JP2005094897A - Single operation prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adaptively detect single operation at a system side. <P>SOLUTION: This single operation prevention device operates in parallel to a commercial power system and one or more distributed power supply apparatuses that are mutually connected to an interconnection bus bar via a breaker, and prevents the single operation of the distributed power supply apparatus when disconnecting a line. The single operation prevention device also comprises: a first means that detects the abnormality of the line by a voltage, a current or a frequency of the line, or the combination thereof; a second means that confirms that the detection of the first means has been continued for a prescribed period of time; a third means that detects that a single system has been generated by the detection of the second means; and a forth means that confirms the operation of the third means and throws in a grounding switch. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an isolated operation preventing device that prevents an isolated operation state when a distributed power supply facility connected to a commercial power system is disconnected.

  FIG. 7 is a schematic diagram for explaining the single operation, which will be described. In FIG. 7, 1 is a commercial power system, 2 is a transformer secondary circuit breaker, 3A and 3B are system side loads, 3C is a premise load, 4 is a substation bus, 5 is a transmission line, 6 is a connection point circuit breaker, 7 is a power receiving breaker, and 8 is a distributed power source.

  In the above configuration, when the grid breaker 6 is opened for some reason when the system is in operation, the distributed power source 8 bears the loads 3B and 3C, and the power generation and the load are balanced. Then, the distributed power source 8 continues to operate.

  That is, this state is a so-called single operation. In this state, the transmission line 5 is in a live line state, so it takes time to parallel the system to the commercial system, and there is a danger to the workers at the time of restoration, and if it continues for a long time, a ground fault can not be detected. There is also the possibility of damaging things.

  Here, some cause of the disconnection circuit breaker 6 being opened is due to an abnormality occurring in the transmission line 5, in addition to the case where the power transmission line protection device operates to open the connection breaker 6, or due to the operation of the operator Release, natural release due to equipment failure.

Conventionally, such an apparatus for preventing isolated operation detects that the system has become a single system at the place where the distributed power source is installed, and stops the distributed power source itself or opens a switch such as the circuit breaker 7 to A method of stopping the supply of power from the power source to the transmission line 5 has been adopted. As an example, FIG. 8 illustrates a case where the distributed power source is a synchronous generator. Refer to Patent Document 1 for detailed technical contents.
Japanese Patent Laid-Open No. 6-311652 (pages 3 to 4, FIG. 1)

  However, the detection of its own single system on the distributed power supply side is not necessarily reliable. For example, in the case of Patent Document 1, when a plurality of distributed power sources provided with such a device are connected to one power transmission line, there is a possibility that a single system cannot be detected due to mutual interference. In this case, the isolated operation continues.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an isolated operation preventing apparatus capable of preventing isolated operation on the system side.

  The isolated operation prevention apparatus according to claim 1 of the present invention is configured such that a commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected to a connected bus, and the distributed type In the isolated operation preventing apparatus for preventing the isolated operation of the power source, the first means for detecting the abnormality of the line by the voltage, current or frequency of the line or a combination thereof, and the detection of the first means are continued for a predetermined time. A second means for confirming this, a third means for detecting the occurrence of a single system by the detection of the second means, and an operation of the third means for confirming the operation of the grounding switch. And a fourth means.

  The isolated operation prevention apparatus according to claim 2 of the present invention is configured such that a commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected to a connected bus, and the distributed operation is performed when a line is interrupted. In the isolated operation prevention apparatus for preventing the isolated operation of the power source, the first means for detecting the abnormality of the line by the voltage, current or frequency of the line or a combination thereof, and the detection of the first means is continued for a predetermined time. A second means for confirming that the second means has been detected; a third means for detecting the occurrence of a single system by the detection of the second means; and a predetermined interconnection point breaker after the detection of the third means And a fifth means for checking the operation of the fourth means and inserting a grounding switch.

  The isolated operation prevention apparatus according to claim 3 of the present invention is configured such that a commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected to a connected bus, and the distributed operation is performed when a line is interrupted. In the isolated operation prevention apparatus for preventing the isolated operation of the power source, the first means for detecting that the line breaker is opened, and the second means for detecting the presence of the voltage on the line after the detection of the first means. Means, third means for detecting that a logical product condition of the means 1 and means 2 has passed for a certain period of time, and fourth means for detecting single system generation when the third means is confirmed. And a fifth means for checking the operation of the fourth means and inserting a grounding switch.

  The isolated operation prevention apparatus according to claim 4 of the present invention is the grounding switch according to any one of claims 1 to 3, wherein after the grounding switch is turned on, the grounding switch is awaited for detection of a specified time after the closing operation. Provided with a means for opening.

  As described above, according to the present invention, when a system is operated independently for some reason, the system is grounded to generate an artificial short circuit, and the generator that is continuously operated is quickly led to disconnection. be able to.

  In addition, when the system becomes independent operation for some reason, the system scale of the single system is reduced by opening the interconnection breaker of the system that is protected by this device from the change in voltage, current, and frequency. The protection range system can be grounded to generate an artificial short circuit, and the generator operating continuously in the protection range system can be promptly led to disconnection.

  In addition, when the connection point breaker is opened for some reason, if the voltage of the system that is the protection range of this device continues for more than the specified time, the isolated operation has occurred. Therefore, it is possible to ground the protection range system to generate an artificial short circuit, and to promptly disconnect the generator that continues to operate in the protection range system.

  In addition, the system can quickly re-transmit power by opening the grounding switch that is turned on after the specified time has elapsed.

The basic concept of the present invention will be described. For example, let us consider a case where a system including a distributed power source is in an isolated operation state for some reason such as an accident.
Normally, the generator is equipped with an overcurrent relay for the purpose of detecting the occurrence of a short circuit in the system or for the purpose of detecting its own overload / reverse power flow. This works to stop the generator to be protected.

  In addition, in the inverter type generator, when a short circuit occurs in the system, a significant voltage drop occurs, so a gate block operation (hereinafter referred to as GB) is performed to protect the element. Or, commutation failure occurs and power generation is stopped. However, in a single system, if there is no accident or there is no device to detect a ground fault overvoltage due to a ground fault, the line voltage in the system does not change, so if the supply and demand balance in the system is balanced Independent operation will continue.

  That is, if the isolated operation is continued, the voltage of the target system does not disappear even though the connection point breaker is open. By detecting this, the present apparatus determines that it is in an isolated operation state, and turns on a grounding switch connected to the system with a predetermined time period.

  In other words, when a single operation occurs in the system, normally, the distributed power source operates the single operation prevention device installed on each generator side to disconnect the generator, but this device remains in each single system. Waiting for the generator to disconnect independently, and when it has not been disconnected by a predetermined time, that is, when the voltage of the system has not disappeared (for example, a voltage of 30% or more of the rated voltage) When there is a voltage, it is judged that there is voltage), forcibly grounding the relevant system and artificially shorting it facilitates the operation of the overcurrent relay installed in each generator in the single system, and Encourage GB operation and guide the generator in the system to disconnect.

 When the system including the protection target system becomes a single system due to opening of the circuit breaker other than the connection point circuit breaker, the single operation state is detected by frequency change, voltage change / current change. That is, if there is a large change in the system frequency, for example, a fluctuation of ± 2 Hz or more with respect to the reference frequency of 50 Hz, and this continues for a predetermined time or more, it can be determined that the system is a single system.

Inverter-type generators are generally operated at a constant power factor of power factor 1, but when these become independent operations and the supply-demand balance is lost, the effect appears in the system voltage. If the load is excessive, the system voltage will be If the voltage drops and is insufficient, the system voltage rises.
Therefore, for example, when a deviation of ± 20% or more of the rated voltage is continued for a predetermined time, it can be determined that the operation is independent.

  In addition, if the change in the impedance locus (step-out center) of the connection point breaker passes through a predetermined value, for example, within the range of the quadrilateral characteristics, from the current / voltage passing through the connection breaker, the system becomes unstable. Can be determined. When this device detects such a state, it opens the interconnection point breaker, and thereafter, using the functions described above, the system to be protected is grounded, and the generator in the system is quickly disconnected. Lead to.

  After carrying out the above operation, the apparatus waits for a predetermined time to open the grounded switch. This is for re-closing relay that will be performed after that and preparation for power transmission by system operation, and for charging the stopped system promptly.

  FIG. 1 is an overall configuration diagram illustrating an embodiment of an isolated operation preventing apparatus. In FIG. 1, reference numeral 100 denotes an isolated operation preventing apparatus body, which includes an input unit 101, a calculation unit 102, and an output unit 103. The input unit 101 receives voltage / current / frequency information of the system and open / close information of the cutoff unit (CB). The calculation content in the calculation unit 102 determines whether or not it is in a single operation state based on each input information, and when it is determined that it is in a single operation, the grounding switch is forcibly turned on, and after a specified time The process of releasing is performed.

  Here, the first independent operation determination in the present invention is based on the fact that a predetermined voltage still exists on the line side after the circuit breaker is opened. That is, voltage / current / frequency information and CB information from the system are input, a series of processing relating to the islanding determination is performed based on each information, and the determination result is output.

  FIG. 2 is a diagram for explaining processing contents by generation of a single system with a specific circuit example. In FIG. 2, 1 is a commercial power system, 2 is an interconnection breaker, 3 is a system load, 4 is a substation bus, 5 is a transmission line, 6 is an interconnection point breaker, 7 is a receiving breaker, and 8 is a receiving breaker. Distributed power source. A range surrounded by a dotted line indicates a range where a single system is generated when the interconnection breaker (hereinafter simply referred to as a breaker) 6 is broken for some reason. Further, 100 is an isolated operation prevention device.

  FIG. 3A is a flowchart showing the processing contents. Now, when the circuit breaker 6 is opened for some reason, the cause is that the power line protection device operates to open the circuit breaker 6 due to an abnormality occurring in the power transmission line 5, and the operator's operation In step S31, the circuit breaker is opened, and the process proceeds to step S32 to detect the line voltage “present”.

  In step S33, it is determined whether or not the specified time A has elapsed. If this is Yes, the calculation unit 102 of the isolated operation determination device 100 determines that an isolated operation has occurred in step S34, and the output unit 103 determines in step S35. The earthing switch (for closing the illustrated contact in the isolated operation preventing device 100) is forcibly turned on.

  As a result, a generator protection device (not shown) of the distributed power supply operates, and the power receiving breaker 7 operates to disconnect the distributed power supply. Also, in the case of a distributed power source using an inverter, the voltage is lost and the circuit is disconnected due to a commutation failure. As described above, according to the present embodiment, the occurrence of isolated operation can be prevented by detection on the system side.

  FIG. 3B is a flowchart showing other processing contents, and the feature point of the processing contents is in step S36. That is, once the grounding switch is forcibly turned on, the grounding switch is opened after a specified time B has elapsed. This process prepares for a reclosing relay that will be performed later and power transmission by system operation, and is for quickly charging the stopped system.

  Here, the second of the independent operation determination in the present invention is that the abnormality of the line is detected by the voltage, current or frequency of the line or a combination thereof, and it is determined that the single system is generated by confirming that this has continued for a predetermined time. . At this time, this apparatus opens a predetermined interconnection breaker. If the voltage of the system in the protection range does not disappear after this operation, it is determined that the protection range is operated independently by the function described above, and the generator that has been operated independently by the previous operation can be quickly led to disconnection.

  FIG. 4 is a circuit example illustrating another embodiment, and shows a case where a single system is generated by opening the circuit breaker 10 other than the circuit breaker 6 described in FIG. In this case, the range of influence due to the generation of a single system is the range surrounded by a dotted line. 4 are the same as those in FIG. 2, and therefore, the description thereof is omitted.

  Now, if the circuit breaker 10 is opened for some reason, the commercial system is cut off, and therefore the range surrounded by the dotted line is assumed to be an independent operation. In this case, if there is an imbalance of demand in the single system or if the generator does not operate stably in the single system and the swaying occurs, the device will be able to detect the voltage, current, It judges with isolated operation from the change of frequency, and breaker 6 is opened. Further, after the circuit breaker 6 is released, if the independent operation of the protection target system continues, the calculation unit 102 detects the circuit breaker open, detects the presence of the line voltage (due to the distributed power supply connection), and passes a predetermined time. Recognize the occurrence of a single system through the process of, and forcibly turn on the grounding switch. The subsequent processing is the same as in FIG. 2, and the opening of the grounding switch is the same as described above. According to the present embodiment, single system generation can be prevented by detection on the system side.

  FIG. 5 is a circuit example illustrating still another embodiment. In this embodiment, the single operation prevention device 100 is installed in the upper system so that the entire single system is stopped by one unit. In the figure, 11 is a breaker 7 of the higher system, 71 is a breaker of a distributed power source, and a dotted line is a range affected by opening of the breaker 10 of the higher system.

  Next, the operation will be described. Consider a case where the circuit breaker 10 installed in the upper system is opened for some reason. When this apparatus detects an isolated operation from changes in voltage, current, and frequency flowing through the circuit breaker 11, the circuit breaker 11 is opened. In this state, if the transformer primary voltage does not disappear for a predetermined time, it is determined that the system in the protection section is operating independently. That is, before the circuit breaker 11 is opened, if the distributed power sources 8 and 81 continue to generate power, if an imbalance in supply and demand occurs, the effect appears in the voltage and frequency. In the present apparatus, the primary voltage and frequency information of the connected transformer are input to the calculation unit 102 via the input unit of the isolated operation prevention device 100.

  Therefore, the calculation unit 102 determines that a single system is generated according to FIG. 3A and forcibly turns on the grounding switch. As a result, a generator protection device (not shown) of each of the distributed power sources 8 and 81 operates, and the power receiving breakers 7 and 71 are opened. As a result, the remaining voltage is extinguished. This prevents isolated operation.

  FIG. 6 is a circuit example illustrating still another embodiment. In this embodiment, even if the circuit breaker is not open, if a system abnormality due to system instability or other factors is detected, the system is quickly separated and the protection section is brought to a stop. In the present embodiment, the same reference numerals as those in FIG.

  In the present embodiment, when a change in impedance locus (step-out locus) from the current / voltage passing through the circuit breaker 6 passes, for example, within the range of the quadrilateral characteristics, it is determined that the system is in a step-out state. Open the circuit breaker.

  Thereafter, as described above, the grounding switch is forcibly grounded, and the distributed power source 8 is disconnected by a generator protection device (not shown). Then, after the above operation is performed, the inserted grounding switch is opened after a predetermined time has elapsed. According to the present embodiment, the system can be separated by disconnecting the distributed power source even when the system is unstable, regardless of the opening of the circuit breaker.

    In a power system connected to a distributed power source, it can be detected on the system side when a single operation of the distributed power source is detected, and the distributed power source can be automatically disconnected simultaneously with the detection. it can.

Whole block diagram explaining embodiment of isolated operation prevention device A diagram illustrating the operation when a single system is generated with a specific circuit example The flowchart which shows the process in the calculating part of an independent system | strain prevention apparatus The figure explaining the operation at the time of single system generation by giving other specific circuit examples Further, a diagram illustrating the operation when a single system is generated by giving another specific circuit example. Further, a diagram illustrating the operation when a single system is generated by giving another specific circuit example. Outline diagram explaining isolated operation The figure explaining the prior art example of an isolated operation prevention device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power system 2 Interconnection breaker 3 System side load 4 Interconnection bus 5 Private power generation equipment (distributed power supply)
6 Parallel circuit breaker 7 Power receiving circuit breaker 8 Synchronous generator 9 Own customer load
10 Target circuit breaker to be opened
100 Islanding prevention device
101 Input section
102 Calculation unit
103 Output section

Claims (4)

  In a single operation prevention apparatus, a commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected to an interconnected bus, and the single operation of the distributed power supply is prevented when the line is interrupted. The first means for detecting the abnormality of the line by the voltage, current or frequency of the line, or a combination thereof, the second means for confirming that the detection by the first means has continued for a predetermined time, and the second means And a third means for detecting the occurrence of a single system by detecting the means, and a fourth means for checking the operation of the third means and inserting a grounding switch. Isolated operation prevention device.   In the independent operation prevention device that the commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected in parallel to each other, and the isolated operation of the distributed power supply is prevented when the line is interrupted. A first means for detecting an abnormality of the line by a voltage, current, frequency or combination of the lines, a second means for confirming that the detection by the first means has continued for a predetermined time, and the second A third means for detecting the occurrence of a single system by the detection of the means; a fourth means for opening a predetermined interconnection breaker after the detection of the third means; and the fourth means. And a fifth means for turning on a grounding switch after confirming the operation of the isolated operation prevention device.   In the independent operation prevention device that the commercial power system and one or more distributed power supply facilities are connected in parallel to each other via a circuit breaker and connected in parallel to each other, and the isolated operation of the distributed power supply is prevented when the line is interrupted. The first means for detecting that the circuit breaker of the line has been opened, the second means for detecting the presence of voltage on the line after the detection of the first means, and the logical product condition of the means 1 and means 2 A third means for detecting that a predetermined time has elapsed; a fourth means for detecting generation of a single system when the third means is confirmed; An isolated operation preventing device comprising a fifth means for charging the vessel.   4. The isolated operation prevention device according to claim 1, further comprising means for opening the grounding switch after detecting the specified time after the closing operation after turning on the grounding switch. Isolated operation prevention device characterized by

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