JPH04340326A - Power interruption/recovery automatic switching unit - Google Patents

Abstract

PURPOSE:To obtain a power interruption/recovery automatic switching unit which can switch the system accurately and quickly even during fault or maintenance/inspection and which can feed power reliably to a load during fault while taking account of the power receiving capacity of normal system and the importance of load. CONSTITUTION:When switching is made from a power receiving system 1 to a power receiving system 2 during fault or maintenance/inspection, a line switcher trips a power receiving circuit breaker to make switching to the power receiving system 2. A decision unit 107 in a load command decision unit 91 then compares the power receiving capacity of the power receiving system 2 with the sum of maximum load capacity of load circuit breakers connected with respective loads and the load circuit breakers are tripped according to an order selected by a load selector 101 until the power receiving capacity exceeds the sum of maximum load capacity of load circuit breakers.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic power failure/recovery switching device for power failure/recovery in a power receiving system.

0002

[Prior Art] In order to receive electricity in general industry, power outages occur due to accidents in the power receiving system, and if the power supply is cut off, it will cause great damage to the factory, so the power receiving system is divided into two circuits and one circuit is used. Even if you are unable to receive electricity due to an accident,
We are trying to minimize damage within the factory by switching to another line to receive power. FIG. 1 shows an example of a typical two-line power reception system.

In FIG. 1, power is received from a power receiving point 1 at a cable head 1, passing through a power receiving disconnector 2, a power receiving circuit breaker 3, an instrument transformer 4, and then from a load circuit breaker 5 to a load circuit breaker 6. Power is supplied to the load through cable heads 7 to 8 through each load circuit breaker.

[0004] At this time, power from the power receiving side 2 is supplied to the power receiving side 2 through the power receiving disconnector 10 using the cable head 9 as a power receiving point. However, since the power reception circuit breaker 11 is disconnected, no power is supplied from the power reception 2 side to each load. In such a power receiving state, the voltage transformer 12 connected to the bus between the power receiving disconnector 2 and the power receiving circuit breaker 3 and the voltage transformer 12 connected to the bus between the power receiving disconnector 10 and the power receiving circuit breaker 11 Since both voltage transformers 13 have voltage on their busbars, undervoltage relays 14 and 15 connected to the secondary sides of voltage transformers 12 and 13 are inoperative. Next, a case will be described in which an accident occurs in the system on the power receiving 1 side that is receiving power in such a power receiving state.

[0005] In order to use the automatic power failure/recovery switching device, the mode selection switch is set to automatic. If an accident occurs in the system on the power receiving 1 side that is receiving power, the voltage in the system on the power receiving 1 side disappears, and the undervoltage relay 14 connected to the bus on the power receiving 1 side Detects the loss of voltage in the power receiving 1 side system. When a predetermined period of time has elapsed, the undervoltage confirmation timer operates, and the tripping coil of the power reception circuit breaker 3 is energized and tripped. After detecting that the power receiving circuit breaker 3 has tripped, each of the tripping coils from the load circuit breaker 5 to the load circuit breaker 6 is excited and tripped to create a no-load state. After each load circuit breaker is disconnected and after confirming that the voltage of the system on the power receiving 2 side is normal by checking the inoperation of the undervoltage relay 15, the closing coil of the power receiving circuit breaker 11 on the power receiving 2 side is energized and turned on. do. After detecting that the power receiving circuit breaker 11 has been closed, the closing coils of each load circuit breaker from the load circuit breaker 5 to the load circuit 6 are energized and closed, and a series of automatic power failure/recovery switching is performed. operation is completed. Further, even if an accident occurs in the system on the power receiving 2 side while power is being received in the system on the power receiving 2 side, a similar series of automatic power failure/recovery switching operations will be performed.

[0006]

[Problems to be Solved by the Invention] Such conventional automatic switching devices for power failure and recovery have the following problems.

(1) When power is being received from the system on the power receiving 1 side and the power reception is switched to the system on the power receiving 2 side due to maintenance and inspection of the power receiving circuit breaker or bus bar on the power receiving 1 side, mode selection is required. Switch the switch 21 from automatic to manual, use the operating switches attached to each circuit breaker to check the operating status of the system and each load status, and check each one according to the order of operation to turn the circuit breaker on or off. This requires expertise and is time-consuming.

(2) When the mode selection switch 21 is selected from automatic to manual and a series of operations are performed, if there is an accident in the system receiving power, the automatic power failure/recovery switching device will not operate. , the power receiving system may not switch to a normal power receiving system, resulting in a complete power outage and causing major damage.

(3) If an accident occurs in the power receiving system when using the power failure/recovery automatic switching device, if there are many load circuit breakers, each load circuit breaker will be tripped at the same time. The current flowing through the trip coil may be superimposed, causing the protective MCCB or fuse of the circuit breaker's control power source to blow, or the circuit breaker may not trip due to a voltage drop in the control power source.

For this reason, when there is an important load, even if the power receiving circuit breaker opens due to an accident on the grid side, the system waits for power to be supplied from the normal power receiving side without turning off the circuit breaker each time. However, if the amount of electric power is large when the important load is turned on, the overcurrent relay for overcurrent detection in the power receiving system will operate and trip at the moment the normal power receiving circuit breaker closes. This may result in you not being able to receive power. SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic switching device for automatic switching during power failure and recovery, which can reliably and quickly perform automatic switching in the event of an accident or during maintenance and inspection. [Structure of the invention]

[0011]

Means for Solving the Problems In order to achieve the above object, the present invention has a plurality of power receiving systems connected from a power supply line to a load circuit breaker via a disconnector and a power receiving circuit breaker. In the power failure/recovery automatic switching device that detects an abnormality in the power receiving system from a power receiving signal obtained through a disconnector and operates the power receiving circuit breaker and the load circuit breaker to switch from the abnormal power receiving system to the normal power receiving system. a line switching means for dividing a power receiving system into a regular system and a backup system and switching to the backup system by tripping a power receiving circuit breaker of the regular system; a load selection means for selecting an order of loads to be cut off; and a power receiving system for the backup system. A setting means for setting the power reception capacity of the load circuit breaker and the maximum load capacity of the load circuit breaker is compared with the sum of the power reception capacity value and the maximum load capacity value from each setting means, and the power reception capacity value is larger. and a comparison/discrimination means for tripping the load circuit breakers in the order selected by the load selection means until the load selection means selects the load circuit breaker.

0012

[Operation] In such a configuration, when the regular system is switched to the standby system by the circuit switching means, the comparison and determination means compares the power receiving capacity value of the power receiving circuit breaker of the standby system and the maximum load of the load circuit breaker from the setting means. The sum of the capacitance values is compared and the load circuit breakers are tripped in the order in which the load selection means is selected until the receiving capacity value becomes large, so that the power can be restored accurately and quickly in the event of an accident or maintenance inspection. Automatic switching is possible.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a load command determination device for an automatic power failure/recovery switching device according to the present invention. In the automatic power failure/recovery switching device of the present invention, a load command determining device 91 is connected to the input sides of the undervoltage relays 14 and 15 in FIG. 2 via a line switching device (not shown).

When automatic switching is performed during maintenance and inspection, the undervoltage relays 14 and 15 do not operate because the system voltage is present on the input sides of the undervoltage relays 14 and 15. Therefore, for example, when performing maintenance and inspection on the power reception 1 side, the line switching device forcibly trips the power reception circuit breaker 3. When the power receiving circuit breaker 3 trips, the load command judgment device 64
works. In the load command determination device 91, there is a storage device 96 that receives signals 92, 93 from each power receiving circuit breaker 3, 11 and signals 94, 95 from each load circuit breaker 5 to 6 and determines the operating state of each circuit breaker. , 97, 98, 99. Also,
A load selection device 101 receives a signal from a load selection switch 100, which selects the order of load breakers according to the importance of each load, and selects which load to select to break when a load breaker is required. , setting devices 102 and 103 that set the allowable power receiving capacity of each power receiving side, setting devices 104 and 105 that set the maximum load capacity when each circuit breaker is closed for each load, and power receiving capacity and maximum load of each load. It is comprised of a comparator 106 that compares the total capacity with the load capacity, and a determination device 107 that determines the degree of difference between the power receiving capacity and the load capacity based on the signal from the comparator 106.

In FIGS. 1 and 2, there are two load breakers, but suppose there are five load breakers (F1, F2, F3, F4).
, F5). The load selection order is determined by the load selection switch 100: load circuit breakers F1→F2→
The order is F3→F4→F5.

Since the contact of the power reception circuit breaker 3 on the power reception side 1 is inserted, the memory device 96 operates, and via this, the setting device 102 determines the allowable power reception capacity PR2 and the circuit breaker for each load circuit breaker. The load containing the circuit breaker is determined by the storage device 96, and each storage device containing the circuit breaker is operated. Each load capacity PL1, P is input from each setting device through each storage device.
The total load capacity ΣPL of L2, PL3, PL4, and PL5 is input to the comparator 106. PL1+PL2+PL3+PL4+PL5=ΣPL If PR2>ΣPL, there is no signal from the discrimination device 107 to the load selection device 101. Therefore, the trip command to each load circuit breaker is cut here.

However, if PR2<ΣPL, the signal from the discrimination device 107 is input to the load selection device 101. As a result, the load selection device 101 cuts the signals from each setter on each load side from entering the comparator based on the load order selected from the load selection switch 100. Depending on the load selection order, the load selection device 101 first cuts the signal from the setter of the load circuit breaker F1. The total load capacity at this time is as follows. PL2+PL3+PL4+PL5=ΣPL1

0018
] If PR2<ΣPL1 at this time, the discriminator 10
Since the signal from 7 is input to the load selection device 101, the load selection device 101 further cuts the signal from the setter of the load circuit breaker F2 selected for the next load. The total load capacity at this time is as follows. PL3+PL4+PL5=ΣPL2 If PR2<ΣPL2 at this time, the next load circuit breaker 52F3 is set to PR2 according to the load selection order.
Cut the signals from each setter of the load breaker until >ΣPL□.

When this condition is satisfied, the signal from the discrimination device 107 is not input to the load selection device 101 at that point, so the operation of the load selection device 101 is stopped and waits for the next signal to come in. .

[0020] If an accident occurs in the power receiving system under such conditions, after the power receiving circuit breaker trips, only the selected load circuit breaker will be tripped by the load command judgment device, and other important load circuit breakers will be tripped. Load circuit breakers for loads, etc. do not trip and remain closed.

[0021] Since each load circuit breaker whose load has been sheared by the load command discriminator 91 has been determined by the storage device of the load command discriminator 91, it is possible to determine whether each load circuit breaker whose load has been sheared has tripped. to catch. Each load circuit breaker connected to the load circuit is disconnected, and the undervoltage relay 15 confirms that there is a normal system voltage, and the closing coil of the power receiving circuit breaker 11 on the normal power receiving side is energized and closed, but it is not normal. Since the power receiving capacity and each load capacity on the power receiving side are confirmed in advance, it is unlikely that the overcurrent relay for overload protection of the power receiving system will operate and cause a complete power outage when a normal power receiving circuit breaker is closed. None.

Further, even after tripping the power receiving circuit breaker due to an accident in the power receiving side system, all of the load circuit breakers are not tripped, so that automatic power failure/recovery switching can be performed in a short time. Note that the same applies when power is being received on the power receiving 2 side.

Further, in this embodiment, an under-voltage relay or the like is used for checking the voltage, but any device such as a voltage relay or a meter relay may be used as long as it can check the voltage. It is also possible to check the operation of the circuit breaker by checking the presence or absence of an output from a current transformer, etc.

[0024]

[Effects of the Invention] As described above, the present invention provides a line switching device,
A load command discrimination device is installed, and in the event of an accident or when a maintenance point is red, the target power receiving side is forcibly shut off and automatic switching is performed based on the power receiving capacity and each load capacity, resulting in the following effects: play.

(1) When it is desired to switch lines for maintenance inspection, etc., all confirmation items such as which line is currently receiving power and whether there is voltage on the side of the line to be switched are carried out within the power failure/recovery automatic switching device. Therefore, the work required during maintenance and inspection can be reduced.

(2) Since the load is set based on the load capacity that takes into account the power capacity of the backup line and the inrush capacity at the time of load application, there is no trouble due to system fluctuation or voltage drop during the inrush. Smooth line switching is possible. (3) Since line switching is performed while leaving only important loads among each load, the time required to cut off each load is significantly shortened.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a load command determination device for an automatic power failure/recovery switching device according to the present invention.

FIG. 2 is a system diagram of a general two-line power reception system.

[Explanation of symbols]

3, 4…Power receiving circuit breaker
5, 6...Load circuit breaker 91...Load command determination device
101...Load selection switch 102, 103...Setting device
106...Comparator 107...Discrimination device

Claims (1)

[Claims] [Claim 1] A power receiving system having a plurality of power receiving systems connected from a power supply line to a load circuit breaker via a disconnector and a power receiving circuit breaker,
A power failure/recovery automatic switching device that detects an abnormality in the power receiving system from a power receiving signal obtained through the disconnector, operates the power receiving circuit breaker and the load circuit breaker, and switches from the abnormal power receiving system to the normal power receiving system, a line switching means for dividing the power receiving system into a regular system and a backup system and switching to the backup system by tripping a power receiving circuit breaker of the regular system; a load selection means for selecting the order of loads to be cut off; A setting means for setting the power reception capacity of the power reception circuit breaker and the maximum load capacity of the load circuit breaker, and the sum of the power reception capacity value and the maximum load capacity value from each setting means are compared, and the power reception capacity value is determined by comparing the sum of the power reception capacity value and the maximum load capacity value from each setting means. and a comparison/discrimination means for tripping load circuit breakers in the order selected by the load selection means until the load selection means becomes larger.