Zinc oxide surge arrester resistance current extraction device and method based on current comparator

Abstract

The application discloses a zinc oxide lightning arrester resistance current extraction device and method based on a current comparator, which comprises an alternating current high-voltage power supply, a zinc oxide lightning arrester sample equivalent model, a current comparator assembly, a standard capacitor, a sampling resistor, a high-voltage probe and an oscilloscope; wherein the current comparator assembly comprises a current comparator and a primary first winding, a primary second winding and a secondary winding arranged on both sides of the current comparator; the zinc oxide lightning arrester sample equivalent model is connected with the primary first winding, and the standard capacitor is connected with the primary second winding; a first channel voltage signal is collected through the high-voltage probe, and a second channel voltage signal is collected through the sampling resistor connected with the secondary winding. The application is simple to operate, and only needs to adjust the number of turns of the primary first winding and the primary second winding of the current comparator, so that the first channel and the second channel voltage signals observed on the oscilloscope are in phase, and then the resistance component of the leakage current of the zinc oxide lightning arrester sample can be extracted.

Description

Technical Field

[0001] This invention relates to the field of electrical testing technology, and in particular to a resistive current extraction device and method for zinc oxide surge arresters based on a current comparator. Background Technology

[0002] Zinc oxide surge arresters are crucial electrical devices protecting electrical equipment from atmospheric and operational overvoltages. Surge arresters not only withstand long-term power frequency AC voltage but are also susceptible to moisture, pollution, and overvoltage surges, which accelerate their aging and can even lead to explosions, seriously threatening the safe and stable operation of the power system. Therefore, monitoring and diagnosing the insulation condition of surge arresters is a key research focus in power system overvoltage protection. It is well known that the leakage current of a surge arrester consists of resistive and capacitive components. When a surge arrester ages, the resistive charge in the leakage current will exhibit a third harmonic. Therefore, a common method for surge arrester condition monitoring and diagnosis is measuring the resistive component of the leakage current. However, the capacitive component of the leakage current is typically more than two orders of magnitude higher than the resistive component, posing a significant challenge to accurately extracting the resistive current component.

[0003] Capacitive current compensation is one method for extracting the resistive current component of surge arresters. This method uses a phase shifter to shift the applied voltage across the surge arrester by 90° to form a capacitive compensation current, which is then used to compensate for the capacitive component in the surge arrester's leakage current, thus obtaining the resistive component. However, because the phase shifter itself has a phase shift, this method cannot truly shift the applied voltage across the surge arrester by 90°. In other words, this method cannot completely compensate for the capacitive component of the surge arrester's leakage current, which increases the measurement error of the resistive component. To address this shortcoming, many improved capacitive current compensation methods have been developed, such as phase-shifting compensation for the third harmonic of the capacitive current. However, these improved methods are theoretically complex and have low efficiency in extracting the resistive current from the surge arrester. Summary of the Invention

[0004] The purpose of this invention is to provide a resistive current extraction device and method for zinc oxide surge arresters based on a current comparator, which, based on compensating for the capacitive component, can accurately and effectively extract the resistive component from the leakage current of the zinc oxide surge arrester.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] The present invention provides a resistive current extraction device for zinc oxide surge arresters based on a current comparator, comprising: an AC high-voltage power supply, an equivalent model of a zinc oxide surge arrester sample, a current comparator assembly, a standard capacitor, a sampling resistor, a high-voltage probe, and an oscilloscope;

[0007] The equivalent model of the zinc oxide surge arrester sample includes equivalent resistance and equivalent capacitance connected in parallel;

[0008] The current comparator assembly includes a current comparator and a primary winding, a secondary winding, and a primary winding of the current comparator disposed on both sides of the current comparator. The primary winding and the primary winding of the current comparator are connected in series, and the series connection point is connected to the grounding terminal of the AC high voltage power supply.

[0009] The high-voltage end of the AC high-voltage power supply is connected to the equivalent model of the zinc oxide surge arrester sample, the standard capacitor, and the input end of the high-voltage probe, respectively.

[0010] The output terminal of the equivalent model of the zinc oxide surge arrester sample is connected to the first winding of the primary side of the current comparator, and the output terminal of the standard capacitor is connected to the second winding of the primary side of the current comparator.

[0011] One end of the sampling resistor is grounded, and the other end is connected to the oscilloscope. The two ends of the secondary winding of the current comparator are respectively connected to the two ends of the sampling resistor.

[0012] The high-voltage probe is connected to the oscilloscope.

[0013] Furthermore, the oscilloscope is provided with a first channel and a second channel, the output terminal of the high-voltage probe is connected to the first channel, and the sampling resistor is connected to the second channel.

[0014] Another aspect of the present invention provides a method for extracting resistive current from a zinc oxide surge arrester based on a current comparator, applied to the aforementioned resistive current extraction device for a zinc oxide surge arrester based on a current comparator, comprising the following steps:

[0015] AC high voltage generated by AC high voltage power supply Under the action of [condition], the leakage current flowing through the equivalent model of the zinc oxide surge arrester sample. From resistive components Harmony and compatibility Composition, leakage current The current flowing into the first winding of the primary side of the current comparator is generated by the standard capacitor. The current flows into the second winding of the primary side of the comparator.

[0016] AC high voltage A proportionally scaled-down first-channel voltage signal is generated using a high-voltage probe. Enter the first channel of the oscilloscope;

[0017] Current flowing through the secondary winding of the current comparator A second channel voltage signal is generated across the sampling resistor. Enter the second channel of the oscilloscope;

[0018] The secondary winding and primary winding of the current comparator have the following relationship:

[0019]

[0020] Where N1 is the number of turns in the first winding of the primary side of the current comparator, N2 is the number of turns in the second winding of the primary side of the current comparator, and N0 is the number of turns in the secondary winding of the current comparator.

[0021] By adjusting the number of turns N1 and N2, the following can be achieved:

[0022]

[0023] The voltage signal of the first channel of the oscilloscope Second channel voltage signal In phase, the resistive component of the leakage current flowing through the zinc oxide surge arrester sample is:

[0024]

[0025] Wherein, R0 is the resistance of the sampling resistor.

[0026] According to specific embodiments provided by the present invention, the following technical effects are disclosed: The resistive current extraction device and method for zinc oxide surge arresters based on a current comparator provided by the present invention, through the current comparator and the ampere-turn balance principle, enables the magnetic flux generated in the primary winding of the current comparator by the current flowing through the standard capacitor and the capacitive component of the leakage current of the zinc oxide surge arrester sample to cancel each other out, thereby accurately obtaining the resistive component of the leakage current of the zinc oxide surge arrester sample on the secondary side of the current comparator; The present invention is simple to operate, only requiring adjustment of the number of turns of the first and second primary windings of the current comparator to make the voltage signals of the first and second channels observed on the oscilloscope in phase, thus realizing the extraction of the resistive component of the leakage current of the zinc oxide surge arrester sample. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of the circuit structure of the resistive current extraction device for zinc oxide surge arresters based on a current comparator provided by the present invention;

[0029] Figure 2 The phasor diagram in the resistive current extraction method for zinc oxide surge arresters based on current comparators provided by this invention;

[0030] Figure labeling: 1-AC high voltage power supply; 2-equivalent model of zinc oxide surge arrester sample; 21-equivalent resistance; 22-equivalent capacitance; 3-current comparator assembly; 31-first winding of primary side of current comparator; 32-second winding of primary side of current comparator; 33-secondary winding of current comparator; 4-standard capacitor; 5-sampling resistor; 6-high voltage probe; 7-oscilloscope; 71-first channel; 72-second channel. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The purpose of this invention is to provide a device and method for extracting resistive current from zinc oxide surge arresters based on a current comparator. By simply adjusting the number of turns of the first and second primary windings of the current comparator so that the voltage signals of the first and second channels observed on the oscilloscope are in phase, the resistive component of the leakage current of the zinc oxide surge arrester sample can be extracted.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, the resistive current extraction device for zinc oxide surge arresters based on a current comparator provided by the present invention includes: an AC high-voltage power supply 1, an equivalent model of a zinc oxide surge arrester sample 2, a current comparator assembly 3, a standard capacitor 4, a sampling resistor 5, a high-voltage probe 6, and an oscilloscope 7.

[0035] The equivalent model 2 of the zinc oxide surge arrester sample includes an equivalent resistance 21 and an equivalent capacitance 22 connected in parallel.

[0036] The current comparator assembly 3 includes a current comparator and a primary winding 31, a primary winding 32, and a secondary winding 33 of the current comparator disposed on both sides of the current comparator. The primary winding 31 and the primary winding 32 of the current comparator are connected in series, and the series connection point is connected to the grounding terminal of the AC high voltage power supply 1.

[0037] The high-voltage end of the AC high-voltage power supply 1 is connected to the input end of the equivalent model 2 of the zinc oxide surge arrester sample, the standard capacitor 4, and the high-voltage probe 6, respectively.

[0038] The output terminal of the equivalent model 2 of the zinc oxide surge arrester sample is connected to the first winding 31 of the primary side of the current comparator, and the output terminal of the standard capacitor 4 is connected to the second winding 32 of the primary side of the current comparator.

[0039] One end of the sampling resistor 5 is grounded, and the other end is connected to the oscilloscope 7. The two ends of the secondary winding 33 of the current comparator are respectively connected to the two ends of the sampling resistor 5.

[0040] The high-voltage probe 6 is connected to the oscilloscope 7.

[0041] The oscilloscope 7 is provided with a first channel 71 and a second channel 72. The output terminal of the high-voltage probe 6 is connected to the first channel 71, and the sampling resistor 5 is connected to the second channel 72.

[0042] like Figure 1-2 As shown, the resistive current extraction method for zinc oxide surge arresters based on a current comparator provided by the present invention includes the following steps:

[0043] The AC high voltage generated by AC high voltage power supply 1 Under the action of [action], the leakage current flowing through the equivalent model 2 of the zinc oxide surge arrester sample [is measured]. From resistive components Harmony and compatibility Composition, leakage current The current flowing into the first winding 31 of the primary side of the current comparator is generated by the standard capacitor 4. The second winding 32 of the primary side of the current comparator flows in;

[0044] AC high voltage The first channel voltage signal is generated by a proportionally reduced voltage probe 6. Enter the first channel 71 of oscilloscope 7;

[0045] The current flowing through the secondary winding 33 of the current comparator A second channel voltage signal is generated across sampling resistor 5. Enter the second channel 72 of oscilloscope 7;

[0046] The secondary winding 33 of the current comparator has the following relationship with the primary windings of the current comparator: the first primary winding 31 and the second primary winding 32 of the current comparator.

[0047]

[0048] Wherein, N1 is the number of turns of the first winding 31 of the primary side of the current comparator, N2 is the number of turns of the second winding 32 of the primary side of the current comparator, and N0 is the number of turns of the secondary winding 33 of the current comparator.

[0049] By adjusting the number of turns N1 and N2, the following can be achieved:

[0050]

[0051] The voltage signal of the first channel of oscilloscope 7 Second channel voltage signal In phase, the resistive component of the leakage current flowing through the zinc oxide surge arrester sample is:

[0052]

[0053] Wherein, R0 is the resistance of the sampling resistor 5.

[0054] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A resistive current extraction device for zinc oxide surge arresters based on a current comparator, characterized in that, include: AC high voltage power supply (1), equivalent model of zinc oxide surge arrester sample (2), current comparator assembly (3), standard capacitor (4), sampling resistor (5), high voltage probe (6) and oscilloscope (7); The equivalent model (2) of the zinc oxide surge arrester sample includes an equivalent resistance (21) and an equivalent capacitance (22) connected in parallel. The current comparator assembly (3) includes a current comparator and a primary winding (31), a primary winding (32), and a secondary winding (33) of the current comparator disposed on both sides of the current comparator. The primary winding (31) and the primary winding (32) of the current comparator are connected in series, and the series connection is connected to the grounding terminal of the AC high voltage power supply (1). The high-voltage end of the AC high-voltage power supply (1) is connected to the input end of the equivalent model (2) of the zinc oxide arrester sample, the standard capacitor (4), and the high-voltage probe (6), respectively. The output terminal of the equivalent model (2) of the zinc oxide surge arrester sample is connected to the first winding (31) of the primary side of the current comparator, and the output terminal of the standard capacitor (4) is connected to the second winding (32) of the primary side of the current comparator. One end of the sampling resistor (5) is grounded, and the other end is connected to the oscilloscope (7). The two ends of the secondary winding (33) of the current comparator are respectively connected to the two ends of the sampling resistor (5). The high-voltage probe (6) is connected to the oscilloscope (7).

2. The resistive current extraction device for zinc oxide surge arresters based on a current comparator according to claim 1, characterized in that, The oscilloscope (7) is provided with a first channel (71) and a second channel (72). The output terminal of the high voltage probe (6) is connected to the first channel (71), and the sampling resistor (5) is connected to the second channel (72).

3. A method for extracting resistive current from a zinc oxide surge arrester based on a current comparator, applied to the resistive current extraction device for a zinc oxide surge arrester based on a current comparator as described in any one of claims 1-2, characterized in that, Includes the following steps: AC high voltage generated by AC high voltage power supply (1) Under the action of the sample equivalent model (2) of the zinc oxide surge arrester, the leakage current flows through the sample. From resistive components Harmony and compatibility Composition, leakage current The current flowing into the first winding (31) of the primary side of the current comparator is generated by the standard capacitor (4). The current flows into the second winding (32) of the primary side of the comparator; AC high voltage A proportionally reduced first-channel voltage signal is generated by the high-voltage probe (6). Enter the first channel (71) of the oscilloscope (7); The current flowing through the secondary winding (33) of the current comparator A second channel voltage signal is generated on the sampling resistor (5). Enter the second channel (72) of the oscilloscope (7); The secondary winding (33) of the current comparator has the following relationship with the primary winding, the first primary winding (31) of the current comparator, and the second primary winding (32) of the current comparator: Wherein, N1 is the number of turns of the first winding (31) of the primary side of the current comparator, N2 is the number of turns of the second winding (32) of the primary side of the current comparator, and N0 is the number of turns of the secondary winding (33) of the current comparator. By adjusting the number of turns N1 and N2, the following can be achieved: The voltage signal of the first channel of the oscilloscope (7) Second channel voltage signal In phase, the resistive component of the leakage current flowing through the zinc oxide surge arrester sample is: Wherein, R0 is the resistance of the sampling resistor (5).

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