JP3854783B2 - Partial discharge diagnostic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device for diagnosing the insulation characteristics of a high-voltage device, particularly a gas insulation device using a gas having excellent insulation properties such as SF6 as an insulation medium, and relates to a signal detection / processing method of the device.
[0002]
[Prior art]
High-voltage switchgear used in substations, etc. has a structure that compresses and fills the ground container with gas with excellent insulation characteristics such as SF6 and mechanically supports the high-voltage charging conductor part with a solid insulator. Mainly gas-insulated equipment.
[0003]
In order to confirm the soundness and reliability of the insulation performance of these devices, it is extremely important to check the presence or absence of partial discharge from the insulators, metal conductors, etc. inside the devices. For this reason, various methods for diagnosing insulation of equipment through partial discharge measurement have been proposed and put into practical use.
[0004]
Sensors for measuring partial discharges can be broadly classified into those that mainly capture mechanical signals associated with partial discharges and those that capture electrical signals. As an example of the latter, a method of attaching a sensor (electromagnetic wave detection antenna) to the wall of a container of a high-voltage device and performing an internal insulation diagnosis based on the signal of the sensor is less affected by external noise and has a high sensitivity inside the device. It is used as a method for detecting abnormalities.
[0005]
High-voltage devices in substations are mainly gas-insulated switchgear in which SF6 gas is sealed in a sealed container, and a circuit breaker, disconnector, etc. are incorporated therein. In this case, it is known that the partial discharge generated in the internal gas becomes a steep pulse as compared with the air corona generated outside, and generates an electromagnetic wave with many high-frequency components. For this reason, it has been confirmed that a method of diagnosing the presence / absence of an abnormality without being affected by external noise by analyzing the frequency component of the partial discharge signal is effective.
[0006]
In the prior art, a partial discharge signal is analyzed by a high frequency component with a device such as a spectrum analyzer, and if a signal exceeding a predetermined threshold is detected, the device is fixed at a frequency indicating the maximum signal strength, and then the partial discharge signal is continued. The phase characteristics of the discharge pulse with respect to the power supply voltage were measured.
[0007]
Hereinafter, this method will be described with reference to FIG. In the figure, a high voltage conductor 3 is supported by an insulating spacer 4 made of a solid insulator, and is housed in a metal grounding container 1. The insulating spacer 4 is fixed to each other by a flange portion 2 provided at an end portion of the ground container 1. Moreover, it is comprised by the required shape as an opening / closing device by combining the connection to an axial direction, and is installed on the mount frame which is not shown in figure as a whole. Built-in electrode sensors 6 are provided at various locations on the ground container 1. This sensor is an antenna designed to detect with high sensitivity an electromagnetic wave propagating in a pipeline accompanying partial discharge, and is installed in a structure that does not disturb the electric field distribution in the container. The partial discharge signal detected by the built-in electrode sensor 6 is drawn out of the ground container 1 through the sealing terminal 31 and input to the partial discharge diagnostic device 5 using the coaxial cable 8.
[0008]
In the partial discharge diagnostic device 5, a signal associated with partial discharge is detected through a wideband filter 9 that passes a predetermined frequency band, an amplifier 10 that amplifies a high frequency signal, and a narrowband filter 11 whose center frequency is swept by a frequency shifter 21. The signal line 15 inputs the signal to the A / D converter 16. At the same time, the signal of the frequency shifter 21 is also taken into the A / D converter 16 through the signal line 13.
[0009]
Further, in the reference voltage generator 12 not shown in detail, a reference signal having the same phase as the main circuit applied voltage is generated and taken into the A / D converter 16 through the signal line 14. The partial discharge signal intensity and frequency information digitized by the A / D converter 16 and the phase information of the reference voltage are subjected to determination processing by the data processor 17 using a predetermined algorithm. The data processing unit 17 includes a CPU 18 and a display unit 19, and when the detected partial discharge signal intensity satisfies a preset condition, the frequency shifter unit 21 via the D / A conversion unit 32 in response to a command from the CPU 18. A command is issued to fix the frequency to a predetermined frequency. In this state, a partial discharge signal having a predetermined frequency component is taken in, and abnormality determination data is created along with reference voltage phase information. When the determination result indicates a partial discharge abnormality, the CPU 18 issues a command to the DI / O unit 20 and outputs an alarm contact 24 to the outside via the input / output I / F unit 22.
[0010]
[Problems to be solved by the invention]
In the above prior art, since the frequency characteristic is fixed and the phase characteristic is obtained, a timing difference occurs between the time zone in which the frequency component is measured and the time zone in which the phase component is measured. Further, when the frequency main component of the partial discharge fluctuates, there is a case where the frequency at which the phase characteristic is measured is not necessarily the maximum signal strength point. In order to avoid this, a method has been adopted in which a large number of data is acquired by changing the number of times of measurement and the measurement time, and these are comprehensively determined. Furthermore, in terms of the device configuration, a circuit unit for fixing the frequency shifter to a predetermined frequency by a command from the CPU is required, which increases the cost of the device.
[0011]
The object of the present invention is to switch the frequency sweep speed when capturing the frequency characteristics and the frequency sweep speed when capturing the phase characteristics, so that the signal strength, frequency characteristics, and phase characteristics of the electromagnetic wave can be adjusted when the frequency sweep speed is low. There is to acquire at the same time. As a result, problems such as a capture timing shift can be solved even for partial discharge signals generated intermittently.
[0012]
Another object is to reduce the size and weight of the device and reduce the cost by simplifying the circuit configuration of the diagnostic device.
[0013]
[Means for Solving the Problems]
In order to achieve this object, the invention of claim 1 is a circuit that detects an electromagnetic wave accompanying partial discharge and extracts its frequency component, wherein the sweep speed of the center frequency that becomes the resonance point of the narrowband filter is variable or switchable. It is characterized by doing.
[0014]
The invention of claim 2 is characterized in that a phase characteristic at a frequency point at the maximum intensity of an electromagnetic wave signal accompanying a partial discharge is made in a state of a low sweep speed, thereby eliminating a circuit to be fixed at that point. To do.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. In addition, about the same part as the prior art example shown in FIG. 5, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0016]
In FIG. 1, the signal from the built-in electrode sensor 6 is taken into the A / D converter 16 by the signal line 15 as the spectral component intensity as in the conventional structure of FIG. 5. The grounding container 1 has a shielding effect against external noise, but the insulating spacer 4 does not have a shielding effect, and electromagnetic waves such as air corona and broadcast / communication waves enter the grounding container 1. On the contrary, the electromagnetic wave accompanying the partial discharge generated inside the ground container 1 leaks out from the insulating spacer 4 part. Therefore, the sensor for partial discharge diagnosis can be combined with the external antenna 7 provided on the outer peripheral surface of the insulating spacer 4 in addition to the type of the built-in electrode sensor 6.
[0017]
Similarly to FIG. 5, voltage information from the reference voltage generator 12 is drawn into the A / D converter 16 through the signal line 14. Similarly, a frequency signal from the frequency shifter 21 is input through the signal line 13. The frequency shifter 21 is configured as shown in FIG. 2 and operates in combination with the sweep signal generation unit 27 in combination with the low-speed sweep control unit 28 or the high-speed sweep control unit 29, and this switching is performed by a switch unit by a signal from the DI / O unit 20. At 30. For example, as shown in FIG. 3, the sweep characteristics are set as in a high-speed sweep mode 25 (repetition of about several tens of ms) and a low-speed sweep mode 26 (repetition of about several seconds).
[0018]
Input signals 13, 14, and 15 are simultaneously processed by the A / D converter 16 and taken into the data processor 17 as instantaneous value data. In the processing device 17, the CPU 18 edits, processes, determines and saves the acquired A / D data by a predetermined program. As a result of the insulation diagnosis, a preset threshold value is compared with the measured signal strength, and when the threshold value is exceeded, an external output is made by the input / output I / F unit 22 via the DI / O unit 20. The contact 24 is turned “ON”. The diagnosis result can also be transmitted to a higher-level device via a communication port 23 not shown in detail.
[0019]
As shown in FIG. 3, the partial discharge signal is repeatedly swept between the center frequency of the narrow-band filter 11 between f1 and f2 by the frequency shifter 21, and the A / D converter 16 corresponds to an arbitrary center frequency therebetween. The signal intensity of the component is taken into the CPU 18 in the form of digital data.
[0020]
The CPU 18 manages the sweep speed of the frequency shifter 21 and normally searches for the presence or absence of a partial discharge signal in the high-speed mode. When a signal component exceeding the threshold is detected, a command is issued to the DI / O unit 20 to switch the frequency shifter 21 to the low speed mode, and the zero point passing point of the voltage signal is determined based on the signal of the reference voltage generating unit 12. As a reference, phase characteristic data for one cycle as shown in FIG. 4 (electrical angle 0 ° to 360 °) is created.
[0021]
The phase characteristics can be obtained by using the data at the maximum point of the partial discharge signal for each repetition of the sweep, or by collecting the data at the same frequency component multiple times and collecting the maximum data or the average data. It is created as characteristic data for one cycle. Further, when capturing a single or sudden partial discharge signal pattern, it is possible to generate phase characteristic data based on one sweep data in the high-speed mode, and this can be handled by a program of the CPU 18.
[0022]
The pattern of the phase characteristic is compared and referred to a characteristic pattern for each partial discharge aspect registered in advance, and if there is a similar pattern, it can be guided as a cause of the detected partial discharge.
[0023]
In addition, the occurrence, disappearance, or continuity of the partial discharge event can be checked by displaying the temporal variation of the phase characteristic on a display device (not shown).
[0024]
【The invention's effect】
The signal processing of the present invention eliminates the time delay between the acquisition of the frequency component data and the phase characteristic data, and even if the frequency component at the maximum point of the partial discharge signal intensity fluctuates, the phase characteristic data at the maximum point can be acquired. The discharge mode judgment is ensured.
[0025]
Even for intermittent and single partial discharges, the phase characteristics for one cycle can be obtained reliably, so that the initial signs of abnormality can be seen. Furthermore, since the function can be realized by a simple mechanism that only switches the sweep speed, the hardware can be reduced in size and cost, and can be applied to a portable diagnostic device or the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of the present invention.
FIG. 2 is a diagram showing switching of a frequency shifter.
FIG. 3 is a diagram showing a comparison of sweep speeds.
FIG. 4 is a diagram showing phase characteristics.
FIG. 5 is a diagram showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ground container, 2 ... Flange part, 3 ... High voltage conductor, 4 ... Insulating spacer, 5 ... Partial discharge diagnostic device, 6 ... Built-in type electrode (sensor), 7 ... External antenna (sensor), 8 ... Coaxial cable , 9 ... wideband filter, 10 ... high-frequency amplifier, 11 ... narrowband filter, 12 ... reference voltage generator, 13 ... partial discharge frequency component signal, 14 ... reference voltage signal, 15 ... partial discharge spectrum component signal, 16 ... A / D converter, 17 ... data processing unit, 18 ... CPU, 19 ... display unit, 20 ... DI / O unit, 21 ... frequency shifter, 22 ... input / output I / F unit, 23 ... communication port, 24 ... external output contact 25 ... High-speed sweep mode, 26 ... Low-speed sweep mode, 27 ... Sweep signal generation unit, 28 ... Low-speed sweep control unit, 29 ... High-speed sweep control unit, 30 ... Switch unit, 31 ... Sealed terminal, 32 ... D / A conversion Department.

Claims (1)

By a sensor inside it was kicked set in the gas-insulated equipment, in a partial discharge diagnosing method for diagnosing an insulation abnormality inside the apparatus by detecting an electromagnetic wave caused by the partial discharge occurring inside the apparatus, by sweeping the center frequency of the narrow-band filter While capturing the frequency spectrum information of the electromagnetic wave signal while simultaneously capturing the phase information of the applied voltage at that time, when performing insulation diagnosis using the phase characteristics at the maximum point of the spectrum signal ,
The sweep speed of the narrow band filter is set in advance to a high speed mode for detecting the presence / absence of a partial discharge signal and a low speed mode for capturing phase characteristics, and the low speed is determined by a CPU command according to the detected partial discharge signal size. A partial discharge diagnosis method characterized in that switching between a mode and a high-speed mode is performed, the phase characteristic is generated with the sweep speed in the low-speed mode, and insulation diagnosis is performed using the phase characteristic .

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