KR20210150185A - Apparatus and Method for diagnosing insulation condition of voltage motor - Google Patents

Abstract

In order to achieve the above object, the present invention provides a device for diagnosing an insulation condition of a motor, which can determine the actual deterioration state in consideration of various insulation characteristics for each manufacturer and a new moisture absorption diagnosis technique which can determine whether the state is dry enough for a high voltage insulation diagnostic test. The device includes: a sensor system for generating state information of the motor; an aggregation unit for collecting the state information; a calculation unit for calculating a measured value using the state information; and an analysis unit for determining a type of gap discharge by using the measured value and generating notification information according to the determination.

Description

Apparatus and Method for diagnosing insulation condition of voltage motor

The present invention relates to insulation state diagnosis technology, and more specifically, a new moisture absorption diagnosis technique that can determine whether the state is dry enough for a high voltage insulation diagnosis test, and a practical deterioration state in consideration of various insulation characteristics for each manufacturer It relates to a diagnostic device and method that can be performed.

In general, the insulation condition evaluation of the stator winding of a high-voltage motor is evaluated by performing insulation resistance, polarization index, alternating current, dielectric loss tangent, and partial discharge tests to determine the condition by good or winding replacement. However, the above test items are greatly affected by moisture absorption or contamination status, and insulation characteristic values such as dielectric loss tangent and partial discharge vary according to different manufacturing methods and insulating materials for each manufacturer.

First, in the prior art, the determination of moisture absorption for the stator winding of a high-voltage motor is based only on insulation resistance and polarization index measurement results, but there is a fear that the standard value is too low to properly filter out devices unsuitable for high voltage test. In the international standard (IEEE std 43-2000), the insulation resistance is 100MΩ and the polarization index is 2.0.

However, this standard does not indicate a good condition, but stipulates the minimum required for operation, and it is insufficient to determine whether the condition is sufficiently dry to be suitable for the high voltage insulation diagnostic test to evaluate the insulation condition. In other words, the determination of moisture absorption for the stator windings of high-voltage motors is made by measuring insulation resistance and polarization index, but the standard value is too low, so there is a high risk of not being able to properly filter out moisture-absorbing devices that are not suitable for high voltage testing.

Second, in the insulation state determination in the prior art, the same standard value as an absolute value is uniformly applied to all devices. However, different manufacturers have different insulating materials and manufacturing methods, so insulation characteristics such as dielectric loss tangent and partial discharge are different, and even in the same manufacturer, the diagnosis results are different depending on the year of manufacture.

As described above, the conventional insulation diagnosis technology does not reflect various manufacturing characteristics, so there is a problem in that there is a high possibility of causing an error in determining the insulation state. In other words, there is a high possibility of erroneous judgment of results because the same standard of absolute value for each test item is applied uniformly to all devices for insulation state judgment, and different manufacturing methods and insulating material characteristics for each manufacturer are not reflected.

Third, the conventional insulation diagnosis technique only makes binary judgments with good and bad winding replacement, so that even devices that are being deteriorated due to a specific type of defect are operated in the same way as before if they fall within the judgment standard. It is not possible to prevent this from continuing and eventually leading to failure.

In addition, the conventional insulation diagnosis technology is insufficient in determining whether the high voltage motor stator winding is well dried enough to be suitable for the high voltage insulation diagnosis test.

In addition, it is not possible to determine the insulation deterioration state considering that the dielectric loss tangent alternating current partial discharge test results vary according to the manufacturing characteristics of the motor manufacturer.

Also, it lacks detailed countermeasures such as customized maintenance according to the type of defect or improvement of operation method.

1. Korea Patent No. 10-1228386 (Registration Date: January 25, 2013)

The present invention has been proposed to solve the problems caused by the above background art, and a new hygroscopic diagnosis technique that can determine whether the state is dry enough for a high voltage insulation diagnostic test and a substantial deterioration state in consideration of various insulation characteristics for each manufacturer An object of the present invention is to provide an apparatus and method for diagnosing the insulation state of a high-voltage motor that can determine

In addition, the present invention proposes a new deterioration determination technique that reflects how much insulation deterioration has actually progressed regardless of different manufacturing characteristics instead of the existing absolute reference value, which can improve the reliability of insulation diagnosis of high-voltage motor insulation Another object is to provide a diagnostic device and method.

In addition, the present invention is not the conventional binary technique of judging only good and bad, but by proposing improvement measures such as a customized maintenance method and operating method change according to various types of defects, preventing or delaying the progress of defects. Another object of the present invention is to provide an apparatus and method for diagnosing the insulation state of a high-voltage motor that can improve the stability of the motor.

The present invention provides a new moisture absorption diagnostic technique that can determine whether the state is dry enough for a high voltage insulation diagnostic test and a motor that can determine the actual deterioration state in consideration of various insulation characteristics for each manufacturer in order to achieve the above object An insulation condition diagnosis device is provided.

The motor insulation state diagnosis device,

a sensor system for generating state information of an electric motor;

an aggregator for collecting the state information;

a calculation unit for calculating a measured value by using the state information; and

and an analysis unit that determines a type of partial discharge (insulation state determination and a defect type) using the measured value, and generates notification information according to the determination.

In this case, the state information includes an insulation resistance (IR) that is a resistance between a stator winding and an enclosure of the motor, a polarization index (PI) indicating a change in insulation resistance of the stator winding over time, and the It is characterized in that it includes dielectric loss tangent (Δtanδ), alternating current (ΔI), indicating the average state of the entire insulator according to the partial discharge phenomenon of the motor, and partial discharge (PD) indicating the size and pattern of discharge.

In addition, when the insulation resistance and the polarization index are greater than or equal to a first reference value set in advance, an initial dielectric loss tangent (tanδ ₀ ) of the dielectric loss tangent is measured.

In addition, when the initial dielectric loss tangent (tanδ ₀ ) is within a preset second reference value, a general dielectric loss tangent (Δtanδ) test, an alternating current (ΔI) test, and a partial discharge (PD) test are performed.

In addition, it is characterized in that the normal partial discharge and the gap discharge according to the PD test are distinguished.

In addition, each dielectric loss tangent (Δtanδ) value, AC current (ΔI) value, and partial discharge (PD) value according to the dielectric loss tangent (Δtanδ) test, AC current (ΔI) test, and partial discharge (PD) test are preset If it is not within the third reference value, the partial discharge (PD) value is determined in advance according to whether the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value have increased twice than before. If it is less than the reference value, it is characterized in that it is determined as any one of the types of partial discharge.

In addition, as for the third reference value, the third reference value is 3% in the case of the dielectric loss tangent (Δtanδ) value, 4% in the case of the alternating current (ΔI) value, and in the case of the partial discharge (PD) value, It is characterized in that it is 30,000pC.

In addition, the fourth reference value is 30,000 pC, and when the partial discharge (PD) value is greater than the fourth reference value, an AC (Alternating Current) withstand voltage test is performed.

In addition, the type of the partial discharge is characterized in that the internal discharge, conductor surface discharge, and slot discharge.

In addition, the motor insulation state diagnosis apparatus, the output unit for outputting the notification information; characterized in that it further comprises.

In addition, the notification information is characterized in that any one of defective, good, and maintenance recommendation is expressed as a combination of text, graphic, and voice.

On the other hand, another embodiment of the present invention, (a) the sensor system generating the state information of the electric motor; (b) collecting the state information by an aggregator; (c) calculating, by the calculator, a measured value using the state information; and (d) the analysis unit determines the insulation state of the motor and the type of fault by using the measured value, and generates notification information according to the determination.

In addition, the method of diagnosing the insulation state of the motor further comprises the step of outputting the notification information by an output unit.

On the other hand, another embodiment of the present invention provides a computer-readable storage medium storing a program code for executing the above-described motor insulation state diagnosis method.

According to the present invention, a new technique for determining the moisture absorption state by analyzing the initial dielectric loss tangent value that appears when only a low test voltage is applied can be proposed, thereby greatly reducing the error in result determination due to environmental influences such as moisture absorption.

In addition, as another effect of the present invention, it is possible to significantly improve the reliability of insulation deterioration determination by presenting a new deterioration determination technique that reflects how much insulation deterioration has actually progressed instead of an absolute reference value.

In addition, as another effect of the present invention, it is possible to increase the stability of equipment by delaying the progress of the defect by suggesting improvement measures such as a customized inspection and maintenance method and a change in operation method according to a specific defect type through diagnosis result pattern analysis. points can be taken.

In addition, as another effect of the present invention, a more precise and reliable evaluation of the insulation state is possible by newly suggesting a method for determining the moisture absorption state, which was insufficient in the conventional insulation diagnosis technology, a method for determining the actual insulation deterioration progress level, and customized countermeasures according to defects. Accordingly, it is possible to greatly improve the stability of the electric power industry, such as power plants, by preventing the sudden insulation breakdown of the generator high-voltage motor.

1 is a graph showing a voltage-dissipation loss tangent characteristic for analyzing a dielectric loss tangent measurement value according to an embodiment of the present invention.
2 is a graph showing dielectric loss tangent characteristics according to moisture absorption according to an embodiment of the present invention.
3 is a graph showing AC current characteristics according to moisture absorption according to an embodiment of the present invention.
4 is a waveform diagram showing a general internal discharge pattern.
5 is a waveform diagram showing a gap discharge pattern among partial discharge patterns.
6 is a waveform diagram showing a slot discharge pattern among partial discharge patterns.
7 is a waveform diagram showing a conductor surface discharge pattern among partial discharge patterns.
Fig. 8 is an example of an actual generator surface discharge actual measurement screen.
9 is a block diagram of an apparatus for diagnosing an insulation state of an electric motor according to an embodiment of the present invention.
10 and 11 are flowcharts showing a process of diagnosing the insulation state of an electric motor according to an embodiment of the present invention.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Hereinafter, an apparatus and method for diagnosing an insulation state of an electric motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a graph showing a voltage-dissipation loss tangent characteristic for analyzing a dielectric loss tangent measurement value according to an embodiment of the present invention. Referring to FIG. 1 , it is possible to increase the reliability of state determination by adding a new moisture absorption determination technique for analyzing the dielectric loss tangent measurement value.

Dielectric loss tangent is the ratio of charging current and leakage current that appears when an AC voltage is applied to an insulator.

In general, as shown in FIG. 1 , the dielectric loss tangent value appears small at a low test voltage, but increases as the partial discharge phenomenon occurs when the voltage is increased. Using these characteristics, comparing the dielectric loss tangent value measured at low voltage before partial discharge with the dielectric loss tangent value at the high voltage rated voltage where partial discharge occurs shows how much discharge is occurring in the entire insulation system. can figure out Therefore, it is used to determine the degree of defects in the insulation system (micropores, gaps between windings and slots, etc.).

However, if there is moisture absorption by moisture on the surface of the winding, the surface leakage current increases even at a low test voltage before the partial discharge phenomenon occurs, resulting in a large dielectric loss tangent. In general, the dielectric loss tangent (tanδ) is very small, about 2 to 3 digits after the decimal point, so it has a characteristic that it responds sensitively to even a small increase in leakage current compared to the charging current because it is multiplied by one hundred and used in % units.

In an embodiment of the present invention, a new technique for judging the moisture absorption state of an electric motor using the characteristic of a dielectric loss tangent sensitive to leakage current is proposed to increase the reliability of insulation diagnosis. For demonstration purposes, when the stator winding of a high-voltage motor with a rated voltage of 6.6kV is completely absorbed immediately after washing with steam, and when it is heated in a heating and drying furnace at 110°C for 12 hours and then naturally cooled to ambient temperature to dry it, diagnosis of insulation (Insulation resistance, polarization index, dielectric loss tangent, AC current, partial discharge) tests were performed and the results were compared and analyzed. This is shown in a table as follows.

Test Items Insulation resistance [㏁] Polarity Index Dielectric loss tangent [%] test voltage DC 5,000 [V] DC 5,000 [V] AC 950 [V] moisture absorption 118 1.16 12.5 dry state 11,500 3.98 0.59

Table 1 shows the insulation resistance polarization index and dielectric loss tangent value at low voltage. As a result of the test, the polarization index value was 1.16, which did not satisfy the international standard (IEEE std 43) of 2.0 or higher, but the insulation resistance even when completely absorbed by moisture. The value was 118[㏁], which satisfies the standard value of 100[㏁], so the results of the two tests were mixed.

As such, the standards of the international standard (IEEE std 43) do not indicate good insulation, but are the minimum values for operation. On the other hand, the dielectric loss tangent value measured at a low test voltage (0.95kV) before the partial discharge phenomenon showed a clear difference between the moisture absorption state and the dry state.

Utilizing this, in one embodiment of the present invention, all three items are good by adding the dielectric loss tangent value measured at a low test voltage before partial discharge as well as the existing insulation resistance and polarization index measurement method when determining whether moisture absorption occurs. After judging that the drying was done well, the partial discharge alternating current dielectric loss tangent test, which is a high voltage test, was performed.

In addition, in light of numerous insulation diagnosis experiences, disassembling the motor and cleaning and drying

The dielectric dissipation tangent value at the initial test voltage measured in the state where there is no influence of contamination or moisture absorption after finishing the work is usually about 0% to 2%, and it is rare that it exceeds 3%.

On the other hand, if the surface of the stator windings absorbs a lot of moisture, the initial dielectric loss tangent value may be 10% or more. There is also a risk of causing insulation breakdown.

2 is a graph showing dielectric loss tangent characteristics according to moisture absorption according to an embodiment of the present invention, and FIG. 3 is a graph showing AC current characteristics according to moisture absorption according to an embodiment of the present invention. In addition, as the test results according to FIGS. 2 and 3 , the dielectric loss tangent test results and the alternating current test results are shown in Tables 2 and 3.

test voltage
[kV] tanδ[%] moisture absorption dry state 0.95 12.52 0.42 1.91 12.23 0.43 2.86 12.26 0.46 3.81 12.41 1.02 4.76 12.68 2.01 5.72 13.12 3.46 6.6 13.56 4.86 Δtanδ[%] 1.33 4.43

test voltage
[kV] AC current [mA] moisture absorption dry state 0.95 97.21 70.28 1.91 194.4 140.6 2.86 291.6 210.9 3.81 388.5 284.4 4.76 486.0 359.9 5.72 583.2 442.3 6.6 672.3 522.3 I ₀ 671.75 485.84 ΔI [%] 0.08 7.51

In addition, the partial discharge test results according to moisture absorption and dry conditions are shown in the following table.

state discharge start voltage
[kV] Partial discharge size [pC] Noise 3.81 kV
(phase voltage) 6.6 kV
(line voltage) moisture absorption 3.9 700 800 1,800 dry state 2.9 700 3,200 10,700

The dielectric loss tangent increase rate (Δtanδ) and alternating current increase rate (ΔI) and the magnitude of partial discharge were smaller in the moisture absorption state than in the dry state. In this case, Δtanδ and ΔI and the partial discharge values are indices proportional to the partial discharge phenomenon. In the state of moisture absorption, moisture enters defective areas where discharge can occur, such as micropores or gaps between windings and slots, and current flows instead of causing discharge, resulting in small Δtanδ and ΔI and partial discharge values. Therefore, in such a state, it is difficult to accurately diagnose the insulation state.

In an embodiment of the present invention, a dielectric loss tangent measurement and analysis technique, which is a new moisture absorption judgment technique for preventing an error in the insulation diagnostic test for the stator winding of a high-voltage motor, is presented as follows.

For the test voltage, the dielectric loss tangent is measured at a voltage of about 10% of the rated voltage before partial discharge occurs. In order to determine the results of insulation diagnostic tests (partial discharge, alternating current, dielectric loss tangent), it is important to compare and analyze the results of previous tests. However, only data tested in the same dry state with an initial dielectric loss tangent (tanδ) less than the reference value is meaningful for comparative analysis.

If the initial dielectric loss tangent value is 3% to 10%, the test result may be distorted due to leakage current due to moisture absorption, so it is necessary to dry the initial dielectric loss tangent value to less than 3%. In addition, if the initial dielectric loss tangent value is more than 10%, there is a risk of insulation breakdown during high voltage test or during start-up.

In the conventional insulation diagnosis technology, the result judgment was determined as good or bad (winding replacement) by setting the reference value as an absolute value with the dielectric loss tangent increase rate (Δtanδ), the alternating current increase rate (ΔI), and the partial discharge size according to the application of the test voltage. However, since insulation materials and manufacturing methods are different for each manufacturer, and insulation characteristics are different even by year of manufacture even for the same manufacturer, uniformly applying the absolute standard value to all motors is not reliable.

In addition, there is a lot of confusion and difficulty in accurately evaluating the insulation deterioration state because the judgment standard values are different for each test institution. As an actual example, the table below shows the change in dielectric loss tangent and alternating current test results by year for a 6.6kV class motor that was manufactured in 1993 by Company A, a domestic high-voltage motor manufacturer, and has been used for 26 years for pumps in domestic power plants. it has been shown

In 2000, when the insulation diagnosis test was performed for the first time after production, both the AC current test results (ΔI) and dielectric loss tangent test results (Δtanδ) greatly exceeded the generally applied judgment standards of 8.5% and 6.5%.

If the criterion of absolute value of the prior art is applied as it is, these motors are already judged to be defective in 2000, when only 7 years have passed since they have been used, so it is necessary to replace the windings.

Or it was judged as a state of caution and had to drive without anxiety. However, despite the elapse of operating time, the insulation diagnostic test results did not show a marked increase, and even now, 26 years after production, the power plant is operating without any abnormality.

Therefore, these motors did not have poor AC current (ΔI) and dielectric loss tangent (Δtanδ) test results due to insulation deterioration, but had insulation characteristics that showed large ΔI and Δtanδ values from the time they were manufactured. It is reasonable to judge that it is not.

The table below shows the partial discharge test results for two 6.6kV class motors manufactured in 2003 by Company B, another high-voltage motor manufacturer in Korea, and used for FAN in domestic power plants for 17 years.

As shown in the table above, in 2008, when the first insulation diagnostic test was performed, the partial discharge value greatly exceeded 30,000pC, which is a generally applied failure standard. If the judgment criteria of the prior art are applied, these motors are judged to be defective even if they have only been used for 5 years, and should be replaced or judged with caution.

Even after 17 years of operation, there was no rapid increase in partial discharge and a stable state was maintained. Therefore, these motors did not show large partial discharge due to deterioration of the insulation, but had a large partial discharge value according to the manufacturing characteristics of the insulation system from the time of manufacture. It is difficult to judge.

On the other hand, the following table shows the insulation diagnosis test results for the 6.6kV high-voltage motor used for pumps in domestic power plants after replacing the stator windings with new ones in 2010.

The electric current (ΔI) and dielectric loss tangent (Δtanδ) values were within 8.5% and 6.5% of the prior art judgment standards in the insulation diagnosis results first performed in 2011 after replacing the stator winding with a new one in 2010. The partial discharge exceeded the failure standard of 30,000pC and was operated under caution. The 2013 test results showed a slight decrease in all test items compared to 2011, and the partial discharge value was also stable at less than 30,000pC. However, in 2015, despite the rapid increase in all test result values, the AC current (ΔI) and dielectric loss tangent (Δtanδ) values are still within 8.5% and 6.5%, which are the judgment standards of the prior art.

In spite of the rapid deterioration of the insulation properties compared to the previous test results, if the standard of the prior art is followed, only one partial discharge exceeds the standard among the three test items. The motor was replaced with a spare part because insulation breakdown may occur.

In order to additionally check the dielectric strength, dielectric breakdown occurred as a result of a dielectric breakdown test in which an AC (Alternating Current) voltage was applied after being taken out of the factory. This was found to be in a state in which insulation breakdown could occur at any time due to the end of the service life as it was less than 14.4kV, which is 2E (rated voltage)+1, which is generally taken as the life limit voltage.

As such, there are many unreasonable aspects to uniformly apply the reference value of the prior art as an absolute value to the devices of various manufacturers. Therefore, in one embodiment of the present invention, a new determination technique for judging the progress of actual insulation deterioration based on numerous diagnostic experiences is presented as follows.

When the insulation diagnosis test result exceeds all the standard values (eg ΔI: 4%, Δtanδ: 3%, partial discharge: 30,000pC) and all items increase more than twice compared to the results of the first test in the past, insulation deterioration progresses a lot It is determined that the stator winding is replaced. However, in order to apply this technique, as described above, comparison should be made only with the results of the test in the same dry condition as in the past without any environmental influence (moisture absorption, temperature) during the test.

In addition, the conventional insulation diagnosis technology only determines the binary result of good and bad (winding replacement), so if customized maintenance or operation method is changed according to the type of defect, it is possible to prevent or delay the progress of the defect. Also, it is not possible to prevent the defect from continuing to develop by driving it in the same way as before.

It is known that the partial discharge pulses generated when a high voltage is applied to a high voltage motor are distributed differently in the phase of the test voltage depending on the type of defect. Accordingly, in one embodiment of the present invention, the defect types of the internal discharge pattern, the gap discharge pattern, the slot discharge pattern, and the conductor surface discharge pattern are used.

4 is a waveform diagram showing a general internal discharge pattern. Referring to FIG. 4 , the most common internal discharge pattern is shown.

5 is a waveform diagram showing a gap discharge pattern among partial discharge patterns. Referring to FIG. 5 , when a gap discharge occurs, discharge pulses of almost the same size appear as shown in FIG. 5 , and in most cases, the magnitude of the pulse is also very large compared to a partial discharge occurring in a general insulator.

Such a gap discharge pattern is generated in a specific gap, not in the insulation system of the stator winding, and the following inspection and maintenance measures can be suggested.

① When a discharge occurs in the temperature detection signal line of the stator winding, visually inspect and retest after all terminals are grounded.

② If the gap discharge disappears, the terminal connection is bad or the signal line coating is damaged.

③ If the gap discharge continues, remove the support insulator in the motor terminal box and retest

④ When the gap discharge disappears, replace the defective insulator

⑤ If the gap discharge continues, the discharge occurs inside the high-voltage motor.

6 is a waveform diagram showing a slot discharge pattern among partial discharge patterns. A semiconductive layer (not shown) is provided on the surface of the stator winding of the high voltage motor to reduce the potential difference between the winding and the iron core. When this semiconducting layer is damaged by abrasion due to vibration, etc., a partial discharge occurs due to the potential difference between the winding and the iron core, and this discharge is called slot discharge. In other words, the winding vibrates in the slot by electromagnetic force, and the semiconducting layer on the surface may be in a state of being worn out except for the air passage.

As shown in FIG. 6 , in the slot discharge pattern, the phase of the test voltage is larger and generated more in the vicinity of 225° in the negative cycle than in the vicinity of 45° in the positive cycle.

When such a slot discharge pattern appears, partial discharge occurs in the gap between the windings and the core, and the following maintenance measures are suggested to reinforce this.

① Cleaning of the discharge generating area (whitening phenomenon) of the terminal winding slot drawing part and reinforcement of the insulation paint

② Vacuum pressure impregnation of the entire iron core of the motor with the stator winding inserted into the resin

③ Check the fixing condition of the Ÿ‡ paper fixing the stator winding and replace the bad Ÿ‡ paper

Vacuum pressure impregnation of a high-voltage motor that generates slot discharge in an impregnation furnace with resin has the effect of eliminating the space where the discharge can occur as the resin penetrates into the gap between the winding and the iron core. On the other hand, if the discharge occurs in a microvoid inside the insulator except for slot discharge or where peeling occurs between the copper conductor and the insulator, the resin does not penetrate the already hardened insulation of the stator winding and enter the inside even after vacuum pressure impregnation. difficult and the effect is insignificant.

On the other hand, partial discharge may occur between different phases in the terminal winding of the high-voltage motor, resulting in whitening. During operation, there is a potential difference between phases, so partial discharge can be detected and detected. can't Therefore, it is necessary to find defective parts and perform maintenance by performing visual inspection as well as electrical tests.

The countermeasures for the phase-to-phase discharge as described above are as follows.

① Cleaning the area of whitening caused by partial discharge and removing foreign substances

② Separation between the phases of the terminal winding where the discharge has occurred and the insertion and reinforcement of insulators

7 is a waveform diagram showing a surface discharge pattern of a conductor among partial discharge patterns, and FIG. 8 is an example of an actual surface discharge screen of a conductor of a generator. 7 and 8 , a conductor surface discharge pattern in which partial discharge occurs between a copper conductor and an insulator of a stator winding occurs.

Contrary to slot discharge, the discharge pulse in the positive cycle (near 45°) appears larger than the discharge pulse in the negative cycle (225°) vicinity. This is due to the peeling phenomenon in which copper conductors and insulators are separated because copper conductors have a property that expansion and contraction by heat are more likely to occur than insulators. In particular, FIG. 8 is a pattern of measuring the actual partial discharge when the cooling water of a large water-cooled generator is lost and an insulation breakdown failure occurs. considered to have occurred.

When the conductor surface discharge pattern as described above appears, the following countermeasures are suggested to reduce the stress caused by thermal expansion and contraction between the copper conductor and the insulator.

① Frequent start and stop operation

② Sudden output evaporation and limited operation

9 is a block diagram of a motor insulation state diagnosis apparatus 900 according to an embodiment of the present invention. Referring to FIG. 9 , the motor insulation state diagnosis apparatus 900 calculates a measured value using the sensor 910 generating state information of the electric motor 90 , the collecting unit 920 collecting state information, and the state information. It may be configured to include a calculation unit 930 that determines the type of discharge by using the measured value, and an analysis unit 940 that generates notification information, an output unit 950 that outputs notification information, and the like.

The sensor system 910 includes each sensor for measuring the voltage and current applied to the motor (especially the high voltage motor) 90, partial discharge of the stator winding, insulation resistance, winding resistance, dielectric loss tangent, AC current, temperature, etc. be prepared Since the electric motor 90 is widely known, a detailed description thereof will be omitted.

Accordingly, the sensor system 910 is a voltage-current sensor that measures voltage and/or current when power is supplied to a high-voltage motor, including a PT (Power Transformer) and a CT (Current Transformer), and a dielectric loss tangent and a capacitance measuring method. It may include a Schering bridge circuit, a partial discharge sensor for measuring a discharge value generated in the stator winding of the high-voltage motor, a contact-type or non-contact type temperature sensor for measuring the temperature of the stator winding of the high-voltage motor, and the like.

The aggregator 920 receives the state information generated by the sensor system 910 and converts it into digital information. Accordingly, the assembling unit 920 may include a digital signal processor (DSP), a communication circuit, a memory, and the like. Of course, the sensor system 910 and the assembling unit 920 may be connected through wired communication, but may also be connected through wireless communication. Wired communication can be S232, RS485, Modbus, CC-Link communication, Ethernet communication, etc. Wireless communication is IrDA (Infrared Data) communication, wireless LAN (Local Area Network), Bluetooth, LiFi (Light Fidelity), WiFi (Wireless Fidelity), NFC (Near Field Control), and the like.

The calculator 930 performs a function of calculating a measured value using the state information.

The analysis unit 940 performs a dielectric loss tangent (Δtanδ), alternating current (ΔI), partial discharge (PD) test, and the like using the measured value, and performs a function of analyzing a discharge pattern. In addition, it determines the type of the discharge pattern according to the analysis of the discharge pattern, and performs a function of generating notification information such as defective, good, and maintenance recommendation.

The output unit 950 performs a function of displaying information processed by the calculation unit 930 , the analysis unit 940 , and the like. Accordingly, the output unit 950 may generate notification information using a combination of text, voice, and graphics. To this end, the output unit 950 may include a display, a sound system, and the like.

The display may be a liquid crystal display (LCD), a light emitting diode (LED) display, a plasma display panel (PDP), an organic LED (OLED) display, a touch screen, a cathode ray tube (CRT), a flexible display, or the like. In the case of a touch screen, it may function as an input means.

The calculation unit 930 and the analysis unit 940 illustrated in FIG. 9 mean units for processing at least one function or operation, which may be implemented as software and/or hardware. In hardware implementation, application specific integrated circuit (ASIC), digital signal processing (DSP), programmable logic device (PLD), field programmable gate array (FPGA), processor, microprocessor, other It may be implemented as an electronic unit or a combination thereof. In software implementation, software component (element), object-oriented software component component, class component component and task component component, process, function, attribute, procedure, subroutine, segment of program code, driver, firmware, microcode, data , databases, data structures, tables, arrays, and variables. Software, data, etc. may be stored in a memory and executed by a processor. The memory or processor may employ various means well known to those skilled in the art.

10 and 11 are flowcharts showing a process of diagnosing the insulation state of an electric motor according to an embodiment of the present invention. Referring to FIGS. 10 and 11 , first, the insulation state of the motor is visually inspected to determine whether it is good (steps S1000 and S1010). If it is not good as a result of judgment, it is a case of foreign matter contamination or whitening. In this case, after washing, drying, cleaning, or insulation reinforcement, the sensor system 910 operates according to a user's command to generate state information of the motor (step S1030).

On the other hand, if the determination result in step S1010 is good, the sensor system 910 operates according to a user's command to generate state information of the electric motor (step S1030). In other words, the sensor system 910 generates state information such as insulation resistance (IR) and polarization index (PI). The polarity index (PI) is one of the data in the DC leakage current method, which is a static diagnostic method for diagnosing the insulation state of the stator winding. This is data that investigates whether the leakage current increases or decreases according to the measurement time, and it is checked whether the leakage current does not increase with the application time.

Insulation resistance (IR) refers to the resistance between the stator winding and the enclosure of the motor (90).

Polarity index (PI) is a quantitative expression of the leakage current value for absorption current as the leakage current value increases as the insulation deteriorates (moisture absorption). It is the value divided by the current value after 10 minutes. The polarization index is the data that investigates whether the leakage current increases or decreases according to the measurement time, and it is to check whether the leakage current does not increase with the application time.

The analysis unit 940 determines whether the values of the insulation resistance and the polarization index generated by the calculation unit 930 are equal to or greater than preset reference values (step S1040). As a result of the determination, if the values of the insulation resistance and the polarization index are smaller than the preset reference values, the drying operation is performed (step S1041). After the drying operation, the insulation resistance and the polarization index are measured again (step S1030), and if the result value is smaller than the preset standard, it is determined as "bad" and the winding is replaced (step S1141).

_{On the other hand, in step S1040, the analysis unit 940 measures the initial dielectric loss tangent tanδ 0} when the values of the insulation resistance and the polarization index are greater than (or greater than) preset reference values (step S1050).

Thereafter, it is determined whether the initial dielectric loss tangent (tanδ ₀ ) is within a preset reference value (step S1060).

In step S1060, if the initial dielectric loss tangent is within the reference value, the analysis unit 940 performs a general dielectric loss tangent (Δtanδ) test, an alternating current (ΔI) test, a partial discharge (PD) test, and the like (step S1070). On the other hand, if the initial dielectric loss tangent (tanδ ₀ ) is not within a preset reference value in step S1060, the drying operation (step S1041) proceeds.

After the test is performed, the analysis unit 940 checks whether a gap discharge is generated according to a general dielectric loss tangent (Δtanδ) test, an alternating current (ΔI) test, a partial discharge (PD) test, or the like (step S1080).

In step S1080, as a result of the check, if a gap discharge occurs, a temperature signal (RTD) line, a terminal box, an insulator, etc. are checked ( S1081 ).

On the other hand, in step S1080, if the gap discharge does not occur as a result of checking, it is checked whether the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value are all within a preset reference value (step S1080) S1100).

In step S1100, as a result of checking, if the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value are all within the preset reference values, it is determined as “good” and the normal operation is maintained (step S1101) .

On the other hand, in step S1100, if at least one of the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value is not within a preset reference value, the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) It is checked whether the value and the partial discharge (PD) value are all doubled compared with the past (or initial) test result (step S1110).

In step S1110, if it is confirmed that the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value are all doubled compared to before, it is determined as “bad” (step S1141).

On the other hand, in step S1110, if the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value are not all doubled than before, the partial discharge value (PD) is higher than 30,000pC It is checked whether it is less than or equal to (step S1120).

In step S1120, as a result of the check, if the partial discharge value PD is greater than 30,000pC, an AC withstand voltage test is performed, and it is checked whether the test is good (steps S1130 and S1140). AC withstand voltage test is a test to test whether a high AC voltage higher than the rated voltage can be applied between the stator winding of the motor and the ground without breaking the insulation.

In step S1140, as a result of the check, if the test is not satisfactory, the process proceeds to step S1141. If the test is satisfactory, the process proceeds to steps S1151, S1152, and S1153.

On the other hand, in step S1120, if the partial discharge value PD is less than or equal to 30,000 pC, it is determined whether it corresponds to an internal discharge, a conductor surface discharge, or a slot discharge (steps S1151, S1152, S1153). Whether the internal discharge, the conductor surface discharge, and the slot discharge are applicable is determined using the graphs shown in FIGS. 4 to 7 .

If it is an internal discharge, it is determined as "good" (S1101). If it is a conductor surface discharge, it is judged as "good" (S1161). In this case, the number of starts and stops is reduced, and sudden output fluctuations are limited.

If it is a slot discharge, it is judged as "recommended maintenance". In this case, notification information such as motor re-impregnation operation and stator Ÿ‡ paper check is generated.

In addition, the steps of the method or algorithm described in relation to the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means such as a microprocessor, a processor, a CPU (Central Processing Unit), etc. It can be recorded on any available medium. The computer-readable medium may include program (instructions) codes, data files, data structures, etc. alone or in combination.

The program (instructions) code recorded on the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs, DVDs, Blu-rays, and the like, and ROM, RAM ( A semiconductor memory device specially configured to store and execute program (instruction) code such as RAM), flash memory, and the like may be included.

Here, examples of the program (instruction) code include not only machine language codes such as those generated by a compiler but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

90: electric motor
900: motor insulation state diagnosis device
910: sensor system
920: assembly part
930: calculator
940: analysis unit
950: output unit

Claims (20)

a sensor system 910 that generates state information of the electric motor 90;
an aggregator 920 for collecting the state information;
a calculation unit 930 for calculating a measurement value by using the state information; and
an analysis unit 940 that determines a type of partial discharge using the measured value and generates notification information according to the determination;
Motor insulation state diagnosis device comprising a.
The method of claim 1,
The state information includes an insulation resistance (IR) that is a resistance between a stator winding and an enclosure of the motor 90, a polarization index (PI) indicating a change in insulation resistance over time of the stator winding, and Dielectric loss tangent (Δtanδ) indicating the average state of the entire insulation according to the partial discharge phenomenon of the motor (90), alternating current (ΔI), and partial discharge (PD) indicating the size and pattern of discharge Motor insulation condition diagnosis device.
3. The method of claim 2,
When the insulation resistance and the polarization index are equal to or greater than a first reference value set in advance, an initial dielectric loss tangent (tanδ ₀ ) of the dielectric loss tangent is measured.
4. The method of claim 3,
If the initial dielectric loss tangent (tanδ ₀ ) is within a preset second reference value, a dielectric loss tangent (Δtanδ) test, an alternating current (ΔI) test, and a partial discharge (PD) test are performed. Device.
5. The method of claim 4,
Each dielectric loss tangent (Δtanδ) value, AC current (ΔI) value, and partial discharge (PD) value according to the dielectric loss tangent (Δtanδ) test, AC current (ΔI) test, and partial discharge (PD) test are all preset If it is not within the third reference value, the partial discharge (PD) value is a predetermined fourth reference value according to whether the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value have increased twice than before. Motor insulation state diagnosis apparatus, characterized in that it is determined as any one of the types of partial discharge if less than.
6. The method of claim 5,
As for the third reference value, the third reference value is 3% for the dielectric loss tangent (Δtanδ) value, 4% for the alternating current (ΔI) value, and 30,000 pC for the partial discharge (PD) value Motor insulation state diagnosis device, characterized in that.
6. The method of claim 5,
The fourth reference value is 30,000 pC, and when the PD value is greater than the fourth reference value, an AC (Alternating Current) withstand voltage test is performed.
The method of claim 1,
The type of partial discharge is a motor insulation state diagnosis device, characterized in that the internal discharge, conductor surface discharge, and slot discharge.
The method of claim 1,
An output unit (950) for outputting the notification information; Motor insulation state diagnosis apparatus characterized in that it further comprises. 10. The method of claim 9,
The notification information is an apparatus for diagnosing an insulation state of a motor, characterized in that it is information expressing any one of bad, good, and maintenance recommendations in a combination of text, graphic, and voice.
(a) generating, by the sensor system 910, state information of the electric motor 90;
(b) collecting the state information by an aggregator 920;
(c) calculating, by the calculator 930, a measured value using the state information; and
(d) determining, by the analysis unit 940, a type of partial discharge using the measured value, and generating notification information according to the determination;
Motor insulation state diagnosis method comprising a.
12. The method of claim 11,
The state information includes an insulation resistance (IR) that is a resistance between a stator winding and an enclosure of the motor 90, a polarization index (PI) indicating a change in insulation resistance over time of the stator winding, and Dielectric loss tangent (Δtanδ) indicating the average state of the entire insulation according to the partial discharge phenomenon of the motor (90), alternating current (ΔI), and partial discharge (PD) indicating the size and pattern of discharge A method of diagnosing the insulation state of a motor.
13. The method of claim 12,
When the insulation resistance and polarization index are equal to or greater than a first reference value set in advance, an initial dielectric loss tangent (tanδ ₀ ) of the dielectric loss tangent is measured.
14. The method of claim 13,
If the initial dielectric loss tangent (tanδ ₀ ) is within a preset second reference value, a dielectric loss tangent (Δtanδ) test, an alternating current (ΔI) test, and a partial discharge (PD) test are performed. Way.
15. The method of claim 14,
Each of the dielectric loss tangent (Δtanδ) value, AC current (ΔI) value, and partial discharge (PD) value according to the dielectric loss tangent (Δtanδ) test, the alternating current (ΔI) test, and the partial discharge (PD) test is set in advance 3 If it is not within the reference value, the partial discharge (PD) value is higher than the predetermined fourth reference value depending on whether the dielectric loss tangent (Δtanδ) value, the alternating current (ΔI) value, and the partial discharge (PD) value have increased twice than before. If it is small, the motor insulation state diagnosis method, characterized in that it is determined as any one of the types of partial discharge.
16. The method of claim 15,
The third reference value is 3% in the case of the dielectric loss tangent (Δtanδ) value, 4% in the case of the alternating current (ΔI) value, and 30,000pC in the case of the partial discharge (PD) value How to diagnose motor insulation status.
16. The method of claim 15,
The fourth reference value is 30,000 pC, and when the partial discharge (PD) value is greater than the fourth reference value, an AC (Alternating Current) withstand voltage test is performed.
12. The method of claim 11,
The type of the partial discharge is a motor insulation state diagnosis method, characterized in that the internal discharge, conductor surface discharge, and slot discharge.
12. The method of claim 11,
The output unit 950 outputting the notification information; Motor insulation state diagnosis method further comprising a.
A computer-readable storage medium storing a program code for executing the motor insulation state diagnosis method according to any one of claims 11 to 19.

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