JPS5915256B2 - network protector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a network protector used in a network system, and particularly to one that promotes overvoltage application during a leading load.

In recent years, there has been a demand for a highly reliable power supply method with less voltage fluctuations for high-density loads such as buildings, and in response to this demand, the network power supply method (hereinafter simply referred to as the network method) has been developed. was developed.

Figure 1 is a system diagram of the conventional network power supply system.
1 is the power transformer installed at substation S, 2 is the secondary circuit breaker of this transformer, 3 is the busbar of substation S, 4A to 4C are feeder circuit breakers, and 5A to 5C supply power to the load. 6A-6C are disconnectors, 7A-IC are network transformers, 8A-8C are network fuses, 91A-91C and 92A-92C are voltage transformers respectively, 10A-10C are current transformers, IIA- 11C is a network relay, and each of the voltage transformers 91A to 9
IC and 92A~92C5 and current transformer 10A~1
Network protectors 12A to 12 from 0C respectively
Input the primary side voltage, secondary side voltage, and primary side current of the protectors 12A to 12C under predetermined conditions.
It opens and closes.

Further, 13 is a network bus line, and 14 is a high-density load group.

By the way, the protectors 12A to 12C are unique to the network system, and are usually used for the relays 11A to 1.
1C provides the following three characteristics.

(a) Reverse current cutoff in the event of an accident, etc. of feeders 5A to 5C.

(b) A no-voltage turn-on characteristic that is automatically turned on when the network bus 13 has no voltage.

(t Overvoltage application characteristics for supplying power to the load group 14 during feeder power transmission.

It goes without saying that the characteristics of the protectors 12A to 12C, that is, the conditions for operating the protectors, are controlled by the functions of the corresponding relays 11A to 11C, but here, the overvoltage characteristics of the protectors 12A to 12C described above will be explained. do.

This characteristic occurs when there are both closed-circuit protectors and open-circuit protectors.

This relates to the closing operation of the open protector.

Therefore, assume that protectors 12A and 12C are now closed, and protector 12B is open.

At this time, if the feeder 5B is energized and a voltage e1 is generated on the secondary side of the network transformer 7B via the disconnector 6B, the protector 12B is charged with the difference between this voltage e1 and the voltage e2 of the network bus 13. voltage △e(△e
=e1-e2) is applied between the two poles of the protector 12B.

When these voltages e1 and e2 have a predetermined vector relationship, the relay 11B operates to close the protector 12B.

Expressing this as a formula, △e=(el −e2)...
......B1) However, △e > O, and putting these together, (el - e2 ) = △e > O...
......(2).

That is, in order for the protector 12B to apply overvoltage, the following conditions are required: (a) (el-82)=Δe>0.

Furthermore, even if these conditions are satisfied, (b) △
Condition where the phase of e is a phase that does not generate pumping.

is necessary.

Here, the phase of Δe that generates the pumping in (b) will be explained with reference to FIG.

FIG. 2 is a characteristic diagram showing overvoltage application and reverse current cutoff regions of relays 11A to 11C.
It is shown in the positive direction of the vertical axis with reference to the voltage e2 of No. 3.

If the voltage Δe between the electrodes of the protector 12B is now generated in the direction of Δea shown in the figure, that is, in the overvoltage closing region of the first quadrant, the relay 11B operates to close the protector 12B.

However, due to the voltage Δea, a transient current ΔIea flows through the protector 12B through the inductance of the transformer of the network system with a delay of nearly 90° relative to the phase of the slope a.

However, as shown in the figure, this transient current ΔIea occurs in the fourth quadrant and enters the reverse current cutoff region, and the relay 11B operates to cut off the protector 12B.

Therefore, the protector 12B causes a so-called pumping phenomenon in which the closing operation and the cutting operation are repeated.

However, the phase of △e advances from e2 like △eb,
In other words, if el is ahead of 82 and exists in the overvoltage input region, the transient current △Ieb due to the above △eb
occurs in the first quadrant as shown in the figure, and does not enter the reverse current cutoff region and there is no risk of pumping occurring.

That is, in this case, the overvoltage is applied to the protector 12B.

So, if el is ahead of e2, will it be thrown in even in the same case?This is not the case.

For example, even if Δe occurs in the second quadrant like Δec, the overvoltage will not be applied because it does not exist in the overvoltage application region.

Further, even when Δe occurs in the third quadrant like Δed, the overvoltage is not applied because it does not exist in the overvoltage application region.

Furthermore, in this case, since △ed exists in the third quadrant, the above condition (a) is satisfied (el-e2)-△
Since the condition e>O is not satisfied, overvoltage is naturally not applied.

In order to form the overvoltage application area, conventionally, as shown in FIG. 3, contacts 21 of a main control relay and contacts 22 of a phase check relay are used as components of a network relay, and the phase check relay is used to prevent pumping. However, as shown in Figure 2, it narrows down areas where it is better to apply the relay (for example, △ec), or narrows down areas where it should not be applied due to the limitations of relay characteristics (for example, △ec). ea)
I also have one.

Therefore, the region in which the contacts 21 and 22 are closed is when Δe exists in the overvoltage application region of FIG. 2, and at this time, the application coil 23 of the protector is energized and the protector is applied with an overvoltage.

However, the purpose of network power supply is to stabilize the power supply, and it is preferable to turn it on unless the protector causes pumping.

This invention was made in view of the above-mentioned circumstances, and as long as there is no possibility of the protector causing pumping (in other words, when el is ahead of 02, △e is the second
or enter the third quadrant and do not cause pumping),
The purpose is to forcefully turn on the protector and thereby stabilize the power supply.

Therefore, the present invention does not use a main control relay and a phase check relay, but uses, for example, a phase detection relay that detects that voltage e1 is ahead of voltage e2 and closes the contact 24 as shown in FIG. This is a forced input.

The region where the contact 24 is closed is the voltage e in FIG.
It will be on the left side of 2.

With the above configuration, the present invention has a simple configuration using a single phase detection relay to apply overvoltage to the protector, instead of applying overvoltage to the protector using two relays, a main control relay and a phase check relay. The system is designed to force the user to make an investment.

As described above, according to the present invention, the protector is forcibly turned on on the condition that the voltage e1 on the power supply line side of the protector is ahead of the voltage e2 on the load side. By using the contacts of the network relay and the contacts of the phase check relay as components of the network relay, it is now possible to forcibly close the area where it was originally possible to close, which was not possible in the past, expanding the overvoltage closing area and increasing the Pumping due to input is eliminated and stable power can be sent to the load.

[Brief explanation of drawings]

Figure 1 is a system diagram of a conventional network power supply system, Figure 2 is a characteristic diagram showing the characteristics of a network relay, Figure 3 is a conventional protector input circuit diagram, and Figure 4 is a protector input circuit diagram of the present invention. . 5A to 5C...Feeder, 12A to 12C...Protector, 14...Load.

Claims (1)

[Claims] 1. A network protector having a plurality of feeders that supply power from a substation to a load, and a network protector connected to each of the feeders via a disconnector, a network transformer, and a network fuse, wherein two of the network transformers A network protector comprising: a phase detection means for detecting that the phase of the next-side voltage is ahead of the phase of the network bus voltage, and forcibly turning on the network protector.