JPH0515048A - Current ratio differential relay equipment - Google Patents

Abstract

PURPOSE:To provide a current ratio differential relay equipment capable of making uniform connecting forms of a current transformers to be connected to the primary side and secondary side of a transformer regardless of the connecting form of a transformer to be detected. CONSTITUTION:Modes of connections at three secondary circuits of auxiliary current transformers 21 to 26 with taps attached can be selected such as either delta connection or star connection by providing change-over switches 61 to 68 for changing the modes of connections in the secondary circuits of said auxiliary current transformers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current ratio differential relay device for detecting an internal failure of a transformer that transforms an AC voltage.

[0002]

2. Description of the Related Art FIG. 6 is an internal circuit diagram of a conventional general current ratio differential relay device 1. In the figure, the tapped auxiliary current transformers 21 to 26 are a transformer ratio of a transformer to be detected, which will be described later,
It is provided for compensating the conversion ratio that is integrated with the current ratio of the current transformer that is connected to the primary side and the secondary side of the transformer and measures the alternating current flowing in the transformer circuit. Ratio differential current detector 31 (87R), 32 (87S), 33 (87T) is an auxiliary current transformer with tap 2
The ratio difference current is detected from the secondary side currents of 1 to 26. Also,
The current ratio differential relay device 1 has external connection terminals a to h.

FIG. 7 is a circuit diagram showing an application example of the above-described current ratio differential relay device 1 when the transformer 4 to be detected has a delta-delta connection. In addition, in the internal circuit of the current ratio differential relay 1, the auxiliary current transformer with tap 21
For ~ 26, the taps are not shown and are simply shown. Current transformers 51 to 53 are connected to each phase of the primary side of the transformer 4. Secondary side one ends of the current transformers 51 to 53 are connected to the external connection terminals a to c of the current ratio differential relay device 1, respectively, and the other ends are commonly connected to the external connection terminal d. Similarly, current transformers 54 to 56 are provided in each secondary side phase of the transformer 4 and are connected to the external connection terminals e to g and h.

FIG. 8 shows the current transformers 51 to 56 and the current ratio differential relay device 1 when the transformer 4 is connected in a star-delta connection mode.
It is a circuit diagram showing the connection with. 7 is different from the circuit shown in FIG. 7 in the manner of connecting the current transformers 51 to 53 to the current ratio differential relay 1. That is, the current transformers 51 to 53 are delta-connected and not connected to the external connection terminal d.

Similarly, FIG. 9 is a circuit diagram in the case where the connection mode of the transformer 4 is a delta-star connection, and is different from the circuit shown in FIG. 7 in the current ratio differential relay devices of the current transformers 54 to 56. The connection mode to 1 is different.

Further, FIG. 10 is a circuit diagram in the case where the wiring mode of the transformer 4 is star-star connection, and is different from the circuit shown in FIG. 7 in the current ratio differential relay device 1 of the current transformers 51 to 56. The connection mode is different.

Next, the operation of the above conventional example will be described. For example, in the circuit of FIG. 7, since the transformer 4 to be detected has a delta-delta connection, the current transformers 51 to
By making the connection of 53 and 54-56 respectively star connection, the transformer of the output current of each phase of the current transformer 51-53 and 54-56 which is input to the current ratio differential relay 1 in the normal state. The difference between the primary current and the secondary current of 4 and the phase difference are eliminated, and the current is compensated so that the waveforms are substantially the same.
This current compensation considers only the connection mode of the transformer 4, and does not compensate for the transformation ratio of the transformer 4 and the transformation ratio of the current transformers 51 to 56.

Compensation for the conversion ratio of the transformer ratio of the transformer 4 and the transformer ratio of the current transformers 51 to 56 is carried out by compensating the current ratio differential relay device 1.
It is performed by tap switching of the auxiliary current transformers 21 to 26 with taps inside. As a result, when the transformer 4 is normal, the ratio difference current (I11-i11) shows a value close to zero in the R phase, for example, and the ratio difference current detectors 31 to 33 do not operate. S phase and T
The same applies to the phases.

When an internal failure occurs in the transformer 4 from the above state, the ratio difference current has a large value and any of the ratio difference current detectors 31 to 33 operates. Although the above description of the operation has been made for the circuit shown in FIG. 7, when the transformer 4 is in the star-delta connection as shown in FIG.
Similar behavior is obtained by making 56 a delta-star connection. The same applies to the circuits shown in FIGS. 9 and 10.

[0010]

In the conventional current ratio actuated relay device as described above, the transformer connected to the primary / secondary side of the transformer 4 according to the connection mode of the transformer 4 to be detected. Sink
It is necessary to change the connection mode of 51-56. However, in reality, there are many mistakes in the wiring diagram at the design stage and mistakes in the wiring work, and although the transformer 4 is normal, the ratio difference current detector inside the current ratio differential relay device 1 There was a problem that 3 worked.

The present invention has been made in order to solve the above problems, and a transformer connected to the primary / secondary side of the transformer 4 regardless of the wiring mode of the transformer 4 to be detected. It is an object of the present invention to provide a current ratio differential relay device capable of keeping the wiring mode of the flow devices 51 to 56 constant.

[0012]

A current ratio differential relay device according to the present invention comprises a first auxiliary current transformer to which a current corresponding to the primary side current of the transformer is to be input, and the transformer. Receiving a second auxiliary current transformer to which a current corresponding to the secondary side current of the first auxiliary current transformer, the output current of the first auxiliary current transformer, and the output current of the second auxiliary current transformer are received. A ratio-difference current detector for detecting a ratio-difference current, a first changeover switch connected to the secondary side of the first auxiliary current transformer and selecting a connection mode of a secondary-side circuit thereof, and the second A second changeover switch which is connected to the secondary side of the auxiliary current transformer and selects the connection mode of the secondary side circuit thereof.

[0013]

The changeover switch according to the present invention selects the connection mode of the secondary side circuit of the auxiliary current transformer, that is, either star connection or delta connection, depending on the connection mode of the primary side and the secondary side of the transformer. If possible.

[0014]

1 is a circuit diagram showing an embodiment of the present invention. In the figure, the current ratio differential relay device 1 includes auxiliary current transformers 21 to 26 with taps, ratio difference current detectors 31 (87R), 32 (87S),
33 (87T) and changeover switches 61 to 68. The changeover switches 61 to 68 are provided between the secondary side circuits of the auxiliary current transformers 21 to 26 with taps and the ratio differential current detectors 31 to 33. The changeover switches 61 to 64 and 65 to 68 are interlocked with each other. The primary side circuits of the tapped auxiliary current transformers 21 to 23 are connected to the external connection terminals a to c, respectively, and have one end connected in common to the external connection terminal d. Similarly, the primary side circuits of the tapped auxiliary current transformers 24 to 26 are also connected to the external connection terminals e to h.

FIG. 2 shows a transformer 4 in a delta-delta connection.
2 is a circuit diagram showing a state where the current transformers 51 to 56 and the current ratio differential relay device 1 shown in FIG. 1 are connected to the primary side and the secondary side of FIG. Note that the tapped auxiliary current transformers 21 to 26 in the current ratio differential relay device 1 are shown with the taps omitted. The current transformers 51 to 53 and 54 to 56 are star-connected, respectively.

Since all the change-over switches 61 to 68 are tilted to the a side, the auxiliary current transformers with taps 21 to 23 and 24 to
Each of the 26 secondary circuits is star-connected and is connected to the ratio difference current detectors 31-33. When the transformer 4 is in a normal state, current compensation is performed so that the difference current and the phase difference for each phase input to the ratio difference current detectors 31 to 33 are eliminated and the waveforms become substantially the same. This current compensation considers only the connection mode of the transformer 4, and does not compensate the transformation ratio of the transformer 4 and the transformation ratio of the current transformers 51 to 56.

Compensation for the conversion ratio, which is the total of the transformation ratio of the transformer 4 and the transformation ratio of the current transformers 51 to 56, is performed by the current ratio differential relay device 1.
It is performed by tap switching of the auxiliary current transformers 21 to 26 with taps inside. As a result, when the transformer 4 is normal, the ratio difference current (I11-i11) shows a value close to zero in the R phase, for example, and the ratio difference current detectors 31 to 33 do not operate. S phase and T
The same applies to the phases.

When an internal failure occurs in the transformer 4 from the above state, the ratio difference current has a large value and any of the ratio difference current detectors 31 to 33 operates.

Next, the application of the current ratio differential relay device when the transformer 4 is star-delta connected will be described with reference to FIG. Also in this case, the connection between the current transformers 51 to 56 and the current ratio differential relay device 1 is the same as in the case of FIG. 2, except that the changeover switches 61 to 64 are tilted to the side a. Auxiliary current transformer with tap 21 ~
The secondary side circuit of 23 is a delta connection, while the secondary side circuits of the tapped auxiliary current transformers 24 to 26 are in a star connection state because the changeover switches 65 to 68 are turned to the a side. Thus, even if the transformer 4 is a star-delta connection, the ratio differential current detector can be operated by operating the changeover switches 61 to 64.
By eliminating the difference current and phase difference for each phase input to 31 to 33, almost the same waveform is obtained.

Similarly, as shown in FIG. 4, when the transformer 4 is a delta-star connection, the changeover switches 61 to 64 are turned to the a side, and 65 to 68 are turned to the a side. The secondary side circuits of the current transformers 21 to 23 are star-connected, and the secondary side circuits of the tapped auxiliary current transformers 24 to 26 are delta connected. Further, as shown in FIG. 5, when the transformer 4 is a star-star connection, by tapping all the changeover switches 61 to 68 to the side a, the tapped auxiliary current transformers 21 to 23 and 24 to 26 are respectively connected to the delta. Make a connection.

In the above embodiment, the case of a so-called two-winding transformer protection device has been described, but it goes without saying that the same effect can be obtained even with a three-winding transformer protection device with the same configuration.

[0022]

As described above, according to the present invention, since the changeover switch for selecting the connection mode of the secondary side circuit of the auxiliary current transformer is provided, the transformer is selected regardless of the connection mode of the transformer to be detected. It is possible to provide a current ratio differential relay device in which the connection mode of the current transformers connected to the primary side and the secondary side of the transformer and the connection mode with these current transformers are invariable, and there are mistakes in connection, etc. The effect is that it can be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

2 is a circuit diagram in which the current ratio differential relay device of FIG. 1 is applied to a delta-delta connected transformer.

FIG. 3 is a circuit diagram in which the current ratio differential relay device of FIG. 1 is applied to a star-delta connected transformer.

FIG. 4 is a circuit diagram in which the current ratio differential relay device of FIG. 1 is applied to a delta-star connected transformer.

5 is a circuit diagram in which the current ratio differential relay device of FIG. 1 is applied to a star-star connected transformer.

FIG. 6 is a circuit diagram showing a conventional current ratio differential relay device.

FIG. 7 is a circuit diagram in which the current ratio differential relay device of FIG. 6 is applied to a delta-delta connected transformer.

8 is a circuit diagram in which the current ratio differential relay device of FIG. 6 is applied to a star-delta connected transformer.

9 is a circuit diagram in which the current ratio differential relay device of FIG. 6 is applied to a delta-star connected transformer.

FIG. 10 is a circuit diagram in which the current ratio differential relay device of FIG. 6 is applied to a star-star connected transformer.

[Explanation of symbols] 21 to 26 Auxiliary current transformer with tap 31 to 33 Ratio differential current detector 61 to 68 Changeover switch

Claims (1)

Claim: What is claimed is: 1. A first auxiliary current transformer to which a current corresponding to a primary side current of a transformer is to be input, and a current corresponding to a secondary side current of the transformer. A second auxiliary current transformer to be performed, and a ratio difference current detector for detecting a ratio difference current by receiving the output current of the first auxiliary current transformer and the output current of the second auxiliary current transformer A first changeover switch connected to the secondary side of the first auxiliary current transformer and selecting a connection mode of the secondary side circuit thereof, and connected to the secondary side of the second auxiliary current transformer And a second changeover switch for selecting a connection mode of the secondary side circuit, and a current ratio differential relay device comprising: