a distribution line, the impact of the accident can be minimized by automatically identifying the fault section and controlling the switch with a distribution automation system (short-circuit relay). It has been broken. By the way, the power distribution system may be extended or changed, and in the existing / existing short-circuit relay and power distribution automation system, the end protection (2φS Protection against phase short-circuit accidents) may not be possible.

  For this reason, the recloser which can interrupt | block an accident electric current is provided, and the technique which divides a distribution line into several sections through the normally closed switch which can interrupt | block only a load current following this recloser (for example, refer patent document 1). ) And a technique for detecting terminal protection by detecting a phase difference of a short-circuit current (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 10-080057 Japanese Patent Laid-Open No. 62-181626

  By the way, in the technology of Patent Document 1, the accident section is identified by the recloser and the switch and the accident is recovered, and it is effective for protecting the terminal outside the protection section of the distribution automation system and the short circuit relay. is not. In addition, a recloser must be arranged, and particularly in a multi-line system in which many distribution lines are arranged, a great amount of cost is required. Similarly, in the technology of Patent Document 2, it is necessary to provide a function / device for detecting a phase difference separately from the protective relay, which requires a great deal of cost.

  Accordingly, an object of the present invention is to provide a power distribution automation system capable of protecting the end with a simple configuration at low cost.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to a protective relay that monitors a distribution line in a predetermined protection section and performs an operation such as trip signal output, and a current at the installation position disposed on the distribution line. In a distribution automation system comprising a plurality of segment switches having a function of measuring the current, the current value of each segment switch is periodically monitored, and the segment switch closest to the proximal end of the distribution line is undecided. This is a case where the current value up to the segment switch changes by a preset terminal fault current value, and there is no current change by the terminal fault current value in the segment switch on the terminal side of the undetermined segment switch. And when the said protective relay is not operate | moving, the terminal protection means which interrupts | blocks the said undetermined division switch is provided, It is characterized by the above-mentioned.

  For example, it is assumed that the division switches 1 to 5 are arranged in order from the proximal end side (substation side) to the distal end side of the distribution line. Then, the current value from the section switch 1 to the section switch 3 changes by the terminal fault current value, and only the terminal fault current value is detected in the section switches on the terminal side of the section switch 3, that is, the section switches 4 and 5. Suppose a situation occurs in which there is no change in current. In this case, it is determined that a short circuit accident has occurred in the distribution line between the section switches 3 and 4 and the protective relay is not operating, that is, the location where the short circuit accident has occurred is a protective section by the protective relay. In the case of the outside (terminal), the section switch 3 is shut off by the terminal protection means.

  According to the first aspect of the present invention, there is an end of the distribution line that cannot be protected by the existing (original) distribution automation system / protection relay due to extension or change of the distribution system, and a short circuit accident or the like has occurred at this end. However, since the section switch on the base end side closest to the accident location is shut off, the end can be protected. In addition, the current measurement function provided in the segment switch is used to determine whether or not the segment switch is necessary, and the segment switch is simply segmented. That is, it is possible to construct the distribution automation system at low cost and at low cost simply by adding a terminal protection means to the existing distribution automation system.

1 is a schematic configuration diagram showing a distribution automation system according to an embodiment of the present invention. It is a figure which shows the control algorithm by the control apparatus of the system of FIG. It is a front view which shows the operation | movement pattern of the system of FIG.

  The present invention will be described below based on the illustrated embodiments.

  FIG. 1 is a schematic configuration diagram showing a distribution automation system 1 according to an embodiment of the present invention. This distribution automation system 1 is a system that automatically identifies an accident section and opens / closes a switch when a short-circuit accident occurs, and is mainly a protective relay such as a short-circuit relay (overcurrent relay) 2. And a plurality of division switches DM1 to DMn (n is an integer) and a control device (terminal protection means) 3.

  Here, the distribution automation system 1 is a system equivalent to the conventional distribution automation system except for the terminal protection function described later. In other words, the conventional power distribution automation system has a terminal protection function. Further, in this embodiment, normal protection in which the base end side (substation 101 side) of the distribution line 100 to the third section switch DM3 described later is protected by the conventional distribution automation system (short-circuit relay 2). It is a section, and the end side from the third section switch DM3 is not protected by a conventional power distribution automation system, but is a terminal protection section protected by a terminal protection function. That is, the first section to be protected is the section up to the third section switch DM3, and the end side from the third section switch DM3 is a section added by extension or change of the distribution system.

  The short-circuit relay 2 is a digital relay that performs an operation such as trip signal output by monitoring a distribution line in a predetermined protection section, that is, a normal protection section. In other words, the distribution line 100 is provided with a current transformer, and an overcurrent (short circuit accident) to the distribution line 100 is detected based on the measurement result of the current transformer, and a trip signal or the like is output. In response to this trip signal, the circuit breaker 102 and the like operate.

  In addition to the short-circuit relay 2, the distribution system requires a relay such as a ground fault selection relay (10G), a ground fault overvoltage relay (OVG), an undervoltage relay (UV), and a direction ground fault relay (DG). It is installed according to.

  The division switches DM <b> 1 to DMn are switches that are disposed on the distribution line 100 and have a function of measuring a current at the disposed position. That is, each of the division switches DM1 to DMn is provided with a current transformer, and a measurement result (current value) and an operation described later are transmitted to the control device 3 in real time. Moreover, according to the control command from the control apparatus 3, each division | segmentation switch DM1-DMn opens and closes.

  And division switch DM1-DMn is arrange | positioned in order from the substation 101 side of the distribution line 100 to the terminal side. Accordingly, the first section switch DM1 to the first section switch DM1 is the first section, the first section switch DM1 to the second section switch DM2 is the second section, and the second section switch. DM2 to the third section switch DM3 are the third section, the third section switch DM3 to the fourth section switch DM4 are the fourth section, and the fourth section switch DM4 to the fifth section. A fifth section is formed up to the switch DM5 (not shown).

  The control device 3 periodically monitors the current values from the respective division switches DM1 to DMn, and the current value from the first division switch DM1 to an undetermined division switch is a preset terminal fault current value. If there is no current change of the terminal fault current value in the terminal switch on the end side of this certain section switch, and this short circuit relay 2 etc. is not operating, this certain section switch It is a device having an end protection function of shutting off the device.

  That is, since the load current usually decreases toward the end side, the current values in the respective division switches DM1 to DMn do not become the same. Further, when considering only the end protection function of protecting the end protection section, protection is possible even when the accident current (2φS · two-phase short-circuit current) is small. That is, the accident current, the load current, and the set value of the short-circuit relay 2 have the following relationship.

  Accident current <Load current <Distribution line setting value

  On the other hand, when an accident occurs in the terminal protection section, an equivalent accident current (2φS, two-phase short-circuit current) flows from the power supply side (substation 101 side) to the accident point, and current flows from the accident point to the terminal. Absent. In other words, when an accident occurs, the fault current is measured in the section switches DM1 to DMn from the substation 101 side to the fault point, and the fault current is not measured in the section switches DM1 to DMn from the fault point to the end. In this way, the accident section is determined.

  Therefore, an accident current (terminal accident current value) when a short-circuit accident occurs at the terminal is calculated in advance, and a settling value is set in consideration of the load impedance etc. in this calculation result. DM1 to DMn operate. Here, the set value is set every time the system is changed, and is set to a value smaller than the minimum short-circuit current (terminal fault current value). For example, when the above-mentioned determination is made at a sampling period of 1 second and the requirement is satisfied, a cutoff command is transmitted to the corresponding division switches DM1 to DMn.

  Further, in order to prevent malfunction and misjudgment, it is determined whether or not the current value has suddenly changed (rapid increase or decrease) in all the division switches DM1 to DMn (fail safe). On the other hand, the end protection function is only for protecting the end protection section, and the normal protection section is protected by the normal / previous functions of the power distribution automation system 1 and the short-circuit relay 2. For this reason, even when the above requirements are satisfied, when the short-circuit relay 2 or the like is operating, the section switches DM1 to DMn are not shut off depending on the terminal protection function.

  Such a control device 3 performs determination and control processing at the timing and time limit as shown in FIG. First, in this embodiment, whether or not the following requirement is satisfied is monitored and checked at a sampling period of 1 second as described above. That is,

  Requirement C1: All the division switches DM1 to DMn on the terminal side from the accident point are not operating.

  Requirement C2: Current values of all the division switches DM1 to DMn are changing suddenly (ΔI = about 0.5 A).

  Requirement C3: All the division switches DM1 to DMn on the substation 101 side from the accident point are operating.

  Requirement C4: The short-circuit relay 2 or the like is not operating.

  It is determined whether or not all the requirements C1 to C4 are satisfied.

  And when satisfy | filling a requirement, interruption | blocking instruction | command is transmitted after time limit (for example, 2 second later) with respect to applicable division switch DM1-DMn. As a result, the corresponding division switches DM1 to DMn are cut off and tripped about 3 seconds after the occurrence of the accident. Here, the corresponding division switches DM1 to DMn are the division switches DM1 to DMn on the side of the substation 101 closest to the accident point. Among the division switches DM1 to DMn that are operating in the requirement C3, It is the division switches DM1 to DMn on the most distal side.

  Next, the operation of the power distribution automation system 1 having such a configuration will be described. Here, as shown in FIG. 1, the setting value of the short-circuit relay 2 is 600A-5A, the terminal fault current value is 390A, the setting values of the individual switches DM1 to DMn are 380A, and the maximum load current on the substation 101 side is The maximum load current on the end side is assumed to be 400A.

  First, in the control device 3, the operation and current value of each of the division switches DM1 to DMn are monitored at a sampling period of 1 second as described above. And when an accident occurs in the 4th section which is an end protection section, as shown in Drawings 1 and 3, 1st division switch DM1-3rd division switch DM3 operate (requirement C3), The operation after the fourth section switch DM4 is inoperative (requirement C1). Further, the current value suddenly changes in all the division switches DM1 to DMn (requirement C2), and further, the short circuit relay 2 and the like become inoperative (requirement C4). In other words, all the above requirements C1 to C4 are satisfied, the control device 3 transmits a shut-off command to the third section switch DM3 after a time limit, and the third section switch DM3 is shut off / tripped. The Thereby, the terminal is protected (the distribution line 100 on the substation 101 side is protected from the third section switch DM3).

  Similarly, when an accident occurs in the fifth section which is the end protection section, as shown in FIG. 3, the first section switch DM1 to the fourth section switch DM4 operate (requirement C3), After the section switch DM5 of No. 5, it becomes inoperative (requirement C1). Further, the current value suddenly changes in all the division switches DM1 to DMn (requirement C2), and further, the short circuit relay 2 and the like become inoperative (requirement C4). That is, it will be in the state which satisfy | filled all said requirements C1-C4, the 4th division switch DM4 is interrupted | blocked / tripped by the control apparatus 3, and the terminal is protected.

  On the other hand, when an accident occurs in the normal protection section, for example, when an accident occurs in the third section, as shown in FIG. 3, the first section switch DM1 and the second section switch DM2 operate. To do. However, since it is not protected by the end protection function and is protected by the normal / previous functions of the distribution automation system 1 and the short-circuit relay 2, the section switches DM1 to DMn as described above are not shut off.

  Further, as shown in FIG. 3, even when the first segment switch DM1 and the second segment switch DM2 are operated by the load current, the third segment switch DM3 is inoperative and the end protection is performed. Since the current values in all the division switches DM1 to DMn are not suddenly changed, the division switches DM1 to DMn are not cut off as described above.

  As described above, according to this distribution automation system 1, there is an end of the distribution line 100 that cannot be protected by the existing (original) distribution automation system / protection relay due to the extension or change of the distribution system. Even if a short circuit accident or the like occurs, the divisional switches DM1 to DMn on the proximal end side closest to the accident location are cut off. Therefore, the distribution line 100 on the substation 101 side should be protected from the divisional switches DM1 to DMn. Can do. That is, backup for the short-circuit relay 2 and the like is possible.

  In addition, the current measuring function provided in the section switches DM1 to DMn is used to determine whether or not the section switches are necessary, and the section switches DM1 to DMn are simply disconnected. In other words, the distribution automation system 1 can be constructed at low cost and at low cost simply by adding the above-described determination element / program of the control device 3 to the existing distribution automation system 1.

  Moreover, since it is not necessary to separately install an overcurrent protection device such as a recloser, the cost can be greatly reduced. In addition, when a recloser or the like is installed, it is necessary to re-send the current to the distribution lines after the recloser to identify the accident point / accident section. Since no transmission is required, quick protection and recovery are possible. Furthermore, it becomes possible to respond flexibly to changes or extensions of the power system by setting the set values for the respective division switches DM1 to DMn in an enlarged manner.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in the above embodiment, the monitoring cycle is set to 1 second and the cutoff time is set to 2 seconds. However, according to the operation of the power system and the short-circuit relay 2, the time can be reliably and safely protected at the end. Good. Further, determination and control (terminal protection means) by the control device 3 may be provided in another device or system.

1 Power distribution automation system 2 Short circuit relay (protective relay)
3 Control device (terminal protection means)
DM1 to DM4 Division switch 100 Distribution line

Claims (1)

A protective relay that monitors the distribution line in a predetermined protection section and performs an operation such as trip signal output, and a plurality of division switches that are disposed on the distribution line and have a function of measuring a current at the installation position. In the distribution automation system
Regularly monitor the current value of each section switch, and the current value from the section switch closest to the base end of the distribution line to the undetermined section switch changes by the preset terminal fault current value. In the case where there is no current change corresponding to the terminal fault current value in the terminal switch on the end side of the undetermined section switch, and the protective relay is not operating, the undetermined section switch A distribution automation system comprising terminal protection means for shutting off the power.

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