JP2012191756A - Power distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power distribution system in which a distributed power supply device side can detect quickly and surely that the power distribution system is in a state of interruption of electric service and individual operation.SOLUTION: An inventive power distribution system includes: a section switch 3 interposed in a high voltage distribution line 1; and a pole-mounted transformer 7 having primary-side terminals 7a, 7b connected with high voltage distribution lines 1b1, 1c1 and secondary-side terminals 7c to 7e connected with low voltage distribution lines 9a to 9c. In this power distribution system, a transformer primary-side short circuit switch 13 is prepared in parallel between the primary side terminals 7a, 7b of the pole-mounted transformer 7. The transformer primary-side short circuit switch 13 is closed when the section switch 3 is opened, thus short-circuiting between the primary side terminals 7a, 7b of the pole-mounted transformer 7.

Description

  The present invention relates to a power distribution system, and more specifically, for example, a primary transformer primary side is connected to a high voltage distribution line interposing a section switch, and a photovoltaic power generation is connected to the low voltage distribution line on the secondary transformer side. The present invention relates to a power distribution system to which a distributed power supply device such as the above is connected.

  Distribution substations in the power system generally distribute 6600V high voltage with high-voltage distribution lines, connect the primary side of the pole transformer to this high-voltage distribution line, and generate low voltages such as 100V and 200V on the secondary side For example, it is supplied to a household load via a low-voltage distribution line.

  In recent years, power generation facilities such as solar power generation, wind power generation, and fuel cell power generation, so-called distributed power supply devices, are connected to the low-voltage distribution lines and connected to the distribution system. It is now possible to supply power to the load.

  A distributed power supply device generally includes a DC power source such as a solar battery, and a power conditioner that converts the DC output of the DC power source into an AC output, and the power conditioner is connected to a distribution system. Can be controlled.

  In such a distributed power supply device, when a power failure occurs in the power distribution system, it is necessary to disconnect the distributed power supply device from the power distribution system to prevent independent operation of the distributed power supply device (for example, Patent Document 1). reference). Independent operation is a state in which the distributed power supply supplies power to the load when the power distribution system has a power failure.

  There are various types of detection conditions for detecting the isolated operation of the distributed power supply device. For example, a so-called passive method (for example, detecting an isolated operation by detecting a change in the amount of electricity such as a frequency or a voltage phase at the time of transition to isolated operation) , See Patent Document 2), or by applying a slight amount of electricity fluctuation to the power system from time to time, and detecting a change in the frequency or the impedance calculated from the change that occurs when shifting to a single operation. There is a so-called active method (see Patent Document 3, for example).

JP 2007-185079 A Japanese Patent Laid-Open No. 08-082646 JP-A-10-248168

  In any system, when the power distribution system is interrupted and the distributed power supply device is operated independently, it is necessary to detect the isolated operation at high speed and to quickly disconnect the distributed power supply device from the power distribution system. Conventionally, however, it is difficult for a distributed power supply device to detect an isolated operation at high speed and reliably.

  The problem to be solved by the present invention is to enable the distributed power supply side to detect the state of the isolated operation at high speed and reliably.

  A power distribution system according to the present invention is a power distribution system including a section switch interposed in a high voltage distribution line, and a transformer having a primary side connected to the high voltage distribution line and a secondary side connected to the low voltage distribution line.

  In such a power distribution system, conventionally, even if distribution to the primary side of the transformer is stopped when the section switch is opened, the primary side of the transformer is not short-circuited. In this state, the power energy remains without being consumed rapidly. For this reason, since the transformer secondary voltage does not rapidly drop to zero, it takes time to detect a power failure in the distribution system. This has conventionally made it difficult to detect at high speed that the distributed power supply is operating independently even if the power distribution system fails.

  According to the present invention, in such a power distribution system, a transformer primary-side short-circuit switch is provided in parallel on the primary side of the transformer, and the transformer primary-side short-circuit switch is closed when the section switch is open, The primary side ends are short-circuited.

  According to the present invention, power distribution to the primary side of the transformer is stopped when the section switch is opened. At this time, the transformer primary-side short-circuit switch is closed, and both ends of the transformer primary-side are short-circuited by the transformer primary-side short-circuit switch. When both ends of the primary side of the transformer are short-circuited, the power energy remaining on the primary side of the transformer is rapidly consumed. As a result, the secondary voltage of the transformer rapidly decreases to 0V (zero volts). Therefore, it becomes extremely easy to detect a power failure in the distribution system at high speed from the distributed power supply side.

  In this way, in the present invention, when the section switch is opened and the distribution system is cut off, the primary side of the transformer is short-circuited, and the secondary side voltage is reduced to zero voltage at high speed. On the power supply device side, the isolated operation state can be detected at high speed based on the change in the secondary side voltage of the transformer.

  A preferred embodiment of the present invention includes a power distribution slave station that responds to a command from a power facility remote monitoring device that is a master station, wherein the power distribution slave station responds to a command from the master station. Is switched from closed to open, the transformer primary short-circuit switch is switched from open to closed.

  According to another preferred aspect of the present invention, a short-circuit prevention switch is interposed between at least one of the primary terminals of the transformer and the load-side high-voltage distribution line to which the one terminal is connected. The power distribution slave station controls the opening and closing of the short-circuit prevention switch so as to eliminate a period during which the section switch and the transformer primary-side short-circuit switch are simultaneously closed.

  According to still another preferred aspect of the present invention, the power distribution slave station maintains the short-circuit prevention switch in an open state, and the division switch controls switching from open to closed, and then after a certain period of time has elapsed. The transformer primary-side short-circuit switch is switched from closed to open, and then the short-circuit prevention switch is switched from open to closed.

  In the present invention, a transformer primary-side short-circuit switch is provided in parallel to the primary side of the transformer, and when the section switch is open, the transformer primary-side short-circuit switch is closed to short-circuit both ends of the transformer primary-side. The transformer secondary voltage when the power distribution system fails is changed to 0V at high speed. And on the distributed power supply side, based on the change of the transformer secondary side voltage, it is detected that the distribution system is in a state of power failure due to power failure. it can.

FIG. 1 is a diagram showing an outline of a power distribution system according to an embodiment of the present invention. FIG. 2 is a diagram showing an outline of a power distribution system according to another embodiment of the present invention. FIG. 3 is a diagram showing an outline of a power distribution system according to still another embodiment of the present invention. FIG. 4 is a timing chart for explaining the operation of the power distribution system of FIG.

  Hereinafter, a power distribution system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  Referring to FIG. 1, a high-voltage distribution line 1 is a 6600 V three-phase AC distribution line. The high-voltage distribution line 1 is divided into a power line 1a to 1c and a load line 1a1 to 1c1 by a segment switch 3.

  The section switch 3 includes contacts on the lines 1a to 1c, contacts on the lines 1a1 to 1c1, and switching contacts 3a to 3c that connect and block between these contacts.

  The division switch 3 is driven to open and close the open / close contacts 3 a to 3 c in accordance with a signal from the control system 5. In addition to the switching contacts 3a to 3c, the section switch 3 includes an excitation coil that opens and closes the switching contact, a control device for energizing the excitation coil, and others, but for convenience of illustration. The illustration is omitted.

  Of the lines 1a1 to 1c1 on the load side of the high-voltage distribution line 1, primary terminals 7a and 7b of the pole transformer 7 are connected to the lines 1b1 and 1c1. The pole transformer 7 transforms the high voltage of AC 6600V into the low voltage of AC 100 and AC 200V, and outputs it between the secondary terminals 7c to 7e. Each voltage between the secondary terminals 7c and 7d and between 7d and 7e is an AC voltage of 100V, and a voltage between the secondary terminals 7c and 7e is an AC voltage of 200V. The secondary side terminals 7 c to 7 e are connected to the lines 9 a to 9 c of the low voltage distribution line 9. Each of the lines 9a to 9c constitutes a single-phase three-wire line. The distributed power supply device 11 is connected to the lines 9a to 9c.

  In the illustrated example, the distributed power supply device 11 includes an interconnection breaker 11a, an inverter (power conditioner) 11b, and a DC power supply 11c such as a solar battery. The distributed power supply device 11 obtains information on the secondary side voltage of the pole transformer 7 from a voltage detector (not shown). Based on this detection, the distributed power supply device 11 determines whether the section switch 3 is opened and a power failure occurs in the power distribution system and is operating independently. When it is determined that the distributed power supply device 11 is in an independent operation state, the interconnection circuit breaker 11a is opened and disconnected from the distribution system, and the independent operation is stopped by stopping the inverter 11b as necessary.

  In the embodiment, the transformer primary-side short-circuit switch 13 is provided in parallel on the primary-side terminals 7a and 7b side of the pole transformer 7. The transformer primary side short-circuit switch 13 can close the primary side terminals 7a and 7b of the pole transformer 7 by closing the circuit.

  The control system 5 opens the section switch 3 in response to, for example, a command input for causing a power failure on the load side of the section switch 3. When the section switch 3 is opened, the load side lines 1a1 to 1c1 of the distribution system are in a power failure state. The control system 5 closes the transformer primary side short-circuit switch 13 simultaneously with the opening of the section switch 3. You may make it perform the opening / closing of the division | segmentation switch 3 and the transformer primary side short circuit switch 13 in the control system 5 with the exciting coil incorporated in this control system 5. FIG. This excitation coil is not built in, but is provided on the section switch 3 and the transformer primary short-circuit switch 13 side, and the control system 5 controls energization of these excitation coils to control the section switch 3 and transformer primary-side short-circuit switch 13 on and off. You may be able to do it.

  When the transformer primary short-circuit switch 13 is closed, the primary terminals 7a and 7b of the pole transformer 7 are short-circuited as described above. When the primary terminals 7a and 7b of the pole transformer 7 are short-circuited, the voltage between the secondary terminals 7c to 7e falls to 0V at a high speed as described above.

  As described above, conventionally, even when the section switch 3 is opened and power distribution on the load side is interrupted, the primary terminals 7a and 7b of the pole transformer 7 are not short-circuited, and the line 1b1 of the high-voltage distribution line is used. , 1c1 is in an open state, and the power energy stored in the pole transformer 7 remains without being rapidly consumed. For this reason, the voltage between the secondary side terminals 7c to 7e of the pole transformer 7 cannot rapidly drop to zero. This makes it difficult for the distributed power supply 11 to detect at high speed that the power distribution system is operating independently due to a power failure.

  In contrast, in the present embodiment, the primary terminals 7a and 7b of the pole transformer 7 are short-circuited, so that the voltage between the secondary terminals 7c to 7e of the pole transformer 7 rapidly falls to 0V. . Thereby, on the distributed power supply 11 side, it is possible to detect at high speed that the power failure of the load side lines 1a1 to 1c1 of the power distribution system, that is, that the distributed power supply 11 is in the single operation state.

  It is preferable that the control system 5 simultaneously opens the section switch 3 and closes the transformer primary short-circuit switch 13.

  At this time, the control system 5 continues the closed state of the transformer primary short-circuit switch 13 for a predetermined time. The predetermined time is preferably a time from when the distributed power supply device 11 detects an isolated operation until the isolated operation is stopped.

  The control system 5 may be able to communicate with the distributed power supply device 11 as indicated by a dotted line between the control system 5 and the distributed power supply device 11. For communication, a distribution line may be used, or a communication line different from the distribution line may be used.

  When the distributed power supply 11 detects an isolated operation and stops the isolated operation based on the detection, the distributed power supply device 11 notifies the control system 5 of the information on the stop. The control system 5 may switch the transformer primary-side short-circuit switch 13 from the closed circuit to the open circuit when notified of the information on the independent operation stop from the distributed power supply device 11 side.

   A power distribution system according to another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing an outline of a power distribution system according to another embodiment of the present invention. The power distribution system of FIG. 2 includes a power facility remote monitoring device 5a, which is a master station, and a power distribution slave station 5b. The power facility remote monitoring device 5a is disposed, for example, in a distribution substation. The power distribution slave station 5b is disposed, for example, on the pole transformer 7 side. The power facility remote monitoring device 5a commands a power outage to the power distribution slave station 5b. In response to this command, the power distribution slave station 5b performs control to drive the section switch 3 to the open side and the transformer primary side short-circuit switch 13 to the close side. As a result, the primary side terminals 7a and 7b of the pole transformer 7 are short-circuited.

  In addition, although it is the pole top transformer 7 in embodiment, it is not limited to this, A ground installation type transformer and another transformer may be sufficient.

  With reference to FIG. 3 and FIG. 4, a power distribution system according to still another embodiment of the present invention will be described. FIG. 3 is a diagram showing an outline of the power distribution system of the embodiment, and FIG. 4 is a timing chart for explaining the operation. In this power distribution system, a resistor 15 for preventing short circuit current inrush is inserted between the primary side terminals 7a and 7b of the pole transformer 7 together with the transformer primary short circuit switch 13, and the primary side of the pole transformer 7 is also connected. A short-circuit prevention switch 17 is interposed between the terminal 7 a and the load side line 1 c 1 of the high-voltage distribution line 1.

  The power distribution slave station 5b controls the timing of opening and closing of the power distribution switch 3, the transformer primary short circuit switch 13, and the short circuit prevention switch 17 at the timing shown in FIG. 4 according to a command from the power facility remote monitoring device 5a. .

  That is, as shown in FIG. 4, the distribution slave station 5b opens the section switch 3 and the short-circuit prevention switch 17 by the signal S1, and opens the transformer primary-side short-circuit switch 13 by the signal S2 after the lapse of the period T1. Switch from to closed. The power distribution slave station 5b switches the section switch 3 from an open circuit to a closed circuit by a signal S3. And after progress of period T2, the transformer primary side short circuit switch 13 is switched from a closed circuit to an open circuit by a signal S4. The power distribution slave station 5b switches the transformer primary short-circuit switch 13 from the closed circuit to the open circuit, and then switches the short-circuit prevention switch 17 from the open circuit to the closed circuit by the signal S5 after the elapse of the period T3.

  That is, by the timing control shown in FIG. 4 by the power distribution slave station 5b, first, the period T1 is secured, that is, the short circuit prevention switch 17 is open, and the opening of the section switch 3 and the opening of the transformer primary side short circuit switch 13 are first performed. By ensuring the period T1 in which both of them occur simultaneously, the transformer primary side is not connected to the power source side lines 1b and 1c of the high-voltage distribution line 1 in a state of being short-circuited by the transformer primary-side short-circuit switch 13.

  In addition, while the period T2 is secured, that is, the short circuit prevention switch 17 is maintained in the open state, the transformer primary side short circuit switch 13 is switched from the closed circuit to the open circuit after the section switch 3 is switched from the open circuit to the closed circuit. By ensuring the period T2 up to, the power failure time required by the general electric utility is secured.

  Furthermore, the period T3 is secured, that is, the short circuit prevention switch 17 is in the open state, the section switch 3 is in the closed state, and in this state, the transformer primary side short-circuit switch 13 is switched from the closed circuit to the open circuit. By securing the period T3 until the prevention switch 17 switches from open to closed, after the transformer primary terminals 7a and 7b are opened, the transformer primary terminals 7a and 7b are connected to the high-voltage distribution lines 1b1 and 1c1 on the load side. Make it connected.

DESCRIPTION OF SYMBOLS 1 High voltage distribution line 3 Division switch 5 Control system 7 Pillar transformer 9 Low voltage distribution line 11 Distributed type power supply device 13 Transformer primary side short circuit switch 17 Short circuit prevention switch

Claims (4)

  In a power distribution system including a section switch interposed in a high voltage distribution line and a transformer having a primary side connected to the high voltage distribution line and a secondary side connected to the low voltage distribution line, the transformer is connected in parallel between the primary terminals of the transformer. A power distribution system comprising a transformer primary-side short-circuit switch, wherein the transformer primary-side short-circuit switch is closed when the section switch is open to short-circuit between primary terminals of the transformer.   A power distribution slave station that responds to a command from a power facility remote monitoring device that is a master station, and the power distribution slave station switches the segment switch from a closed circuit to an open circuit in response to a command from the master station The power distribution system according to claim 1, wherein the transformer primary-side short-circuit switch is switched from an open circuit to a closed circuit. A short-circuit prevention switch is interposed between at least one terminal of both primary terminals of the transformer and the load-side high-voltage distribution line to which the one terminal is connected,
The power distribution slave station controls the opening and closing of the short-circuit prevention switch to eliminate a period during which the section switch and the transformer primary-side short-circuit switch are closed simultaneously. 2. The power distribution system according to 2.   The distribution slave station switches the section switch from an open circuit to a closed circuit (first switching) while maintaining the short-circuit prevention switch in an open circuit (first switching), and after a certain period of time has elapsed from the first switching, 4. The power distribution system according to claim 3, wherein the side short-circuit switch is switched from a closed circuit to an open circuit (second switch), and the short-circuit prevention switch is switched from the open circuit to the closed circuit after a lapse of a certain period from the second switch. .

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