KR102600662B1 - Method for detecting partial discharge in arc-detecting system and a partial discharge detecting device for preveting arc in power system - Google Patents

Abstract

A method and device for detecting partial discharge in an arc detection system of a power system are provided, comprising: detecting a signal occurring between a power line and a ground terminal of a switchboard or receiving board of a power system with a high-frequency current sensor, the detected signal; It includes determining whether the detected partial discharge signal is a partial discharge signal by determining the frequency range, and determining that the occurrence of the partial discharge signal is related to arc generation through the frequency with which the detected partial discharge signal occurs during a predetermined period. do.

Description

Method for detecting partial discharge in arc-detecting system and a partial discharge detecting device for preveting arc in power system}

The present disclosure relates to a method and device for determining partial discharge as a precursor symptom of system instability in which an arc occurs in an arc detection system for removing arcs occurring in a power system such as a switchboard or receiving board in an electric power system.

The invention according to this disclosure was conducted as part of a technology development project sponsored by the Korea Institute of Energy Technology Evaluation and Planning with funding from the Ministry of Trade, Industry and Energy in 2020 (Project identification number: 20192910100080, Project name: Construction of an arc removal system through arc signal detection and establishment of related safety standards, research project name: Energy safety management core technology development).

Switchboards and switchboards are places where human touch can occur frequently, so safety from electrical accidents is more important than anything else. Safety is important not only because it is frequently touched by humans, but also for the stability of the power system. However, since there are devices such as power switches that can generate electric arcs in switchboards or switchboards, it is important to continuously monitor whether arcs occur for the safety of the power system. Usually, a switchboard or switchboard does not explode due to a single arc, but if arcs continue to accumulate, an explosion due to an arc usually occurs in a switchboard or switchboard.

The arc removal system is a device that grounds three-phase power to the ground through a prepared switch when detecting an arc related to a fault in order to minimize casualties and electrical fires due to arcs that may occur in switchboards or switchboards. . These arc elimination systems have the capability of detecting only arcs that are purely related to permanent faults. When the arc removal system operates, the three-phase power of the same feeder is designed to maintain a power outage, resulting in a temporary stoppage of the system. Therefore, the operation of this arc removal system is sometimes designed to operate based on very conservative judgment. many.

In power equipment that is at risk of arc occurrence, a high-frequency partial discharge phenomenon occurs as a precursor to the arc. Therefore, in order to ensure the stability of the power system, it is necessary to detect the occurrence of partial discharge in the switchboard or receiving board and remove risk factors from the system in advance before the stability of the system is threatened.
Power devices that are at risk of arc generation are usually installed in a dark room, and to ensure the stability of the power system, it is important to detect arcs occurring as early as possible to prevent safety accidents such as explosions in the power system. And, when there is a risk of arc occurrence, various precursor symptoms usually occur in the power system. This may be due to a drop in the voltage of the power line or the current in the system increasing beyond an appropriate level. There are many reasons for this phenomenon, but the reasons include aging of power lines or insulation breakdown due to neglect of management. In this way, when the insulation of power lines in a power system is weakened, a high-frequency partial discharge signal is typically detected. Therefore, in order to prevent arcs affecting the power system, detecting and analyzing these partial discharge signals can determine the risk of explosion due to arcs in the power system in advance, thereby increasing the efficiency and safety of the power system.

Japanese Patent Publication No. 2005-049326 (2005.02.24.) - "Arc failure detection device"
Registered Patent Publication No. 10-1553005 (2015.10.01.) - “Partial discharge monitoring and diagnosis system for power equipment”
Registered Patent Publication No. 10-2229637 (2021.03.12.) - “Arc detection method and device in power system”

It is necessary to prevent arcs in advance before serious failures occur in the power system due to arc generation, and technology is needed to prevent the risk of failure in the power system in advance by determining precursor symptoms of arc occurrence.

A partial discharge detection method is provided in the arc detection system of the power system to solve the above-mentioned problems. The method includes the steps of detecting a signal occurring between terminals of a switchboard or receiving board of the power system with a high-frequency current sensor, the detection determining whether the detected partial discharge signal is a partial discharge signal by determining the frequency range of the detected signal, and determining that the occurrence of the partial discharge signal is related to arc generation through the frequency with which the detected partial discharge signal occurs during a predetermined period. Includes.

In one embodiment, the power line is a three-phase power line, and determining whether the detected signal is a partial discharge signal is characterized in that it is determined to be a partial discharge signal if the detected signal is in a frequency range of 5 MHz to 15 MHz.

In one embodiment, the step of determining an increase trend of the partial discharge signal by comparing the frequency at which the partial discharge signal occurs during the predetermined time with the frequency of the partial discharge signal during the predetermined time before a predetermined time interval. do.

In one embodiment, the method further includes notifying a risk of arc occurrence when the increase trend of the partial discharge signal is above a predetermined level.

In order to solve the above-mentioned problems, a partial discharge detector of the arc detection system of the power system is provided. The partial discharge detector includes a high-frequency current sensor that detects a signal occurring between the power line and the ground terminal of the switchboard or receiving board of the power system, and The frequency range of the detected signal is determined to determine whether the detected signal is a partial discharge signal, and the partial discharge signal is related to arc generation through the frequency at which the detected partial discharge signal occurs during a predetermined period. Includes a processor that determines.

In one embodiment, the partial discharge detector further includes a high-frequency detection antenna that independently detects partial discharge signals.

In one embodiment, the processor of the partial discharge detector verifies the validity of the partial discharge signal by comparing the partial discharge signal detected through the high frequency detection antenna with the partial discharge signal frequency detected by the high frequency current sensor. .

In one embodiment, the processor notifies the arc detection system of an arc occurrence risk signal when it determines that the partial discharge signal is related to arc occurrence.

According to the present disclosure, it is possible to protect the power system by detecting the risk of failure in advance by checking a partial discharge signal before a failure occurs in a switchboard or distribution board due to an arc in the power system.

Figure 1 shows an example of an arc detection system that detects the occurrence of an arc in a power system according to an embodiment of the present disclosure.
Figure 2 is a system diagram showing partial discharge detection according to an embodiment of the present disclosure.
3 is a partial discharge generation waveform of a power system according to an embodiment of the present disclosure.
Figure 4 is a flowchart of a method for detecting a partial discharge signal in a power system according to an embodiment of the present disclosure.

Terms used in this specification will be briefly described, and the present disclosure will be described in detail.

The terms used in this disclosure are general terms that are currently widely used as much as possible while considering the functions in the present invention, but this may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description part of the relevant disclosure. Therefore, the terms used in this disclosure should be defined based on the meaning of the term and the overall content of this disclosure, rather than simply the name of the term.

When it is said that a part "includes" a certain element throughout the specification, this means that, unless specifically stated to the contrary, it does not exclude other elements but may further include other elements. In addition, terms such as "... unit" and "module" used in the specification refer to a unit that processes at least one function or operation, which may be implemented as hardware or software, or as a combination of hardware and software. .

Below, with reference to the attached drawings, embodiments will be described in detail so that those skilled in the art can easily implement them. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present disclosure in the drawings, parts that are not related to the description have been omitted, and identical reference numerals have been assigned to identical components throughout the specification.

Power devices that are at risk of arc generation are usually installed in a dark room, and to ensure the stability of the power system, it is important to detect arcs occurring as early as possible to prevent safety accidents such as explosions in the power system. And, when there is a risk of arc occurrence, various precursor symptoms usually occur in the power system. This may be due to a drop in the voltage of the power line or the current in the system increasing beyond an appropriate level. There are many reasons for this phenomenon, but the reasons include aging of power lines or insulation breakdown due to neglect of management. In this way, when the insulation of power lines in a power system is weakened, a high-frequency partial discharge signal is typically detected. Therefore, in order to prevent arcs affecting the power system, detecting and analyzing these partial discharge signals can determine the risk of explosion due to arcs in the power system in advance, thereby increasing the efficiency and safety of the power system.

Figure 1 shows an example of an arc detection system that detects the occurrence of an arc in a power system according to an embodiment of the present disclosure.

The arc detection system 100 that detects the occurrence of the arc 101 mainly uses an optical sensor 120 that detects the arc 101 with light.

Referring to FIG. 1, when an arc 101 occurs in the power switch 110 of a switchboard or distribution board, the optical sensor 120 detects the arc light and generates a fault signal 111 to activate the protection circuit 130. send to The protection circuit 130 starts a power system protection function according to a fault signal. An example of the protection function is to protect the switch 110 by shorting the ground switch 140 connected to the power switch 110.

However, the occurrence of an arc can be seen as a sign that the insulation breakdown of the power line has already progressed to a significant extent in the switchboard or switchboard. Considering that the power level of the power system is quite high, the arc occurs in advance before the arc occurs in the switchboard or switchboard. There is a need to detect the risk of occurrence in advance.

Figure 2 is a diagram of a system 200 showing partial discharge detection according to an embodiment of the present disclosure.

As an example, this power system receives three-phase high power of 22.9kV as input. A high-frequency current sensor (HFCT, 220) is installed for each phase between the three-phase power line (2001) and the ground (2003), and a partial discharge signal is detected through the high-frequency current sensor (220). The high frequency current sensor (HFCT, 220) can check whether a high frequency component occurs in the leakage current flowing between the three-phase power line (2001) and the ground (2003). The current sensor 260 detects a current signal flowing in the three-phase power line 2001.

The arc detector 230 detects arcs occurring in a switchboard or distribution board equipped with a three-phase power line 2001. Usually, the arc is detected through the light sensor 250, and the door open signal (2005) of the switchboard or distribution board is also checked to prevent false detection of external light caused by the door opening, rather than an arc, as an arc. When it is determined that an arc has occurred, the arc detector 230 operates the protection relay 240 to block the three-phase power line 2001 through the arc eliminator 270. The arc detector 230 internally generates control commands for arc detection and includes a controller (not shown) to control peripheral devices.

The arc detector 230 may optionally be equipped with an antenna 280 that detects high-frequency signals. The antenna 280 detects a partial discharge signal showing a high frequency pattern of 5 MHz to 15 MHz. Usually, partial discharge signals occur frequently in the range of 8MHz to 10MHz. The arc detector 230 may include a partial discharge detector 290 to detect partial discharge according to an embodiment of the present disclosure. In one embodiment, the partial discharge detector may be provided as a separate device from the arc detector 230. The partial discharge detector 290 may be composed of a high-frequency current sensor 220, a processor 291, and a memory 293 that stores computer instructions and signal data. The processor 291 determines the frequency range of the high-frequency signal detected by the high-frequency current sensor 220 and/or the antenna 280, and if the frequency range is a predetermined frequency range, the processor 291 may determine that the high-frequency signal is a partial discharge signal. . Since the partial discharge signal is related to arc generation, the detected high-frequency signal is determined to be a partial discharge signal related to arc generation.

The arc detector 230 may replace the function of the partial discharge detector 290 in the present disclosure, but will be referred to as the arc detector 230 for convenience.

Figure 3 shows a partial discharge signal detected by a high-frequency current sensor according to an embodiment of the present disclosure.

As shown in (a) to (d) of Figure 3, the basic sine waveforms (301, 303, 305, 307) are the voltage waveforms of the power system sensed through the power line, and are found like pulses with a higher frequency and shorter time than the sine waveform. The resulting signals 311, 313, 315, and 317 are partial discharge signals. It can be seen that the partial discharge signal occurs in a high frequency pattern. The partial discharge signal can be detected through the high-frequency current sensor 220 or the antenna 280.

The high-frequency short pulse signal found in the power system may be a temporary noise signal, so determine the frequency and whether it reoccurs to determine whether it is a partial discharge signal rather than a noise signal. First, the partial discharge signal can be verified by comparing and analyzing the signal detected through the antenna 280 and the signal detected by the high-frequency current sensor 220.

In other words, the high frequency signal commonly found between the two can be processed as a partial discharge signal.

Based on the detected and verified partial discharge signal, the possibility of arc occurrence can be determined in advance. If the frequency of partial discharge signals increases, there is a high possibility that a problem has occurred in the insulation of the power line. Since these insulation problems can lead to arc problems in switchboards or switchboards and even bigger safety accidents such as explosions, determine in advance whether arcs will occur by checking the frequency of partial discharge signals. For example, the number of partial discharge signals can be confirmed based on a predetermined time interval. A hazard notification indicating that there is a high risk of arc occurrence in the power system when partial discharge signals that occur for a certain period of time, for example, 0.1 seconds (1 second, 10 seconds, etc.) are counted and the number exceeds a certain number (e.g. 100). Can be generated in the arc detector 230. The degree of increase in the partial discharge signal can be estimated by comparing the partial discharge signal that occurred during a predetermined time with the previously counted partial discharge signal. For example, the partial discharge signal that occurred during a predetermined time (e.g., 0.1 seconds) a week ago is compared with the partial discharge signal that occurred during the same predetermined time (e.g., 0.1 seconds) a day ago and the partial discharge signal that occurred during a predetermined time that occurred today. By determining the trend of increasing frequency of discharge signal occurrence, the processor 291 of the arc detector 230 may generate an arc occurrence warning notification. In other words, if the current partial discharge signal generation trend compared to the previous partial discharge signal generation trend is at a certain level (for example, a frequency increase of more than 50% or more than before), the user is informed that the power system has entered an unstable state and arcing has occurred. Notifies of high risk. Of course, at this time, the frequency of the previous partial discharge signal to be compared may be compared when it exceeds a predetermined frequency. In other words, if the previous partial discharge signal frequency was less than 10 times for 0.1 second, there is no need to significantly consider the risk due to partial discharge yet, so comparing it with the previous partial discharge occurrence frequency as above may not be meaningful. However, if the partial discharge signal frequency previously (a week ago or a day ago) exceeded a certain frequency (100 times) for 0.1 second, now if the frequency exceeds twice in one day, it is determined that the power system has entered an unstable state. It is necessary to promptly notify users of the risk.

Figure 4 is a flowchart of a method for detecting a partial discharge signal in a power system according to an embodiment of the present disclosure.

In a high-voltage power system, the power lines are usually high-voltage, three-phase power lines.

In step S401, the high-frequency current sensor detects a signal occurring between the power line and the ground terminal of the distribution board or receiving board of the power system.

In step S403, the processor 291 of the partial discharge detector determines whether it is a partial discharge signal by determining the frequency range of the detected signal. The processor 291 determines that the detected high-frequency signal is a partial discharge signal if it is in the 5 MHz to 15 MHz frequency range. For more precise detection of partial discharge signals, a high-frequency detection antenna that detects partial discharge signals independently of the high-frequency current sensor is installed, and the authenticity of the partial discharge signal can be verified by comparing the high-frequency signals generated from two places.

In step S405, the processor 291 determines that the occurrence of the partial discharge signal is related to arc generation based on the frequency with which the detected partial discharge signal occurs during a predetermined period. In addition, the increase trend of the partial discharge signal can be determined by comparing the frequency with which the partial discharge signal occurs during the predetermined time period with the frequency of the partial discharge signal with the same predetermined time period preceding the predetermined time interval. According to this increase trend determination, if the increase trend in the occurrence frequency of the partial discharge signal is above a predetermined level, the processor 291 notifies the user of the risk of arc occurrence.

The methods according to embodiments may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., singly or in combination. Program instructions recorded on the medium may be specially designed and constructed for the present invention or may be known and usable by those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -Includes optical media (magneto-optical media) and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine language code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

Although the embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims are also included in the scope of the present invention. belongs to

100; arc detection system
101; arc
110; power switch
111; fault signal
120; light sensor
130; protection circuit
140; ground switch
2001; 3 phase power line
2003; ground connection
2005; door open signal
220; High frequency current sensor
230; arc detector
240; protection relay
250; light sensor
260; current sensor
270; arc eliminator
290; partial discharge detector
291; processor
293; Memory
260; current sensor

Claims (8)

Detecting a signal occurring between a power line and a ground terminal of a switchboard or receiving board of a power system using a high-frequency current sensor;
detecting a signal generated between a power line of a switchboard or receiving board of the power system and the ground terminal through an antenna;
By comparing and analyzing the signal detected by the high-frequency current sensor and the signal detected by the antenna, the signal detected by the high-frequency current sensor occurs between the power line and the ground terminal of the switchboard or receiving board of the power system. Verifying that it is a partial discharge signal, wherein the verification includes determining a high frequency signal commonly found in the high frequency current sensor and the antenna as a partial discharge signal;
determining whether the determined signal is a partial discharge signal by determining the frequency range; and
A partial discharge detection method in an arc detection system of a power system, comprising the step of determining that the occurrence of the partial discharge signal is related to arc occurrence based on the frequency at which the determined partial discharge signal occurs during a predetermined period of time. The power line of claim 1, wherein the power line is a three-phase power line, and determining whether the detected signal is a partial discharge signal is determined to be a partial discharge signal if the detected signal is in a frequency range of 5 MHz to 15 MHz. Partial discharge detection method in grid arc detection system. The method of claim 1, further comprising determining a trend of increase in the partial discharge signal by comparing the frequency with which the partial discharge signal occurs during the predetermined time with the frequency with which the partial discharge signal occurs during the predetermined time before a predetermined time interval. Partial discharge detection method in an arc detection system of a power system, including: The partial discharge detection method according to claim 3, further comprising notifying the risk of arc occurrence when the increase trend of the partial discharge signal is above a predetermined level. A high-frequency current sensor that detects high-frequency signals generated between the power line and the ground terminal of the switchboard or receiving board of the power system;
a high-frequency detection antenna that separately detects the high-frequency signal generated between the ground terminal and a power line of a switchboard or receiving board of the power system, separately from the high-frequency current sensor; and
By comparing and analyzing the signal detected by the high-frequency current sensor and the signal detected by the high-frequency detection antenna, the signal detected by the high-frequency current sensor occurs between the power line and the ground terminal of the switchboard or receiving board of the power system. Verifying that the high-frequency signal is a partial discharge signal, and determining a high-frequency signal commonly found in the high-frequency current sensor and the antenna to be a partial discharge signal; and
Determine whether the determined high-frequency signal is a partial discharge signal by determining the frequency range of the determined high-frequency signal, and
A partial discharge detector for preventing arcing in a power system, including a processor that determines that the partial discharge signal is related to arc occurrence based on the frequency at which the determined partial discharge signal occurs during a predetermined period of time. delete delete The partial discharge detector for preventing arcing in a power system according to claim 5, wherein when the processor determines that the partial discharge signal is related to arc occurrence, it notifies an arc occurrence risk signal to the arc detection system.

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