JPS586078Y2 - Electricity derivation device - Google Patents

Description

[Detailed description of the invention] This invention uses a switch to change the input electricity amount and the output electricity amount of an electrical device into which a plurality of input electricity quantities are input and output an output electricity quantity corresponding to each of these input electricity quantities. The present invention relates to an electrical quantity deriving device that sequentially derives electric quantities using .

Hereinafter, for convenience of explanation, the conventional electrical quantity deriving device of this kind and the electrical quantity deriving device according to this invention will be explained by showing an example of its use in a digital differential relay that protects a transformer. The use of the quantity derivation device is not limited to digital differential relays that protect transformers;
It can be applied to electrical devices in general.

FIG. 1 is a block diagram showing an example of a conventional electrical quantity deriving device used in an input circuit of a digital differential relay for protecting a transformer.

In Figure 1, 1 is a transformer, 2 A1 s 2 A2
t2A3 is an input current transformer that detects the input current, 2B1
゜2B2, 2B3 are output side current transformers that detect the output current,
3 is a sampling hold circuit, 4 is an analog-to-digital converter, 5A1, 5A2, 5A3 are input side switching contacts,
5B1, 5B2, and 5B3 are output side switching contacts, and 6 is a switching device consisting of a rotary switch or the like.

Although the current to be detected by the input current transformer 2At v 2 A2 s 2 A3 passes through the transformer 1, the current to be detected by the output current transformer 2B1.2B2.2B3 corresponds to the current to be detected by the output current transformer 2B1.2B2.2B3. There is.

In practice, the sampling and holding circuit 3 analog-to-digital converter 4 connects each current transformer 2 A1 t 2 A
One each is provided for 2 s 2 A3 t2B1, 2B2, and 2B3, but those corresponding to 2A1゜2 A2.2 Bt and 2 B2 are not shown in order to avoid complication of the drawing.

Switching contacts 5A, 5A2, 5A3, 5B□. 5B2,5
B3 are current transformers 2A1, 2A2゜2 A3.2, respectively.
It is provided corresponding to Blt 2 B2 t 2 B3.

The sampling hold circuit 3 is a circuit that is driven by a gate signal synchronized with the changeover switch 6 and temporarily stores input.

The electric quantity deriving device shown in FIG. 5A1, 5A2, 5A3, 5
It is derived by switching in the order of B1, 5B2, and 5B3.

When the time required for the switch 6 to switch all the switching contacts is very short, for example, the input current value derived from the input side switching contact 5A1, which is a mutually corresponding current value, and the output side switching The output current value derived from the contact 5B1 is sampled at the same time by the sample/halt circuit 3, and can be treated as having been derived at the same time. Therefore, the input current value and the output current The difference between the two values can be used as the input signal of the differential protection relay.

As is well known, in a differential protection relay, it is necessary to use the difference between an input current value and an output current value detected at the same time as an input signal.

The switching speed of a switching device such as a rotary switch is very fast, and the time required to switch one step is several nanoseconds (In seconds is 10-9 seconds), so the above is not necessary unless the number of switching contacts becomes extremely large. You can satisfy your sexual needs.

As this type of conventional electric quantity deriving device, various devices other than the one shown in FIG. 1 have been proposed.

The electric quantity deriving device shown in FIG. 2 has one analog-to-digital converter 4 common to the entire device, thereby reducing the number of analog-to-digital converters 4, thereby making the device cheaper.

The electrical quantity detection circuit shown in FIG.
The cost of the entire device can be further reduced by providing only one unit.

The switching order by the switch 6 of the electrical quantity deriving device shown in FIGS. 2 and 3 is the same as that of the electrical quantity deriving device shown in FIG. 1.

In other words, the input side switching contacts are 5 AI, 5 A2.5
Switch in the order of A3, then switch the output side switching contact to 5B1
It switches in the order of 5B2 and 5B3.

However, in the electric quantity deriving devices shown in FIGS. 1, 2, and 3, when the number of detectors such as current transformers increases, or in other words, when the number of switching contacts increases, the switching device 6 can switch all the switches. This has the disadvantage that it takes a long time to switch the contacts, making it difficult to derive and compare the amount of electricity at the same time.

That is, for example, the input amount of electricity derived from the input side switching contact 5A1 must be compared with the output amount of electricity derived from the corresponding output side switching contact 5B1 at the same time.

However, when the number of switching contacts becomes very large, it takes a considerable amount of time for the switching device 6 to select the input side switching contact 5A1 and select the corresponding output side switching contact 5B1.
It becomes difficult to derive and compare the input electrical quantity and the output electrical quantity, which correspond to each other, at the same time.

The reason for this is that in all of the conventional electric quantity deriving devices described above, the switching order of the switch 6 is such that first, all input side switching contacts are switched and selected, and then all output side switching contacts are switched and selected. This is because

This idea was devised in view of the drawbacks of the conventional electric quantity deriving device described above, and when the number of switching contacts is very large,
This paper proposes an electrical quantity derivation device that derives corresponding input electrical quantities and output electrical quantities almost at the same time.

FIG. 4 is a block diagram showing an embodiment of the electrical quantity deriving device according to this invention.

In FIG. 4, the switching order of the switch 6 is input end switching contact 5A1, output end switching contact 5B1. Input side switching contact 5A
2, the output side switching contact 5B2, the input side switching contact 5A3, and the output side switching contact 5B3.

That is, the outputs of the input-side current transformer and the output-side current transformer that are in a corresponding relationship are alternately derived.

By doing so, when deriving the input electrical quantity and the corresponding output electrical quantity, for example, the input electrical quantity is obtained from the input side switching contact 5A1, and then the input electrical quantity is inputted from the output side switching contact 5A1.
The corresponding output electricity amount can be derived from B1 by the time difference required for the switch 6 to switch by l steps.

Since the switching speed of a switching device such as a rotary switch is several nanoseconds per step, an input electrical quantity and a corresponding output electrical quantity can be derived almost at the same time.

Therefore, an accurate input signal can be given to the differential protection relay which receives the current of the difference between the corresponding input and output currents detected at the same time.

In the above, the electrical quantity deriving device according to this invention has been explained by showing the input circuit of a digital differential protection relay that protects a transformer, but the electrical quantity derivation target is not limited to transformers, but also buses, transmission and distribution lines. The target may be electrical equipment such as

Furthermore, it goes without saying that the use of the electrical quantity deriving device according to this invention is not limited to digital differential protection relays, but can be generally used for devices that compare the input electrical quantity and output electrical quantity of electrical equipment.

As described above, the electric quantity deriving device according to the present invention detects the output and output electric quantity of the input electric quantity detector in the above-mentioned correspondence relationship in an electrical device in which a plurality of electric quantities in a corresponding relationship are input and output. Since the output of the device is alternately derived, an accurate input signal can be given to a device that compares the amount of input electricity and the amount of electricity output from the electrical equipment.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing an example of a conventional electrical quantity deriving circuit, and FIGS. 2 and 3 are block diagrams showing other examples of the conventional electrical quantity deriving circuit. FIG. 4 is a block diagram showing an embodiment of the electric quantity deriving circuit according to this invention. In the figure, 1 is an electrical device such as a transformer, 2A1゜2
A2 t 2 A3 is an input electricity quantity detector such as a current transformer,
2B1.2B2, 283 is an output electricity quantity detector such as a current transformer, 5 A1 y 5 A2.5 A3 is a switching contact provided corresponding to the input electricity quantity detector 2A1, 2A2, 2As, 5B1, 5B2 , 5B3 are switching contacts provided corresponding to the output electricity quantity detectors 2B, , 2B2, 2B3, and 6 are switching contacts 5A1, 5A2, 5A3° 5B2.
, 5B3. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] a plurality of input electricity quantity detectors that derive an input quantity of electricity from each phase on the input side of the electrical equipment; a plurality of output electricity quantity detectors that derive an output quantity of electricity from each phase on the output side of the electrical equipment; has a switching terminal, and connects each output terminal of the input and output electricity quantity detector to the switching terminal so as to guide the input and output electricity quantities of mutually corresponding phases to the adjacent switching terminals. and a switching device that sequentially outputs each input and output amount of electricity by switching each of the switching terminals at a predetermined switching speed.