JP2932724B2 - Insulation degradation diagnosis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can non-destructively and accurately determine the degree of insulation deterioration of a high-voltage power device such as a multi-circuit switch. The present invention relates to a new insulation deterioration determination method.

[0002]

2. Description of the Related Art When insulation degradation occurs in a high-voltage power device such as a switch or a transformer, corona discharge occurs in the deteriorated portion. Conventionally, to measure this corona discharge, the high-voltage power equipment in the operating state is temporarily stopped, a high voltage is applied for diagnosis after insulating the housing of the high-voltage power equipment, and the corona generated from the insulation degraded part. It has been common practice to detect the discharge by using a ground electrode and to output it as an electric signal to a measuring unit.

[0003]

According to the above-mentioned conventional method, the operation of the high-voltage power equipment must be temporarily stopped.
A power failure for that purpose is a problem, and a bypass device is required to prevent the power failure. In addition, a high-voltage power supply is required to insulate the housing after stopping the operation of the high-voltage power device and apply a high voltage for diagnosis.
There are also inconveniences, which involve various troublesome operations and deteriorate workability.

[0004] In addition, there is a superphone system or the like for detecting ultrasonic waves due to corona discharge. However, there is a problem that detection cannot be performed in a sound-insulating state.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to measure corona discharge with high reliability while a high-voltage power device is in an operating state, and as a result, a more accurate diagnosis of an insulation state can be made. It is an object of the present invention to provide a new method of diagnosing insulation deterioration.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a high-voltage power device in which a corona generating portion is covered with an insulating layer.
By installing an electrode outside the insulating layer and capacitively coupling the electrode with the corona discharge generator, the corona discharge of the high-voltage power equipment in the operating state is detected as a change in the potential of the electrode, and the detected signal is output. 100kHz to 1GHz
Perform frequency analysis within the range, and determine the magnitude and
An insulation deterioration diagnosis method characterized by examining the insulation state of high-voltage power equipment based on the nature and frequency of appearance .

[0007]

According to the present invention, the high-voltage power equipment is covered with an insulating material, and the electrodes are installed outside the high-voltage power equipment. By measuring the fluctuation (hereinafter, referred to as a voltage pulse signal), the occurrence state of corona discharge is estimated, so that insulation diagnosis with high accuracy can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic diagram of a method of measuring a voltage pulse signal by partial discharge, and first, the principle of the method will be described. Here, as an example, a high-voltage power device in which a high-voltage electrode 1a is uniformly covered by a device insulating portion 2a made of an insulating material is considered. The measuring electrode 4a as shown in FIG. 1 is installed on the surface of the high-voltage power equipment. The measuring electrode 4a shown in the figure is covered with a measuring electrode insulating portion 5a made of an insulating material in order to ensure safety. And
Also connected to the measurement and analysis instrument 7 using a low impedance connection line 6 in the high frequency than the electrode 4a, also measured
The constant / analyzer 7 is also connected to the ground by using a connection line 8 having a low impedance at a high frequency.

With the above configuration, the circuit configuration is represented as shown in FIG. Ground E for high voltage power equipment
When the impedance of the earth on the measurement / analyzer 7 side is very small with respect to the impedance on the side, and a corona discharge occurs in the corona discharge generating section 3b in FIG.
It is conceivable that the electric charge generated by the discharge flows in both directions of the earth E side of the high-voltage power equipment and the measurement / analyzer 7 , but since the electric charge does not flow to the earth E of the high-voltage power equipment, the electric potential of the measuring electrode 4b is changed. Changes. The change in the potential is measured by the measurement / analyzer 7 in the partial discharge detection method applied to the insulation deterioration diagnosis method of the present invention.

[0010] Here, with respect to ground E side of the impedance of the high voltage power equipment, earth from measurement and analyzer 7 side 8
The question is whether or not the impedance that falls on the surface becomes really small. However, the rise of charge generation by corona discharge is extremely fast, has extremely high frequency components, and the ground of high-voltage power equipment has low impedance at commercial frequencies, but only high impedance at high frequencies. It is common not to have. Therefore, with respect to the corona discharge, the impedance of the measurement / analyzer 7 with respect to the impedance on the earth E side of the high-voltage power device is determined.
The impedance that falls to earth 8 from the side becomes smaller,
The voltage signal pulse can be measured. Therefore,
Corona discharge can be detected.

An embodiment in which the present invention is applied to an airborne multi-circuit switch as a high-voltage power device will be described below.

[0012] When moisture enters into the aerial multi-circuit switch housing during operation and further penetrates into the epoxy electrode,
A minute corona discharge starts from inside the electrode due to long-term power application. With the passage of time, the corona discharge develops into glow discharge, scintillation, and tracking, and eventually leads to dielectric breakdown of the epoxy electrode portion. As described above, a corona discharge is always generated in the process from the occurrence of the corona discharge to the dielectric breakdown. Therefore, a voltage pulse signal is always observed from the above-described electrode 4b.
It has been found from the results of the research by the inventors of the present application that this signal is characteristic in each process.

In particular, as a result of frequency analysis of the voltage pulse signal using a spectrum analyzer, the frequency component of the voltage pulse when a minute corona discharge occurs immediately after the start of deterioration is relatively several + MHz to several GHz. It was found that while the frequency components were biased toward the high frequency side, as the deterioration progressed to glow discharge, scintillation, and tracking, the frequency components spread from the high frequency side to lower frequencies. FIGS. 3 and 4 show measurement examples of the high-frequency voltage pulse.
Shown in That is, FIG. 3 shows the case where the deterioration has progressed relatively, and FIG. 4 shows the case where the deterioration has not progressed yet. Then, for example, in the state where tracking is started, the frequency band of the voltage pulse is 100 kHz to several GHz.
It became clear that the frequency component spread to 100 KHz.

On the other hand, with respect to the magnitude and frequency of appearance of the voltage pulse signal, it has been found that the voltage pulse signal increases and the frequency of appearance increases with the deterioration of the insulating state as described above.

Table 1 shows that the operating multi-circuit switch is
A metal electrode with a size of 70 x 180 mm was attached to the surface of the movable electrode epoxy insulating material, and after measuring and analyzing the voltage pulse, the switch was removed from the site and the partial discharge charge was detected using a conventional partial discharge detection device. It shows the results of the measurement and the investigation of the details of the surface of the epoxy electrode.

[0016]

[Table 1]

As is apparent from Table 1, a partial discharge pulse signal is generated from the epoxy electrode portion where the electromagnetic wave is detected from the multi-circuit switch, and a discharge mark is formed on the surface of the epoxy electrode. In this case, in the sample 2 (No. 2) having only a small corona discharge mark with a small degree of deterioration, the frequency component of the voltage pulse signal remains in the high frequency band. However, in Sample 5 (No. 5), in which the corona discharge marks are slightly larger, the lower limit of the frequency band is 30.
MHz. Furthermore, in the sample 8 (No. 8) that has progressed to tracking, the lower limit of the frequency band is as low as 100 KHz and covers a wide range.

As is clear from the results, by examining the frequency component distribution of the detected voltage pulse signal,
It can be seen that the degree of insulation deterioration of the epoxy electrode part can be accurately grasped with high accuracy.

Also, the magnitude of the voltage pulse signal tends to increase as the appearance of the epoxy deteriorates, and the frequency of appearance of the voltage pulse signal tends to increase. This shows that the magnitude and appearance frequency of the voltage signal also have a good correlation with the degree of deterioration of the epoxy electrode.
Therefore, it is possible to grasp the degree of deterioration of the epoxy electrode section with high accuracy by measuring these amounts together with the phase information of the applied voltage using an oscilloscope (synchroscope), a pulse counter or the like. Regarding the output current frequency is used the current frequency output pulse at an applied voltage of 1 cycle.

In addition, by using FFT, for example, by applying FFT to a signal generated during one cycle of an applied voltage, the strength of each frequency component in the process of deterioration is checked in advance, so that a diagnosis target is actually obtained. The state of deterioration can also be estimated by comparing the results of the measurements.

Therefore, by measuring the voltage pulse using the insulation deterioration diagnosis method of the present invention, the deterioration degree of the high-voltage power equipment in which the insulation has been deteriorated and the partial discharge has occurred can be non-destructively and operated. Can be determined without a power failure. Therefore, by adding this measurement as one of the normal maintenance operations and constantly monitoring the degree of insulation deterioration, it is possible to prevent the occurrence of a serious accident such as a power failure caused by insulation breakdown.

Although a multi-circuit switch has been described above as a specific example, it is needless to say that the technical idea of the present invention can be applied to other power equipment as it is.

[0023]

As described above, according to the insulation deterioration diagnosing method of the present invention, the degree of deterioration progresses only by detecting the voltage change of the installed electrode caused by the corona discharge generated in the high-voltage power equipment. It is possible to accurately diagnose and judge the degree of progress of its deterioration, and to apply this invention as a form of maintenance to prevent a serious accident such as a power failure due to insulation breakdown. And its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a method of measuring a voltage pulse signal due to corona discharge generation.

FIG. 2 is a principle diagram of a method of measuring a voltage pulse signal by generation of corona discharge.

FIG. 3 is a graph showing a measurement example of a high-frequency-side voltage pulse when deterioration has progressed relatively.

FIG. 4 is a graph showing a measurement example of a high-frequency voltage pulse when deterioration has not yet progressed.

[Explanation of symbols]

 1a, 1b High-voltage electrode 2a, 2b Equipment insulation 3a, 3b Corona generator 4a, 4b Measurement electrode 5a, 5b Measurement electrode insulation 6,8 Connection line 7 Measurement / analyzer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-154171 (JP, A) JP-A-59-85966 (JP, A) JP-A-2-161369 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G01R 31/12

Claims (1)

(57) [Claims] In a high-voltage power device in which a corona generating portion is covered with an insulating layer, an electrode is provided outside the insulating layer, and the corona discharge generating portion and the electrode are capacitively coupled to each other so that the high-voltage power in an operating state is obtained. The corona discharge of the equipment is detected as a change in the potential of the electrode, and the detected signal is
Perform frequency analysis in the range of kHz to 1 GHz,
As the insulation deterioration progresses, the frequency component of the detection signal becomes higher.
Insulation degradation diagnosis characterized by examining the insulation state of high-voltage power equipment by checking that it spreads to the lower frequency side from the side and that the magnitude of the detection signal and the frequency of appearance increase. Method.