KR100901855B1 - Method for diagnosing the insulation condition of three phase alternating current rotating machinery, and a medium having computer readable program for executing the method - Google Patents

Abstract

Disclosed is a three-phase alternating current rotating device insulation state diagnosis apparatus and method. The three-phase alternating current rotating device insulation state diagnosis device includes a differential leakage current measurement unit, an average insulation factor calculation unit, and a degradation insulation determination unit. The differential leakage current measurement unit measures the differential leakage current of each phase of the three-phase AC motor, and the average insulation factor calculation unit calculates the average equivalent insulation resistance and average equivalent insulation capacitance of the three-phase AC motor stator winding insulator from the differential leakage current, and discriminates degradation insulation. The unit compares the average equivalent insulation resistance and the average equivalent insulation capacitance with a predetermined equivalent insulation resistance of the three-phase AC motor, and the equivalent insulation capacitance to determine the insulation deteriorated during the insulation between each phase and each phase of the three-phase AC motor. By comparing the average equivalent insulation resistance and the average equivalent insulation capacitance calculated by measuring the differential leakage current with the average equivalent insulation resistance and the average equivalent insulation capacitance before deterioration obtained by offline diagnosis, it is possible to obtain low The deterioration position of main insulation and interphase insulation can be grasped.

Alternator, stator winding insulation, differential leakage current

Description

Method for diagnosing the insulation condition of three phase alternating current rotating machinery, and a medium having computer readable program for executing the method

1 is a schematic block diagram of one embodiment of an apparatus for diagnosing insulation state of a three-phase alternating current rotating device according to the present invention;

2 is a table showing the change in insulation factor due to deterioration of phase and interphase insulation.

3 is a modeling diagram of a stator winding insulation system for three phases of low and medium voltage equipment.

4 is a configuration diagram for performing insulation diagnosis using the AC rotating device insulation state diagnosis apparatus of FIG.

TECHNICAL FIELD The present invention relates to an electrical device, and more particularly, to an apparatus and a method for individually diagnosing an insulation state between phases and phases of a three-phase AC rotating device stator such as an electric motor or a generator.

Electrical isolation is one of the most essential components for the operation of electrical equipment and plays an important role in determining the reliability of electrical equipment. According to the survey of reliability of electrical equipment published by IEEE, EPRI, Allianz, etc. in the last 20 years, the average annual failure rate of the equipment is 3%, and the annual failure rate is high when the operation rate or load is high, or when operating under adverse conditions such as paper industry and mining. Up to 12%.

According to the failure cause analysis, the motor failure due to stator insulation failure is 30-40% of the total, 60-70% for high voltage equipment, electrical insulation is one of the weakest components of the equipment.

Electric equipment failure is not only a loss due to the cost of repairing or repairing the malfunctioning equipment, but also causes a huge economic loss due to the productivity decrease due to the process stop because the process itself including the motor or the generator is stopped.

Among electrical equipment failures, failures caused by breakdown of electrical insulation can cause short circuits and arcing accidents, which can cause fire and human injury. Therefore, in order to prevent damage caused by device failure, regularly and accurately diagnosing the insulation state of the device may be essential for reliable operation.

Offline diagnostics, which are commonly used for diagnosing the insulation of a device, interrupts the operation of the device during periodic inspections, resulting in expensive diagnostic costs due to factory outages and low diagnostic frequency (1/3/3 years). It is difficult to guarantee reliability.

In the case of on-line diagnosis performed during the operation of the device, the temperature / chemical monitoring method can be diagnosed immediately before the failure occurs, and the collection / phase current relay method can be diagnosed after the failure, so that the state of insulation cannot be diagnosed early. .

In addition, in the partial discharge detection method, since only the partial discharge of the insulation is detected, it is difficult to diagnose the overall state of the insulation, and it is difficult to interpret the diagnosis result. In addition, all three online diagnostic methods mentioned above have a problem in that high costs are required for diagnosing low and low voltage devices.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to precisely detect the deterioration of insulation at an early stage by identifying the deterioration position of the main insulation and the interphase insulation in the stator winding insulation and quantifying the insulation state at low cost even in the medium and low voltage equipment. An object of the present invention is to provide an on-line diagnostic apparatus and method for diagnosing.

In order to achieve the above object, the three-phase AC rotating device insulation state diagnosis apparatus according to the present invention includes a differential leakage current measurement unit, an average insulation factor calculation unit, and a degradation insulation determination unit.

The differential leakage current measurement unit measures the differential leakage current of each phase of the three-phase AC motor, and the average insulation factor calculation unit calculates the average equivalent insulation resistance and average equivalent insulation capacitance of the three-phase AC motor stator winding insulator from the differential leakage current, and discriminates degradation insulation. The unit compares the average equivalent insulation resistance and the average equivalent insulation capacitance with a predetermined equivalent insulation resistance of the three-phase AC motor, and the equivalent insulation capacitance to determine the insulation deteriorated during the insulation between each phase and each phase of the three-phase AC motor.

By comparing the average equivalent insulation resistance and the average equivalent insulation capacitance calculated by measuring the differential leakage current with the average equivalent insulation resistance and the average equivalent insulation capacitance before deterioration obtained by offline diagnosis, it is possible to obtain low The deterioration position of main insulation and interphase insulation can be grasped.

The average insulation factor calculation unit further calculates an average dielectric loss tangent of the three-phase AC motor stator winding insulator, and the degradation insulation discriminator further compares the average dielectric loss tangent with a predetermined dielectric loss tangent of the three-phase AC motor to each phase and between each phase. Degradation of insulation can be determined.

By comparing dielectric tangents in addition to equivalent insulation resistance and equivalent insulation capacitance, it is possible to more effectively determine the location of degradation of interphase insulation.

In addition, the three-phase AC rotating machine insulation state diagnosis device compares the resistive current of the differential leakage current and the resistive current of the predetermined differential leakage current to calculate the ratio of magnitude, and the phase of the phase where the ratio of magnitude and the deteriorated equivalent insulation resistance is located. Calculate the deteriorated equivalent insulation resistance using the equivalent insulation resistance except the deteriorated equivalent insulation resistance among the predetermined equivalent insulation resistances between the phase where the deteriorated equivalent insulation resistance is located, and the measured differential leakage current. The apparatus may further include a deterioration insulation factor calculator.

With such a configuration, it is possible to accurately diagnose deterioration of insulation at an early stage by not only identifying the equivalent resistance deteriorated but also quantifying the insulation state.

The degradation insulation factor calculator may further calculate the degradation dielectric tangent by using the degraded equivalent insulation resistance and the predetermined equivalent insulation capacitance. As such, by using the deteriorated dielectric resistance as well as the deteriorated equivalent resistance, it is possible to more effectively carry out the diagnosis of deterioration of insulation through quantification of the insulation state.

In addition, a medium having recorded therein the invention embodying the apparatus as a method and a computer readable program for executing the method is claimed.

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

1 is a schematic block diagram of an embodiment of an apparatus for diagnosing insulation state of a three-phase alternating current rotating device according to the present invention.

In FIG. 1, the three-phase AC rotating device insulation state diagnosis device 100 includes a differential leakage current measuring unit 110, an average insulation factor calculating unit 120, a degradation insulation determining unit 130, and a degradation insulation factor calculating unit 140. It includes.

The differential leakage current measuring unit 110 measures the differential leakage current of each phase of the three phase AC motor, and the average insulation factor calculating unit 110 measures the average equivalent insulation resistance of the three phase AC motor stator winding insulator, and the average equivalent insulation from the differential leakage current. The capacitance is calculated, and the deterioration insulation determination unit 130 compares the average equivalent insulation resistance and the average equivalent insulation capacitance with a predetermined equivalent insulation resistance of the three-phase AC motor, and the equivalent insulation capacitance, and each phase and each phase of the three-phase AC motor. Determine the insulation that is degraded during insulation.

By comparing the average equivalent insulation resistance and the average equivalent insulation capacitance calculated by measuring the differential leakage current with the average equivalent insulation resistance and the average equivalent insulation capacitance before deterioration obtained by offline diagnosis, it is possible to obtain low The deterioration position of main insulation and interphase insulation can be grasped.

The average insulation factor calculation unit 120 further calculates an average dielectric loss tangent of the three-phase AC motor stator winding insulator, and the degradation insulation determination unit 130 further compares the average dielectric loss tangent with a predetermined dielectric loss tangent of the three-phase AC motor. The deteriorated insulation can be discriminated among the phases of the AC motor and the insulation between the phases.

By comparing dielectric tangents in addition to equivalent insulation resistance and equivalent insulation capacitance, it is possible to more effectively determine the location of degradation of interphase insulation.

The predetermined equivalent insulation resistance, equivalent insulation capacitance and dielectric loss tangent may be a predetermined value and may be an average equivalent insulation resistance, average equivalent insulation capacitance and dielectric loss tangent before deterioration.

Figure 2 is a table showing the change in insulation factor due to phase and inter-phase insulation.

As can be seen in the table of FIG. 2, deterioration of the equivalent insulation resistance between specific phases or phases causes a change in the average equivalent insulation resistance or the average equivalent insulation capacitance, and thus the change in the average equivalent resistance, average equivalent insulation capacitance, and dielectric loss tangent is used. The exact position of the deteriorated equivalent insulation resistance can be identified.

The degradation insulation factor calculator 140 compares the resistive current of the differential leakage current with the resistive current of the predetermined differential leakage current, and calculates a ratio of magnitudes. The deteriorated equivalent insulation resistance is calculated using the equivalent insulation resistance except the deteriorated equivalent insulation resistance among the predetermined equivalent insulation resistance between the phase where the deteriorated equivalent insulation resistance is located and the deteriorated equivalent insulation resistance, and the measured differential leakage current.

With such a configuration, it is possible to accurately diagnose deterioration of insulation at an early stage by not only identifying the equivalent resistance deteriorated but also quantifying the insulation state.

The degradation insulation factor calculator 140 may further calculate the degradation dielectric loss tangent by using the degraded equivalent insulation resistance and a predetermined equivalent insulation capacitance. As described above, by using the deteriorated dielectric loss tangent as well as the deteriorated equivalent resistance, it is possible to more effectively perform the diagnosis of deterioration of insulation through quantification of the insulation state.

The ratio of magnitude can be designated as the deterioration constant K, where K has a value between 0 and 1, and the magnitude of the deterioration decreases as the deterioration progresses. Degradation constants can be derived for all three phases and can be used on average.

3 is a modeling diagram of a stator winding insulation system for three phases of medium and low voltage equipment.

과 커패시턴스로 흐르는 전류

로 나누어 유전정접(DF)을 알 수 있다.In general, the insulator is modeled by the parallel connection of the insulation capacitance (C) and the insulation resistance (R), and the current flowing through the insulator is a current flowing through the resistor.

Current flowing through and capacitance

Dividing by gives the genetic tangent (DF).

Based on this, Figure 1 is a model of the insulation system of the stator windings for the three phases of medium and low voltage equipment, and the main and interphase insulation of each phase is modeled by the parallel connection of the insulation resistance (R) and the insulation capacitance (C). Can be.

FIG. 4 is a configuration diagram for performing insulation diagnosis using the AC rotating device insulation state diagnosis apparatus of FIG. 1.

As shown in FIG. 4, when the differential leakage current is measured to measure the differential leakage current of each phase of each of the three phases of the low and medium voltage devices in operation, the differential leakage current of each phase is different from that of the offline medium and low voltage devices. Since the average voltage across the winding is 1/2, the following equation can be obtained.

Through this, the following method is used to find the insulation resistance and insulation capacitance, which are the insulation factors to know the state of the main insulation and interphase insulation of each phase, and to solve the ill-condition.

와

그리고 DF의 변화를 통해 문제의 주절연 또는 상간절연을 파악한다. 일반적으로 고정 자 권선 절연의 열화로 인한 고장의 경우 3상의 주절연과 상간 절연 중 하나의 절연이 열화로 인한 고장을 일으킨다. IEEE std. An off-line test based on 286 was used to measure the insulation resistance (R), insulation capacitance (C), and DF of each phase's main and interphase insulations prior to deterioration and to calculate the average leakage current of each phase during insulation degradation during operation. Insulation Factor

Wow

The DF changes to identify the main or phase insulation in question. In general, in the case of failure due to deterioration of stator winding insulation, the insulation of one of the three phase main insulation and the interphase insulation causes the failure due to deterioration.

Determine the average deterioration of insulation from the phase without problems. The insulation capacitance of the main insulation and the phase insulation of each phase is insignificant even when deterioration occurs. Therefore, the value obtained through offline measurement is used. If the initial leakage current of phase A before deterioration occurs is

The measured leakage current after deterioration is as follows.

The leakage current before deterioration and after deterioration can indicate the overall degree of deterioration and can be expressed as follows.

If deterioration occurs in the main insulation or interphase insulation of phase A, the following equation can be obtained.

Through this, it is possible to quantitatively identify the equivalent resistance of the main insulation of phase A or the insulation resistance between phases in which deterioration has occurred, and quantify the remaining main insulation and interphase insulation through the degree of total deterioration. In addition, by identifying the dielectric loss tangent (DF) together with the insulation capacitance derived through offline, these three insulation states can quantitatively determine the state of insulation between phases.

The present invention can serve to improve the reliability, productivity stability of the industry.

More specifically, since the state of each component of the insulation is diagnosed, resolution of many insulation diagnoses can be increased, so that degradation of the insulation can be diagnosed early.

In addition, the diagnosis of the status of individual isolation components allows for more efficient determination of priorities and timings when repairing or inspecting individual devices if they operate simultaneously.

In addition, since there is information on the most vulnerable parts of stator insulation, it is necessary to repair / replace because the concentrated part can be checked and the judgment on the inspection / repair / replacement of the stator winding can be made quickly during maintenance / inspection. This can minimize the time and costs of doing so.

According to the present invention, it is possible to accurately diagnose deterioration of insulation at an early stage by locating the deterioration position of the main insulation and the interphase insulation and quantifying the insulation state in the stator winding insulation of the low and medium voltage device.

Although the present invention has been described in terms of some preferred embodiments, the scope of the present invention should not be limited thereby, but should be construed as modifications or improvements of the embodiments supported by the claims.

Claims (9)

delete delete delete delete Differential leakage current measuring step of measuring differential leakage current of each phase of three-phase AC motor; Calculating an average equivalent insulation resistance and an average equivalent insulation capacitance of the three-phase AC motor stator winding insulator from the differential leakage current; Degradation for determining the deteriorated insulation among the phases and the phases of each of the three-phase AC motors by comparing the average equivalent insulation resistance and the average equivalent insulation capacitance with a preset equivalent insulation resistance of the three-phase AC motor and the equivalent insulation capacitance. And an insulation discrimination step. 3. The method of claim 5, The average insulation factor calculating step further calculates an average dielectric loss tangent of the three-phase AC motor stator winding insulator, The deterioration insulation determination step may further compare the average dielectric loss tangent with a preset dielectric loss tangent of the three-phase AC motor to determine the deteriorated insulation among the phases and the phases of each of the three-phase AC motors. How to diagnose instrument insulation. The method of claim 5, Comparing the resistive current of the differential leakage current and the resistive current of the preset differential leakage current to calculate the ratio of magnitude, Equivalent insulation except for the deteriorated equivalent insulation resistance among the predetermined equivalent insulation resistance between the ratio of the magnitude, the phase voltage and the phase where the deteriorated equivalent insulation resistance is located, and the phase and the phase where the deteriorated equivalent insulation resistance is located. And a deterioration insulation factor calculating step of calculating the deteriorated equivalent insulation resistance using the resistance and the measured differential leakage current. The method of claim 7, wherein The deterioration insulation factor calculation step of the three-phase AC rotary device insulation state diagnostic method, characterized in that for further calculating a deterioration dielectric loss tangent using the deteriorated equivalent insulation resistance and the predetermined equivalent insulation capacitance. A medium having a computer readable program recorded thereon for executing the method of claim 5 or 8.

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