Zinc oxide arrester leakage current resistive component extraction method and system

Abstract

The invention relates to a zinc oxide arrester leakage current resistive component extraction method and system, and the method comprises the following steps: starting from the zero passage of the leakage current of a zinc oxide arrester, obtaining the transient value of the leakage current at the same time interval in a leakage current period of the arrester, and obtaining a first data sequence; subtracting the value after the preset period from each value in the first data sequence to obtain a second data sequence; searching the maximum value in the second data sequence and the position of the maximum value in the second data sequence, and constructing a third data sequence changing according to the sine rule; subtracting the third data sequence from the first data sequence to obtain a fourth data sequence; searching the maximum value in the fourth data sequence and the position of the maximum value in the fourth data sequence in the limited area, and constructing a fifth data sequence which changes according to the sine rule according to the maximum value and the position of the maximum value in the fourth data sequence; and subtracting the fifth data sequence from the fourth data sequence to obtain data of the resistive component of the leakage current of the lightning arrester.

Description

Technical Field

[0001] The invention relates to a method and a system for extracting a resistive component of a zinc oxide arrester leakage current, belonging to the technical field of arrester leakage current analysis. Background Art

[0002] Zinc oxide arresters are important equipment to ensure the reliable operation of power systems. However, defects such as poor structure, loose sealing, and aging of valve plates will increase the resistive leakage current, which will lead to damage or explosion of the arrester, seriously threatening the safe operation of the power system. Online monitoring of the arrester's leakage current can timely detect the arrester's defects, which is of great significance to ensure the safe and stable operation of the power system.

[0003] The leakage current of zinc oxide arrester contains capacitive component and resistive component, among which the resistive component only accounts for 5%-20% of the total leakage current. Although its content is small, it is a key indicator reflecting the health status of the arrester. Therefore, accurately measuring the resistive component of the arrester leakage current is the key to timely discovering arrester defects.

[0004] The capacitive component of the leakage current generated by the sinusoidal voltage applied to the arrester is also a sinusoidal wave, and its phase leads the voltage by 90°; the resistive component of the leakage current has a small value only when the voltage is close to the amplitude, and the resistive component of the leakage current is almost zero in a wide range before and after the voltage passes zero. This area is called the "zero value area" of the resistive component of the leakage current. The amplitude of the capacitive component of the leakage current is just within the "zero value area" of the resistive component of the leakage current. When the system voltage contains the third harmonic, the capacitive component of the arrester leakage current contains the fundamental wave and the third harmonic, and the resistive component is composed of the fundamental wave and a series of higher harmonics. The "zero value area" of the resistive component still exists.

[0005] Decomposing the arrester leakage current into capacitive and resistive components helps to determine the health of the arrester, but in practical applications, only the synthesis of the two, that is, the full current of the leakage current, can be measured. How to extract the resistive component required to determine the health of the arrester from the full current is a difficult problem. Currently, the commonly used arrester online monitoring methods include the full current method, fundamental wave method, third harmonic method, capacitive current compensation method, and harmonic analysis method.

[0006] The full current method measures the full current flowing through the arrester by connecting an AC ammeter in series with the ground terminal of the arrester. The fundamental wave method obtains the amplitude and phase of the full current and system voltage through fast Fourier transform, and then calculates the resistive current fundamental component in the full current through the phase difference of the fundamental waves of the two. The third harmonic method monitors the sum of the three-phase leakage current. When the three phases are balanced, the sum of the fundamental current is zero. The result is the sum of the three-phase harmonic components, among which the third harmonic is the main one. The capacitive current compensation method provides a reverse capacitive current through an external compensation circuit, and by continuously adjusting the size of the compensation current, the capacitive current component is offset, thereby obtaining the resistive current component. The harmonic analysis method obtains the fundamental wave and each harmonic signal of the two signals by digitizing the voltage signal and the full current signal, and then performing fast Fourier transform.

[0007] The above methods are unable to completely extract the resistive component of the leakage current, so they are unable to accurately determine the health of the arrester. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, the present invention proposes a method and system for extracting the resistive component of leakage current of a zinc oxide arrester.

[0009] The technical solution of the present invention is as follows:

[0010] On the one hand, the present invention provides a method for extracting the resistive component of the leakage current of a zinc oxide arrester, comprising the following steps:

[0011] Starting from the zero crossing of the zinc oxide lightning arrester leakage current, the transient value of the leakage current is acquired at the same time interval in a lightning arrester leakage current cycle to obtain a first data sequence;

[0012] Subtract the value after a preset period from each value in the first data sequence to obtain a second data sequence;

[0013] Searching for a maximum value in the second data sequence and a position of the maximum value in the second data sequence, and constructing a third data sequence that changes according to a sinusoidal law;

[0014] Subtract the third data sequence from the first data sequence to obtain a fourth data sequence;

[0015] Searching for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby constructing a fifth data sequence that changes according to a sinusoidal law;

[0016] The fifth data sequence is subtracted from the fourth data sequence to obtain data of one cycle of the resistive component of the leakage current of the zinc oxide arrester.

[0017] As a preferred implementation, the method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically as follows:

[0018] By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained;

[0019] Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

[0020] As a preferred implementation, in the step of subtracting the value after a preset period from each value in the first data sequence to obtain the second data sequence:

[0021] The preset period is 1 / 3 of the arrester leakage current period or 2 / 3 of the arrester leakage current period.

[0022] As a preferred implementation, the third data sequence constructed to change according to the sinusoidal law is specifically:

[0023] The period of the third data sequence is equal to the arrester leakage current period;

[0024] The maximum value in the third data sequence is equal to the maximum value in the second data sequence divided by ;

[0025] The position of the maximum value in the third data sequence in the third data sequence is the same as the position of the maximum value in the second data sequence in the second data sequence shifted forward by 1 / 12 of the arrester leakage current cycle.

[0026] As a preferred implementation, the limited area is specifically:

[0027] The position of the center of the limited area in the fourth data sequence is the same as the position of the maximum value of the third data sequence in the third data sequence; and the width of the limited area is 1 / 3 of the period of the fourth data sequence.

[0028] As a preferred implementation, the fifth data sequence constructed to change according to the sinusoidal law is specifically:

[0029] The period of the fifth data sequence is equal to 1 / 3 of the period of the arrester leakage current;

[0030] The maximum value in the fifth data sequence is equal to the maximum value in the limited area in the fourth data sequence;

[0031] The position of the maximum value in the fifth data sequence in the fifth data sequence is the same as the position of the maximum value within the defined area in the fourth data sequence in the fourth data sequence in the fourth data sequence.

[0032] On the other hand, the present invention also provides a zinc oxide arrester leakage current resistive component extraction system, comprising:

[0033] An initial data measurement module is used to obtain the transient value of the leakage current at the same time interval in a leakage current cycle of the zinc oxide arrester starting from the zero crossing of the leakage current of the zinc oxide arrester to obtain a first data sequence;

[0034] A second data sequence building module, used for subtracting the value after a preset period from each value in the first data sequence to obtain a second data sequence;

[0035] A third data sequence construction module, used for searching for a maximum value in the second data sequence and a position of the maximum value in the second data sequence, and thereby constructing a third data sequence that changes according to a sinusoidal law;

[0036] a fourth data sequence building module, configured to subtract the third data sequence from the first data sequence to obtain a fourth data sequence;

[0037] A fifth data sequence construction module, used to search for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby construct a fifth data sequence that changes according to a sinusoidal law;

[0038] The resistive component extraction module is used to subtract the fifth data sequence from the fourth data sequence to obtain data of one cycle of the resistive component of the leakage current of the zinc oxide arrester.

[0039] As a preferred implementation, the method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically as follows:

[0040] By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained;

[0041] Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

[0042] On the other hand, the present invention further proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any embodiment of the present invention is implemented.

[0043] On the other hand, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any embodiment of the present invention.

[0044] The method for extracting the resistive component of the zinc oxide arrester leakage current proposed by the present invention can extract the resistive component of the arrester leakage current when the power grid contains the third harmonic, thus meeting the requirement of online monitoring of the arrester leakage current. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure is a schematic diagram of the method flow of the first embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be understood that the step numbers used in this document are only for convenience of description and are not intended to limit the order in which the steps are executed.

[0048] It should be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0049] The terms “include” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0050] The term "and / or" means and includes any and all possible combinations of one or more of the associated listed items.

[0051] Embodiment 1:

[0052] See also Figure 1 This embodiment provides a method for extracting the resistive component of the leakage current of a zinc oxide arrester, comprising the following steps:

[0053] S100, starting from the zero crossing of the zinc oxide arrester leakage current, the transient value of the leakage current is obtained at the same time interval in one arrester leakage current cycle, N points are measured in one arrester leakage current cycle, and the preferred value of N is an integer multiple of 12. The measurement results are recorded in sequence as D1[i], i=1,2,3...N, and a data sequence D1 is obtained.

[0054] S200, subtract the value after a preset period from each value in the first data sequence to obtain a second data sequence D2;

[0055] The preset period may be 1 / 3 of the arrester leakage current period or 2 / 3 of the arrester leakage current period. For example, when the 1 / 3 period is selected, D2[i]=D1[i]-D1[i+N / 3], i=1,2,3...N.

[0056] S300, searching for the maximum value in the second data sequence D2 and the position of the maximum value in the second data sequence, and constructing a third data sequence D3 that changes according to a sinusoidal law;

[0057] In this embodiment, the period of the constructed third data sequence is equal to the arrester leakage current period; the maximum value D3max in the third data sequence is equal to the maximum value in the second data sequence divided by The position of the maximum value in the third data sequence in the third data sequence is the same as the position of the maximum value in the second data sequence in the second data sequence after the position Maxi1 is moved forward by 1 / 12 of the arrester leakage current cycle, that is:

[0058] D3[i]=D3max×cos(2π(i-Maxi1+N / 12) / N), i=1,2,3...N.

[0059] S400, subtract the third data sequence D3 from the first data sequence D1 to obtain a fourth data sequence D4; that is, D4[i]=D1[i]-D3[i], i=1,2,3...N.

[0060] S500, searching for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby constructing a fifth data sequence that changes according to a sinusoidal law;

[0061] In this embodiment, the position of the center of the limited area in the fourth data sequence is the same as the position of the maximum value of the third data sequence in the third data sequence; and the width of the limited area is 1 / 3 of the period of the fourth data sequence. <i<Maxi1+N / 6。

[0062] In this embodiment, the period of the constructed fifth data sequence is equal to 1 / 3 of the arrester leakage current period; the maximum value in the fifth data sequence is equal to the maximum value D4max in the defined area in the fourth data sequence; the position of the maximum value in the fifth data sequence in the fifth data sequence is the same as the position Maxi2 of the maximum value in the defined area in the fourth data sequence in the fourth data sequence, that is:

[0063] D5[i]=D4max×cos(6π(i-Maxi2) / N), i=1,2,3...N.

[0064] S600, subtract the fifth data sequence D5 from the fourth data sequence D4 to obtain data D6 of one cycle of the resistive component of the zinc oxide arrester leakage current, that is:

[0065] D6[i]=D4[i]-D5[i], i=1,2,3...N.

[0066] As a preferred implementation of this embodiment, the method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically:

[0067] By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained;

[0068] Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

[0069] Embodiment 2:

[0070] This embodiment provides a system for extracting resistive components of leakage current of a zinc oxide arrester, including:

[0071] An initial data measurement module is used to obtain the transient value of the leakage current at the same time interval in a leakage current cycle of the zinc oxide arrester starting from the zero crossing of the leakage current of the zinc oxide arrester, and obtain a first data sequence; this module is used to implement the function of step S100 in the first embodiment, and will not be repeated here;

[0072] A second data sequence building module, used to subtract the value after a preset period from each value in the first data sequence to obtain a second data sequence; this module is used to implement the function of step S200 in the first embodiment, and will not be described in detail here;

[0073] A third data sequence construction module, used to search for the maximum value in the second data sequence and the position of the maximum value in the second data sequence, and thereby construct a third data sequence that changes according to a sinusoidal law; this module is used to implement the function of step S300 in the first embodiment, and will not be described in detail here;

[0074] A fourth data sequence construction module, used for subtracting the third data sequence from the first data sequence to obtain a fourth data sequence; this module is used to implement the function of step S400 in the first embodiment, and will not be described in detail here;

[0075] a fifth data sequence construction module, used to search for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby construct a fifth data sequence that changes according to a sinusoidal law; this module is used to implement the function of step S500 in the first embodiment, and will not be described in detail herein;

[0076] The resistive component extraction module is used to subtract the fifth data sequence from the fourth data sequence to obtain data of one cycle of the resistive component of the zinc oxide arrester leakage current; this module is used to implement the function of step S600 in the first embodiment, which will not be repeated here.

[0077] As a preferred implementation of this embodiment, the method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically:

[0078] By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained;

[0079] Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

[0080] Embodiment three:

[0081] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any embodiment of the present invention is implemented.

[0082] Embodiment 4:

[0083] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any embodiment of the present invention is implemented.

[0084] In the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0085] Those of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0086] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0087] In several embodiments provided in the present application, if any function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory; hereinafter referred to as: ROM), random access memory (Random Access Memory; hereinafter referred to as: RAM), disk or optical disk, and other media that can store program codes.

[0088] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for extracting the resistive component of leakage current of a zinc oxide arrester, characterized in that: The following steps are involved: Starting from the zero crossing of the zinc oxide lightning arrester leakage current, the transient value of the leakage current is acquired at the same time interval in a lightning arrester leakage current cycle to obtain a first data sequence; Subtract the value after a preset period from each value in the first data sequence to obtain a second data sequence; Searching for a maximum value in the second data sequence and a position of the maximum value in the second data sequence, and constructing a third data sequence that changes according to a sinusoidal law; Subtract the third data sequence from the first data sequence to obtain a fourth data sequence; Searching for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby constructing a fifth data sequence that changes according to a sinusoidal law; The fifth data sequence is subtracted from the fourth data sequence to obtain data of one cycle of the resistive component of the leakage current of the zinc oxide arrester.

2. A method for extracting resistive component of leakage current of zinc oxide arrester according to claim 1, characterized in that: The method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically as follows: By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained; Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

3. The method for extracting the resistive component of the leakage current of a zinc oxide arrester according to claim 1, characterized in that: In the step of obtaining the second data sequence by subtracting the value after a preset period from each value in the first data sequence: The preset period is 1 / 3 of the arrester leakage current period or 2 / 3 of the arrester leakage current period.

4. The method for extracting the resistive component of the leakage current of a zinc oxide arrester according to claim 1, characterized in that: The third data sequence constructed to change according to the sinusoidal law is specifically: The period of the third data sequence is equal to the arrester leakage current period; The maximum value in the third data sequence is equal to the maximum value in the second data sequence divided by The position of the maximum value in the third data sequence in the third data sequence is the same as the position of the maximum value in the second data sequence in the second data sequence shifted forward by 1 / 12 of the arrester leakage current cycle.

5. The method for extracting the resistive component of the leakage current of a zinc oxide arrester according to claim 1, characterized in that: The limited areas are specifically: The position of the center of the limited area in the fourth data sequence is the same as the position of the maximum value of the third data sequence in the third data sequence; and the width of the limited area is 1 / 3 of the period of the fourth data sequence.

6. A method for extracting resistive component of leakage current of zinc oxide arrester according to claim 1, characterized in that: The fifth data sequence constructed according to the sinusoidal law is specifically: The period of the fifth data sequence is equal to 1 / 3 of the period of the arrester leakage current; The maximum value in the fifth data sequence is equal to the maximum value in the limited area in the fourth data sequence; The position of the maximum value in the fifth data sequence in the fifth data sequence is the same as the position of the maximum value within the defined area in the fourth data sequence in the fourth data sequence in the fourth data sequence.

7. A zinc oxide arrester leakage current resistive component extraction system, characterized in that: include: An initial data measurement module is used to obtain the transient value of the leakage current at the same time interval in a leakage current cycle of the zinc oxide arrester starting from the zero crossing of the leakage current of the zinc oxide arrester to obtain a first data sequence; A second data sequence building module, used for subtracting the value after a preset period from each value in the first data sequence to obtain a second data sequence; A third data sequence construction module, used for searching for a maximum value in the second data sequence and a position of the maximum value in the second data sequence, and thereby constructing a third data sequence that changes according to a sinusoidal law; a fourth data sequence building module, configured to subtract the third data sequence from the first data sequence to obtain a fourth data sequence; A fifth data sequence construction module, used to search for a maximum value in the fourth data sequence and a position of the maximum value in the fourth data sequence within a limited area, and thereby construct a fifth data sequence that changes according to a sinusoidal law; The resistive component extraction module is used to subtract the fifth data sequence from the fourth data sequence to obtain data of one cycle of the resistive component of the leakage current of the zinc oxide arrester.

8. A zinc oxide arrester leakage current resistive component extraction system according to claim 7, characterized in that: The method for obtaining the transient value of the leakage current at the same time interval in a lightning arrester leakage current cycle is specifically as follows: By measuring the entire arrester leakage current cycle, the transient value of the leakage current at each time interval is obtained; Alternatively, the transient values ​​of the leakage current at some of the time intervals are measured, and then the transient values ​​of the leakage current at all the time intervals are obtained in a waveform symmetric manner.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any one of claims 1 to 6 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method for extracting the resistive component of the leakage current of a zinc oxide lightning arrester as described in any one of claims 1 to 6 is implemented.

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