JPH07230929A - Internal failure-diagnosing method for oil immersed stationary electric machine - Google Patents

Abstract

PURPOSE:To improve failure-diagnosing accuracy in an internal failure- diagnosing method for a machine by a method wherein a pulse detector and a plurality of microphones, used to detect the sound signal when an internal failure is generated, are provided in an oil immersed stationary transformer. CONSTITUTION:An electric pulse (earthing current) and sound signals 1 to 4 are converted into digital form, and when the sound signal 2 is triggered (time T), for example, all other signals are lock-stored. The time difference t<2> between the sound signal 2 and the time differences t1, t3' and t4' between the electric pulse signal and the sound signal 2 and other sound signals 1, 3 and 4 are measured. The time difference between the electric pulse signal and other signals 1, 3 and 4 are computed by adding the t1', t3' and t4' to the time difference t2. Based on the computed time differences t1 to t4 the mounting position of a microphone and the transmission speed of sound, the position of sound source is oriented using the principle of triangulation and the failure in the machine is diagnosed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for diagnosing internal faults in oil-filled static electrical equipment, and more particularly to a method for diagnosing internal faults in oil-filled static electrical equipment for locating internal faults and fault positions by sound and electrical pulses.

[0002]

2. Description of the Related Art Conventionally, in order to diagnose an internal failure of an oil-filled static electric device, for example, an electric pulse signal and a sound signal are detected as shown in FIG. 2, and a sound source position is located based on these detection signals. The method was used.

In FIG. 2, reference numeral 11 is an oil-filled transformer, and microphones MIC _{1 to} MIC ₄ for collecting internal sound are attached to the outer wall of the tank. Reference numeral 12 is a current transformer for detecting the tank ground current i (electrical pulse signal). The detection signal (electrical pulse signal) of the current transformer 12 becomes the ground current shown in FIG. 3, and the detection signals of the microphones MIC _{1 to} MIC ₄ are the sound signals 1 to 1 shown in FIG.
It becomes a sound signal 4.

A plurality of sound signals 1 to 4 are swept with the trigger time of the electric pulse signal as T, and the time difference t ₁ to the electric pulse from the point where the amplitude of each sound signal 1 to 4 becomes large.
The t ₄ is measured, said time difference t ₁ ~t ₄ and microphone MI
The sound source position is determined by the principle of triangulation from the installation position of C _{1 to} MIC ₄ by back calculation of the sound propagation velocity.

[0005]

Since the internal fault diagnosis method as described above is triggered by an electric pulse signal, it is easily affected by external noise. That is, in the electric power system, load switching noise in the final consumer and switching noise of the power converters used in recent years intrude. For this reason, there is a drawback that the time measurement of the sound signal and the true electric pulse becomes impossible, the position of the sound source cannot be located, and the accuracy of the internal failure diagnosis is remarkably poor.

The present invention has been made in view of the above points, and an object thereof is to provide a method for diagnosing an internal failure of an oil-filled static electric device that is not affected by electrical noise.

[0007]

According to the present invention, there is provided a pulse detector provided in an oil-filled static electric device for detecting an electric pulse at the time of an internal failure, and provided in a plurality of positions of the oil-filled static electric device. A sound sensor for detecting a sound signal at the time of an internal failure, and analog / digital converting the output signals of the pulse detector and the sound sensor respectively, and when any one of the output signals of the plurality of sound sensors is triggered. The output signals and electrical pulses of all the sound sensors are locked and stored, the time difference t _X between the triggered sound signal and the electrical pulse before the sound signal is obtained from the memory contents, and the triggered sound signal is obtained. And the time difference t between the sound signal of another sound sensor
_{Y1 to} t _Yn are obtained, and the time differences t _{Y1 to} t _Yn are added to the time difference t _X separately to obtain time differences t _{Z1 to} t _Zn between the sound signal of the other sound sensor and the electric pulse. Based on the mounting position, the time difference t _X , the time differences t _{Z1 to} t _Zn, and the sound propagation velocity, the sound source position is located by using the principle of triangulation, and the failure inside the device is diagnosed.

[0008]

Since the trigger is performed by the sound signal instead of the electric pulse, it is not affected by electric noise such as load switching noise and switching noise. Therefore, the sound source position at the time of internal failure can be accurately located, and the accuracy of internal failure diagnosis is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows each detection signal detected by the diagnostic device of FIG. In the present invention, first, the electrical pulse (ground current) and the sound signal 1 to the sound signal 4 are digitally converted, and when any one of the plurality of sound signals, for example, the sound signal 2 is triggered (time T), Locks all other signals. Then, the time difference t ₂ between the electric pulse signal before the sound signal 2 and the time difference t ₁ ′, t ₃ ′, t ₄ ′ between the sound signal 2 and the other sound signals 1, ₃ , ₄ are measured. To do.

Next, the measured time difference t ₂ is t ₁ ′,
The time differences t ₁ , t ₃ , t ₄ between the electric pulse signal and the other sound signals ₁ , ₃ , ₄ are obtained by adding t ₃ ′ and t ₄ ′, respectively. And these time difference t ₁ ~t ₄ obtained, the based on the propagation velocity of the mounting position and the sound of the microphone MIC ₁ ~MIC _4, and orientation of the sound source position by using the principle of triangulation, the internal equipment failure To diagnose.

The following method is used to detect the electric pulse signal (an example of an oil-filled transformer). (1) Tank ground current detection (detection by high frequency current transformer). (2) Neutral point (ground type) ground current detection. (3) Detected from the bushing tap.

[0012] For outdoor use, the system of the present invention may not function properly under a natural phenomenon such as rain that impacts the tank wall or the like. However, it is only necessary to diagnose the internal failure for a long period of time, so
Noise due to natural phenomena is transient, and diagnosis is not hindered even if there is no data during that period. In addition to the above, even if there is a sound signal trigger due to contact with the tank wall by birds or insects, there is no problem because it can be processed as clear noise without correlation with the electrical pulse.

The present invention is not limited to the oil-filled transformer, but can be applied to other oil-filled static electric equipment to achieve the same effect.

[0014]

As described above, according to the present invention, since the trigger is performed by the sound signal instead of the electric pulse,
It is not affected by electrical noise such as load switching noise and switching noise. Therefore, the sound source position at the time of internal failure can be accurately located, and the accuracy of internal failure diagnosis is significantly improved.

[Brief description of drawings]

FIG. 1 is a signal waveform diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a conventional internal failure diagnosis method for an oil-filled transformer.

FIG. 3 is a signal waveform diagram showing a conventional internal failure diagnosis method.

[Explanation of symbols]

11 ... Oil-filled transformer 12 ... Current transformer MIC _{1 to} MIC ₄ ... Microphone

Claims (2)

[Claims] 1. A pulse detector provided in an oil-filled static electric device for detecting an electrical pulse at the time of internal failure, and a pulse detector provided in a plurality of locations of the oil-filled static electric device to detect a sound signal at the time of internal failure. Output signals of all the sound sensors when any one of the output signals of the plurality of sound sensors is triggered by analog / digital conversion of the output signals of the pulse detector and the sound sensor. Lock memory for signals and electrical pulses,
The time difference t _X between the triggered sound signal and the electrical pulse before the sound signal is obtained from the memory contents, and the time difference t _Y1 between the triggered sound signal and the sound signal of another sound sensor is calculated.
t _Yn is calculated, and the time differences t _{Y1 to} t _Yn are individually added to the time difference t _X to obtain time differences t _{Z1 to} t _Zn between the sound signal of the other sound sensor and the electric pulse, and the sound sensor is attached. Based on the position, the time difference t _X , the time differences t _{Z1 to} t _Zn, and the sound propagation velocity, the sound source position is located by using the principle of triangulation, and the failure inside the equipment is diagnosed by diagnosing the failure inside the equipment. Internal failure diagnosis method for electrical equipment. 2. The internal failure diagnosis method for an oil-filled static electric device according to claim 1, wherein the sound sensors are provided at three or more locations of the oil-filled static electric device.