KR100445239B1 - On-line Partial Discharge Measurement in the Stator Windings of High-voltage Rotating Machine - Google Patents

Abstract

The present invention is to determine the state of the insulator used in the stator winding of a high voltage rotor, such as a generator, electric motor, in particular peak-hold and analog-to-digital converter to detect the signal detected by using a partial discharge measurement sensor The present invention relates to a method of measuring partial discharge during operation in a stator winding of a high voltage rotor by measuring a partial discharge signal by a maximum detector method using an analog to digital converter, thereby ensuring measurement reliability and implementing more economically. Detecting a zero point of the power supply frequency (S301-S303); Separating into a positive (+) and a negative (-) partial discharge signal (S304); The separated signal is divided into dual paths (S305), and for each signal on the dual paths, one set period is divided into a plurality of predetermined unit sections on the phase axis to detect a phase of the partial discharge signal and the divided section Detects / maintains the maximum value in units and performs analog / digital conversion, and performs this alternately on the phase axis for each signal on the dual path (S306-S308), thereby operating a high-pressure rotor partially applied only to a large capacity generator. By developing the measuring equipment for diagnosing the insulation deterioration state of the stator winding at low cost, it can be applied to high-voltage motors as well as large generators. Improve national competitiveness

Description

On-line Partial Discharge Measurement in the Stator Windings of High-voltage Rotating Machine}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring partial discharge during operation in a high voltage rotor stator winding, and more particularly, to determine a state of an insulator used in a stator winding of a high voltage rotor such as a generator or an electric motor. By measuring the partial discharge signal by using the maximum value detector method using the peak-hold and analog-to-digital converter, the signal detected by using It is about how to.

As industrial production facilities are expanded and automated, the size of the rotor is also increased, and the reliability of operation becomes a requirement, and sudden stoppages caused by deterioration due to the long-term operation of the rotor cause great disruption to production. In order to prevent such a sudden stop, such as measures to improve the performance of the rotor, preventive diagnosis and economical maintenance methods are necessary.

The preventive diagnosis of the rotor is divided into a mechanical diagnosis and an electrical diagnosis. The mechanical diagnosis is a technique for diagnosing an abnormal state by measuring noise and vibration, and the electrical diagnosis is a diagnosis technique for an insulation state of the rotor stator winding.

The electrical diagnosis is divided into a method performed while the rotor is stopped and a method performed during operation. Since the method of diagnosing while stopping has to stop the rotor, there is a disadvantage in that it is not possible to detect an abnormal condition occurring in an actual operating state as well as economic loss due to the stop of operation of the device.

In order to compensate for this disadvantage, the method of diagnosing the insulation state of the stator windings by measuring the partial discharge signal generated during the actual operation of the rotor is most frequently used. A representative example of a diagnostic method during operation is a single channel analyzer.

The single channel analysis pulse detection method detects only partial discharges of a certain magnitude and a specific pulse width preset within a period of 60 Hz commercial frequency.The partial discharges are gradually increased or decreased for partial discharges. Find the size of.

Referring to the conventional system using this technique using the drawings, as shown in Fig. 1, after receiving the partial discharge signal generated in the stator winding of the rotor through the sensor (S110), and performs a noise reduction filtering (S120). Thereafter, as shown in step S130, partial discharge measurement level setting (S131) → phase detection (S132) → separation into (+/−) partial discharge signals (S133) → measurement for each separated partial discharge signal. The partial discharge signal is measured by a single channel analysis method including a step of partial discharge measurement according to a level (S134) to an analog / digital (A / D) conversion (S135), and the partial discharge measurement data according to size and the part by phase The partial discharge signal is made into a database based on the discharge measurement data (S140), and a partial discharge signal capable of determining the state of the stator winding is output as a 2D / 3D graph (S150).

A representation of the singular channel analysis part in the step S130 of FIG. 1 is illustrated in FIG. 2. FIG. 2 is a case where the measurement level is set to 3 levels (Level 1, Level 2, Level 3), and it is shown that the measured partial discharge signals are repeatedly measured in order of level for a predetermined time, and reference numeral T1 in the drawings. Denotes a measurement period of Level 1, T2 denotes a measurement period of Level 2, T3 denotes a measurement period of Level 3, and a portion indicated by a dot denotes an A / D sampling point.

However, the conventional single channel pulse detection technique described above has a disadvantage in that it is impossible to detect all the partial discharge signals occurring in one cycle, and this conventional technique is a high-voltage large-capacity generator of 11 [kV], 100 [MVA] or more. Although it is economical for, the economics are low for the rotor of 6.6 [kV] and 20 [MVA] or less. In other words, the conventional partial discharge measurement system employing this method is reliable due to the application of high-performance components, but has a disadvantage in that it is not properly applied to an electric motor which is relatively inexpensive compared to an actual field, especially a generator because of its high price.

The present invention has been made to solve the above problems, and its object is to provide a new partial discharge measurement method that can more economically and reliably monitor the insulation state in the stator winding of the high-voltage rotor compared with the existing. will be.

1 is a flow chart of a partial discharge measurement method using a single channel analysis of the conventional partial discharge measurement technique,

FIG. 2 is a graph of a partial discharge signal for explaining step S130 in FIG. 1,

3 is a flowchart of a method for measuring partial discharge during operation in a high voltage rotor stator winding according to an embodiment of the present invention;

4 is a graph of partial discharge signals illustrating an ideal performance of steps S306-S308 of FIG. 3,

5 (a) and 5 (b) are graphs of the partial discharge signals on the dual path illustrating the practical performance of steps S306-S308 of FIG.

※ Explanation of code for main part of drawing

T1, T2, T3: each level measurement cycle

A: Maximum detection area

B: A / D sampling area

C: maximum discharge capacitor discharge area

A / D sampling time

In order to achieve the above object, a method of measuring partial discharge during operation in a stator winding of a high voltage rotor according to the present invention is a method of measuring a partial discharge signal generated in a stator winding of a rotor. Detecting and separating into positive and negative partial discharge signals; Separating the separated signal into a dual path; For each signal on the dual path, one set period is divided into a plurality of predetermined unit sections on the phase axis to detect a phase of the partial discharge signal, and a maximum value in units of the divided sections based on the detected phase. A third step of detecting / maintaining and performing analog / digital conversion, alternately on the phase axis for each signal on the dual path; And a fourth step of analyzing the insulation state of the stator windings based on the converted digital data.

The phase detection may be performed based on a predetermined phase based on a power supply frequency and detected based on the power supply frequency. The one period is 360 ° as a period of a partial discharge signal set based on a power supply frequency, and the unit section is 1 °. The maximum value detection period is 46.3 ms.

Hereinafter, a method of measuring partial discharge during operation in a high voltage rotor stator winding according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart of a method for measuring partial discharge during operation in a high voltage rotor stator winding according to an exemplary embodiment of the present invention.

First, a partial discharge signal is input from a corresponding high voltage rotor stator winding through an online sensor (not illustrated) for partial discharge detection (S301), and after noise reduction filtering (S302), a random phase is set at a power source frequency and then referenced. In step S303, the phase of the filtered partial discharge signal is detected.

Thereafter, the partial discharge signal is separated into a positive region and a negative region (S304), and then each separated partial discharge signal is separated into a double path again (S305). Subsequently, for each signal on the dual path, a phase and a maximum value are detected (S306), the detected maximum value is maintained (S307), and analog / digital conversion is performed (S308) to calculate a partial discharge parameter. do.

Finally, the calculated parameter is divided into partial discharge measurement data for each size and partial discharge measurement data for each phase to make a partial discharge signal as a database (S309), and based on the database, the state of the stator winding in a 2D / 3D graph. A partial discharge signal capable of determining the output is output (S310).

The phase detection is such that the phase angle is detected while maintaining / detecting the maximum value of each phase angle by 1 degree for 360 degrees of one cycle after detecting the zero point of the power source frequency.

Hereinafter, the process of steps S305 to S308, which are essential steps of the present invention, will be described in detail.

4 is a graph of a partial discharge signal on a phase axis for explaining a method of detecting a maximum value of a partial discharge signal of an ideal form, and detects and maintains the maximum value at an interval of 1 ° on a single path, and converts the analog signal to digital A. / D Indicates sampling. In other words, by setting an arbitrary phase at the power supply frequency, the peak-hold and analog-to-digital converter method is used to obtain and sample the maximum value of the phase section (ie, 1 ° interval). Is showing.

However, since such a method has difficulty in hardware configuration in an actual circuit, the partial discharge signal is separated into two dual paths as shown in FIGS. 5A and 5B in step S305, and each path is received. By performing the processes of steps S306 to S308 alternately in phase, the maximum value of each phase is detected and the maximum value of the partial discharge signal is obtained using an economical analog-to-digital converter.

That is, FIGS. 5A and 5B illustrate partial discharge signals on the dual path, and the steps S306 to S308 performed in (a) and the second path on the first path will be described. One period 360 ° set on the basis of the power frequency is divided into 360 unit sections (each unit section is 1 °) preset on the phase axis, and every 1 ° of the divided section unit according to the phase detected in step S303. A maximum value is detected / maintained and an analog / digital conversion is performed alternately on the phase axis for each signal (a) and (b) on the dual path. That is, the signal (a) on the first path is performed on the signal (a) on the first path at the time of 1 °, 3 °, 5 °, ..., and the steps S306 to S308 are alternately performed. In the following, the processes of steps S306 to S308 are performed at the time of 2 °, 4 °, 6 °, .... In FIG. 5, only the maximum value detection / maintenance and A / D sampling of the positive partial discharge signal are shown, and the same process is applied to the negative partial discharge signal. In Fig. 5, reference numeral 'a' denotes a maximum value detection region, 'i' denotes an A / D sampling region, and 'a' denotes a maximum value capacitor discharge region.

As described above, when steps S306 to S308 are alternately performed on the dual path, even when a relatively low-speed analog-to-digital converter is applied, the maximum value of partial discharge can be easily detected, and the system can be configured at low cost.

As an example of applying the scheme proposed in the present invention, a partial discharge signal of one cycle is divided into 360 sections, and a peak-detector hold circuit and an analog-to-digital converter built in the 81096KC itself about once every 46.3 ms. The actual system was configured to apply the scheme of the present invention described above to the field. As a result of comparing and analyzing the calculated data with the data measured by the existing product, it was possible to obtain a satisfactory result that is close to the reliability of the existing product while constructing at a lower cost than the existing product.

As described in detail above, according to the method of measuring the partial discharge during operation in the high voltage rotor stator winding according to the present invention, the measurement equipment for diagnosing the insulation deterioration state of the stator winding during the operation of the high voltage rotor, which was partially applied only to the existing high-capacity generator, is inexpensive. It can be applied to high-voltage motors as well as large-scale generators, and it is competitive in price compared to existing foreign products, thus preoccupying the domestic market and participating in the export wire in the future will create the effect of improving the national competitiveness.

Claims (3)

In the method for measuring the partial discharge signal generated in the stator winding of the rotor, Detecting a zero point of the power supply frequency and separating the positive and negative partial discharge signals; Dividing the separated partial discharge signal into a dual path; A third step of detecting a phase by dividing one period set based on a power source frequency into a plurality of predetermined unit sections on a phase axis for each signal on the dual path; A fourth step of detecting / maintaining a maximum value in units of the divided intervals based on the detected phases and performing analog / digital conversion, and alternately performing them on the phase axis for each signal on the dual path; And And a fifth step of analyzing the insulation state of the stator windings based on the converted digital data. The method of claim 1, The phase detection is a partial discharge measurement method during operation in the high-voltage rotor stator winding, characterized in that for detecting a reference to set a phase based on the power frequency. The method of claim 2, In one cycle, the period of the partial discharge signal set based on the cycle of the power frequency is 360 °, the unit section is 1 °, and the period of detection of the maximum value is 46.3 ms. How to measure partial discharge during operation.