CN106324444B - Transformer test platform - Google Patents

Abstract

The invention provides a transformer test platform which comprises a single-phase transformer, a voltage regulating winding, a high-voltage connector, an on-load voltage regulating switch and a local discharge model, wherein the single-phase transformer is connected with the voltage regulating winding through the high-voltage connector; the voltage regulating winding is connected with the high-voltage end of the high-voltage winding in the single-phase transformer, and the on-load voltage regulating switch is arranged on the voltage regulating winding; the high-voltage connector is arranged in the middle of the high-voltage winding; the partial discharge model extends into the transformer oil tank of the single-phase transformer through the sealing cylinder. Compared with the prior art, the transformer test platform provided by the invention can generate a true partial discharge signal under the normal operation voltage of the transformer, so that the propagation process of the partial discharge signal along the high-voltage winding of the transformer is simulated, the high-voltage winding of the transformer can be at a rated voltage, and the high-voltage insulation characteristic and the partial discharge source positioning technology of a partial discharge monitoring technology can be conveniently researched; and the partial discharge test and the winding local overheating test can be simultaneously carried out.

Description

A transformer test platform

technical field

The invention relates to the technical field of power transformers, in particular to a transformer test platform.

Background technique

The power transformer is one of the key equipments in the power system, and it is very important to monitor the operation status of the transformer. The current popular smart transformer requires a status monitoring device to be installed on the transformer. In the implementation of transformer condition monitoring, it is necessary to first study each monitoring technology, and it is required to conduct experimental research on the sensitivity, accuracy, long-term operation stability and other performance of each monitoring technology under the actual operating conditions of power transformers as much as possible. In order to realize the above test research, the transformer test platform can provide conditions closer to the actual working conditions, thereby improving the test efficiency and saving the test time. At present, the transformer test platform mainly includes:

1. A test platform for the propagation law of partial discharge signals in transformer windings

The main cause of transformer equipment failure is the deterioration of its insulation performance, and partial discharge is one of the main reasons for transformer insulation failure. In order to grasp the development process and propagation law of partial discharge inside the transformer, the common methods currently used are:

(1) Use the partial discharge model such as pin-plate discharge, ball-plate discharge, and air-gap discharge model to conduct partial discharge test research; however, this kind of test platform only simulates the partial discharge signal characteristics and defect development process of oil-paper insulation materials, but cannot study The propagation law of the partial discharge signal on the inner winding of the transformer.

(2) Establish a mathematical model of transformer windings, and use computer simulation to analyze the propagation law of signals similar to partial discharge pulses in the windings; in view of the complexity of transformer windings, the theoretical simulation results are very rough and have large errors.

(3) On the 10kV transformer winding, or on the specially designed and processed small transformer winding model, inject the pulse signal, measure the response signal on each turn of the winding at the same time, and analyze and study the propagation law of the partial discharge signal in the winding structure; but these The electromagnetic characteristics of transformer windings with small voltage levels and small volume winding models are far from the electromagnetic characteristics of actual large-scale power transformer windings.

(4) Transform the decommissioned actual power transformer and connect the partial discharge model to the lead wire of its high-voltage winding; this test method is mainly used to study the positioning of the partial discharge source inside the transformer. Because the partial discharge model is connected From the wire to the lead wire of the winding, the partial discharge pulse signal has been transmitted out of the high-voltage bushing without passing through the winding structure, so it is difficult to extract the law of the pulse signal propagation in the winding from the partial discharge signal monitored on the high-voltage bushing.

Therefore, there is currently no partial discharge test platform for transformers with high voltage levels (such as 220kV and above) that can reflect the propagation law of partial discharge pulse signals in transformer windings.

2. Test platform for transformer winding temperature monitoring technology

When the oil-paper insulation or the iron core lamination insulation inside the transformer is damaged, the damaged part generates abnormal heat and the temperature rises. Therefore, it is very important to monitor the internal temperature of a power transformer in the field during operation to determine the temperature and location of the fault point. The current research methods on abnormal heating fault monitoring of transformers include:

(1) Use the existing top oil temperature sensor on the power transformer to monitor the top oil temperature of the transformer, and bring it into the transformer winding temperature model to estimate the highest temperature on the winding; due to the complex internal structure of the transformer, the flow of the transformer oil used for heat dissipation is also It is relatively complex, resulting in a very rough transformer temperature model, and the maximum error of the transformer winding maximum temperature estimated by this model and the top oil temperature value is large.

(2) Install optical fiber temperature sensors on the power transformer windings to monitor the temperature of the transformer windings in real time; however, the power transformers installed with winding temperature monitoring can only monitor the current temperature of the transformer windings, because overheating faults rarely occur in the daily operation of the transformer Therefore, it is impossible to carry out the research on the temperature monitoring technology of the transformer winding by using the transformer in operation.

The power transformer with winding temperature monitoring installed can pass the temperature rise test in the laboratory to increase the temperature of the winding, and then test the winding temperature monitoring technology. Using this method to study winding temperature monitoring technology has the following three shortcomings:

①: This method makes the short-circuit current flow through the entire winding, thereby increasing the temperature of the entire winding; however, most of the overheating faults that occur in the actual transformer are short-circuit overheating of some windings, partial insulation arc discharge overheating, etc. Therefore, the overall temperature increase of the winding produced by this method is not only very different from the actual local winding temperature increase, but also cannot be used for the study of the hot spot temperature location method.

②: This method makes the short-circuit current flow through the entire winding, thereby increasing the temperature of the entire winding; but the required power is very large, and the general laboratory does not have the test conditions, only the laboratory of the transformer factory and other institutions can carry out this method. class test.

③: This method short-circuits the high-voltage winding, so the voltages of the high-voltage winding and the low-voltage winding are very low, only the voltage on the short-circuit impedance, which is often less than 10% of the rated voltage of the transformer winding. In a state where the winding temperature is abnormally increased in a transformer in actual operation, the voltage of the winding still maintains a high operating voltage (eg, rated voltage). Therefore, the voltage of the windings obtained by this method in a state of elevated temperature of the windings is very low, which cannot reflect the combined effect of the high temperature and the high voltage on the monitoring device.

Therefore, at present, there is no transformer winding temperature monitoring test platform that can provide abnormal temperature rise of the winding while the winding is in a high voltage state.

3. Multifunctional test platform for transformer monitoring technology

Existing transformer monitoring technologies, including partial discharge monitoring, winding temperature monitoring, detection of decomposed gas in oil, etc. Test platforms for various monitoring technologies are only partially functional. In particular, there is currently no test platform that can provide both partial discharge monitoring and winding temperature monitoring, so there are the following shortcomings:

(1) The influence of the partial discharge pulse in the winding on the winding temperature monitoring sensor cannot be studied; the influence of the winding temperature measuring device on the propagation process of the partial discharge pulse on the winding cannot be studied. That is, the existing single-function test platform cannot study the interaction between multiple monitoring technologies.

(2) When carrying out long-term stability experiments of partial discharge monitoring technology and winding temperature monitoring technology, it is necessary to use their own test platforms. The large number of test platforms causes inconvenience in actual operation and management.

In summary, it is necessary to provide a multi-functional transformer test platform, which can not only simulate partial discharge faults of windings during rated operation of the transformer, study the partial discharge characteristics of oil-paper insulation and the propagation law of partial discharge pulse signals in the windings, but also simulate the partial windings of the transformer at the same time. Heat is generated, and the winding is still in a high voltage state when the winding temperature rises.

SUMMARY OF THE INVENTION

In order to meet the needs of the prior art, the present invention provides a transformer test platform.

The technical scheme of the present invention is:

In the first aspect, the test platform includes a single-phase transformer, a voltage regulating winding, a high-voltage connector, an on-load voltage regulating switch and a partial discharge model;

The voltage regulating winding is connected to the high voltage end of the high voltage winding in the single-phase transformer, and the on-load voltage regulating switch is arranged on the voltage regulating winding; the high voltage joint is arranged in the middle of the high voltage winding; the partial discharge model passes The sealing cylinder extends into the inside of the transformer tank of the single-phase transformer.

Preferably, the on-load voltage regulating switch includes an active branch, a transition branch, and tap taps sequentially arranged on the voltage regulating winding, and the number of the tap taps is at least 3;

The active branch circuit includes a first moving contact, a first switch, a first reactor and a terminal fixed contact connected in sequence;

The transition branch includes a second movable contact, a second switch, a second reactor and the terminal fixed contact connected in sequence;

the first moving contact and the second moving contact are respectively slidingly connected with the tap;

Preferably, the tap tap includes a head tap tap and an end tap tap; the head tap tap is arranged at the connection end of the voltage regulating winding and the single-phase transformer, and the end tap tap is arranged at the connection end of the voltage regulating winding and the single-phase transformer. the other end of the voltage regulating winding;

The first end tap is connected to the first high-voltage sleeve, and the end fixed contact is connected to the second high-voltage sleeve;

Preferably, the partial discharge model includes a high-voltage electrode provided with a spring; the high-voltage electrode is in contact and connected with the high-voltage joint through spring compression;

Preferably, the sealing cylinder is welded and arranged on the top window of the transformer oil tank; the top of the sealing cylinder is higher than the liquid level in the transformer oil pillow, so that the partial discharge model is not inserted and taken out. oil leakage occurs;

Preferably, the high-voltage joint comprises a copper plate welded on one end of a wire; the other end of the wire is connected to the middle of the high-voltage winding in the single-phase transformer;

The copper plate is a copper plate with smooth surface and edge.

In the second aspect, the method of using the above-mentioned test platform to carry out the local heating test of the transformer winding, the steps are:

Step 11: Connect a reactor between the first high-voltage bushing and the second high-voltage bushing;

Step 12: Supply power to the low-voltage winding of the single-phase transformer;

Step 13: Adjust the value of the reactor to change the short-circuit current in the voltage regulating winding, thereby changing the temperature of the voltage regulating winding.

In the third aspect, the method of using the above-mentioned test platform to supply power to electrical equipment, the steps are:

Step 21: connecting a reactor between the first high-voltage bushing and the second high-voltage bushing, and connecting the electrical equipment and the reactor in series;

Step 22: supply power to the low-voltage winding of the single-phase transformer;

Step 23: adjusting the value of the reactor, thereby adjusting the voltage value output to the electrical equipment;

The maximum value of the voltage that the test platform supplies to the electrical equipment is the rated voltage of the high-voltage winding in the single-phase transformer, and the current value is the short-circuit current in the voltage regulating winding.

In the fourth aspect, the method of using the above-mentioned test platform to conduct partial discharge test of transformer windings is as follows:

The partial discharge model is placed inside the transformer along the sealed cylinder, so that the spring of the high-voltage electrode in the partial discharge model is in close contact with the copper plate of the high-voltage joint.

Compared with the closest prior art, the excellent effects of the present invention are:

1. A transformer test platform provided by the present invention can generate a real partial discharge signal under the normal operating voltage of the transformer, which not only simulates the propagation process of the partial discharge signal along the high-voltage winding of the transformer, but also the high-voltage winding of the transformer can be at rated voltage, which is convenient for Research the high-voltage insulation characteristics of partial discharge monitoring technology and partial discharge source location technology;

2. In the transformer test platform provided by the present invention, when the voltage regulating winding of the transformer is heated, the impedance of the reactor connected between the high-voltage bushings is not equal to zero, so that the voltage regulating winding is not completely short-circuited, so the high-voltage winding and the voltage regulating winding are not completely short-circuited. The voltage of the winding is still very high, which can be equal to the rated voltage, which is convenient for studying the high-voltage insulation characteristics of the transformer winding temperature monitoring technology;

3. In the transformer test platform provided by the present invention, the partial discharge test and the partial overheating test of the winding can be carried out at the same time; on the one hand, the influence of the partial discharge pulse through the voltage regulating winding on the temperature sensor installed on the voltage regulating winding can be studied; On the one hand, the long-term stability of the partial discharge monitoring technology and the winding temperature monitoring technology can be studied at the same time, and the test time can be shortened;

4. A transformer test platform provided by the present invention can provide high voltage and high current to other electrical equipment, where the high voltage is the rated voltage of the high-voltage winding of the transformer, and the current is the short-circuit current of the voltage regulating winding.

Description of drawings

The present invention will be further described below with reference to the accompanying drawings.

Figure 1: a schematic structural diagram of a transformer test platform in an embodiment of the present invention;

Figure 2: a schematic diagram of the connection between the high-voltage connector and the partial discharge model in the embodiment of the present invention;

Among them, 1: high voltage winding; 2: high voltage connector; 21: partial discharge model; 22: sealed cylinder; 23: copper plate; 24: wire; 3: voltage regulating winding; 4: first high voltage bushing; 5: second High voltage bushing; 6: Reactor; 7: Low voltage winding; 8: On-load tap changer; 9: Iron core; 10: Low voltage bushing; 11: Active branch; 12: Transition branch; 13: Primary reactor 14: second reactor; 15: transformer oil tank; 16: transformer oil pillow.

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

The transformer test platform provided by the invention can not only simulate the partial discharge fault of the winding during the rated operation of the transformer, study the partial discharge characteristics of the oil-paper insulation and the propagation law of the partial discharge pulse signal in the winding, but also simulate the heating of the partial winding of the transformer at the same time. When the winding temperature rises, the winding is still in a high voltage state.

The embodiment of the transformer test platform provided by the present invention is shown in FIG. 1, and is specifically:

The test platform includes a single-phase transformer, a voltage regulating winding 3, a high voltage connector 2, an on-load voltage regulating switch 8 and a partial discharge model 21, wherein,

The voltage regulating winding 3 is connected to the high voltage end of the high voltage winding 1 in the single-phase transformer; the on-load voltage regulating switch 8 is arranged on the voltage regulating winding 3; the high voltage joint 2 is arranged in the middle of the high voltage winding 1; 22 extends into the transformer tank of the single-phase transformer.

(1) On-load voltage regulator switch

The on-load voltage regulating switch includes an active branch 11, a transition branch 12, and tap taps sequentially arranged on the voltage regulating winding 3, and the number of tap taps is at least 3. As shown in FIG. The number of taps is 6.

The active branch 11 includes a first moving contact, a first switch, a first reactor 13 and an end fixed contact connected in sequence;

The transition branch 12 includes a second moving contact, a second switch, a second reactor 14 and a terminal fixed contact connected in sequence;

The first moving contact and the second moving contact are respectively slidingly connected with the tap tap.

The tap tap includes a head tap tap and an end tap tap; the head tap tap is set at the connection end of the voltage regulating winding 3 and the single-phase transformer, and the end tap tap is set at the other end of the voltage regulating winding 3; the head end The tap tap is connected to the first high-voltage sleeve 4 , and the fixed contact at the end is connected to the second high-voltage sleeve 5 .

(2) Partial discharge model

The partial discharge model 21 includes a high-voltage electrode provided with a spring; the high-voltage electrode is connected in contact with the high-voltage terminal by compression of the spring. In this embodiment, the partial discharge model adopts one or more of partial discharge models such as pin-plate discharge, ball-plate discharge, and air-gap discharge model.

(3) Sealing cylinder

As shown in FIG. 2, the sealing cylinder 22 is welded on the top window of the transformer oil tank 15; the top of the sealing cylinder 22 is higher than the liquid level in the transformer oil pillow 16, so that when the partial discharge model 21 is put in and taken out No oil leakage occurs.

(4) High pressure connector

The high-voltage joint 2 includes a copper plate 23 welded to one end of a wire 24, and the other end of the wire 24 is connected to the middle of the high-voltage winding 1 in the single-phase transformer; the copper plate 23 is a copper plate with smooth surface and edge.

In the embodiment of the present invention, the test types and operation methods included in the above-mentioned transformer test platform are:

1. When using the test platform to carry out the partial heating test of the transformer winding, it includes:

(1) Connect the reactor 6 between the first high-voltage bushing 4 and the second high-voltage bushing 5;

(2) supply power to the low-voltage winding 7 of the single-phase transformer;

(3) Adjust the value of the reactor 6 to change the short-circuit current in the voltage regulating winding 3 , thereby changing the temperature of the voltage regulating winding 3 .

When the value of the reactor 6 is small, it is equivalent to the short circuit of the voltage regulating winding 3 through the reactor 6 . When supplying power to the low-voltage winding 7, the short-circuit current will flow in the voltage-regulating winding 3, while only the load current will flow in the high-voltage winding 1, so that the calorific value of the voltage-regulating winding 3 is much larger than that of the high-voltage winding 1, making the temperature of the voltage-regulating winding 3 higher than the high voltage winding. By changing the impedance value of the reactor 6 , the short-circuit current in the voltage regulating winding 3 can be changed, thereby changing the temperature of the voltage regulating winding 3 .

Since the impedance value of the reactor 6 is not equal to zero, the voltage regulating winding 3 is not completely short-circuited, so the voltage of the high voltage winding 1 and the voltage regulating winding 3 is still very high, which can be equal to the rated voltage, so the experimental platform can be used for the temperature of the transformer winding. Monitoring technology research.

2. When using the test platform to supply power to electrical equipment, including:

(1) Connect the electrical equipment and the reactor 6 in series between the first high-voltage bushing 4 and the second high-voltage bushing 5;

(2) Supply power to the low-voltage winding 7 of the single-phase transformer, and adjust the value of the reactor 6 to change the short-circuit current in the voltage regulating winding 3 . The maximum value of the voltage that the test platform supplies to the electrical equipment is the rated voltage of the high-voltage winding 1 in the single-phase transformer, and the current value is the short-circuit current in the voltage regulating winding 3.

3. When using the test platform for partial discharge test of transformer winding, it includes:

The partial discharge model 21 is placed inside the single-phase transformer along the sealing cylinder 22 , so that the spring of the high voltage electrode in the partial discharge model is in close contact with the copper plate 23 of the high voltage joint 2 .

The high-voltage connector 2 transmits the voltage in the middle of the high-voltage winding 1 to the partial discharge model 21, so that the partial discharge model 21 generates power. Since the high-voltage connector 2 is electrically connected to the middle of the high-voltage winding 1, it has the following advantages:

①: After the partial discharge pulse propagates along the high-voltage winding 1 for a certain distance, it is transmitted from the first high-voltage bushing 4 and the second high-voltage bushing 5, so that the partial discharge pulse signal output from the end of the high-voltage bushing contains the partial discharge pulse along the winding. disseminated information;

②: The voltage on the partial discharge model 21 is only a part of the high-voltage terminal voltage of the high-voltage winding 1, so that the withstand voltage of the partial discharge model 21 does not have to be greater than or equal to the high-voltage terminal voltage of the high-voltage winding 1, thereby reducing the partial discharge model 21. volume. Therefore, when the partial discharge test is carried out, the voltage on the high-voltage winding 1 is still the rated voltage, which is consistent with the transformer of the same voltage level in actual operation;

③: In the partial discharge test, there is a risk of the partial discharge model 21 being broken down. Compared with the existing transformer test platform that directly connects the partial discharge model 21 with the lead wire of the high-voltage winding 1, the partial discharge model 21 in this embodiment Connected to the middle of the high-voltage winding 1, the voltage on the partial discharge model 21 is low, and the impact damage caused to the transformer test platform when the partial discharge model is broken down is small.

Finally, it should be noted that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Claims (6)

1. a transformer test platform, is characterized in that, described test platform comprises single-phase transformer, voltage regulating winding, high-voltage joint, on-load voltage regulating switch and partial discharge model; The voltage regulating winding is connected to the high voltage end of the high voltage winding in the single-phase transformer, and the on-load voltage regulating switch is arranged on the voltage regulating winding; the high voltage joint is arranged in the middle of the high voltage winding; the partial discharge model passes The sealing cylinder extends into the transformer oil tank of the single-phase transformer; The on-load voltage regulating switch includes an active branch, a transition branch, and tap taps sequentially arranged on the voltage regulating winding, and the number of the tap taps is at least 3; The active branch circuit includes a first moving contact, a first switch, a first reactor and a terminal fixed contact connected in sequence; The transition branch includes a second movable contact, a second switch, a second reactor and the terminal fixed contact connected in sequence; the first moving contact and the second moving contact are respectively slidingly connected with the tap; The tap tap includes a head tap tap and an end tap tap; the head tap tap is arranged at the connection end of the voltage regulating winding and the single-phase transformer, and the end tap tap is arranged on the regulator winding. the other end of the pressure winding; The first end tap is connected to the first high-voltage sleeve, and the end fixed contact is connected to the second high-voltage sleeve; The sealing cylinder is welded on the top window of the transformer oil tank; the top of the sealing cylinder is higher than the liquid level in the transformer oil pillow, so that no oil leakage occurs when the partial discharge model is put in and taken out ; A reactor is connected between the first high-voltage bushing and the second high-voltage bushing, and the value of the reactor is adjusted to change the short-circuit current in the voltage regulating winding, thereby changing the temperature of the voltage regulating winding. 2 . The test platform according to claim 1 , wherein the partial discharge model comprises a high-voltage electrode provided with a spring; the high-voltage electrode is in contact and connected with the high-voltage joint through spring compression. 3 . 3. The test platform of claim 1, wherein the high-voltage joint comprises a copper plate welded on one end of a wire; the other end of the wire is connected to the middle of the high-voltage winding in the single-phase transformer; The copper plate is a copper plate with smooth surface and edge. 4. adopt the test platform described in any one of claim 1-3 to carry out the method for transformer winding partial heating test, and its step is: Step 11: Connect a reactor between the first high-voltage bushing and the second high-voltage bushing; Step 12: Supply power to the low-voltage winding of the single-phase transformer; Step 13: Adjust the value of the reactor to change the short-circuit current in the voltage regulating winding, thereby changing the temperature of the voltage regulating winding. 5. The method for supplying power to electrical equipment using the test platform according to any one of claims 1-3, the steps are: Step 21: Connect a reactor between the first high-voltage bushing and the second high-voltage bushing, and connect the electrical the device is connected in series with the reactor; Step 22: supply power to the low-voltage winding of the single-phase transformer; Step 23: adjusting the value of the reactor, thereby adjusting the voltage value output to the electrical equipment; The maximum value of the voltage that the test platform supplies to the electrical equipment is the rated voltage of the high-voltage winding in the single-phase transformer, and the current value is the short-circuit current in the voltage regulating winding. 6. adopt the test platform described in any one of claim 1-3 to carry out the method for partial discharge test of transformer winding, and its step is: put the partial discharge model into the inside of the transformer along the sealing cylinder, so that the high voltage electrode in the partial discharge model is put into the transformer. The spring is in close contact with the copper plate of the high voltage connector.

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