KR102029745B1 - System and method for insulation deterioration monitoring analysis of transformer bushing with bushing tap - Google Patents

Abstract

The present invention relates to a system and a method for monitoring and analyzing an insulation deteriorating state of a transformer bushing having a bushing tap, which can increase the accuracy of insulation deteriorating diagnosis. The system of the present invention comprises: a partial discharge detection unit for receiving and detecting a partial discharge frequency; a current detection unit for receiving and detecting a leakage current; a voltage detection unit for receiving and detecting a driving voltage; a phase synchronizing unit for synchronizing a phase of voltage; a comparator for receiving the leakage current from the current detection unit; and an analysis determination unit for analyzing an insulation deteriorating state of a transformer bushing.

Description

System and method for insulation deterioration monitoring analysis of transformer bushing with bushing tap}

The present invention relates to a system and method for analyzing the state of insulation degradation monitoring of a transformer bushing having a bushing tap, and more particularly, to analyze the leakage current measurement technology and the analysis of transient currents and harmonic voltages or harmonic currents due to breakdown of transmission and transformation lines. The present invention relates to a system and method for monitoring and analyzing the insulation degradation state of a transformer bushing having a bushing tab for comparing and determining the integrity of the insulation of the transformer bushing and diagnosing the insulation degradation of the bushing of the transformer.

In recent years, a transformer fire of a power company is frequently occurring, and one of the causes is a poor insulation of a transformer bushing. In general, transformers, circuit breakers, and motors that transmit or generate power using AC power must have insulation performance determined according to the voltage used. If insulation performance is degraded, failures due to short circuits and ground faults occur.

Insulation deterioration of transmission and transmission equipment means that the basic property of the insulation for electrical isolation between the conductor and the ground (or between the conductors) is deteriorated by a certain factor. In particular, when various insulating materials inside the power transformer are deteriorated, and the deteriorated insulating material is mechanically damaged by an impact such as surge, vibration, and external short circuit, the transformer is damaged by contact between the windings, the windings, and the core.

The insulation oil is contaminated by the generated heat inside the transformer, and the strength of the insulating material deteriorates due to deterioration, and the insulation material is physically destroyed by an abnormal voltage such as surge, earthquake, vibration, or electromagnetic force during external short circuit. Short circuits, winding-to-core contact, and winding-to-enclosure contact eventually result in breakdown of the insulation inside the transformer.

In general, there are two methods of analyzing the insulation state of a transformer bushing: a tan delta (tanδ) method and a partial discharge diagnosis method that measure total leakage current, measure the magnitude of resistive current components, and analyze measured and reactive currents. .

Republic of Korea Patent No. 10-1520230 (announced May 13, 2015)

Therefore, the technical problem to be achieved by the present invention is to solve the disadvantages of the prior art, and as a method for measuring the leakage current, the current indirect measurement method using Rogowski coil and the voltage conversion method of the leakage current value by the shunt resistance selectively. Its purpose is to facilitate the diagnosis of thermal degradation of the transformer bushing. It also aims to increase the accuracy of diagnosing insulation deterioration of transformer bushings by providing analysis element technology with harmonic components of operating system voltages that can act as inaccuracies of leakage current and instantaneous voltage drops that can occur during system troubles. .

In order to achieve the above technical problem, an insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an embodiment of the present invention may include a detector, a comparator, a controller, a display, a communicator, a positioning unit, and a storage unit.

The detector may include a partial discharge detector, a current detector, a voltage detector, and a phase synchronizer. The partial discharge detector may receive the partial discharge frequency generated by the transformer bushing through a current transformer (CT) to detect the partial discharge frequency. The current detector may receive and detect a leakage current generated in the transformer bushing through a current transformer (CT).

The voltage detector may detect and receive an operating voltage from a transformer through a potential transformer (PT). The phase synchronizer may synchronize a phase of a leakage current input from the current detector and a voltage input from the voltage detector.

The comparator may receive a leakage current from the current detector and an operation voltage from the voltage detector to compare a change in capacitance of the transformer bushing itself with an inherent capacitance. The control unit may receive the comparison result data from the comparator and determine whether the change of the leakage current is caused by the change of the operating voltage, and analyze the insulation deterioration state of the transformer bushing based on the determination result.

In accordance with an embodiment of the present invention, a method for analyzing insulation degradation monitoring of a transformer bushing having a bushing tap may include measuring leakage current of a transformer bushing (S10), measuring a partial discharge frequency of the transformer bushing (S20), and a transformer. It may include the step of receiving the grid voltage from the measurement (S30).

In addition, synchronizing the leakage current of the step (S10) and the phase of the grid voltage measured in the step (S30) (S40), the leakage current in which the phase is synchronized with the capacitance according to the change of the insulation deterioration state of the transformer bushing Comparative analysis with the reference value (S50) and

The method may include determining an insulation deterioration state of the transformer bushing based on a comparison analysis result of the operation S50.

As described above, the system and method for analyzing the insulation deterioration state monitoring of a transformer bushing with a bushing tap according to the present invention is the current indirect measurement method using Rogowski coil and the leakage current value by the shunt resistance. By selectively using the voltage conversion method it is possible to facilitate the diagnosis of the thermal degradation of the transformer bushing. In addition, the analysis element technology provides the harmonic components of the operating system voltage and the instantaneous voltage drop that may occur when the system is troubled, which may act as an inaccurate factor of leakage current, thereby increasing the accuracy of diagnosing insulation degradation of the transformer bushing. have.

1 is a conceptual diagram illustrating an insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an exemplary embodiment of the present invention.
2 is a block diagram illustrating an insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an exemplary embodiment of the present invention.
3 is a view showing a power supply short circuit in the insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an embodiment of the present invention.
4 is a flowchart illustrating a method for analyzing insulation deterioration monitoring of a transformer bushing having a bushing tab according to an exemplary embodiment of the present invention.
5 is a flowchart illustrating a method for analyzing insulation degradation monitoring of a transformer bushing having a bushing tab according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “… module” described in the specification mean a unit that processes at least one function or operation, which is implemented by hardware or software or a combination of hardware and software. Can be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Like reference numerals in the drawings denote like elements.

Transformer bushing 10 is operated by applying a special high-voltage voltage, most of the physical properties of the capacitance, the long-term use may change the characteristics (capacitance), the transformer may be burned out by fire. In addition, the insulation state of the transformer bushing 10 may be diagnosed by measuring a change in capacitance. That is, the leakage current of the bushing 10 may be measured and diagnosed, and the following Equation 1 may be applied.

[Equation 1]

I _C = ωCE

Here, I _C is the leakage current of the bushing 10, ω is the angular velocity, C is the capacitance, E may represent the induced voltage.

The leakage current may be diagnosed even during operation of the transformer 1 by connecting a wire to the transformer bushing tab 11. Current transformers (CTs) 111 and 121 are connected to the transformer bushing tabs 11 so that leakage current flows, and the Rogowski coil principle may be used for the current transformers.

In addition, the leakage current appears as a voltage drop across the shunt resistor 122, and can be calculated according to the formula of V = IR based on the extracted resistance value to diagnose the leakage current.

1 is a conceptual diagram illustrating an insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an embodiment of the present invention, Figure 2 is an insulation degradation state monitoring analysis of a transformer bushing having a bushing tab according to an embodiment of the present invention It is a block diagram which shows a system.

The insulation degradation state monitoring analysis system 20 of a transformer bushing having a bushing tab according to an embodiment of the present invention includes a detector 100, a comparator 200, a controller 300, a display unit 400, a communication unit 500, It may include a positioning unit 600 and the storage unit 700.

The detector 100 may detect the leakage current and the partial discharge frequency measured by the transformer bushing tab 11 during the operation of the high voltage transformer. In addition, the detector 100 may include a partial discharge detector 110, a current detector 120, a voltage detector 130, and a phase synchronizer 140.

The partial discharge detection unit 110 may detect the partial discharge frequency generated by the transformer bushing 10. Here, the partial discharge signal is applied to the partial discharge detection unit 110 through a current transformer (CT) 111 connected to the transformer bushing tab 11.

The detected partial discharge frequency may include at least one of a spectral method for sequentially analyzing in a sweeping form and a method for analyzing in a magnitude-phase-frequency = form.

In addition, the partial discharge frequency detection is used in the current transformer method using the Rogowski coil principle, the analysis results can be expressed in a two-dimensional or three-dimensional graph through the display unit 400. The current transformer (CT) 111 may be a sensor for detecting partial discharge in the form of Rogowski coil for detecting the partial discharge frequency.

The partial discharge signal is applied from a Rogowski coil (CT) type sensor for partial discharge detection and analyzed by the partial discharge detection unit 110 and the control unit 300, and the measurement band of the partial discharge frequency is the limit that allows the characteristics of the sensor. It can include all frequencies within.

The current detector 120 may detect a leakage current generated by the transformer bushing 10. Here, the leakage current signal may be applied to the current detector 120 through a current transformer 121 connected to the transformer bushing tab 11. In addition, a shunt resistor 122 may be provided between the current transformer 121 and the current detector 120.

That is, the leakage current may be detected through at least one of a current transformer measuring method using Rogowski coil principle and a method of extracting the leakage current as the voltage drop of the resistance.

Through this, the insulation degradation state monitoring analysis system 20 of the transformer bushing having a bushing tab according to an embodiment of the present invention uses a method of indirectly measuring Rogowski coil or by a shunt resistor 122. The voltage drop can be used to measure leakage current selectively. Typically, voltage measurement is more accurate than current measurement.

The voltage detector 130 may receive a driving voltage from the transformer 1 through a potential transformer PT 131 to detect the voltage. The voltage detector 130 may detect a total harmonic distortion (HDD) and an instantaneous voltage drop (SAG) based on the voltage measured by the potential transformer 131. That is, the voltage detector 130 may extract how much harmonics are contained in the operating voltage monitored by the potential transformer 131.

The system operating voltage may include harmonic components derived from a fault or distributed power supply, and the judgment reference harmonic analysis may be used as judgment data when leakage current is measured in a high frequency environment with high harmonic content. In addition, the voltage system may be represented by a sag voltage drop (SAG) at the time of the line failure, and may also appear as an error of the leakage current used as diagnostic data for degradation of the transformer bushing 10.

Meanwhile, based on the detection result of the voltage detector 130, when the instantaneous voltage is generated, the information may be wirelessly informed to the user by using the communication unit 500. In addition, by using the voltage waveform generated the instantaneous voltage drop (SAG) to track the trajectory can be confirmed the change in size. That is, it is possible to grasp the fluctuating voltage by following the inflection line of the voltage waveform indicating the instantaneous voltage drop SAG.

Accordingly, the insulation state information of the transformer bushing 10 according to the occurrence of the instantaneous voltage drop SAG is stored in the SAG information storage module 7101, and the transformer bushing 10 is based on the stored state information when the instantaneous voltage drop SAG occurs. Can be compared with the state of In addition, the insulation state information of the transformer bushing 10 according to the harmonic content is stored in the harmonic content storage module 720, and the harmonic content and the state of the transformer bushing 10 measured based on the stored state information of the harmonic content are compared. Can be analyzed.

The phase synchronizer 140 may synchronize the phase of the current received from the current detector 120 and the voltage received from the voltage detector 130, and represent the voltage and the phase of the current as vectors. The phase synchronizer 140 synchronizes to display a vector of voltage and current so that the representation of the vector is stable.

The controller 300 may provide a reference voltage for measuring the leakage current to the phase synchronizer 140 to indicate the voltage and the current phase so that an accurate reference value is set.

The comparator 200 receives the leakage current from the current detector 120, receives the operating voltage of the transformer 1 from the voltage detector 130, and changes the capacitance change and the inherent capacitance of the transformer bushing 10 itself. Can be compared. In other words, the capacitance of the transformer bushing 10 based on the operating voltage supplied from the transformer 1 and the change in capacitance according to the progress of the insulation deterioration state of the transformer bushing 10 may be compared.

In addition, the comparator 200 may increase the resolution of the partial discharge frequency measured by the partial discharge detector 110. That is, the comparator 200 may include a frequency comparator 210 for differentiating the phase for displaying the vector of the voltage and the measured current to a value below the decimal point with resolution more than 360 degrees. In addition, the controller 300 may set the frequency resolution of the frequency comparator 210.

The control unit 300 may obtain the operating voltage through the potential transformer 131 to analyze the cause of the variation of the leakage current, and express the leakage current and the voltage as a vector. The vector may be expressed by differentiating 360 degrees to several numbers or less. In addition, the controller 300 may analyze how the harmonic content and the instantaneous voltage drop detected by the voltage detector 130 affect the leakage current.

In addition, the controller 300 may include an analysis determining unit 310 and a driving control unit 320. The analysis determination unit 310 may receive the comparison result data from the comparator 200 and determine whether the change of the leakage current is caused by the change of the voltage.

 In addition, the driving controller 320 may control operations of the detector 100, the display unit 400, the communication unit 500, and the positioning unit 600. According to an embodiment of the present invention, the control unit 300 may be a CPU which is a central processing unit.

The communication unit 500 may communicate with another diagnostic system or transmit and receive a conventional power communication network. The communication unit 500 may be configured based on IEC61850, RS-422, and RS-485.

In addition, the positioning unit 600 may receive and use event occurrence time information and operation time, including the detection time through the detection unit 100 and the instantaneous voltage drop occurrence time, from the satellite. The positioning unit 600 may include a GPS (satellite device identification system) 610 and a GPS antenna 620. The positioning unit 600 may receive satellite time through the GPS (Satellite Positioning System) 610 and may display the received time information through the display unit 400 in real time.

The storage unit 700 may include a SAG information storage module 710, a harmonic content storage module 720, and a capacitance information storage module 730. The SAG information storage module 710 may store the insulation state information of the transformer bushing 10 according to the change of the instantaneous voltage drop SAG occurring in the transformer bushing 10.

In addition, the harmonic content storage module 720 may store the insulation state information of the transformer bushing 10 according to the change in the harmonic content generated in the transformer bushing 10. In addition, the capacitance information storage module 730 may store the insulation state information of the transformer bushing 10 according to the change in the capacitance value of the transformer bushing 10.

In addition, the insulation deterioration state monitoring analysis system 20 of the transformer bushing having a bushing tab according to an embodiment of the present invention is to prevent damage to the transformer bushing 10 due to leakage current in the case of disconnection and disconnection of the transformer 1. In order to prevent the power supply unit 800 may further include a power short circuit during the operation of the transformer (1).

3 is a diagram illustrating a power short circuit 800 in an insulation degradation state monitoring analysis system of a transformer bushing having a bushing tab according to an exemplary embodiment of the present invention.

When the leakage current measuring line input to the transformer bushing tab 11 is opened, both terminals of the transformer bushing tab 11 are induced with voltage, and the transformer bushing 10 may be burned out if the voltage persists. It is preferable not to open.

However, when the transformer 1 is in operation, it is difficult to stop the transformer 1 in operation when necessary, such as removing or resetting the transformer 1 for repair. To this end, the power supply short circuit 800 may be provided in the terminal box of the transformer 1 to short-circuit the input signal even while the transformer 1 is in operation. That is, by selectively adjusting the bolt 810 of the power supply short circuit 800, the connected power may be grounded even during operation of the transformer 1.

In addition, the insulation degradation state monitoring analysis system 20 of the transformer bushing having a bushing tab according to an embodiment of the present invention may be manufactured to be portable.

Insulation degradation state monitoring analysis system 20 of a transformer bushing having a bushing tab according to an embodiment of the present invention can analyze the change trend of the capacitance of the transformer bushing 10 by measuring the leakage current of the transformer bushing 10. And, through this it is possible to analyze the insulation state of the transformer bushing (10). In addition, by measuring the operating voltage of the transformer (1), extracting the harmonic content and the instantaneous voltage drop included in the operating voltage to compare with the leakage current of the transformer bushing (10) it is possible to increase the accuracy of the insulation state analysis .

In general, harmonic measurements and instantaneous voltage drop measurements are used for power quality measurements. In addition, it is possible to quickly cope by transmitting the generated information to the user when the instantaneous voltage drop occurs.

4 is a flowchart illustrating a method for analyzing insulation degradation monitoring of a transformer bushing having a bushing tab according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating insulation degradation monitoring of a transformer bushing having a bushing tab according to an embodiment of the present invention. A flowchart showing the method.

In accordance with an embodiment of the present invention, a method of analyzing insulation degradation monitoring of a transformer bushing having a bushing tap may include measuring a leakage current of the transformer bushing 10 (S10) and measuring a partial discharge frequency of the transformer bushing 10. (S20) and the step (S30) for measuring the grid voltage from the transformer (1).

In addition, synchronizing the leakage current of the step (S10) and the phase of the grid voltage measured in the step (S30) (S40), comparing the phase-locked leakage current with the capacitance reference value of the transformer bushing (10) The method may include determining an insulation deterioration state of the transformer bushing 10 based on a result of the comparative analysis of steps S50 and S50.

In addition, the insulation degradation state of the transformer bushing 10 by reflecting the analysis result of the step (S70) and the step (S70) based on the grid voltage measured in the step (S30) and the (S70) to the leakage current. Determining step (S80) may be included.

In addition, the step of analyzing the instantaneous voltage drop (SAG) based on the grid voltage measured in the step (S30) (S90) and providing the analysis results of the step (S90) to the user through the display unit 400 ( 100) may be further included.

As shown in FIG. 4, in the current analysis step S50, a change value and a reference value of the operating voltage are presented to determine whether the change of the leakage current is caused by a voltage increase or a rise of the leakage current. The leakage current It measured in this way may be determined in a set value analysis.

In addition, the measurable voltage connected to the three-phase potential transformer (PT) and lowered to a low voltage is applied to the voltage detector 130 to be used for harmonic analysis (S70) and voltage drop (SAG) analysis (S90). Can be.

In addition, the measured operating voltage information may be input information of the current analysis step (S50).

On the other hand, the partial discharge diagnostic method includes a spectral method for sequential analysis in a sweeping form from a low partial discharge frequency to a high frequency band, and a method for analyzing in a size-phase-frequency form, and the result is a two-dimensional or three-dimensional graph Can be displayed.

The grid voltage measurement is performed from the potential transformer 131, and the harmonic analysis step S70 may be analyzed by the current component THD (i) and the voltage component THD (v) which are total harmonic content (THD). In addition, the measured and analyzed results may be displayed through the display unit 400.

For example, THD (v) may be represented by Equation 2 below.

[Equation 2]

Here, V is a system voltage measured through the potential transformer 131, and THD _F may be a voltage component THD (v) of the total harmonic content THD.

In addition, the sag (Sag, Under voltage) analysis step (S90) corresponds to the case where the operating voltage of the power equipment drops instantaneously when a short circuit or ground fault occurs due to a line or equipment failure, and the transformer bushing ( As it can be judged as above, it is necessary for the purpose of comparative analysis and power quality analysis.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and easily changed and equalized by those skilled in the art from the embodiments of the present invention. It includes all changes to the extent deemed acceptable.

1: transformer 10: transformer bushing
11: transformer bushing tap
20: insulation degradation monitoring system
100 detection unit 110 partial discharge detection unit
111: current transformer (CT) 120: current detection unit
121: current transformer (CT) 122: shunt resistance
130: voltage detector 131: potential transformer (PT)
140: phase synchronizer 200: comparator
300: control unit 310: analysis determination unit
320: drive control unit 400: display unit
500: communication unit 510: wireless transmission unit
600: positioning unit 610: GPS
620: GPS antenna 700: storage unit
710: SAG information storage module 720: harmonic content storage module
730: capacitance information storage module
800: power short 810: bolt

Claims (10)

In the insulation degradation monitoring system of a transformer bushing having a bushing tap,
A partial discharge detector for receiving and detecting a partial discharge frequency generated in the transformer bushing through a current transformer (CT);
A current detector which receives and detects a leakage current generated by the transformer bushing through a current transformer (CT);
A voltage detector for detecting and receiving an operating voltage from a transformer through a potential transformer (PT);
A phase synchronizing unit for synchronizing the phase of the leakage current inputted from the current detector and the voltage inputted from the voltage detector;
A comparator for receiving a leakage current from the current detector and a driving voltage from a voltage detector to compare a change in capacitance of the transformer bushing itself with an inherent capacitance; And
Insulation degradation state monitoring including an analysis determination unit for receiving a comparison result data from the comparator to determine whether the change in leakage current is due to the change in the operating voltage, and analyzes the insulation degradation state of the transformer bushing based on the determination result Analysis system.
The method of claim 1,
The partial discharge detection unit
An insulation degradation condition monitoring analysis system comprising at least one of a spectral method of sequentially analyzing partial discharge frequencies in a sweeping form and a method of analyzing the partial discharge frequency in a magnitude-phase-frequency form.
The method of claim 1,
The partial discharge detection unit
Insulation degradation state monitoring analysis system, characterized in that for detecting the partial discharge frequency using a Rogowski coil.
The method of claim 1,
The current detection unit
Insulation degradation condition monitoring analysis including at least one of a current transformer measurement method for measuring the leakage current indirectly by using a logo ski coil and a voltage drop measurement method for measuring a leakage current using a voltage drop by a shunt resistor. system.
The method of claim 1,
The voltage detector
Insulation degradation state monitoring analysis system characterized in that for detecting the total harmonics (Total Harmonic Distortion, THD) and the instantaneous voltage drop (SAG) by using the voltage input through the potential transformer.
The method of claim 5,
And the analysis determining unit analyzes the effects of the total harmonic quantity and the instantaneous voltage drop detected on the leakage current by the voltage detecting unit.
The method of claim 1,
A SAG information storage module for storing insulation state information of the transformer bushing according to a change in the instantaneous voltage drop (SAG) occurring in the transformer bushing;
A harmonic content storage module for storing insulation state information of a transformer bushing according to a change in harmonic content occurring in the transformer bushing;
And a capacitance information storage module for storing the insulation state information of the transformer bushing according to the change of the capacitance value of the transformer bushing.
In the method of monitoring insulation degradation status of a transformer bushing having a bushing tap,
Measuring a leakage current of the transformer bushing (S10);
Measuring a partial discharge frequency of the transformer bushing (S20);
Receiving a grid voltage from a transformer (S30);
Synchronizing the leakage current of the step (S10) with the phase of the system voltage measured in the step (S30) (S40);
Comparing the phase-locked leakage current with a capacitance reference value according to a change in insulation deterioration state of a transformer bushing (S50) and
Determination of the insulation degradation state monitoring method comprising the step (S60) of determining the insulation degradation state of the transformer bushing on the basis of the comparative analysis results of the step (S50).
The method of claim 8,
Analyzing harmonic content (THD) based on the grid voltage measured in the step (S30) (S70) and
And determining (S80) the insulation degradation state of the transformer bushing by reflecting the analysis result of the step (S70) to the leakage current synchronized with the phase of the (S50) step (S80).
The method of claim 8,
Analyzing the instantaneous voltage drop (SAG) based on the system voltage measured in the step (S30) (S90) and
The insulation degradation state monitoring analysis method further comprising the step (100) of displaying the analysis result of the step (S90) and providing it to the user.

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