JPH0765658A - Method to distinguish earthing trouble due to insulator stain - Google Patents

Abstract

PURPOSE:To distinguish an earthing trouble due to stain of an insulator from other earthing troubles by concentrated monitoring by detecting the troubles based on zero phase voltage which changes drastically at the time of earthing trouble due to insulator stain. CONSTITUTION:An electric power switch 11 is turned on to supply electric power to a high voltage wiring circuit 10 from a high voltage electric power supply 12 and voltage and current waveforms are supplied to a trouble point orientating apparatus 15 through transformers 13, 14. When leaking current of an insulator 17 flows, zero phase voltage is generated and the generation of the zero phase voltage is detected by trouble point orientating apparatuses 15, 16 and when the detected value is a set threshold value or higher, the waveforms are analyzed. One cycle of each waveform at the time of trouble is expanded to Fourier's series to carry out high frequency analysis and the various ratios of the sum of effective values of the high frequency to the effective value of a fundamental wave are mutually compared and the earthing trouble due to the stain of the insulator is distinguished from other earthing troubles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying a ground fault due to insulator contamination, which easily distinguishes a ground fault due to a contamination insulator on a high-voltage distribution line from other ground faults.

[0002]

2. Description of the Related Art Up to now, a device for detecting a leakage current of an insulator has either installed each device individually or carried the device to the site in order to measure the pollution control or deterioration judgment of the insulator. .

However, there is a drawback in that a large amount of labor is required when actually measuring.

[0004] Specifically, due to the power failure of the high-voltage distribution line, it was necessary to repeat the ascending pillar work in order to measure the insulator individually by each device.

As a countermeasure for this, there is a method using harmonic noise. However, this method is troublesome in that it is necessary to determine the distinction between the external noise radio wave and the noise from the object and to measure each equipment.

[0006]

The problem to be solved is that measurement must be carried out for each equipment.

SUMMARY OF THE INVENTION The present invention is characterized in that a ground fault due to contamination of an insulator and another ground fault are identified by centralized monitoring from a substation or the like.

[0007]

[Operation] Zero-phase voltage is observed at the substation due to the leakage current due to the fouling insulator. By measuring and analyzing the waveforms of the zero phase voltage and the ground fault phase voltage, the ground fault due to the pollution insulator is determined.

[0008]

1 is a block diagram of an embodiment of the present invention.
Reference numeral 10 is a high-voltage power distribution line, and when the power switch 11 is turned on, power is supplied from the high-voltage power source 12 in the substation. Transformers 13 and 14 are installed at the start end and the end of the power distribution line 10 on the power switch 11 side, respectively. Transformer 1
Voltage and current waveforms are supplied to the fault locators 15 and 16 via 3 and 14. Reference numeral 17 is an insulator that is artificially soiled.

It is generally known that a zero-phase voltage is generated when a ground fault occurs in a high voltage distribution line. If a leakage current flows due to the pollution insulator, a ground fault occurs and a zero-phase voltage is generated. The magnitude and waveform distortion of this zero-phase voltage change due to the cause of the ground fault described above.

FIG. 2 shows measured waveforms of each phase according to the configuration of FIG. R-phase voltage waveform 21 at the time of a ground fault due to the leakage current of the insulator 17 artificially polluted at the terminal end of the distribution line 10
, The S-phase voltage waveform 22 and the T-phase voltage waveform 23, and the zero-phase voltage waveform is 24. The ground fault phase is R.

When the leakage current of the insulator flows, a zero-phase voltage 24 is generated, and its magnitude is attenuated in about 3 cycles.

The fault locating devices 15 and 16 analyze the waveform if the generated zero-phase voltage is above a set threshold value. The waveform analysis portion is one cycle of the fourth cycle of the R-phase voltage 21 in FIG. 2, and other waveforms are also processed for one cycle at the same time.

The waveform of this one cycle is expanded into a Fourier series to obtain the effective value of each harmonic, and the distortion rate defined in the equation 1 in the present invention is calculated.

[0014]

[Equation 1]

Table 1 shows the result of calculation for each typical ground fault carried out by replacing the distortion rate in the equation 1 with the pollution insulator 17 in the configuration shown in FIG.

[0016]

[Table 1]

From Table 1, it is possible to discriminate from a metal ground fault from the distortion factor of the zero-phase voltage, and from the cable ground fault from the distortion factor of the ground fault phase voltage.

[0018]

As described above, by measuring the voltage and current waveforms at the substation and analyzing the harmonics thereof, it is possible to determine a ground fault due to leakage of the insulator. Therefore, it becomes possible to judge the pollution situation of the insulator by the centralized monitoring by the substation and the like, and it becomes possible to greatly reduce the labor.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram of each phase voltage and zero-phase voltage when a leakage current of the fouling insulator is calculated according to the present invention.

[Explanation of symbols]

 10 High-voltage power distribution line 11 Power switch 12 High-voltage power supply 13, 14 Transformer 15, 16 Fault locator 17 Fouling insulator 21 R-phase voltage waveform (ground fault phase) 22 S-phase voltage waveform 23 T-phase voltage waveform 24 Zero-phase voltage waveform

Claims (2)

[Claims] 1. A device which is installed in a railway substation, etc., which constantly monitors the voltage and current at the transmitting end and the receiving end of a high-voltage distribution line, detects a failure that has occurred in the high-voltage distribution line, and locates the failure point, A method for identifying a ground fault due to insulator contamination, which enables the detection of insulator contamination through centralized monitoring by detecting a fault with a zero-phase voltage that greatly changes during a ground fault due to insulator contamination. 2. The method according to claim 1, wherein one period of the voltage waveform at the time of a failure is expanded into a Fourier series and harmonic analysis is performed, and the ratio of the sum of the effective values of the harmonics and the effective value of the fundamental wave is compared. A method for identifying ground faults due to insulator contamination, characterized by distinguishing ground faults due to insulator contamination from other ground faults.