JP2910905B2 - Misconnection detection device for ratio differential relay and current transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current transformer erroneous connection detection device for checking the correctness of connection of a current transformer, and a ratio differential relay incorporating the erroneous connection detection device.

[0002]

2. Description of the Related Art As a digital type protection relay, the Electric Cooperative Research Vol. 41, No. 4, "Digital Relay", Showa 6
Published by the Japan Electric Cooperative Research Association in January 2001. FIG. 18 shows the basic configuration. In the figure, 11 is a current transformer (hereinafter referred to as CT), 12 is a filter circuit for removing a harmonic component contained in the output of CT 11 to extract the fundamental frequency (50 Hz or 60 Hz) of the power system, and 13 is a sampling circuit at sampling time. A sample and hold circuit 14 for holding the output value of the filter circuit 12; a multiplexer circuit 14 for multiplexing the output from the sample and hold circuit 13;
Is an analog / digital converter which quantizes the output of the multiplexer circuit 14 and converts it into time data based on a digital quantity.

Reference numeral 16 denotes an arithmetic processing unit which is formed of a microprocessor, a random access memory, a read-on memory, etc., performs arithmetic processing on time data from the A / D converter 15 to generate a control signal, and 17 denotes an arithmetic processing unit 16 An output interface circuit that converts a control signal of a logical level, which is an output of the relay circuit, into a control signal of a level capable of driving a relay, 18 is an exciting coil driven by a control signal from an output interface circuit 17, and 19 is an exciting coil 18. It is a contact that is opened and closed.

[0004] The specific rate differential relay to exiting the output in comparison judgment of the differential current value and the suppression current value, "protective relay technology" writer Susumu Kobayashi, electrical Shoin, 1972 October 15, first 1
The first edition is issued, 9 transformers are protected, and 9-1 power transformers are protected. FIG. 19 shows the basic configuration.

In the figure, reference numeral 40 denotes a ratio differential relay;
Is an input converter for adjusting the primary current (I ₁ ) and the secondary current (I ₂ ) so as to be equal to each other with the protection target 41 interposed therebetween. Means for generating a differential current of I ₁ -I ₂ , means for generating a suppression current of I ₁ + I ₂ , determination means for determining an abnormality of the protection target 41 by comparing the differential current and the suppression current, An output unit 49 outputs an abnormal signal at the time of abnormality determination. 46, 4
Reference numerals 7 and 48 denote A-phase, B-phase, and C-phase operation determining means for performing operation determination in each of the A, B, and C phases and detecting an abnormality.

The digital type ratio differential relay 20 shown in FIG. 20 is a combination of the digital type protection relay shown in FIG. 18 and the ratio differential relay shown in FIG. Here, for explanation of the operation, the filter 1 shown in FIG.
2, sample and hold circuit 13, multiplexer circuit 1
4, analog / digital converter 15, excitation coil 1
8. The contact 19 is included in the digital type differential relay 20 but is omitted.

In FIG. 20, reference numeral 20 denotes a digital type differential relay, 16 denotes an arithmetic processing section, and A-phase operation determining means 24 and B-phase operation determining means 2 for digitally determining an operation.
5. It includes a C-phase operation determination means 26, and performs arithmetic processing on these together. This corresponds to the A-phase operation determining means 46 and the B-phase operation determining means 4 for performing the operation determination by analog in FIG.
7, corresponding to the C-phase operation determining means 48.

[0008] 21 is a means for calculating a differential current value of I ₁ -I ₂ , 22 is a means for calculating a suppression current value of I ₁ + I ₂ , 23
In determining means for determining abnormality of the protected 41 by comparison of the differential current and restrained current are run each unit by calculating respectively the 21, 22 and 23 a microprocessor, the ratio of the conventional 19 43,4 of rate differential relay
4, 45 are supported.

As a description of the operation principle, a case of a single phase will be described. FIG. 21 shows the operation of the ratio differential relay in a steady state.
If the magnitudes of I ₁ and I ₂ change due to the above, this converter is for adjusting the current value taken into the A-phase operation determining means 24 to the same magnitude, and has already been adjusted in FIGS. 21 to 23. And

This ratio differential relay is connected to the primary side CT11.
The protection section is a protection section 51 for the ratio differential relay. The ratio differential relay outputs an operation output only when a failure such as a ground fault or a short circuit occurs in the protection section 51, and does not operate outside the protection section 51.

[0011] In Figure 21, from I ₁ ≒ I _2, differential current value means 21 for calculating the differential current value of I ₁ -I ₂ is I ₁ -I ₂ ≒
0. Here, even if an accident occurs outside the protection section 51 of the ratio differential relay as shown in FIG.
When for the ratio of I ₁ and I ₂ flowing through the secondary side CT11 is not different from the steady, differential current value is not activated next I ₁ -I ₂ ≒ 0. When an accident occurs in a section of the guard interval 51 ratio differential relay as shown in Figure 23, the I ₁ -I ₂ ≠ 0 occurs is a change in the magnitude of I ₁ and I _2. This allows the ratio differential relay to:
It operates when an accident occurs only in the section of the protection section 51.

[0012]

Since INVENTION Problems to be Solved conventional proportions differential relay is configured as described above, in the input transducer 42 of FIG. 21, adjusted to align the size of I ₁ and I ₂ Therefore, even if the adjustment is made, there is a difference between the magnitudes of I ₁ and I ₂ . Therefore, the differential current value of the means 21 for calculating the differential current value of I ₁ −I _{2 in} FIG. 20 is not I ₁ −I ₂ ≠ 0 even in the steady state, and a value of I ₁ −I ₂ = I ₃ is obtained. Come.

[0013] Here, in FIG. 21, the wrong CT11 polarity of the primary or secondary side (phase connection), for example, I ₂ is -I ₂ becomes, I ₁ - (- I ₂₎ = current value of K Comes out. Here, since the differential current value K due to the wrong polarity (phase connection) of CT and the differential current value I ₃ of the adjustment error have a certain magnitude, even if the CT polarity (phase connection) is wrong, There is a problem that a wrong CT polarity (phase connection) cannot be found in a steady state.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an apparatus for detecting an erroneous connection of a current transformer capable of detecting an erroneous polarity and phase connection of a CT. It is intended to obtain a ratio differential relay provided.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided an apparatus for detecting incorrect connection of a current transformer, comprising a protection pair connected to an AC line of a power system.
Elephant transformer, on the primary and secondary sides of this protected transformer
Two current transformers each connected, the output end of this current transformer
Power system with a ratio actuated relay connected to a
A of the erroneous connection detection device current transformer, an input amount of electricity from the two current transformers, a phase changing means for varying the phase between the two electrical quantities, corresponding to the change in the phase And a display means for displaying the value of the changed phase angle and the calculation result of the difference electric quantity corresponding to the phase angle.

In addition, the protection connected to the AC line of the power system
The transformer to be protected, the primary and secondary sides of the transformer to be protected
Current transformers connected to each side, the output of this current transformer
Power system with a ratio actuated relay connected to the
A said erroneous connection detection device current transformer systems out, as input electrical quantity from the two current transformers, a phase changing means for varying the phase between the two electrical quantity, corresponding to the change of the phase Computing means for calculating the electric quantity of the difference between the two electric quantities, and phase detecting means for detecting at least one of the phases in which the electric quantity of the difference is minimum and maximum.

[0017] In addition, before in accordance with the detection result of the position phase detection means
The current transformer is provided with a phase determining means for determining whether or not the connection is normal.

Further, the phase determining means determines that the polarity of one of the current transformers is reverse connection if the phase at which the difference electric quantity is the maximum is 0 ° or the phase at which the difference is the minimum is 180 °. It is a means to do it.

When the electric circuit is a three-phase AC circuit, the phase judging means determines that the phase at which the amount of difference is the maximum is + 60 ° or -60 °, or the phase at which the difference is the minimum is +12.
If it is 0 ° or −120 °, it is a means for determining that the current transformers of different phases are erroneously connected.

When the electric circuit is a three-phase AC circuit, the phase judging means determines that the phase at which the electric quantity of the difference is the maximum is +120.
{Or -120}, or the minimum phase is +6
If it is 0 ° or −60 °, it is a means for determining that the current transformers of different phases are erroneously connected and that the polarity of one of the current transformers is erroneously connected.

Further, the phase changing means is means for changing the phase by 0 ° to 360 ° in steps of a predetermined phase angle.

The ratio differential relay according to the present invention incorporates an erroneous connection detection device for a current transformer.

[0023]

The erroneous connection detection apparatus for a current transformer according to the present invention receives electric quantities from two current transformers to be detected as erroneous connection among the current transformers provided on the AC line. The phase between the quantities is changed by the phase changing means, the quantity of electricity corresponding to the change in the phase is calculated by the calculating means, and the value of the changed phase angle and the difference corresponding to the phase angle are calculated. The calculation result of the quantity of electricity is displayed on the display means.

Also, among the current transformers provided on the AC line,
The amount of electricity from the two current transformers to be detected as an erroneous connection is input, the phase between these two amounts of electricity is changed by the phase changing means, and the amount of electricity between the two amounts of electricity corresponding to the change in the phase is calculated. The operation is performed by the operation means, and at least one of the phases at which the amount of difference is minimum and maximum is detected by the phase detection means.

Further, among the current transformers provided on the AC line,
The amount of electricity from the two current transformers to be detected as an erroneous connection is input, the phase between these two amounts of electricity is changed by the phase changing means, and the amount of electricity between the two amounts of electricity corresponding to the change in the phase is calculated. The operation is performed by the operation means, and at least one of the phases at which the amount of difference is minimum and maximum is detected by the phase detection means, and the phase of the current transformer is determined based on the detection result. The judgment is made by the judgment means.

The phase determining means determines that the polarity of one of the current transformers is reverse connection if the phase at which the difference electric quantity is the maximum is 0 ° or the phase at which the difference is the minimum is 180 °. I do.

When the electric circuit is a three-phase AC circuit, the phase judging means determines that the phase at which the difference electric quantity is the maximum is + 60 ° or -60 °, or the phase at which the difference is the minimum is +12.
If it is 0 ° or −120 °, it is determined that current transformers of different phases are erroneously connected.

When the electric line is a three-phase AC line, the phase determining means determines that the phase at which the amount of difference is the maximum is +120.
{Or -120}, or the minimum phase is +6
If it is 0 ° or −60 °, it is determined that current transformers of different phases are erroneously connected, and that the polarity of one of the current transformers is erroneously connected.

The phase changing means changes the phase by 0 ° to 360 ° in steps of a predetermined phase angle.

The ratio differential relay of the present invention incorporates an erroneous connection detection device for a current transformer.

[0031]

【Example】

Embodiment 1 FIG. First, the operation principle of detecting polarity and phase connection due to erroneous CT connection will be described. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 to 9 are vector diagrams for explaining the principle.

In FIG. 1, reference numerals 30 to 35 constitute an erroneous connection detection device for detecting erroneous connection of a current transformer. 3
0 is a test switch for phase change, it sends a signal for changing the phase between I ₁ and I ₂ by a predetermined angle between 0 ° and 360 ° with each press of the test switch. Reference numeral 31 denotes a phase changing means for changing the phases of I ₁ and I ₂ by a predetermined angle in accordance with a signal from the phase change test switch 30. Numeral 32 denotes a calculating means for calculating a differential current value of I ₁ -I ₂ . 33 is a phase detecting means for detecting a phase at which the differential current value of I ₁ -I ₂ is maximum or minimum.

The currents I ₁ and I ₂ from the input converter 42 are supplied to the phase changing means 3 in response to a command from the phase changing test switch 30.
1 changes the phase between I ₁ and I ₂ at predetermined intervals. To change this phase, the analog waveforms I ₁ and I ₂ are sampled and digitized, and the digitized I 2
To obtain a desired phase from ₁ and I ₂ of the waveform, it can be a phase change by extracting the two waveform values with a time difference corresponding to the phase.

The difference between the extracted I ₁ and I ₂ is calculated by arithmetic means 3
2 to obtain a differential current value of I ₁ −I ₂ . The phase detecting means 33 detects the phase (angle) at which the differential current value of I ₁ -I ₂ is maximized. If the phase at which the detected differential current value becomes the maximum is a phase that causes an erroneous connection, the phase determining means 34 determines that the erroneous connection is made. In response to this determination, the output means 35 sends an erroneous connection signal to the outside. As described above, the erroneous connection of the current transformer can be detected.

The operation described above will be described using vectors. FIG. 2 shows that a differential current of I ₁ −I ₂ (= I ₃ ) is generated when the polarity of CT11 is correctly connected in FIG. Here, as shown in FIG.
The phase is sequentially changed from 0 ° to 360 ° by pressing the phase change test switch 30 of FIG. In this figure, I ₂ is fixed and I ₁ is changed, and the vector I shown by the dotted line is changed.
A differential current value of ₁₋ I ₂ (= I ₃ ) is obtained.

FIG. 4 shows the locus of the differential current value of I ₁ -I ₂ (= I ₃ ). That is, at the phase 0 °, I ₃ becomes minimum, and at the phase 180 °, I ₃ becomes maximum. If, if the wrong polarity, the phase of I ₁ or I ₂ is changed 180 degrees, I ₃ as 180 ° in Figure 4 Ru maximized Do <br/>. If the phase of I ₁ is changed by 180 ° in this state, the vector value becomes the vector value at the position of 0 ° in the figure, and I ₁ −I ₂ (=
It can be seen that the differential current value of I ₃ ) is minimized and the polarity is wrong. Therefore, when the phase is changed by 0 ° or 360 °, the polarity is wrong if the differential current value of I ₁ −I ₂ (= I ₃ ) becomes maximum.

Next, the case of three phases will be described. In FIG. 5, when the relay adopts a three-phase alternating current in which the A-phase, the B-phase, and the C-phase have a phase shift of 120 ° from each other, CT
Are the same, and I ₁ and I ₂ are A phases (B phases and C phases, whichever may be).
2 to 4 are maintained.

However, if the phases taken in by I ₁ and I ₂ are wrong, the phases of I ₁ and I ₂ are different by 120 ° as shown in FIG. 6, and the value of I ₁ −I ₂ becomes large. Here, by pressing the phase change test switch 30 in FIG. 1 the phase of I ₁ 0
When the phase is changed from 方向 (the state where I ₁ -I _{2 in} FIG. 6 is 120 °) to 360 °, the vector locus becomes I ₁ -I ₂ as shown in FIG. That is, it becomes maximum at 60 ° and becomes minimum at 240 °. (300 ゜) in parentheses,
(120 °) is an angle when the phase is changed in the direction of delay.

[0039] If it is this way, the polarity of the CT will match you make a mistake phase to incorporate to the relay in the I ₁ and I _2, I ₁ and I ₂
, A phase difference of 120 ° appears. When the phase is changed from this state by ± 60 ° (leading and lagging by 60 °),
If the differential current value of I ₁ −I ₂ (= I ₃ ) is at the maximum in either one of the lead and the delay, it can be determined that only the phase connection is wrong. Further, when the phase is changed by ± 120 ° (lead or lag by 120 °), if either one of the leading and the lag, the differential current value of I ₁ −I ₂ (= I ₃ ) becomes minimum , It can be determined that only the phase connection is wrong. Similarly, if the phase is advanced at 60 ° and becomes maximum at 240 ° and becomes minimum, or if the phase is delayed and becomes 120 ° and minimum at 300 °, only the phase connection is wrong. Can be determined.

Next, let us consider a case where the phase to be taken into the relay is wrong between I ₁ and I ₂ and the polarity of the wrongly taken phase is wrong. The phase relationship between the input of I ₁ and I ₂ is 180 ° for wrong polarity, 120 ° for wrong phase input,
Therefore, 300 °, that is, the phase difference between I ₁ and I ₂ is 60 ° as shown in FIG. If the phase is changed from 0 ° to 360 ° in this state, a vector locus of I ₁ -I ₂ as shown in FIG. 9 is obtained.

The phase is set to ± 120 ° (12
0 ゜) When changed, either I lead or lag, I
_If the differential current value of ₁₋ I ₂ (= I ₃ ) becomes the maximum, it can be determined that the phase connection and its polarity are also wrong. Also,
When the phase is changed by ± 60 ° (leading and delaying by 60 °), I ₁ −I ₂ (= I ₃ )
If the differential current value is the minimum, it can be similarly determined that the phase connection and its polarity are also wrong. When the phase is advanced and becomes minimum at 60 ° and becomes maximum at 240 °, or when the phase is delayed and becomes maximum at 120 ° and becomes minimum at 300 °, the phase connection and its polarity are similarly performed. Can also be determined to be incorrect.

FIG. 10 is a diagram showing the relationship between the maximum and the minimum of the differential current value when the phase is changed, and the determination result.

The above is the operating principle of the present invention for detecting an erroneous CT connection. Next, specific examples will be described. FIG. 11 is a diagram showing a main part of an apparatus for detecting an erroneous connection of a CT in the ratio differential relay. The arithmetic processing unit 16 of the ratio differential relay shown in FIG. 1, a protection target 41 such as a transformer, CT11, and an input conversion are shown. The device 42 and the like are omitted, and the I
It is shown from the part where ₁ and I ₂ are introduced.

In the figure, 30, 31, 32, and 35 are the same as those in FIG. 61 is the calculating means 3
Means for detecting the phase when the differential current value becomes the maximum among the differential current values of I ₁ -I ₂ calculated in 2 and 62 are means for determining whether the phase detected in 61 is 0 °. .

In operation, every time the phase change test switch 30 is pressed, the phase is changed by the phase changing means 31, and the value of I ₁ -I ₂ corresponding to the changed phase is calculated by the calculating means 3.
2, the means 61 for detecting the phase at which the differential current value of I ₁ -I ₂ is the maximum detects the phase at the maximum value, and the means 62 for determining whether the phase is 0 ° is detected. If the phase is 0 °, a signal is sent from the output means 35 to the outside. This signal may be displayed on a display device such as "current transformer polarity misconnection". It may be an alarm sound or a sound output such as "The polarity of the current transformer is wrong."

FIG. 12 is a flowchart showing the operation of detecting the erroneous connection. The currents I ₁ and I ₂ are read (S1), and I ₁
And I ₂ are sequentially changed by 0 ° to 360 ° (S
2). The differential current value between I ₁ and I ₂ is calculated (S3), and is repeated until the phase reaches 360 ° (S4). When the angle reaches 360 °, the phase at which the differential current value becomes the maximum value is detected (S
5) It is determined whether the detected phase is 0 ° (S6). If the result of the determination is YES, a signal of incorrect polarity connection is output (S
7) If NO, send a signal of normal polarity connection (S)
8). If the polarity is normal, the signal need not be sent, but sending the normal signal will help the person who checks the signal.

As described above, it is possible to easily check a wrong polarity of the CT, which cannot be detected by the conventional ratio differential relay, and to prevent a malfunction of the relay due to a wrong connection of the CT. Further, in this case, the content of the wrong connection of the CT can be determined to be “incorrect of the polarity of the CT”, so that when the CT is replaced, the construction content is very clear and the work efficiency is improved.

Embodiment 2 FIG. In the present embodiment, similarly to the first embodiment, a CT polarity error is detected, and the configuration of the main part is shown in FIG. As shown in FIG. 13, there are provided means 71 for detecting a phase at which the differential current value of I ₁ -I ₂ is minimized, and means 72 for determining whether the phase is 180 °.
Means 73 for storing the minimum value of the differential current value of ₁₋ I ₂ is provided.

In operation, a phase at which the differential current value becomes a minimum value is obtained, and if the phase is 180 °, it is determined that the polarity of CT is wrong. Here, the means 73 for storing the value determined that the differential current value of I ₁ −I ₂ is the minimum is provided by I
Because and storing the minimum value of ₁ -I ₂ differential current, I ₁ -I ₂ being detected during normal at I ₁ and I ₂ of the adjustment limit (error)
This is because there is an advantage that the differential current value can also be stored and the normal I ₁ -I ₂ differential current value can be known.

Embodiment 3 FIG. A description will be given of a case where, in three-phase AC, erroneous connection between CTs of different phases is detected. FIG. 14 is a diagram showing a configuration of a main part of the erroneous connection detection device, which is the same as FIG. 11 of the first embodiment except for a means 74 for determining whether the phase is ± 60 °. I ₁ -I ₂
The phase at which the differential current value of (= I ₃ ) becomes maximum is detected, and if the phase is ± 60 ° (+ 60 ° or −60 °), it is determined that CTs of different phases are erroneously connected.

Embodiment 4 FIG. In this embodiment, similarly to the third embodiment, an erroneous connection between CTs of different phases is detected.
It is shown in FIG. FIG. 15 is provided with a means 75 for determining whether the phase is ± 120 °, and the other configuration is the same as that of FIG. 13 of the second embodiment. The phase at which the differential current value of I ₁ −I ₂ (= I ₃ ) is minimum is detected, and the phase is ± 120 ° (+ 120 ° ).
{Or -120}), it is determined that CTs of different phases are erroneously connected.

Embodiment 5 FIG. This embodiment detects an erroneous connection between CTs of different phases in a three-phase alternating current, and detects an erroneous connection when any one of the CTs has an incorrect polarity. FIG. The configuration is shown. FIG. 16 shows a configuration in which means 75 for determining whether the phase is ± 120 ° is provided.
Is the same as The phase at which the differential current value of I ₁ −I ₂ (= I ₃ ) is maximum is detected, and the phase is ± 120 ° (+ 120 ° ).
{Or -120}), it is determined that there is an erroneous connection between CTs of different phases and that the polarity of one of the CTs is wrong.

Embodiment 6 FIG. In this embodiment, similarly to the fifth embodiment, an erroneous connection between CTs of different phases is detected when one of the CTs has an incorrect polarity, and FIG. 2 shows the configuration of the unit. FIG. 17 is provided with a means 74 for judging whether the phase is ± 60 °, and the other parts are the same as FIG. 15 of the fourth embodiment. A phase in which the differential current value of I ₁ −I ₂ (= I ₃ ) is minimum is detected, and if the phase is ± 60 ° (+ 60 ° or −60 °), erroneous connection of CTs of different phases is performed. It is determined that the polarity of one of the CTs is wrong.

Embodiment 7 FIG. In the above embodiment, the configuration of the erroneous connection detection device has been described for various cases of erroneous connection.
The phase detecting means 33 shown in FIG. 1 is means for detecting one or both of the phase at which the differential current value of I ₁ -I ₂ (= I ₃ ) is the minimum and the phase at which the differential current value is the maximum. As shown, the maximum / minimum relation of the differential current value when the phase is changed and the result of the determination are stored in a memory as a table, and the phase detected by the phase detection means 33 and the table And a phase determining means for determining in accordance with the comparison. Then, a display means may be provided to display the content of the determination result and output it by voice. In this way, even if there are various causes of erroneous connection, the CT connection check can be performed at once, and all checks can be easily performed in a short time.

Embodiment 8 FIG. In this embodiment, the phase is not changed every time the phase change test switch 30 is pressed in FIG. 1, but the phase change test switch 30 only sends a start signal for detecting the start of erroneous connection. The means 31 sets the phase at a predetermined interval (for example, 10
The angle may be automatically changed from 0 ° to 360 ° at each time.

Embodiment 9 FIG. In addition, I ₁
When the phase at which the differential current value of −I ₂ is minimum or maximum is detected, the phase is displayed or printed out using a display or a printer as a display means, and a person who checks the phase is shown in FIG. The connection state may be determined using the chart of FIG. Also, I ₁ −I ₂ (= I ₃ ) when the phase is changed by 0 ° to 360 ° by the calculating means 32.
The calculation result of the differential current value, I ₁ as shown in FIGS. 4 and 7 and 9 using a display or a printer as a display means
The locus of the differential current value of −I ₂ may be drawn so that the person who checks the information can make the determination.

Embodiment 10 FIG. In the above embodiment, the example in which the erroneous connection detection device of the CT is incorporated in the ratio differential relay is described. However, the erroneous connection detection device may be configured as a single device without being incorporated in the ratio differential relay.

[0058]

As described above, according to the present invention, the phase between two electric quantities for checking the connection state is changed, and an error is detected from the relationship between the magnitude of the difference between the two electric quantities and the phase. Since the connection is determined, it is possible to easily detect an erroneous connection.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a ratio differential relay according to Embodiment 1 of the present invention.

FIG. 2 is a vector diagram of an I ₁ -I ₂ differential current generated when a CT connection is correct.

FIG. 3 is a vector diagram when the phases of I ₁ and I ₂ are changed in FIG. 2;

FIG. 4 is a diagram showing a vector locus of the differential current in FIG. 3;

FIG. 5 is a diagram illustrating a phase relationship of three-phase alternating current.

FIG. 6 is a vector diagram showing a phase relationship when phases of I ₁ and I ₂ are wrong.

FIG. 7 is a diagram showing a vector locus of the differential current in FIG. 6;

FIG. 8 is a vector diagram showing phases of I ₁ and I ₂ and a phase relationship in the case of wrong polarity along with one polarity.

9 is a diagram illustrating a vector locus of the differential current in FIG.

FIG. 10 is a diagram illustrating a relationship between a differential current and a connection of CT according to a phase angle.

FIG. 11 is a configuration diagram of a main part of a comparative differential relay according to Embodiment 1 of the present invention.

FIG. 12 is a flowchart of a current transformer connection check according to the first embodiment of the present invention.

FIG. 13 is a configuration diagram of a main part of a comparative differential relay showing Embodiment 2 of the present invention.

FIG. 14 is a configuration diagram of a main part of a comparative differential relay showing Embodiment 3 of the present invention.

FIG. 15 is a configuration diagram of a main part of a comparative differential relay showing Embodiment 4 of the present invention.

FIG. 16 is a configuration diagram of a main part of a comparative differential relay showing Embodiment 5 of the present invention.

FIG. 17 is a configuration diagram of a main part of a comparative differential relay showing Embodiment 6 of the present invention.

FIG. 18 is a configuration diagram of a conventional digital relay.

FIG. 19 is a configuration diagram of a conventional analog type ratio differential relay.

FIG. 20 is a configuration diagram of a conventional digital type differential differential relay.

FIG. 21 is a diagram illustrating the operation of the ratio differential relay when the protection section is normal.

FIG. 22 is a diagram illustrating the operation of the ratio differential relay at the time of an accident outside the protection section.

FIG. 23 is a diagram illustrating the operation of the ratio differential relay at the time of an accident in a protection section.

[Explanation of symbols]

11 current transformer (CT), 12 filter circuit, 13 sample hold circuit, 14 multiplexer circuit, 15
Analog / digital converter, 16 arithmetic processing unit, 1
7 output interface circuit, 18 excitation coil, 19
Contact, 20 digital type ratio differential relay, 21 I
Means for calculating the differential current of ₁₋ I ₂ , means for calculating the suppression current value of 22 I ₁ + I ₂ , 23 judging means, 24 A-phase operation judging means, 25 B-phase operation judging means, 26 C-phase operation judging Means, 30 test switch for phase change, 31
Phase changing means, 32 calculating means, 33 phase detecting means,
34 phase determination means, 35 output means, 40 ratio differential relay, 41 protection target, 42 input converter, 43 I
Means for generating a differential current of ₁₋ I ₂ , means for generating a suppression current of 44 I ₁ + I ₂ , 45 determination means, 46 A
Phase operation determining means, 47 B-phase operation determining means, 48 C-phase operation determining means, 49 output means, 51 protection section, 61
Means for detecting the phase at which the differential current value of I ₁ -I ₂ is maximum; 62 means for determining whether the phase is 0 °; 71 I ₁ -I ₂
Means for detecting the phase at which the differential current value of
Means for determining whether the phase is 180 °; means for storing the minimum value of the differential current 73 I ₁ -I ₂ ; 74 means for determining whether the phase is ± 60 °; 75 means for determining whether the phase is ± 120 °.

Claims (8)

(57) [Claims] 1. A protection system connected to a polyphase AC line of a power system.
The transformer to be protected, the primary and secondary sides of the transformer to be protected
Current transformers connected to each side, the output of this current transformer
Power system with a ratio actuated relay connected to the
A said erroneous connection detection device current transformer systems out, as input electrical quantity from the two current transformers, a phase changing means for varying the phase between the two electrical quantity, corresponding to the change of the phase Calculating means for calculating the electric quantity of the difference between the two electric quantities, and display means for displaying the value of the changed phase angle and the calculation result of the electric quantity of the difference corresponding to the phase angle. Current transformer incorrect connection detection device. 2. A protection pair connected to an AC line of a power system.
Elephant transformer, on the primary and secondary sides of this protected transformer
Two current transformers each connected, the output end of this current transformer
Power system with a ratio actuated relay connected to a
A of the erroneous connection detection device current transformer, an input amount of electricity from the two current transformers, a phase changing means for varying the phase between the two electrical quantities, corresponding to the change in the phase The calculating means for calculating the electric quantity of the difference between the two electric quantities, of the phases where the electric quantity of the difference is minimum and maximum,
An erroneous connection detection device for a current transformer, comprising: a phase detection unit that detects at least one phase. Wherein erroneous current transformer according to claim 2, wherein the detection connection of the current transformer according to the result of the phase detection means comprises a phase determination means determines normal or not Connection detection device. 4. The phase determining means according to claim 3, wherein the phase at which the electric quantity of the difference is maximum is 0 ° or the phase at which the difference is minimum is 180 °. Erroneous connection detection device for a current transformer, characterized in that it is means for determining reverse connection. 5. The method according to claim 3, wherein when the electric circuit is a three-phase AC circuit, the phase determining means determines that the phase at which the difference electric quantity is the maximum is + 60 ° or −60 °, or the phase at which the difference is the minimum is + 120 °. If it is {or -120}, a means for judging an improper connection between current transformers of different phases is provided. 6. The phase determining means according to claim 3, wherein when the electric circuit is a three-phase AC circuit, the phase judging means sets the phase at which the electric quantity of the difference is maximum to + 120 ° or −120 ° or the phase at which the difference is minimum is + 60 °. {Or −60}, the current transformer having a wrong connection between current transformers of different phases and a means for determining that the polarity of one of the current transformers is a wrong connection. Misconnection detection device. 7. The method according to claim 1, wherein the phase change means sets the phase change in a range of 0 ° to 3 ° in steps of a predetermined phase angle.
A connection inspection device for a current transformer characterized by changing by 60 °. 8. A ratio differential relay, comprising the erroneous connection detection device for a current transformer according to any one of claims 1 to 7.