JP3330010B2 - Transformer partial discharge detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a partial discharge of a three-phase dry transformer in which a state in an insulator is externally tested by detecting a partial discharge between the transformer and the ground.

[0002]

2. Description of the Related Art In a dry-type transformer provided with a molded insulator, if a void is generated in the insulator, a partial discharge (corona discharge) is generated there and the deterioration proceeds. In order to deal with insulation deterioration, non-destructive testing (diagnosis) of the state of an insulator is performed by detecting partial discharge between a transformer and ground.

FIG. 8 shows an example of a partial discharge detection method conventionally performed in a three-phase molded transformer. In FIG. 8, a test transformer 1 to be subjected to partial discharge detection includes a three-phase high voltage side coil 2 (star connection) for each phase winding 2.
u, 2v, 2w are collectively connected to the test terminal 4, and each phase winding 3 of the three-phase low voltage side coil 3 (delta connection) is connected.
U, 3V and 3W are collectively grounded.

An output voltage of a test power supply 5 composed of, for example, a motor generator is applied to the test terminal 4 via a voltage regulator 6, a test transformer 7, and a blocking coil 8. In this case, the blocking coil 8 is connected to the test transformer 7.
To prevent external noise from entering the test circuit from the
In addition, it is provided to prevent a harmonic component accompanying partial discharge generated in the test transformer 1 from flowing back to the test power supply 5 side.

[0005] Between the test terminal 4 and the ground terminal,
A coupling capacitor 9 for flowing a discharge pulse signal generated by partial discharge in the test transformer 1 and a corona measuring device 10 for measuring the discharge pulse signal are interposed.
The corona measuring device 10 detects the partial discharge level between the test transformer 1 and the ground.

[0006]

However, in the case of the above-mentioned conventional partial discharge detection method, a test transformer 7 for obtaining a test voltage and a blocking coil 8 for suppressing noise are required. For this reason, the configuration of the test circuit for detecting the partial discharge becomes large, which causes problems such as complicated on-site testing, and also causes the deterioration of the detection sensitivity of the partial discharge. Moreover, a troublesome operation such as insertion of the blocking coil 8 and the like into the test circuit is required, and there is a problem that the preparation work for detecting the partial discharge takes time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to greatly simplify the configuration of a test circuit for detecting partial discharge, and to easily perform a field test. An object of the present invention is to provide a method for detecting partial discharge of a transformer, which can simplify the preparation work for detecting partial discharge.

[0008]

In order to achieve the above object, the present invention provides a partial discharge of a transformer in which partial discharge of a three-phase dry transformer is detected based on a signal generated in accordance with the discharge. In the detection method, the three-phase transformer U,
By dividing each phase winding constituting the high-voltage side coil of each phase of V and W at the winding lead portion, the interphase connection of each phase of U, V and W is established.
Open the phase windings to make them independent from each other.
Induct at least one phase winding of each phase
In addition to functioning as an active winding, another one-phase winding
By supplying an exciting current to any of the phase windings constituting the low-voltage side coil of the three-phase transformer by functioning as a partial discharge detection target winding, the test is performed in accordance with the supply of the exciting current. wherein the voltage induced in the voltage induced winding portions
A test voltage is applied to the discharge detection winding and the partial discharge
Actual partial discharge detection operation of detecting the presence or absence of a ground partial discharge electrostatic detected winding through a coupling capacitor
And thereafter, of the phase windings independent of each other,
Winding serving as a test voltage inducing winding and the partial discharge detection target
The partial discharge detection operation by sequentially switching the windings
Is obtained by a configuration in which the execution (claim 1).

According to this configuration, the high voltage side coil is formed.
For the U, V, and W phase windings , open the
Release each phase winding so that they are independent of each other.
In this state, each phase winding is sequentially tested for partial discharge to ground. In this case, for example, both ends of the first phase winding of the high-voltage side coil (winding start outlet, winding end outlet) are connected collectively, and the first phase winding is subjected to partial discharge detection. Winding and
Function. Also, for example, the third phase winding is connected to a test voltage.
To function as test voltage induced winding
And the state in which the exciting current flows through the third phase winding of the low-voltage side coil.
I do. Further, the second phase winding causes play a role of supplying a flux in the iron core at both ends as opened.

In such a state, the third phase winding on the high voltage side
The voltage induced in the (test voltage induction winding ) is applied to the first phase winding (partial discharge detection target winding) as a test voltage. In this case, when a partial discharge to the ground occurs in the first phase winding, a signal associated with the partial discharge is detected via the coupling capacitor.
Based on the signal level detected by such a partial discharge detection operation , the presence or absence of the ground discharge can be verified.
The second phase winding and the third phase winding of the high voltage side coil are also used as test voltage induction windings and partial discharge detection.
The target winding is sequentially switched, and the same partial discharge
By performing the electricity detection operation , it is possible to verify the presence / absence of a ground discharge, and thus to verify the presence / absence of a partial discharge to the entire three-phase transformer.

In this case, the function of the test transformer required by the conventional partial discharge detection method can be obtained by using a part of the high voltage side coil and the low voltage side coil of the test transformer. In addition, a test transformer can be omitted for detecting partial discharge. In addition, as the test transformer becomes unnecessary, the influence of external noise from the test transformer can be reduced, and the accuracy of partial discharge detection can be improved. Thus, the configuration for detecting partial discharge can be simplified as a whole.

Meanwhile, the test and partial discharge detection pairs Zomaki line voltage induced
Is intended may be configured to insert a blocking coil between the electromotive windings (Claim 2), according to this configuration,
Since the noise reduction effect of the blocking coil can be expected, the detection accuracy of the partial discharge can be further improved.

Further, the test voltage induction winding is provided with the U,
Of each phase winding constituting the high voltage side coil of each phase of V and W,
Two windings other than the partial discharge detection winding are connected in series.
Continue to can also be configured (claim 3), according to such a configuration, the above-mentioned series-connected test voltage induced winding, the test electric圧誘Okoshimaki line than in the case of one double , The partial discharge can be detected accurately even when the test voltage is insufficient.

In addition, in the partial discharge detection method for a transformer, wherein the partial discharge of the three-phase dry transformer is detected based on a signal generated by the discharge, the U, V, By dividing each phase winding constituting the high-voltage side coil of each W at the winding exit , the phase between U, V, and W
After releasing the connection to make each phase winding independent from each other,
Test at least one phase winding of each phase winding
In addition to functioning as a voltage induction winding, the winding for another phase
Line a to function as partial discharge detection target winding, by supplying an exciting current to any of the phase windings constituting the low-voltage coil of the three-phase transformer, in accordance with the supply of the exciting current before the voltage induced in the test voltage induced winding
Apply the test voltage to the winding targeted for partial discharge detection as
The inserted corona instrument between the test voltage induced winding and the ground terminal performs the partial discharge detection operation of detecting the presence or absence of a ground partial discharge of the partial discharge detection target winding, this
Later, of the independent phase windings, the test voltage induction
Winding to be the starting winding and the winding to be subjected to the partial discharge detection
It is also possible to adopt a configuration in which the partial discharge detection operation is executed by sequentially switching the windings .

According to this configuration, partial discharge can be detected without using a coupling capacitor, and partial discharge can be easily detected.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The first embodiment shows an example of detecting a partial discharge between the ground of a three-phase molded transformer having a Δ-Y connection.

That is, in FIG. 1, a test transformer 11 (three-phase dry transformer) is connected to a delta-connected high-voltage side coil 12.
The U, V, W phase windings 12u, 12v, 12w are removed from the winding leads to open the U, V, W phase connections.
Release the windings 12u, 12v, and 12w to make them independent from each other. One end (e.g., a winding start outlet) of the winding 12u serving as a test voltage induction winding is connected to a ground terminal, and the other end (winding end outlet) is connected to an output for extracting a test output. Connect to terminal 14. Also in this case
In this case , both ends of the winding 12v serving as the partial discharge detection target winding (winding start outlet, winding end outlet) are connected together to the output terminal 14 (one end of the winding 12u on the non-ground terminal side). And both ends of the winding 12w are left open.

On the other hand, the star-connected low voltage side coil 13
, The neutral point of each phase winding 13u, 13v, 13w is connected to the ground terminal. One end (non-neutral point side) of the winding 13u is connected to the input terminal 15 for applying a test voltage, and the other ends of the other windings 13v and 13w are left open.

Between the input terminal 15 and the ground terminal,
For example, the output voltage of the test power supply 16 composed of a motor generator is applied while being adjusted to an arbitrary voltage by the voltage regulator 17. A coupling capacitor 18 for flowing a discharge pulse signal generated by the partial discharge in the test transformer 11 between the output terminal 14 and the ground terminal, and a discharge pulse signal flowing through the coupling capacitor 18 are provided. A corona measuring device 19 for detection is interposed.

According to such a configuration, when the test voltage is applied to the input terminal 15, the winding 12u of the high voltage side coil 12 responds to the excitation current flowing through the winding 13u of the low voltage side coil 13. The boosted voltage is induced in the (test voltage induction winding) , and the induced voltage is applied as a test voltage to the winding 12v (partial discharge detection target winding) . In this case, the winding 12w whose both ends are opened plays a role of flowing magnetic flux through the iron core.

When a partial discharge (corona discharge) occurs between the winding 12v and the ground terminal in a state where the high voltage is applied to the winding 12v as described above, the discharge accompanying the partial discharge is generated. Pulse signal is coupling capacitor 1
8 to the corona measuring device 19, and based on the signal level detected by the corona measuring device 19,
It is possible to detect whether or not a partial discharge to ground has occurred in the winding 12v.

That is, in this case, the low-voltage side coil 13
Winding 13u and the winding 12u of the high voltage side coil 12 fulfill the function of a conventional test transformer (indicated by reference numeral 7 in FIG. 8).

The other windings 12 of the high voltage side coil 12
With respect to w and 12u as well, the connection as shown in FIGS. 2 and 3 makes it possible to detect the state in which a partial discharge has occurred between the ground and the ground. The presence or absence of partial discharge can be verified.

In short, according to the configuration of the first embodiment described above, the function of the test transformer required by the conventional partial discharge detection method (see FIG. 8) is replaced by the high voltage side of the test transformer 11. The coil 12 and a part of the low-voltage side coil 13 are used to obtain the partial discharge, so that a test transformer is not required for detecting the partial discharge.

As described above, since the test transformer is not required, the influence of external noise from the test transformer can be reduced, and the accuracy of partial discharge detection can be improved. 8 (indicated by reference numeral 8) can also be omitted.

Therefore, since a simple configuration without the need for the test transformer and the blocking coil is required, the test circuit for detecting the partial discharge does not become large as in the prior art, and the field test can be performed. It can be easily implemented. Further, as described above, since the test transformer and the blocking coil are not required, the wiring length of the test circuit can be shortened, and the noise superimposed on the wiring can be reduced. The accuracy can be improved.

Of course, it is also possible to use a blocking coil 20 as shown in FIG. 4 showing a second embodiment of the present invention. In this case, the noise reduction effect of the blocking coil 20 can be expected. Thus, the detection accuracy of the partial discharge can be further improved. As shown in FIG. 4, the blocking coil 20 is connected to the partial discharge detection pair.
Zomaki lines (winding in the example of FIG. 4 12v), it is to be inserted between the (winding 12u in the example of FIG. 4) Test Voltage induced windings.

The third embodiment shows an example of detecting a partial discharge between the ground of a three-phase molded transformer in a Y-Y connection, and a test transformer 11 'includes a star-connected high-voltage transformer. Phase windings 12u ' , 12v ' , 12 of the side coil 12 '.
by removing the winding mouth out of the w ', their winding 12
u ′ , 12v ′ , and 12w ′ are once in a state of being independent. Then, each winding 12u ', 12v', among 12w ', partial discharge detection pairs Zomaki line, i.e. the winding in the example of FIG. 5 1
Only 2v ' is made independent and both ends are connected to the output terminal 14. The other windings 12u ' and 12u '
w ′ is connected in series, and one end of the series circuit is connected to the output terminal 14 and the other end of the series circuit is connected to the ground terminal, whereby the series connection is established.
Windings 12u 'and 12w' are referred to as test voltage induced windings.
Function .

The low voltage side coil 13 has the first
As in the embodiment, the neutral point of each phase winding 13u, 13v, 13w is connected to the ground terminal, one end of the winding 13u is connected to the input terminal 15 for test voltage application, and the other windings are connected. 1
The other ends of 3v and 13w are left open.

According to the configuration of the third embodiment, when the test voltage is applied to the input terminal 15, the exciting current flows through the winding 13 u of the low-voltage side coil 13.
And 12 w 'windings 12u' of the high-pressure side coil 12 'to the series circuit of, look like twice the voltage of the induced voltage in the case of the first embodiment is induced, the induced voltage winding 12v'
To be applied. As a result, even when the test voltage is insufficient, the partial discharge can be accurately detected.

Therefore, even when a test voltage is obtained by using the output of the commercial power supply 21 as in the fourth embodiment of the present invention shown in FIG. 6, a large test voltage (twice the output voltage of the commercial power supply 21). Therefore, even when a motor generator cannot be prepared, it becomes possible to cope with the situation.

FIG. 7 shows a fifth embodiment of the present invention, and only the parts different from the first embodiment will be described below. That is, the fifth embodiment is an example in which a coupling capacitor can be made unnecessary, and a test voltage is induced.
'Connected to its output terminal 14' cause winding output terminal 14 to one end of the (winding 12u in the example of FIG. 7) to insert the corona meter 19 between the ground terminal and the. In this case, the test
The other end of the 圧誘Okoshi winding (12u), the partial discharge detection pairs Zomaki <br/> line (in the example of FIG. 7 winding 12v) connected to both ends of the.

According to this configuration, although the detection sensitivity is reduced, the partial discharge can be detected without the coupling capacitor, which is useful when the partial discharge is easily detected.

[0034]

According to the present invention, as is apparent from the above description, in detecting the partial discharge of the high-voltage side coil of the three-phase dry-type transformer, the function of the test transformer is determined by the coil of the transformer itself. The configuration of the test circuit for partial discharge detection can be greatly simplified, making it possible to easily carry out on-site tests and simplifying the preparation work for partial discharge detection. It has the beneficial effect of being able to.

[Brief description of the drawings]

FIG. 1 is a test circuit diagram showing a partial discharge detection method according to a first embodiment of the present invention;

FIG. 2 is a test circuit diagram showing a partial discharge detection method, part 2

FIG. 3 is a test circuit diagram showing a partial discharge detection method, part 3

FIG. 4 is a test circuit diagram showing a partial discharge detection method according to a second embodiment of the present invention.

FIG. 5 is a test circuit diagram showing a partial discharge detection method according to a third embodiment of the present invention.

FIG. 6 is a test circuit diagram showing a partial discharge detection method according to a fourth embodiment of the present invention.

FIG. 7 is a test circuit diagram showing a partial discharge detection method according to a fifth embodiment of the present invention.

FIG. 8 is a test circuit diagram showing a conventional partial discharge detection method.

[Explanation of symbols]

11, 11 'are test transformers (three-phase dry type transformers), 12,
12 'is a high voltage side coil, 13 is a low voltage side coil, 16 is a test power supply, 18 is a coupling capacitor, 19 is a corona measuring instrument, 20 is a blocking coil, and 21 is a commercial power supply.

Continuation of the front page (56) References JP-A-56-115156 (JP, A) JP-A-52-87615 (JP, A) JP-A-61-117464 (JP, A) JP-B-52-18372 (JP) , B1) JP-B-62-59268 (JP, B1) JP-B-58-17260 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/00-31/06 G01R 31/12-31/14

Claims (4)

(57) [Claims] 1. A partial discharge of a three-phase dry-type transformer,
Transformation detected based on the signal generated by
The method for detecting partial discharge of a transformer, comprising:U, V, WConstructs high-voltage side coil
By dividing each phase winding at the winding exitU,
Open the inter-phase connection between V and W phases andEach other
After being independent,Test at least one phase winding of each phase winding
In addition to functioning as a voltage induction winding, the winding for another phase
The wire functions as a partial discharge detection winding,  Each phase winding constituting the low-voltage side coil of the three-phase transformer
Supply excitation current to anyByThis encouragement
Depending on the supply of magnetic currentThe test voltage inductionInduced by the winding
VoltagePartial discharge detection targetMarking test voltage on winding
In additionPartial discharge detection targetPresence or absence of partial discharge to the ground
Is detected via the coupling capacitorPart
Execute the discharge detection operation, After this, the test voltage of the phase windings independent of each other is
A winding serving as a pressure-induced winding and the winding targeted for partial discharge detection
The partial discharge detection operation is executed by sequentially switching the windings
Do A method for detecting partial discharge of a transformer. Wherein said partial discharge detection pairs Zomaki line a partial discharge detection method of a transformer according to claim 1, wherein the inserting the blocking coil between said test voltage induced windings. 3. The test voltage induction winding according to claim 1 , wherein
W of each phase winding constituting the high-voltage side coil of each phase,
Connect two windings other than the partial discharge detection target winding in series.
Claim 1 or 2 transformer partial discharge detection method according to, characterized in that constructed Te. 4. A partial discharge of a three-phase dry-type transformer,
Transformation detected based on the signal generated by
The method for detecting partial discharge of a transformer, comprising:U, V, WConstructs high-voltage side coil
By dividing each phase winding at the winding exitU,
Open the inter-phase connection between V and W phases andEach other
After being independent,Test at least one phase winding of each phase winding
Machine as voltage induced winding And the other one-phase winding
The wire functions as a partial discharge detection winding,  Each phase winding constituting the low-voltage side coil of the three-phase transformer
Supply excitation current to anyByThis encouragement
Depending on the supply of magnetic currentThe test voltage inductionInduced by the winding
VoltagePartial discharge detection targetMarking test voltage on winding
Plus the aboveTest voltage inductionInsert between the winding and the ground terminal
Above corona meterPartial discharge detection targetWinding ground
Detecting partial dischargePartial discharge detection operation
Line, After this, the test voltage of the phase windings independent of each other is
A winding serving as a pressure-induced winding and the winding targeted for partial discharge detection
The partial discharge detection operation is executed by sequentially switching the windings
Do A method for detecting partial discharge of a transformer.