WO2024062653A1 - Système de diagnostic de fil sous tension et procédé de diagnostic de fil sous tension - Google Patents

Système de diagnostic de fil sous tension et procédé de diagnostic de fil sous tension Download PDF

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Publication number
WO2024062653A1
WO2024062653A1 PCT/JP2023/009569 JP2023009569W WO2024062653A1 WO 2024062653 A1 WO2024062653 A1 WO 2024062653A1 JP 2023009569 W JP2023009569 W JP 2023009569W WO 2024062653 A1 WO2024062653 A1 WO 2024062653A1
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WO
WIPO (PCT)
Prior art keywords
current transformer
frequency characteristic
live line
diagnostic system
current
Prior art date
Application number
PCT/JP2023/009569
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English (en)
Japanese (ja)
Inventor
淳 額賀
深大 佐藤
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株式会社日立産機システム
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Publication date
Application filed by 株式会社日立産機システム filed Critical 株式会社日立産機システム
Publication of WO2024062653A1 publication Critical patent/WO2024062653A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
    • G01R27/18—Measuring resistance to earth, i.e. line to ground
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/56—Testing of electric apparatus

Definitions

  • the present invention relates to a live line diagnostic system and a live line diagnostic method.
  • High-voltage equipment such as switchboards, switchgear, and switching equipment are used for a long period of time after being installed, and as a result, deterioration over time such as a decline in insulation performance may occur. It is generally known that partial discharge occurs when the insulation performance of power equipment deteriorates. If electrical discharge (hereinafter also referred to as partial discharge) repeatedly occurs inside power equipment, it may lead to insulation breakdown, which may lead to disasters such as fire. Therefore, in order to safely operate power equipment, it is important to detect the insulation performance of equipment.
  • the load electrical equipment
  • a power outage is assumed, and an insulation tester is installed in the circuit to measure the resistance.
  • Patent Document 1 discloses a technique for detecting insulation resistance shown below. Specifically, a low-frequency signal is injected into the ground wire of the device using an injection transformer, and this signal voltage flows through the insulation resistance and ground capacitance, and the current that returns to the ground wire is detected by the current transformer. A method is used in which the insulation resistance of the electrical circuit is measured by extracting only the leakage current component of the measurement low-frequency signal using a filter and then detecting only the insulation resistance component using a synchronous rectifier.
  • the measurable insulation resistance value is determined by the noise voltage of the filter following the current transformer and the magnitude of the noise voltage included within the passband.
  • the method of injecting a low frequency signal using a transformer in order to measure in a live line state as disclosed in Patent Document 1 has a problem in that the measurable resistance value is limited by noise in the filter section.
  • an object of the present invention is to provide a live line diagnostic system that can detect the insulation state inside a device with high accuracy in a live line state.
  • a live line diagnostic system is a live line diagnostic system for diagnosing the state of ground insulation of equipment in a live line state, the system including a first current transformer provided on the input side of a power line of the equipment. and a second current transformer provided on the output side of the power line of the device, and a processing section that is connected to the first current transformer and the second current transformer and performs a predetermined process.
  • a diagnostic device, and the processing unit measures the outputs of the first current transformer and the second current transformer, respectively, at the start of operation of the device, and determines the output of the first current transformer.
  • a first frequency characteristic and a second frequency characteristic of the second current transformer are obtained, a first ratio of the first frequency characteristic and the second frequency characteristic is determined as an initial value, and the process After operation of the device, the section measures the outputs of the first current transformer and the second current transformer, and determines the third frequency characteristic of the first current transformer and the third frequency characteristic of the second current transformer.
  • Obtain each fourth frequency characteristic of the current transformer determine a second ratio of the third frequency characteristic and the fourth frequency characteristic, and calculate the amount of change of the second ratio from the first ratio.
  • the method is characterized in that deterioration of the ground insulation of the device is detected when the value exceeds a predetermined threshold value.
  • the insulation state inside a device can be detected with high accuracy in a live line state.
  • FIG. 2 is a schematic diagram showing the device configuration of the live line diagnostic system of the present embodiment.
  • FIG. 3 is a vector diagram showing components of leakage current of the device. It is a figure which shows the calibration of a current transformer.
  • FIG. 3 is a schematic diagram showing changes in output characteristics of a current transformer.
  • FIG. 3 is a schematic diagram showing a direct comparison of frequency characteristics.
  • FIG. 5 is a diagram showing a diagnostic algorithm corresponding to FIG. 4;
  • FIG. 3 is a schematic diagram showing diagnosis using differential signals.
  • FIG. 6 is a diagram showing a diagnostic algorithm corresponding to FIG. 5;
  • a current transformer 2 is provided on the entrance side of an electric circuit on a panel 1 such as a switchboard.
  • a variable impedance 3 and a variable capacitor 4 are arranged in parallel in the current transformer 2.
  • a current transformer 5 is provided on the outlet side of the electrical circuit of the panel 1.
  • a variable impedance 6 and a variable capacitor 7 are also arranged in parallel with the current transformer 5.
  • a voltage divider 13 is arranged on the entrance side of the electric circuit of the panel 1.
  • Diagnostic device 100 which includes a processing unit that performs predetermined processing.
  • the processing unit has a Fourier transform unit 8, a signal storage and comparison operation unit 9, a calibration circuit 10, a difference processing unit 12, and switches 15 and 16.
  • the processing section switches the switches 15 and 16 to output the output signals of the current transformer 2 and the current transformer 5 to the calibration circuit 10 or the Fourier transform section 8, the signal storage/comparison calculation section 9, and the difference processing section 12, respectively. control so that
  • the current transformer 2 and the current transformer 5 are installed outside the power line 11 so as to be electrically insulated from the internal wiring of the device.
  • the processing unit of the diagnostic device 100 detects deterioration of the ground insulation of the equipment in a live line state.
  • the equipment in the panel 1 can be divided into resistance Ra and capacitance Ca. If the equipment in the panel 1 is in a normal state, the leakage current ⁇ Ia from the equipment is extremely small, and the earth insulation resistance of the equipment is several G ⁇ or more.
  • the leakage current ⁇ Ia is represented by a composite vector ofInvent and Iac.
  • the leakage current ⁇ Ia increases and the vector angle ⁇ decreases.
  • the leakage current is a very small current
  • noise that flows into the signal detected by the current transformer has a significant effect on the measurement accuracy.
  • common mode noise flows into both current transformer 2 and current transformer 5
  • theoretically the leakage current component can be extracted by calculating the difference between the output signals of current transformer 2 and current transformer 5.
  • each current transformer has its own output characteristics, and due to differences in output characteristics, the output signal will differ even for the same input signal. Therefore, when extracting a minute signal, there is a high possibility that the signal will be buried in error components if only the difference processing is performed.
  • the current transformers 2 and 5 are calibrated at at least two types of current values (I1, I2) smaller than the rated current at the time of starting up the equipment. to match the output characteristics of current transformer 2 and current transformer 5. This minimizes the influence of noise on the differential signal.
  • I1, I2 the horizontal axis is the input current I
  • V the transformer output V.
  • the current transformer is Calibration of current transformer 2 and current transformer 5 is performed using a plurality of current values to make the output characteristics of current transformer 2 and current transformer 5 uniform.
  • the frequency characteristics of each individual signal are held as initial values at the start of operation.
  • the impedance of the panel 1 changes and the ground resistance value decreases.
  • board 1 exhibits characteristics close to a low-pass filter (LPF). Therefore, the frequency characteristics of the output signal of the current transformer 2 and the frequency characteristics of the current transformer 5 differ due to the insertion of the panel 1 between them. Specifically, in the current transformer 5, the high frequency component decreases (see FIG. 4).
  • LPF low-pass filter
  • the determination method in FIG. 4 is based on the ratio of the frequency characteristics of current transformer 2 and the frequency characteristics of current transformer 5 at the initial value at the start of operation, and the ratio of the frequency characteristics of current transformer 2 and the frequency characteristic of current transformer 5 after the start of operation. This method compares the ratio of frequency characteristics.
  • the advantage of this determination method is that by using the ratio as an evaluation function and comparing the ratio of frequency characteristics at the start of operation and after the start of operation, changes in the absolute amount of the signal due to factors other than deterioration factors can be offset.
  • the current transformers 2 and 5 are calibrated to align the output characteristics of the current transformers 2 and 5 at a current value smaller than the rated current (step 601 ).
  • the outputs of current transformer 2 and current transformer 5 are measured to obtain frequency characteristics (step 602). Specifically, the frequency characteristics of the output signals of the current transformers 2 and 5 are acquired by the Fourier transform unit 8 and the signal storage/comparison calculation unit 9, and the output signals of the current transformers 2 and 5 are obtained by obtaining the frequency characteristics of the output signals of the current transformers 2 and 5. is stored as a frequency component.
  • step 603 the ratio of the frequency characteristics of current transformer 2 and current transformer 5 is calculated (step 603), and the above ratio is set as an initial value (step 604).
  • the signals of current transformer 2 and current transformer 5 are acquired to acquire frequency characteristics (step 605).
  • the ratio of the frequency characteristics of current transformer 2 and current transformer 5 is calculated (step 606).
  • step 607 it is determined whether the amount of change in the above ratio (after operation has started) from its initial value exceeds a threshold value (step 607). If the amount of change in the above ratio from its initial value exceeds the threshold value, a warning of a drop in resistance is issued (step 608). If the amount of change in the above ratio from its initial value does not exceed the threshold value, the process returns to step 605.
  • the fundamental frequency of the power line 11 is a commercial frequency wave, it also contains harmonic components.
  • the ground resistance is so large that it can be considered almost infinite. Therefore, the frequency components of the currents flowing through current transformer 2 and current transformer 5 are equal.
  • the high frequency component of the intensity is small, changes in the high frequency component can also be evaluated by taking the ratio.
  • the ratio of the frequency characteristics of current transformer 2 and current transformer 5 is close to 1. This ratio is stored as an initial value.
  • the grounding resistance decreases.
  • the impedance of the equipment changes, and high-frequency components leak through the capacitive components of the equipment, causing the equipment to act as an LPF. This reduces the high-frequency components in the frequency characteristics of current transformer 5.
  • a change also appears in the ratio between current transformer 2 and current transformer 5, and if the value of current transformer 5 is used as the numerator, the high-frequency components of the ratio value will decrease.
  • a comparison is made with the initial value of the ratio, and if frequency components exceeding the threshold value are generated, an alarm is issued to warn of an abnormality in the insulation resistance.
  • the current transformer 2 and the current transformer 5 are installed outside the power line 11, and are electrically insulated from the wiring inside the panel 1, so that the current transformer 2 and the current transformer 5 are connected even when the line is live.
  • the output signal of is detectable. By analyzing this output signal, the state of insulation deterioration of the panel 1 in the live wire state can be determined with high accuracy.
  • the determination method shown in FIG. 5 is a method of directly comparing the initial frequency characteristics (at the start of operation) and the frequency characteristics after an elapsed time (after the start of operation) of the same current transformer 5.
  • current transformer 2 and current transformer 5 are calibrated to make the output characteristics of current transformer 2 and current transformer 5 the same at a current value smaller than the rated current (step 801 ).
  • the output of the current transformer 5 is measured to obtain frequency characteristics (step 802). Specifically, the frequency characteristics of the output signal of the current transformer 5 are acquired by the Fourier transform section 8 and the signal storage/comparison calculation section 9, and the output signal of the current transformer 5 is stored as a frequency component.
  • the output of the current transformer 5 is set to an initial value (step 803).
  • the signal of the current transformer 5 is acquired and the frequency characteristics are acquired (step 804).
  • step 805 it is determined whether the amount of change from the initial value of the frequency characteristic (after the start of operation) exceeds a threshold value (step 805). If the amount of change from the initial value of the frequency characteristic exceeds the threshold value, a warning of a decrease in resistance is issued (step 806). If the amount of change from the initial value of the frequency characteristic does not exceed the threshold, the process returns to step 804.
  • Example 2 will be described with reference to FIG.
  • the difference signal between the current transformer 2 and the current transformer 5 is acquired by the difference processing section 12 (see FIG. 1), and this difference signal is used.
  • the frequency characteristics at the start are held as initial values.
  • insulation deterioration is measured by comparing the frequency characteristics of the output signal after the start of operation and detecting that the amount of change exceeds a threshold value.
  • the live line diagnostic system is capable of highly accurately detecting the insulation state inside the device in a live line state.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Testing Electric Properties And Detecting Electric Faults (AREA)

Abstract

Ce dispositif de diagnostic compare les caractéristiques de fréquence d'un transformateur de courant au début de l'opération et les caractéristiques de fréquence du transformateur de courant après le début de l'opération, et, lorsqu'une quantité de changement correspondante a dépassé une valeur de seuil prescrite, détecte une détérioration de l'isolation par rapport à la masse d'un dispositif.
PCT/JP2023/009569 2022-09-22 2023-03-13 Système de diagnostic de fil sous tension et procédé de diagnostic de fil sous tension WO2024062653A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022151878A JP2024046467A (ja) 2022-09-22 2022-09-22 活線診断システム及び活線診断方法
JP2022-151878 2022-09-22

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WO2024062653A1 true WO2024062653A1 (fr) 2024-03-28

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020020611A (ja) * 2018-07-30 2020-02-06 株式会社日立製作所 絶縁診断装置、絶縁診断方法、および絶縁診断プログラム
JP2021103099A (ja) * 2019-12-25 2021-07-15 パナソニックＩｐマネジメント株式会社 劣化検知方法、プログラム及び劣化検知システム

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020020611A (ja) * 2018-07-30 2020-02-06 株式会社日立製作所 絶縁診断装置、絶縁診断方法、および絶縁診断プログラム
JP2021103099A (ja) * 2019-12-25 2021-07-15 パナソニックＩｐマネジメント株式会社 劣化検知方法、プログラム及び劣化検知システム

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