KR20140033979A - Apparatus for diagnosing a power transformer - Google Patents

Abstract

The present invention relates to a diagnostic device of a transformer. According to an embodiment of the present invention, the diagnostic device of a transformer includes: a partial discharge sensor detecting ultrasonic waves generated by partial discharge to generate a partial discharge signal when partial discharge occurs inside the transformer; a vibration measurement sensor generating a vibration signal by detecting the vibration generated from the transformer when the transformer is activated; and a diagnosis unit for diagnosing the state of the transformer using the partial discharge signal and the vibration signal. [Reference numerals] (1) Transformer; (30) Diagnosis unit

Description

Transformer Diagnostics {Apparatus for diagnosing a power transformer}

The present invention relates to a transformer diagnostic apparatus, and more particularly, to a transformer diagnostic apparatus capable of diagnosing a temporary state change and a long term state change occurring in a transformer.

In recent years, with the increase in electric power demand, transformers have become larger and ultra-high pressure, and substations are becoming unmanned. When an accident occurs in such a large-capacity transformer, its ripple effect is widespread, and economic loss and psychological anxiety are enormous. Therefore, the necessity of insulation diagnosis to prevent a transformer accident is increasing. Therefore, in order to secure the reliability of the transformer and to supply the power stably, a transformer diagnostic apparatus for measuring the signs of an internal defect that causes an accident at all times in the operation state of the transformer has been developed. However, the conventional transformer diagnosis device is composed of diagnosing the abnormal state of the electrical voltage and current, chemically analyzing the components of the insulating oil used internally or analyzing the generated gas, and mechanical state analysis is not performed separately. not.

The present invention is to provide a transformer diagnostic apparatus capable of diagnosing temporary state changes and long-term state changes occurring in the transformer.

Transformer diagnostic apparatus according to an embodiment of the present invention, when a partial discharge occurs in the transformer, the partial discharge sensor for generating a partial discharge signal by detecting the ultrasonic wave generated by the partial discharge; A vibration measuring sensor for detecting a vibration generated from the transformer when the transformer is operated and generating a vibration signal; And a diagnosis unit for diagnosing a state of the transformer using the partial discharge signal and the vibration signal.

The diagnosis unit may detect a partial discharge generated in the transformer by using at least one of the partial discharge signal and the vibration signal.

The diagnosis unit may detect a change in state of the transformer by comparing a change state of the vibration signal with a vibration signal database in which the change of the vibration signal is recorded.

Here, the diagnosis unit may convert the vibration signal into a frequency domain to set a representative value representing the magnitude of vibration generated in the transformer, and set the vibration class of the transformer using the representative value.

Here, the diagnosis unit may set whether or not to perform maintenance work on the transformer and a maintenance method according to the vibration level.

Here, the diagnosis unit may determine a position of a defect occurring in the transformer by using a difference between propagation speeds of the ultrasonic wave and the vibration.

Here, the diagnosis unit may determine a distance from the vibration measuring sensor to the point where the defect occurs by using the difference between the propagation speeds of the ultrasonic waves and the vibration, and input ultrasonic waves above a reference value among a plurality of partial discharge sensors attached to the transformer. The location of the defects occurring in the transformer can be determined using the sequence of the steps.

According to an embodiment of the present invention, the transformer diagnosis apparatus may measure and diagnose a temporary state change and a long term state change appearing in the transformer at the same time, thereby enabling comprehensive diagnosis of the transformer.

According to the transformer diagnostic apparatus according to an embodiment of the present invention, since the position at which a defect occurs, such as a partial discharge, can be accurately identified, the transformer can be easily repaired.

According to the transformer diagnostic apparatus according to an embodiment of the present invention, the vibration generated in the transformer can be analyzed and databased, and the transformer can be classified and managed according to the vibration class.

Figure 1 is a block diagram showing a transformer diagnostic apparatus according to an embodiment of the present invention.
Figure 2 is a vibration class classification table for the vibration signal of the transformer diagnostic apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a method of diagnosing a transformer using a transformer diagnostic apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention. In the following detailed description of the preferred embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In the drawings, like reference numerals are used throughout the drawings.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . Also, to "include" an element means that it may include other elements, rather than excluding other elements, unless specifically stated otherwise.

Figure 1 is a block diagram showing a transformer diagnostic apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a transformer diagnostic apparatus according to an embodiment of the present invention may include a partial discharge sensor 10, a vibration measuring sensor 20, and a diagnosis unit 30.

Hereinafter, a transformer diagnosis apparatus according to an embodiment of the present invention will be described with reference to FIG. 1.

The partial discharge sensor 10 may generate a partial discharge signal by detecting an ultrasonic wave generated by the partial discharge when the partial discharge occurs in the transformer 1. The partial discharge sensor 10 may be attached to the outer wall of the transformer 1, the plurality of partial discharge sensor 10 may be a plurality. The number and positions of the partial discharge sensors 10 may be adjusted according to the state of the transformer 1 or the signal acquisition situation.

Specifically, the transformer 1 may include an insulator such as insulating oil together with an iron core and a coil. Therefore, even when a high voltage is applied to the transformer, it can be insulated by the insulating oil or the like and operate stably. However, the insulator and the like may deteriorate, and accordingly, a part of the internal structure of the transformer 1 may be partially broken. In this case, partial discharge may occur inside the transformer 1, and when the partial discharge occurs, a pulsed current may appear and a sound wave having a wide frequency distribution from an audible frequency to an ultrasonic wave may occur. Therefore, the partial discharge sensor 10 may be positioned on the outer wall of the transformer 1, and the partial discharge may be detected by measuring ultrasonic waves generated by the partial discharge.

Here, since the ultrasonic wave generated in the partial discharge is a small signal, the sensor may be very important when measuring. That is, since transmission and reflection occur at the boundary between two different materials, an air layer exists at the interface between the partial discharge sensor 10 and the outer wall of the transformer 1 in case of poor contact, thereby preventing or greatly transmitting the ultrasonic waves. May be attenuated. Therefore, the partial discharge sensor 10 may be attached to the outer wall of the transformer 1 through a bolt nut fixing method or a magnetic fixing method. Furthermore, silicone oil, glycerin, or the like may be injected between the partial discharge sensor 10 and the transformer 1 in order to improve interfacial ultrasonic wave transmission characteristics.

The vibration measuring sensor 20 may generate a vibration signal by detecting vibration generated by the transformer 1 when the transformer 1 operates. The vibration measuring sensor 20 may be attached to an outer wall of the transformer 1, and a plurality of vibration measuring sensors 20 may be provided. The number and position of the vibration measuring sensor 20 can be adjusted according to the state of the transformer 1 or the signal acquisition situation.

When the transformer 1 is operated, the transformer 1 vibrates with its own frequency. The natural frequency of the transformer 1 is a value determined by the shape of the transformer 1, an operating condition, a location, an ambient environment, etc., but a change in shape according to the use of the transformer 1, aging of materials such as insulating oil, and the like. Accordingly, the natural frequency of the transformer 1 may change gradually. In addition, when the partial discharge occurs, there may be a change in the frequency of the transformer 1 instantaneously. As described above, when the partial discharge occurs, sound waves are generated, and thus vibrations caused by the sound waves may affect the natural frequency of the transformer 1. Therefore, using the vibration measuring sensor 20 can detect a long-term state change, including the degree of aging of the transformer (1), it is also possible to determine whether or not a partial discharge.

The diagnosis unit 30 may diagnose the state of the transformer 1 by using the partial discharge signal and the vibration signal. The diagnosis unit 30 may provide a diagnosis result to a user by diagnosing a temporary state change and a long term state change of the transformer 1.

Specifically, the temporary state change may include a partial discharge generated in the transformer 1. The partial discharge is generated by a partial breakdown of insulation inside the transformer 1, and may return to an insulating state after the momentary discharge. Therefore, the diagnosis unit 30 may detect the temporary state change occurring in the transformer 1 by detecting the partial discharge using the partial discharge signal. In addition, as described above, since the ultrasonic wave generated by the partial discharge may affect the vibration of the transformer 1, it is also possible to determine whether the partial discharge using the change amount of the vibration signal. That is, when a partial discharge signal of more than a reference value is input or a vibration signal of more than a reference change amount is input, the partial discharge may be considered to have occurred. In addition, the partial discharge may be regarded as the occurrence of the partial discharge only when the partial discharge signal and the vibration signal are combined to simultaneously input the partial discharge signal of the reference value or more and the vibration signal of the reference change amount or more.

The long-term state change of the transformer 1 can be detected by comparing the change trend of the vibration signal with the vibration signal database in which the change of the vibration signal is recorded. As described above, since the frequency of the transformer 1 may change due to the shape change, aging, etc. of the transformer 1, the frequency of the transformer 1 may be changed using the change trend of the frequency of the transformer 1. Long-term condition changes can be diagnosed.

Specifically, electrical, mechanical stress and high temperature operation of the transformer 1 may degrade the electrical performance and mechanical performance of the transformer 1, which may lead to a decrease in the mechanical strength of the transformer 1. As the mechanical strength of the transformer 1 decreases, the vibration of the transformer 1 may gradually increase, and finally, the transformer 1 may be connected to a failure of the transformer 1 including a short circuit or an insulation breakdown. Accordingly, the diagnosis unit 30 may determine in advance the failure time of the transformer 1 by using the frequency change trend of the transformer 1, and the user may respond in advance to the failure time in response to the transformer 1. ) Can be prevented. For example, the vibration signal of the transformer 1 is gradually increasing with a constant slope, and compared with the vibration signal database, the transformer 1 has a maximum frequency allowed at a time exceeding five years. It can be expected to have the above frequency. Therefore, it is possible to prevent the occurrence of a failure of the transformer 1 by stopping the operation of the transformer 1 and performing maintenance work before the five years have elapsed.

Here, in order to diagnose a long-term state change of the transformer (1), the diagnosis unit 30 can set the vibration class according to the magnitude of the vibration, whether to perform maintenance work on the transformer (1) according to the vibration rating And maintenance methods can be set differently. In this case, the reference for setting the vibration rating may vary depending on the cumulative operation time of the transformer (1).

Specifically, the diagnostic unit 30 may convert the measured vibration signal into a frequency domain using a Fast Fourier Transform (FFT), a wavelet transform, or the like. A representative value representing the magnitude of vibration generated by the transformer can be set. For example, any one of an average value, a maximum value, and a dispersion value for each frequency band of the vibration signal may be set as the representative value. Subsequently, the vibration class of the transformer 1 may be set based on the representative value, and the state of the transformer 1 may be determined according to the vibration class, and whether or not the repair operation may be performed on the transformer 1. It is possible to set the method.

2 is an example of the vibration class classification table, the diagnosis unit 30 may set the vibration class of the transformer 1 according to the vibration class classification table. Referring to Figure 2, the vibration grade may be divided from A grade to E grade. Class A is the normal permissible vibration level allowed for the transformer when the transformer is newly installed and is the safest state. Class B is a level that allows long-term operation without any restriction, and class C is a level that is not allowed for continuous operation, but operation is possible, and maintenance is required for the transformer (1). Class D is limited to the operation of the transformer (1), in the case of the D class is severe vibration can damage the transformer (1). Lastly, in the case of the E grade, the transformer 1 is damaged, so a restriction on use of the transformer 1 is required, and the grade cannot be operated without the repair of the transformer 1. Therefore, the diagnosis unit 30 sets the vibration level by using the representative value, and then provides the vibration level to the user, so that the user performs maintenance work on the transformer 1 according to the vibration level. You can do that.

In addition, the diagnosis unit 30 may determine a location of a defect occurring in the transformer 1 by using a difference in propagation speed of the ultrasonic wave generated by the partial discharge and the vibration of the transformer 1. Since the ultrasonic wave and the vibration have a difference in propagation speed, when the partial discharge occurs, there may be a difference in the time when the ultrasonic wave and the vibration start to be input to each of the partial discharge sensor 10 and the vibration sensor 20. That is, by comparing the difference between the starting point at which the abnormal signal is input, such as a partial discharge signal of more than a reference value or a vibration signal of more than a reference change amount is input to the diagnosis unit 30, the distance to the position of the partial discharge can be calculated. have. In this case, the partial discharge sensor 10 and the vibration sensor 20 may be located in close proximity to each other, when the partial discharge sensor and the vibration sensor is provided with a plurality of partial discharge occurs after setting a certain reference position The distance to the location can be calculated.

Here, the plurality of partial discharge sensors 10 and the vibration sensor 20 may be provided in the transformer 1 to more accurately grasp the position where the partial discharge occurs. Specifically, the position at which the partial discharge occurs may be determined using the order in which the ultrasonic waves generated by the partial discharge reach the respective partial discharge sensors 10. When the partial discharge occurs, the ultrasonic waves may propagate along the insulating oil inside the transformer 1, and the ultrasonic waves may sequentially arrive from the partial discharge sensor 10 provided near the position where the partial discharge occurs. . Therefore, when the position of the partial discharge sensor 10 to which the ultrasonic wave is first input, the propagation speed of the ultrasonic wave, and the distance from the reference position to the position where the partial discharge occurs, the position where the partial discharge occurs can be accurately calculated. Can be.

3 is a flowchart illustrating a method of diagnosing a transformer using a transformer diagnostic apparatus according to an embodiment of the present invention. Hereinafter, a method of diagnosing a transformer using a transformer diagnostic apparatus according to an embodiment of the present invention will be described with reference to FIG. 3.

First, the partial discharge sensor and the vibration measuring sensor may be attached to the transformer to receive the partial discharge signal and the vibration signal from the partial discharge sensor and the vibration measuring sensor (S10). The partial discharge sensor may generate a partial discharge signal by detecting a partial discharge generated by a defect such as insulation breakdown inside the transformer, and the vibration measuring sensor measures a frequency generated during operation of the transformer to determine a vibration signal. Can be generated.

Since the measured partial discharge signal and the vibration signal include information on the temporary state change and the long-term state change of the transformer, it is possible to check whether the state of the transformer changes using this (S20). For example, when a partial discharge signal of more than a reference value is input or a vibration signal change of more than a reference change amount is detected, it may be considered that there is an error in the transformer. However, there may be a case where the state change of the transformer is temporarily and continuously maintained for a long time, and in each case, it is necessary to make a different diagnosis.

Accordingly, the input of the partial discharge signal and the vibration signal may be grasped to determine whether the state of the transformer is temporarily generated or whether the state of the transformer continues to be changed in the long term (S30). When the state change of the transformer is temporary, it may be considered that partial discharge has occurred in the transformer, and in this case, a position where the partial discharge occurs in the transformer may be determined (S50). After knowing the location of the partial discharge, the repair work on the transformer can be performed more easily.

On the other hand, if the change in the transformer is a long-term change it can analyze the trend of the vibration signal (S40). That is, the state of the transformer may be determined by comparing the trend of the vibration signal with the trend stored in the vibration signal database. Thereafter, by converting the vibration signal into a frequency domain and obtaining a representative value, it is possible to set a vibration class with respect to the vibration signal (S60), and it is possible to set whether to repair or repair the transformer according to the set vibration level. .

The present invention is not limited by the above-described embodiment and the accompanying drawings. It is intended that the scope of the invention be defined by the appended claims, and that various forms of substitution, modification, and alteration are possible without departing from the spirit of the invention as set forth in the claims. Will be self-explanatory.

1: transformer 10: partial discharge sensor
20: vibration measuring sensor 30: diagnostic unit

Claims (7)

A partial discharge sensor generating a partial discharge signal by detecting an ultrasonic wave generated by the partial discharge when a partial discharge occurs in a transformer;
A vibration measuring sensor for detecting a vibration generated from the transformer when the transformer is operated and generating a vibration signal; And
And a diagnosis unit for diagnosing a state of the transformer by using the partial discharge signal and the vibration signal.
The method of claim 1, wherein the diagnostic unit
And a partial discharge signal generated in the transformer by using at least one of the partial discharge signal and the vibration signal.
The method of claim 1, wherein the diagnostic unit
Transformer diagnosis device for detecting a change in the state of the transformer by comparing the change of the vibration signal with the vibration signal database recorded the change of the vibration signal.
The method of claim 1, wherein the diagnostic unit
Converting the vibration signal into the frequency domain to set a representative value representing the magnitude of the vibration generated in the transformer, and the transformer diagnostic apparatus for setting the vibration class of the transformer using the representative value.
The method of claim 4, wherein the diagnostic unit
Transformer diagnostic apparatus for setting whether to perform the maintenance work and the repair method for the transformer according to the vibration class.
The method of claim 1, wherein the diagnostic unit
Transformer diagnosis apparatus for determining the location of the defect occurred in the transformer by using the difference between the propagation speed of the ultrasonic wave and the vibration.
The method of claim 6, wherein the diagnostic unit
The distance from the vibration measuring sensor to the point where the defect is generated is determined by using the difference between the propagation speeds of the ultrasonic waves and the vibration, and the ultrasonic waves above the reference value are input from the plurality of partial discharge sensors attached to the transformer. Transformer diagnostic apparatus for determining the location of the defect occurred in the transformer.

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