JPH0837728A - Transformer protection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a transformer protection device that does not reduce the abnormality detection sensitivity for detecting an abnormality that has occurred in a tap switching transformer during load. [Structure] A transformer provided with a correction means for correcting an amount of inconsistency caused by a relationship between information on an input side and information on an output side of the load tap switching transformer by tap switching of the load tap switching transformer. It is a protective device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer protection device capable of detecting an abnormality in a transformer with high accuracy and protecting the transformer in which the abnormality has occurred.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a main part of a conventional transformer protection device 100. In the figure, 1 is a load tap switching transformer having a function of suppressing fluctuation of terminal voltage due to load by tap switching, 2 and 3 are transformer terminals, and 4 is a current on the primary side of the load tap switching transformer 1. I1
Is a current transformer that detects the
It is a current transformer that detects the current I2 on the secondary side. 6a is a midpoint switching tap on the secondary side of the tap tapping transformer 1 on load, and 6b changes the transformation ratio by + n% with respect to the midpoint tapping tap 6a +
An n% switching tap 6c is a -n% switching tap that changes the transformation ratio by -n% with respect to the midpoint switching tap 6a. Reference numeral 7 is a current transformer output adjustment tap for adjusting the output of the current transformer 4 supplied to the current differential relay 9, and 8 is current transformer output adjustment for adjusting the output of the current transformer 5 supplied to the current differential relay 9. It is a tap. i ₁ is a current transformer output adjusting tap 7 and a current differential relay 9
It is the current that flows between the and tap change transformer at load 1
Is proportional to the current I1 on the primary side. i ₂ is a current flowing between the current transformer output adjustment tap 8 and the current differential relay 9, and is in a proportional relationship with the current I 2 on the secondary side of the load tap switching transformer 1.

Next, the operation will be described. When the load tap switching transformer 1 has a constant transformation ratio and the load tap switching transformer 1 is operating normally, the current i ₁ is adjusted by adjusting the current transformer output adjusting taps 7 and 8. And the current i ₂ can be matched so that the vector difference current ΔI between the current i ₁ and the current i ₂ becomes zero.

However, the tap change transformer 1 under load
Since it is possible to change the transformation ratio ± n% around the midpoint switching tap 6a, the tap position does not move even if the matching is established while being switched to the midpoint switching tap 6a. , The vector difference current ΔI has a value other than zero. At this time, if the errors of the current transformers 4 and 5 are ignored, this vector difference current ΔI is expressed by the following equation (1).

[0005]

[Equation 1]

In order not to erroneously determine this vector difference current ΔI as an accident inside the tap switching transformer 1 under load,
Vector differential current ΔI when the current differential relay 9 operates
Is set to ξ (ξ> n)%, and the vector difference current ΔI at which the current differential relay 9 operates is set to be larger than the vector difference current ΔI of the equation (1). Even when the center point switching tap 6a is changed by ± n%, the tap does not operate.

According to the equation (1), the magnitude of the vector difference current ΔI caused by the mismatch caused by the movement of the tap position when the tap change transformer 1 under load is operating normally is n _{0 of the} current i ₂ according to the equation (1). %. 2 of current transformers 4 and 5 at this time
N ₁ % due to the mismatch between the secondary current and the current transformer output adjustment taps 7 and 8 and n ₂ % due to the error of the current transformers 4 and 5.
Then, ξ (%) is | n ₀ | + | n ₁ | + | n ₂
It is necessary to set it to a value larger than | (%).

As a result, an accident occurs in the tap switching transformer 1 under load, and the magnitude of the vector difference current ΔI is ξ% of i ₂ .
When it becomes larger, the current differential relay 9 operates and performs a transformer protection operation such as disconnecting the load tap switching transformer 1 from the circuit.

[0009]

Since the conventional transformer protection device is constructed as described above, the vector difference current ΔI when the transformation ratio changes by ± n% is stored in the load tap switching transformer 1. In order not to make an erroneous determination as an accident, the change in the transformation ratio corresponding to the vector difference current ΔI when the current differential relay 9 operates is set to ξ (ξ> n)%, and the current differential relay 9 operates. If the transformation ratio is ±
It is necessary to set it to be larger than the vector difference current ΔI when it changes by n%, and there is a problem that the larger the value of ξ, the lower the abnormality detection sensitivity when performing the transformer protection operation.

The invention of claim 1 has been made to solve the above problems, and protects a transformer without lowering the abnormality detection sensitivity for detecting an abnormality occurring in a load tap switching transformer. The purpose is to obtain the device.

It is an object of the present invention to provide a transformer protection device which does not reduce the abnormality detection sensitivity for detecting an abnormality that has occurred in a transformer with a voltageless tap changer.

It is an object of the present invention to provide a transformer protection device which does not reduce the abnormality detection sensitivity when performing a transformer protection operation.

It is an object of the present invention to provide a transformer protection device which does not reduce the abnormality detection sensitivity when performing the transformer protection operation.

[0014]

According to a first aspect of the present invention, there is provided a transformer protection device, in which information on an input side and an output side of the load tap change transformer is changed by tap change of the load tap change transformer. The correction means is provided to correct the amount of inconsistency caused by the relationship with the information.

The transformer protection device according to the invention of claim 2 is
Due to the tap switching of a transformer with a non-voltage tap changer having a non-voltage tap changer, the error caused by the relationship between the information on the input side and the information on the output side of the transformer with a non-voltage tap changer A correction means for correcting the matching amount is provided.

The transformer protection device according to the invention of claim 3 is
By changing the tap of the load tap change transformer or the transformer with no-voltage tap changer, the input current value information according to the current value of the input side of the load tap change transformer or the transformer with no-voltage tap changer or Output current value information according to the current value on the output side, or increase or decrease generated in both, is suppressed or supplemented based on tap position information detected by the tap position information detecting means, and the input side by tap switching. Is provided with a correction means for correcting the amount of mismatch generated in the differential current between the current value and the current value on the output side.

The transformer protection device according to the invention of claim 4 is
By changing the tap of the load tap change transformer or the transformer with no-voltage tap changer, the input current value information according to the current value of the input side of the load tap change transformer or the transformer with no-voltage tap changer or The input side of the load tap switching transformer or the transformer with a no-voltage tap switching, which is obtained by the correction amount detecting means for the increment or decrement generated in the output current value information according to the output side current value or both. Suppressing or compensating based on the ratio of the terminal voltage of the output terminal voltage to the output terminal voltage, and correcting the amount of mismatch generated in the differential current between the input side current value and the output side current value due to tap switching. The correction means is provided.

[0018]

The correction means in the invention of claim 1 results from the relationship between the information on the input side and the information on the output side of the load tap switching transformer by tap switching of the load tap switching transformer. It corrects the amount of mismatch and prevents a drop in the abnormality detection sensitivity when performing the protection operation of the tap switching transformer during load.

According to the second aspect of the present invention, the correcting means performs tap switching of a transformer with a non-voltage tap changer having a non-voltage tap changer, thereby providing information on the input side of the transformer with a non-voltage tap changer. The amount of inconsistency caused by the relationship with the information on the output side is corrected to prevent a decrease in abnormality detection sensitivity when performing the protective operation of the transformer with a voltageless tap changer.

According to a third aspect of the present invention, the correction means is a tap change transformer for a load or a transformer with a non-voltage tap changer by changing the tap of a transformer with a tap change switch for a load or a transformer with a non-voltage tap changer. Input current value information according to the input side current value or output current value information according to the output side current value, or the increase or decrease generated in both are suppressed or compensated based on the tap position information, and by tap switching A mismatch amount generated in the differential current between the current value on the input side and the current value on the output side is corrected to prevent a decrease in abnormality detection sensitivity when performing the transformer protection operation.

The correction means according to the invention of claim 4 is based on the ratio of the terminal voltage on the input side to the terminal voltage on the output side of the load tap change transformer or the transformer with a no-voltage tap changer. An increase or a decrease generated in the input current value information or the output current value information or both of them is suppressed or compensated, and a difference generated between the current value on the input side and the current value on the output side due to tap switching does not occur. The matching amount is corrected to prevent the abnormality detection sensitivity from decreasing when the transformer protection operation is performed.

[0022]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of a transformer protection device 200 of this embodiment. In FIG. 1, the same parts as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. 1 in the figure
1 is a tap position obtained from a tap control panel or the like, which is a current i ₂ proportional to the current on the secondary side of the tap switching transformer 1 under load flowing between the current transformer output adjustment tap 8 and the current differential relay 9 a correction circuit information in the K times the value corresponding to the tap position based on the i _'2 (correction means). This value K changes according to the tap position based on the tap position information.

In the load tap switching transformer 1, a state where the matching is established by switching to the midpoint switching tap 6a (ΔI = 0)
However, since the tap position moves and the transformation ratio is changed by ± n%, the vector difference current ΔI does not become zero when the transformation ratio is changed by ± n%, and the error due to the current transformers 4 and 5 does not occur. Is ignored, ± i ₂ · n _0/1 as shown in the above equation (1)
A vector difference current ΔI of 00 occurs. This vector difference current ΔI is the amount of mismatch generated on the plus side or the minus side due to the tap position moving and the transformation ratio being changed by ± n%. The correction circuit 1 is provided to correct this mismatch amount.
1 is K times the current i ₂ corresponding to the tap position,
That outputs _{1 / (± n 0/100} ) multiplied by the current differential relay 9. As a result, the current i ′ ₂ output to the current differential relay 9 is (± i ₂ · n _0/100 ) · {1 / (±
n _0/100 )}, and correction when the transformation ratio changes by ± n ₀ % becomes possible.

That is, when the tap position is switched to ± n% and the value of K is 1 / (± n _0/100 ), the mismatch amount i ₁ -i ' ₂ is corrected to zero.

In practice, an error of n due to the mismatch between the secondary currents of the current transformers 4 and 5 and the current transformer output adjusting taps 7 and 8 is n.
_It is necessary to allow ₁ % and n ₂ % as an error of the current transformers 4 and 5, and ξ (%) at which the current differential relay 9 operates is | n ₁ |
It needs to be set to a value larger than + | n ₂ | (%).
As a result, an accident occurs inside the tap change transformer 1 under load, and the magnitude of the vector difference current ΔI flows between the current transformer output adjusting tap 8 and the current differential relay 9 in a state where the magnitude is matched. Ξ (%) of the current value i ₂ present, that is, | n ₁ | +
When it becomes larger than │n ₂ │ (%), the current differential relay 9 detects an accident that has occurred inside the load tap switching transformer 1 and performs a protective operation, and disconnects the load tap switching transformer 1 from the circuit. I do. In this case, the current differential relay 9
Since the value of ξ at which is operated does not need to consider the offset amount due to tap switching compared to the conventional value,
It is possible to set a low value, and it is possible to perform a good protection operation with high accident detection sensitivity and high responsiveness.

Example 2. Hereinafter, another embodiment of the present invention will be described with reference to the drawings. In the first embodiment, the load tap changeover transformer is used as the single-phase transformer, but
It can also be applied to a three-phase transformer having a plurality of windings of a phase star winding or a three-phase delta winding. FIG. 2 is a configuration diagram showing a main part of the transformer protection device 300 of this embodiment. 2, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the figure, reference numeral 21 is a load tap switching transformer having a three-phase star winding 21a and three-phase delta windings 21b and 21c. The three-phase star winding 21a of the transformer 21 is provided with a plurality of taps for each phase, and the taps of each phase are simultaneously switched according to the magnitude of the load to adjust the magnitude of the line voltage. . Although the transformer protection device 300 is shown for one phase in the drawing, it is actually provided for each phase. Each transformer protection device (not shown) has a three-phase star winding 21a and a three-phase delta. The line current values of the corresponding phases on the windings 21b and 21c side are detected by respective current transformers (not shown), and currents corresponding to the line current values are supplied.

22 and 23 and 24 are transformer terminals, and 25 and 2
6 and 27 are current transformers. 28 is a current transformer output adjusting tap for adjusting the current i ₁ supplied to the current differential relay 31 by the output of the current transformer 25, and 29 is current supplied to the current differential relay 31 by the output of the current transformer 26. A current transformer output adjustment tap for adjusting i ₂ and a current transformer output adjustment tap 30 for adjusting the current i ₂ supplied to the current differential relay 31 by the output of the current transformer 27. Reference numeral 32 denotes a correction circuit (correction means) that outputs the current i ₂ to the current differential relay 31 by multiplying the current i ₂ by a coefficient K that is a value corresponding to the tap position based on the tap position information.

In the case of a three-phase transformer having a plurality of windings such as a three-phase star winding and a three-phase delta winding, the number of current transformers including an error increases, and the vector difference current based on this error increases. Although many patterns will be generated in ΔI, it is not necessary to consider the mismatch amount due to the change of the transformation ratio due to the movement of the tap position, and the mismatch based on the error of the current transformer based on the tap position information. It is possible to set ξ (%) at which the current differential relay 9 operates in consideration of only the amount, and the value of ξ at which the current differential relay 9 operates is lower than that of the conventional one as in the first embodiment. Can be set to, and it is possible to perform good protection operation with high accident detection sensitivity and good responsiveness.

Example 3. Hereinafter, another embodiment of the present invention will be described with reference to the drawings. The first embodiment has been described by using the load tap switching transformer in which the tap of the secondary winding is switched as the single-phase transformer. In this embodiment, a case where tap switching is performed also in the primary winding will be described.
FIG. 3 is a configuration diagram showing a main part of the transformer protection device 400 of this embodiment. In FIG. 3, the same parts as those in FIG. In the figure, 6d is a midpoint switching tap for the primary side of the tap switching transformer 1 under load, 6
e is a switching tap that changes the transformation ratio to the plus side with respect to the midpoint switching tap 6d, and 6f is a switching tap that changes the transformation ratio to the minus side with respect to the midpoint switching tap 6d. 41
Is a current i ₁ proportional to the current on the primary side of the tap switching transformer 1 under load flowing between the current transformer output adjusting tap 7 and the current differential relay 9 at the tap position based on the tap position information. It is a second correction circuit (correction means) for multiplying by K times which is a corresponding value to obtain i ′ ₁ . This value K changes according to the tap position based on the tap position information.

Also in the present embodiment, it is not necessary to consider the mismatch amount due to the change of the transformation ratio due to the movement of the tap position as in the case of the first embodiment, and the error of the current transformer is determined based on the tap position information. The minimum ξ (%) at which the current differential relay 9 operates can be set by considering only the amount of mismatch based on it, and the value of ξ at which the current differential relay 9 operates is set to a lower value than that of the conventional one. Therefore, it is possible to perform good protection operation with high accident detection sensitivity and high responsiveness.

Example 4. An embodiment of the present invention will be described below with reference to the drawings. Although the above-described first to third embodiments have been described using the load tap changeover transformer, the present invention can also be applied to a transformer with a nonvoltage tap changer having a nonvoltage tap changer. FIG. 4 is a configuration diagram showing a main part of the transformer protection device 500 of this embodiment. In FIG.
The same parts as the above are given the same reference numerals and the description thereof will be omitted. In the figure, 51 is a no-voltage tap changer, and 52 is a transformer with a no-voltage tap changer 51. Reference numeral 53 denotes a tap position information detection unit 53 that detects a handle position for performing a tap switching operation of the non-voltage tap changer 51, a moving distance of a mechanism section for tap movement, and generates tap position information.

In the present embodiment, the minimum ξ (%) at which the current differential relay 9 operates is set in consideration of the transformation ratio which changes when the tap is changed, but this is automatically performed. The minimum ξ (%) at which the current differential relay 9 operates can be automatically set by considering only the amount of mismatch based on the error of the current transformer based on the tap position information, and the current differential relay can be set. The value of ξ at which 9 operates can be set to a lower value than that of the related art, and it becomes possible to perform a good protection operation with high accident detection sensitivity and good responsiveness.

In this case, the tap position information is generated by the tap position information detecting means 53 detecting the handle position for performing the tap switching operation of the non-voltage tap switch 51, the moving distance of the mechanism for tap movement, and the like. .

Example 5. An embodiment of the present invention will be described below with reference to the drawings. Although the first to fourth embodiments have been described as using the tap position information to correct the mismatch amount of the vector difference current ΔI due to the change in the transformation ratio due to the movement of the tap position, the tap position information is used instead. It is also possible to use the ratio of the primary-side terminal voltage and the secondary-side terminal voltage of the transformer.

FIG. 5 is a block diagram showing the essential parts of the transformer protection device 600 of this embodiment. 5, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the figure, 61 is a voltage transformer that detects the primary side terminal voltage of the tap change transformer 1 during load, 62 is a voltage transformer that detects the secondary side terminal voltage of the tap change transformer 1 during load, and 63 is a voltage transformer. It is a correction amount detection means (correction means) for obtaining a ratio between the primary side terminal voltage and the secondary side terminal voltage of the tap switching transformer 1 under load detected by the transformers 61 and 62.

In this embodiment, it is not necessary to obtain tap position information from the tap operation panel, and the transformer protection device can be simplified.

[0037]

As described above, according to the first aspect of the present invention, the tap changeover of the load tap changeover transformer causes
Since it is configured to have a correction means for correcting the amount of mismatch caused by the relationship between the information on the input side and the information on the output side of the tap change transformer at load, the tap change transformer at load occurs. There is an effect that a transformer protection device that does not reduce the abnormality detection sensitivity for detecting an abnormality can be obtained.

According to the second aspect of the present invention, by tap switching of the transformer with a non-voltage tap changer having the non-voltage tap changer, information and output about the input side of the transformer with the non-voltage tap changer. Since it is configured to include a correction unit that corrects the amount of mismatch caused by the relationship with the information on the side, it is possible to reduce the abnormality detection sensitivity for detecting an abnormality that has occurred in the transformer with a voltageless tap changer. There is the effect that no transformer protection device can be obtained.

According to the third aspect of the invention, the tap switching of the load tap change transformer or the transformer with the non-voltage tap changer is performed, whereby the input of the load tap change transformer or the transformer with the no-voltage tap changer is input. Side input current value information or output current value information according to the output side current value, or increase or decrease generated in both of them are suppressed or compensated based on tap position information, and tap switching Since the correction means for correcting the amount of mismatch generated in the differential current between the current value on the input side and the current value on the output side is provided, the abnormality detection sensitivity at the time of performing the transformer protection operation is lowered. There is an effect that a transformer protection device that can prevent the above can be obtained.

According to the fourth aspect of the present invention, the tap switching of the load tap change transformer or the transformer with the non-voltage tap changer allows the input of the load tap change transformer or the transformer with the no-voltage tap changer. Side input current value information or output current value information according to output side current value, or increase or decrease generated in both, with load tap change transformer or non-voltage tap changer The voltage difference is suppressed or compensated based on the ratio of the input side terminal voltage and the output side terminal voltage of the transformer, and the difference generated between the input side current value and the output side current value due to tap switching does not occur. Since the correction means for correcting the matching amount is provided, it is possible to obtain a transformer protection device that does not reduce the abnormality detection sensitivity when performing the transformer protection operation. That.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of a transformer protection device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a main part of a transformer protection device according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing a main part of a transformer protection device according to another embodiment of the present invention.

FIG. 4 is a configuration diagram showing a main part of a transformer protection device according to an embodiment of the present invention.

FIG. 5 is a configuration diagram showing a main part of a transformer protection device according to an embodiment of the present invention.

FIG. 6 is a configuration diagram showing a main part of a conventional transformer protection device.

[Explanation of symbols]

1 load tap change transformer, 9 current differential relay, 11, 32 correction circuit (correction means), 41 second correction circuit (correction means), 63 correction amount detection means (correction means), 51 non-voltage tap changer , 52 transformers with non-voltage tap changer, 53 tap position information detecting section (tap position information detecting means), 200, 300, 400, 500,
600 Transformer protection device.

Claims (4)

[Claims] 1. A differential relay detects that the amount of mismatch obtained from the relationship between the information on the input side and the information on the output side of the transformer is different from that during normal operation of the transformer, and In the transformer protection device for protection, a compensation unit is provided for compensating the amount of mismatch caused by the relationship between the input side and the output side by tap switching when the transformer is a load tap switching transformer. And transformer protection device. 2. The transformer protection device according to claim 1, wherein the transformer is a transformer with a non-voltage tap changer having a non-voltage tap changer. 3. A tap position information detecting means for detecting tap position information, wherein the input side information of the transformer and the output side information of the transformer are the current value of the input side of the transformer. Input current value information according to the output current value information according to the output current value, the differential relay is a current differential relay, the correction means, by tap switching based on the tap position information A differential between the current value on the input side and the current value on the output side by tap switching is suppressed or compensated for an increase or a decrease generated in the input current value information, the output current value information, or both. 3. The transformer protection device according to claim 1, wherein the amount of mismatch generated in the current is corrected. 4. A correction amount detecting means for obtaining a ratio of a terminal voltage on an input side of the transformer and a terminal voltage on an output side of the transformer, the correction means including the correction amount detecting means instead of the tap position information. Based on the ratio of the terminal voltage on the input side of the transformer and the terminal voltage on the output side obtained in step 1, the input current value information or the output current value information due to tap switching, or the increase or decrease generated in both 4. The transformer protection according to claim 3, wherein the amount of mismatch generated in the differential current between the current value on the input side and the current value on the output side due to tap switching is suppressed or compensated for. apparatus.