KR100765108B1 - System and method for preventing dielectric breakdown in a power cable - Google Patents

Abstract

The present invention relates to a system and method for preventing breakdown of power cables.

The present invention has a non-inductive resistance in a system for preventing the occurrence of electrical insulation breakdown in the power cable that delivers the high voltage of the voltage applying unit, the insulation breakdown when the power breakdown occurs in the power cable A first partial discharge signal detection unit detecting a partial discharge signal transmitted at a time difference from the generation point; The first breakdown point detection unit detects the partial breakdown signal transmitted from the power cable and the breakdown point generation point that calculates the position of the breakdown point by analyzing the partial discharge signal transmitted by the time difference sensed by the first partial discharge signal detector. 2 partial discharge signal detection unit; The magnitude of the partial discharge signal output from the second partial discharge signal detection unit is calculated to determine whether the signal is generated by an insulation breakdown phenomenon of a power cable, and the insulation breakdown point calculation unit is controlled using the determination result. To calculate the location of the dielectric breakdown point, and when the calculated position of the dielectric breakdown point is reported from the dielectric breakdown point calculation unit, a partial discharge determining unit for controlling to block the overvoltage applied to the power cable. Wow; It is configured to include an over-current cut-off unit for blocking the over-voltage applied to the power cable from the voltage applying unit under the control of the partial discharge determination unit.

Accordingly, the present invention detects the occurrence of electrical breakdown phenomenon in the power cable that delivers high voltage, calculates the location of the breakdown occurrence point as a result of the detection, and calculates the location of the breakdown occurrence point as the power cable By automatically cutting off the overvoltage applied to the system, it is possible to prevent the damage of the power cable caused by removing some metal shielding of the power cable and to find the point of insulation breakdown automatically, so it is easy even when the length of the power cable is long. It is effective to detect the breakdown point of insulation.

Description

SYSTEM AND METHOD FOR PREVENTING DIELECTRIC BREAKDOWN IN A POWER CABLE}

1 is a block diagram showing the configuration of the breakdown prevention system of the power cable of the present invention.

Figure 2 is a flow chart showing the operation of the method of preventing breakdown of the power cable of the present invention.

3 is a graph illustrating an example of determining whether the partial discharge signal detected by the partial discharge determining unit is a signal immediately before insulation breakdown in FIG. 2.

4 is an exemplary view showing an example of calculating the position of the breakdown occurrence point in the breakdown occurrence point calculation unit in FIG.

*** Description of the symbols for the main parts of the drawings ***

10 power cable 11 voltage applying unit

12: first partial discharge signal detection unit 13: breakdown occurrence point calculation unit

14 second discharge signal detecting unit 15 first amplifier

16 noise filter 17 second amplifier

18: partial discharge determination unit 19: over-discharge blocker

The present invention relates to a system and method for preventing breakdown of power cables, and particularly, to detect the occurrence of electrical breakdown in power cables carrying high voltage, and to calculate the location of the breakdown point as a result of the detection. By calculating the location of the breakage occurrence point, the overvoltage applied to the power cable is automatically cut off, thereby preventing damage to the power cable caused by removing some metal shielding of the power cable, and automatically detecting the breakdown occurrence point. The present invention relates to a system and method for preventing breakdown of a power cable that can easily detect a breakdown point even when the power cable is long.

Lightbulb breaker for high voltage power cable is a test device for observing the cause of electrical breakdown of power cable, and is expected to breakdown by quickly removing the overvoltage immediately before carbonization of insulator due to electrical breakdown of power cable occurs. A device that makes it possible to observe a point or section and the interior of the insulator at that point.

Conventional ultra-high voltage electric bulb light shielding device has a pair of metal electrodes of a predetermined size on both sides of the point where the metal shielding of the power cable is removed, and then the micro discharge signal (partial discharge) detected by the metal electrode When the magnitude and polarity are analyzed, and the analyzed signal is determined to be a signal appearing immediately before insulation breakdown, the voltage that is being overloaded in the power cable is removed.

At this time, whether or not the signal immediately before the dielectric breakdown is determined using a device that compares the magnitude and polarity of the signal at each metal electrode, and the expected breakdown point is a micro-discharge signal of this type while the metal shielding is continuously interrupted. The detection and analysis are repeated to narrow the scope of the point of occurrence.

By the way, in the conventional light bulb breaker for ultra-high voltage power cable as described above, the metal shield of the power cable must be partially removed to detect the micro discharge signal (partial discharge) using a pair of metal electrodes, thereby preventing damage to the power cable. Inevitably, if the length of the power cable is long, the tester should repeatedly perform shield separation, installation of metal electrodes, and signal detection to find an expected point of occurrence of insulation breakdown to a desired section. There was a problem that requires a lot of manpower for detection.

Therefore, the present invention has been proposed to solve the above-mentioned problems, and detects the occurrence of electrical breakdown phenomenon in the power cable that delivers high voltage, and calculates the position of the breakdown occurrence point as a result of the detection, It is an object of the present invention to provide a system and method for automatically cutting off the overvoltage applied to the power cable by calculating the position of the breakdown occurrence point.

In order to achieve the above object, the present invention provides a system for preventing electrical breakdown from occurring in a power cable that delivers a high voltage of a voltage applying unit, and includes a non-inductive resistance. A first partial discharge signal detecting unit detecting a partial discharge signal transmitted at a time difference from the breakdown point of insulation when a breakdown phenomenon occurs; The first breakdown point detection unit detects the partial breakdown signal transmitted from the power cable and the breakdown point generation point that calculates the position of the breakdown point by analyzing the partial discharge signal transmitted by the time difference sensed by the first partial discharge signal detector. 2 partial discharge signal detection unit; The magnitude of the partial discharge signal output from the second partial discharge signal detection unit is calculated to determine whether the signal is generated by an insulation breakdown phenomenon of a power cable, and the insulation breakdown point calculation unit is controlled using the determination result. To calculate the location of the dielectric breakdown point, and when the calculated position of the dielectric breakdown point is reported from the dielectric breakdown point calculation unit, a partial discharge determining unit for controlling to block the overvoltage applied to the power cable. Wow; It characterized in that it comprises an over-current cut-off unit for blocking the over-voltage applied to the power cable from the voltage applying unit under the control of the partial discharge determination unit.

In addition, the present invention provides a control method of a system for preventing the occurrence of electrical insulation breakdown in the power cable that delivers the high voltage of the voltage applying unit, the step of detecting the partial discharge signal transmitted from the power cable to calculate the magnitude Wow; Determining whether the calculated partial discharge signal is a signal immediately before insulation breakdown; Calculating the position of the breakdown occurrence point when the signal is immediately before the breakdown; And cutting off the overvoltage applied to the calculated power breakdown point of the power cable.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a configuration of a breakdown prevention system of a power cable according to the present invention. As shown in FIG. 1, an electrical breakdown phenomenon occurs in a power cable 10 that transmits a high voltage of a voltage applying unit 11. A system for preventing a first portion, comprising: a first portion having a noninductive resistance and detecting a partial discharge signal transmitted with a time difference from a breakdown occurrence point when a breakdown phenomenon occurs in the power cable 10. A discharge signal detector 12; An insulation breakdown point calculation unit 13 for calculating a position of the insulation breakdown point by analyzing the partial discharge signal transmitted by giving a time difference sensed by the first partial discharge signal detector 12; A second partial discharge signal detector 14 detecting a partial discharge signal transmitted from the power cable 10; A first amplifier 15 for amplifying the partial discharge signal sensed by the second partial discharge signal detector 14; A noise filter (16) for removing a surge from the output of the first amplifier (15) or removing noise of an AC component; A second amplifier (17) for amplifying the output of said noise filter (16); The magnitude of the partial discharge signal output from the second amplifier 17 is calculated to determine whether the signal is generated by the insulation breakdown phenomenon of the power cable 10, and the insulation breakdown point is calculated using the determination result. A partial discharge determination unit 18 controlling the unit 13 to receive a report of the location of the breakdown occurrence point, and accordingly block and control the application of the overvoltage to the power cable 10; Under the control of the partial discharge determining unit 18, the overvoltage blocking unit 19 cuts off the overvoltage applied from the voltage applying unit 11 to the power cable 10.

In addition, the method for implementing the present invention, as shown in Figure 2, the control of the system for preventing the occurrence of electrical breakdown phenomenon in the power cable 10 for transmitting the high voltage of the voltage applying unit 11 A method, comprising: detecting a partial discharge signal transmitted from a power cable (10) and calculating a magnitude (S20, S21); Determining whether the calculated partial discharge signal is a signal immediately before insulation breakdown (S22); As a result of the determination, in the case of a signal immediately before insulation breakdown, calculating the position of the breakdown occurrence point (S23); Blocking the over voltage applied to the power cable 10 of the calculated breakdown occurrence point (S24).

Through the above configuration, the present invention detects the occurrence of electrical breakdown phenomenon in the power cable carrying a high voltage, calculates the position of the breakdown occurrence point as a result of the detection, calculates the position of the breakdown occurrence point By automatically cutting off the overvoltage applied to the power cable, it is possible to prevent the damage of the power cable caused by removing some of the metal shielding of the power cable, and to automatically find the point of occurrence of insulation breakdown, the length of the power cable Even if the length is long, it is possible to easily detect the occurrence point of the dielectric breakdown.

The present invention can be applied to a system for preventing the occurrence of electrical breakdown phenomenon in the power cable that delivers the high voltage of the voltage applying unit, in particular the system of the present invention is the insulation that the breakdown phenomenon occurs in the power cable 10 In order to calculate the location of the breakdown point, the first partial discharge signal detector 12 detecting the partial discharge signal transmitted from the dielectric breakdown point, and the partial discharge signal transmitted from the power cable 10 are subjected to the dielectric breakdown phenomenon. Using the second partial discharge signal detection unit 14 for detecting whether the signal is just before generation, the partial discharge signal detection before the occurrence of the dielectric breakdown phenomenon and the position thereof are calculated, and the respective detection units 12 and 14 By using the detection result of the) it serves to block the over voltage applied to the power cable 10 through the over-current blocking unit 19.

In the system of FIG. 1, the voltage applying unit 11 applies a high voltage to the power cable 10, and the first partial discharge signal detecting unit 12 is configured using noninductive resistance, and the power cable When the breakdown phenomenon occurs in (10), it detects the partial discharge signal transmitted with a time difference from the breakdown point.

Here, the reason for using the non-inductive resistor in the first partial discharge signal detection unit 12 is that the partial discharge signal transmitted from the breakdown occurrence point is the first portion directly transmitted to one end from the breakdown occurrence point It consists of a discharge signal and a second partial discharge signal reflected from the other end and return. In the case of the second partial discharge signal, because the signal is weak due to the moving distance, it is for easy detection. In addition, the non-inductive resistance refers to a resistance without inductance, and does not actually have no inductance, but means a resistance in which the influence of inductance is ignored, and a carbon film resistor, a solid resistor, and the like are used.

The breakdown occurrence point calculating unit 13 analyzes the partial discharge signal transmitted with the time difference sensed by the first partial discharge signal detector 12 to calculate the position of the breakdown occurrence point, thereby determining the partial discharge determination unit 18. Report).

The second partial discharge signal detector 14 detects the partial discharge signal transmitted from the power cable 10, and the first amplifier 15 uses the transistor for isolation to perform the second partial discharge signal. The partial discharge signal sensed by the detector 14 is amplified to a predetermined level, and the noise filter 16 removes a surge from the output of the first amplifier 15 or removes noise of an AC component. The second amplifier 17 amplifies the output of the noise filter 16 to a high level such that the partial discharge signal sensed by the second partial discharge signal detector 14 is signal-processed so that the partial discharge determination unit ( 18).

Here, the second partial discharge signal detector 14 is configured by using an inductor and a capacitor to block signals other than the frequency band of the partial discharge signal.

The partial discharge determiner 18 calculates the magnitude of the partial discharge signal output from the second amplifier 17 to determine whether the signal is generated by an insulation breakdown phenomenon of the power cable 10, and determines the result of the determination. By controlling the dielectric breakdown generation point 13 by using the control unit to calculate the position of the dielectric breakdown generation point, and if the calculated position of the dielectric breakdown generation point is reported from the dielectric breakdown generation point calculation unit 13, The blocking unit 19 is controlled to cut off the overvoltage applied to the power cable 10.

Here, the partial discharge determiner 18 is configured to output a power cable through the second partial discharge signal detector 14 at a voltage cycle of about 20 ms, which is a period at which the voltage is output from the voltage applying unit 11. 10) check whether the partial discharge signal is detected, and having an analog digital converter (ADC) (not shown) therein, converting the identified partial discharge signal into a digital signal through the ADC (not shown) Calculate the size.

In addition, the over-current blocking unit 19 serves to switch off the over-voltage applied from the voltage applying unit 11 to the power cable 10 under the control of the partial discharge determining unit 18.

Meanwhile, a method of preventing insulation breakdown of a power cable implemented using the system operating as described above is as follows.

In the present invention, the first and second partial discharge signal detection unit 12 on the power cable 10 in order to prevent the electrical insulation breakdown occurs in the power cable 10 that delivers the high voltage of the voltage applying unit 11. By detecting the partial discharge signal transmitted from the power cable 10 by connecting the 14 and 14, it is determined whether each of the breakdown occurrence points and the corresponding partial discharge signal are detected.

That is, the second partial discharge signal detector 14 detects the partial discharge signal transmitted from the power cable 10 (S20), the first amplifier 15, the noise filter 16, and the second amplifier 17. When the signal is processed by amplification, surge, or noise removal of an AC component and transmitted to the partial discharge determiner 18, the partial discharge determiner 18 calculates the magnitude of the detected partial discharge signal. (S21).

In this case, the partial discharge determiner 18 may perform a power cable through the second partial discharge signal detector 14 at a voltage period of about 20 ms, which is a period at which the voltage is output from the voltage applying unit 11. 10) check whether the partial discharge signal is detected, and convert the identified partial discharge signal into a digital signal through an internal analog converter (ADC) (not shown) to calculate the magnitude thereof, and then As shown in the graph of FIG. 3, by checking whether pulses having a threshold voltage or more are detected continuously for a predetermined delay time, it is determined whether the calculated partial discharge signal is a signal immediately before insulation breakdown. (S22).

Here, the threshold voltage and the delay time are values that may vary depending on the magnitude of the overvoltage, the material, the characteristics of the power cable 10, and the like, and adjust the threshold voltage level and the delay time interval by experiment according to the number of cases. According to the determination of the step S22, it is possible to predict when the carbonization of the insulator occurs due to the electrical insulation breakdown phenomenon of the power cable 10.

Next, when the partial discharge detection signal detected by the second partial discharge signal detection unit 14 is a signal immediately before the insulation breakdown, the partial discharge determination unit 18 performs an insulation breakdown point calculation unit 13. By controlling the first partial discharge signal detection unit 12 to calculate the location of the dielectric breakdown generation point (S23), and the calculated position of the dielectric breakdown generation point from the dielectric breakdown generation point calculation unit 13 When the report is received, the control signal is transmitted to the overload cutoff unit 19 to cut off the overvoltage applied to the corresponding power cable 10 by the switching operation of the overload cutoff unit 19 (S24).

Here, the method of calculating the position of the dielectric breakdown generation point by the dielectric breakdown generation point calculating unit 13 will be described with reference to the exemplary diagram shown in FIG. 4. When the breakdown phenomenon occurs at any point 'x', the first partial discharge signal detecting unit 12 transmits the first partial discharge signal t1 directly transmitted to one end transmitted from the breakdown occurrence point x. ) And the second partial discharge signal t2 reflected and returned from the other end of the power cable 10 arrives, and the breakdown occurrence point calculating unit 13 receives the first and second partial discharge signals. Substituting (t1, t2) into Equation 1 below, the position of the breakdown occurrence point x is calculated.

Here, L is the total length of the power cable, V is the speed of the first and second partial discharge signal, V is a value that varies depending on the material, characteristics, etc. of the power cable to be calculated in advance for each power cable by experiment.

In addition, the first partial discharge signal t1 is driven by the breakdown occurrence point calculating unit 13 to be a partial discharge signal first detected by the first partial discharge signal detector 12, and the second partial discharge signal ( t2) is assumed to be a partial discharge signal detected thereafter.

As described above, the present invention is to detect the occurrence of electrical breakdown phenomenon in the power cable carrying a high voltage, to calculate the location of the breakdown occurrence point as a result of the detection, to calculate the location of the breakdown occurrence point Accordingly, by automatically cutting off the overvoltage applied to the power cable, it is possible to prevent the damage of the power cable caused by removing some of the metal shielding of the power cable, and to automatically find the occurrence point of insulation breakdown, so that the length of the power cable Even when it is long, there is an effect of easily detecting the occurrence point of dielectric breakdown.

Claims (6)

In the system for preventing the occurrence of electrical breakdown in the power cable that delivers the high voltage of the voltage applying unit, A first partial discharge signal detection unit having a noninductive resistance and detecting a partial discharge signal transmitted at a time difference from a breakdown occurrence point when a breakdown phenomenon occurs in a power cable; The first breakdown point detection unit detects the partial breakdown signal transmitted from the power cable and the breakdown point generation point that calculates the position of the breakdown point by analyzing the partial discharge signal transmitted by the time difference sensed by the first partial discharge signal detector. 2 partial discharge signal detection unit; The magnitude of the partial discharge signal output from the second partial discharge signal detection unit is calculated to determine whether the signal is generated by an insulation breakdown phenomenon of a power cable, and the insulation breakdown point calculation unit is controlled using the determination result. To calculate the location of the dielectric breakdown point, and when the calculated position of the dielectric breakdown point is reported from the dielectric breakdown point calculation unit, a partial discharge determining unit for controlling to block the overvoltage applied to the power cable. Wow; And an over-current cut-off unit which cuts off over-voltage applied from the voltage applying unit to the power cable under the control of the partial discharge determiner. The method of claim 1, A first amplifier amplifying the partial discharge signal detected by the second partial discharge signal detector; A noise filter for removing a surge or removing noise of an AC component from an output of the first amplifier; And a second amplifier for amplifying the output of the noise filter and outputting the noise filter to the partial discharge determining unit. The method of claim 1, The first partial discharge signal detection unit, the breakdown prevention system of the power cable, characterized in that configured using a non-inductive resistor. The method of claim 1, The second partial discharge signal detection unit, the breakdown prevention system of the power cable, characterized in that configured using an inductor (capacitor). In the control method of the system to prevent the occurrence of electrical breakdown phenomenon in the power cable that delivers the high voltage of the voltage applying unit, Detecting the partial discharge signal transmitted from the power cable and calculating a magnitude of the partial discharge signal; Determining whether the calculated partial discharge signal is a signal immediately before insulation breakdown; Calculating the position of the breakdown occurrence point when the signal is immediately before the breakdown; And blocking an overvoltage applied to the calculated power breakdown point of the power cable. The method of claim 5, Determining whether the calculated partial discharge signal of the magnitude is a signal immediately before insulation breakdown, by checking whether a pulse of a threshold voltage or more is continuously detected for a predetermined delay time, the partial discharge of the calculated magnitude A method for preventing breakdown of power cables, characterized in that it is determined whether the signal is a signal immediately before breakdown.

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