Lightning arrester leakage current resistive component extraction method and system

Abstract

The invention relates to a lightning arrester leakage current resistive component extraction method and system. The method comprises the following steps: synchronously acquiring a lightning arrester leakage current signal and a system voltage signal of at least one period; performing Fourier transform decomposition on the system voltage signal to obtain a system voltage decomposition signal; constructing a characteristic function representing the capacitive current according to the system voltage decomposition signal; calculating a characteristic current signal based on a characteristic function representing the capacitive current, and calculating the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time when the amplitude moment of the leakage current signal is ahead of the amplitude moment of the characteristic current signal; and calculating the resistive component of the lightning arrester leakage current according to the ratio of the leakage current signal to the characteristic current signal amplitude and the characteristic time.

Description

Technical Field

[0001] The present invention relates to a method and system for extracting the resistive component of the leakage current of a lightning arrester, belonging to the technical field of on-line monitoring of power equipment. Background Art

[0002] A lightning arrester is an important device to ensure the reliable operation of a power system. However, defects such as poor structure, loose sealing, and aging of the valve plate can cause an increase in its resistive leakage current, which may further lead to damage or explosion of the lightning arrester, seriously threatening the safe operation of the power system. Online monitoring of the resistive component of the leakage current of a lightning arrester can timely detect the defects of the lightning arrester, which is of great significance for ensuring the safe and stable operation of the power system.

[0003] Decomposing the leakage current of a lightning arrester into a capacitive component and a resistive component helps to judge the health status of the lightning arrester. However, in actual applications, only the synthesis of the two, that is, the total current of the leakage current, can be measured. How to extract the resistive component required to judge the health status of the lightning arrester from the total current is a difficult problem.

[0004] Most of the existing methods for extracting the resistive component of the leakage current of a lightning arrester ignore the influence of high-order harmonics of the system voltage on the leakage current, and do not fully consider the influence of the amplitude and phase errors in the measurement process of voltage and current signals, resulting in large errors or even fallacies in the extracted resistive component. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention proposes a method and system for extracting the resistive component of the leakage current of a lightning arrester.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, the present invention proposes a method for extracting the resistive component of the leakage current of a lightning arrester, including the following steps:

[0008] Synchronously collect the leakage current signal and the system voltage signal of the lightning arrester for at least one cycle;

[0009] Perform Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal;

[0010] Construct a characteristic function representing the capacitive current according to the system voltage decomposition signal;

[0011] Calculate the characteristic current signal based on the characteristic function representing the capacitive current, and calculate the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal, and the characteristic time when the amplitude moment of the leakage current signal leads the amplitude moment of the characteristic current signal;

[0012] Calculate the resistive component of the leakage current of the lightning arrester according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time.

[0013] As a preferred embodiment, the Fourier transform decomposition of the system voltage signal to obtain the system voltage decomposition signal is specifically to decompose the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically:

[0014]

[0015] where k is the harmonic order, U k is the amplitude of each harmonic, ω is the fundamental angular frequency, is the initial phase angle of each harmonic.

[0016] As a preferred embodiment, the construction of the characteristic function representing the capacitive current according to the system voltage decomposition signal is specifically:

[0017]

[0018] where D is a non-zero constant.

[0019] As a preferred embodiment, the formula for calculating the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically:

[0020] I R (t) = I(t - t0) - CI c1 (t);

[0021] where I R (t) is the resistive component of the arrester leakage current, t0 is the characteristic time, I c1 (t) is the characteristic current signal, and C is the ratio of the leakage current signal to the amplitude of the characteristic current signal.

[0022] On the other hand, the present invention also proposes a system for extracting the resistive component of the arrester leakage current, including:

[0023] A signal acquisition module for synchronously acquiring the arrester leakage current signal and the system voltage signal for at least one cycle;

[0024] An operation module for performing Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal; constructing a characteristic function representing the capacitive current according to the system voltage decomposition signal; calculating the characteristic current signal based on the characteristic function representing the capacitive current, and calculating the ratio of the leakage current signal to the amplitude of the characteristic current signal, and the characteristic time when the amplitude of the leakage current signal leads the amplitude of the characteristic current signal;

[0025] An output module for calculating and outputting the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time.

[0026] As a preferred embodiment, in the operation module, the system voltage signal is decomposed by Fourier transform to obtain the system voltage decomposition signal, specifically by decomposing the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically:

[0027]

[0028] where k is the harmonic order, U k is the amplitude of each harmonic, ω is the fundamental angular frequency, is the initial phase angle of each harmonic.

[0029] As a preferred embodiment, in the operation module, constructing a characteristic function representing the capacitive current according to the system voltage decomposition signal is specifically:

[0030]

[0031] where D is a non-zero constant.

[0032] As a preferred embodiment, in the output module, the formula for calculating the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically:

[0033] I R (t) = I(t - t0) - CI c1 (t);

[0034] where I R (t) is the resistive component of the arrester leakage current, t0 is the characteristic time, I c1 (t) is the characteristic current signal, and C is the ratio of the leakage current signal to the amplitude of the characteristic current signal.

[0035] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method for extracting the resistive component of the arrester leakage current as described in any embodiment of the present invention.

[0036] On the other hand, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for extracting the resistive component of the arrester leakage current as described in any embodiment of the present invention.

[0037] The beneficial effects of the present invention are as follows:

[0038] The present invention constructs a characteristic function representing capacitive current based on the system voltage decomposition signal, which can accurately reflect the internal relationship between the capacitive current and the system voltage. Based on the characteristic function representing the capacitive current, the characteristic current signal is calculated, and further, the ratio of the leakage current signal to the amplitude of the characteristic current signal, and the characteristic time when the amplitude of the leakage current signal leads the amplitude of the characteristic current signal are calculated, so as to accurately calculate the resistive component of the arrester leakage current. This calculation method comprehensively considers various current characteristic parameters, and compared with the traditional method, can more effectively eliminate interference factors and improve the accuracy of resistive component extraction.

[0039] Additional aspects and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. In addition, the various aspects and advantages of the present invention may be realized and obtained by the method steps and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic flowchart of the method according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0042] It should be understood that the step numbers used herein are only for convenience of description and do not limit the execution order of the steps.

[0043] It should be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0044] The terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0045] The term "and / or" refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0046] Embodiment 1:

[0047] See Figure 1 , this embodiment provides a method for extracting the resistive component of the arrester leakage current, including the following steps:

[0048] S100. Synchronously collect the arrester leakage current signal and the system voltage signal for one cycle, and store them as arrays I[n] and U[n]. The preferred value of n is an integer power of 2;

[0049] S200. Apply the fast Fourier transform algorithm to perform Fourier decomposition on the system voltage signal U[n]. Specifically, decompose the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically:

[0050]

[0051] where k is the harmonic order, U k is the amplitude of each harmonic, ω is the fundamental angular frequency, is the initial phase angle of each harmonic.

[0052] Obtain the amplitudes U k of each harmonic and the initial phase angles of each harmonic, where k is the harmonic order;

[0053] S300. According to the obtained amplitudes U k of each harmonic and the initial phase angles of each harmonic, construct a characteristic function I c1 that characterizes the capacitive current.

[0054] S400. Calculate the characteristic current signal based on the characteristic function that characterizes the capacitive current, and obtain the characteristic array I c1 [n] of the capacitive current; and calculate the ratio C of the maximum value of the array I[n] to the maximum value of the array I c1 [n] as the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal;

[0055] Calculate the characteristic time t0 when the amplitude moment of I(t) leads the amplitude moment of I c1 (t), and cyclically shift the members of the array I c1 [n] to the same position as the maximum value of the array I[n] according to the characteristic time t;

[0056] S500. Calculate the resistive component of the arrester leakage current according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time.

[0057] As a preferred implementation manner of this embodiment, the construction of the characteristic function that characterizes the capacitive current according to the system voltage decomposition signal is specifically:

[0058]

[0059] Among them, D is a non-zero constant. When D is equal to 1, the characteristic function is:

[0060]

[0061] As a preferred implementation manner of this embodiment, the formula for calculating the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically:

[0062] I R (t) = I(t - t0) - CI c1 (t);

[0063] Among them, I R (t) is the resistive component of the arrester leakage current, t0 is the characteristic time, and I c1 (t) is the characteristic current signal, and C is the ratio of the leakage current signal to the amplitude of the characteristic current signal.

[0064] Embodiment 2:

[0065] This embodiment proposes a system for extracting the resistive component of the arrester leakage current, including:

[0066] A signal acquisition module, configured to synchronously acquire the arrester leakage current signal and the system voltage signal for at least one cycle; this module is used to implement the function of step S100 in Embodiment 1, which will not be elaborated here;

[0067] An operation module, configured to perform Fourier transform decomposition on the system voltage signal to obtain a system voltage decomposition signal; construct a characteristic function representing the capacitive current based on the system voltage decomposition signal; calculate a characteristic current signal based on the characteristic function representing the capacitive current, and calculate the ratio of the leakage current signal to the amplitude of the characteristic current signal, and the characteristic time when the amplitude moment of the leakage current signal leads the amplitude moment of the characteristic current signal; this module is used to implement the functions of steps S200 - S400 in Embodiment 1, which will not be elaborated here;

[0068] An output module, configured to calculate and output the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time; this module is used to implement the function of step S500 in Embodiment 1, which will not be elaborated here.

[0069] As a preferred implementation manner of this embodiment, in the operation module, performing Fourier transform decomposition on the system voltage signal to obtain a system voltage decomposition signal is specifically to decompose the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically:

[0070]

[0071] Among them, k is the harmonic order, Uk where \(A_n\) is the amplitude of each harmonic, \(\omega\) is the fundamental angular frequency, and \(\varphi_n\) is the initial phase angle of each harmonic.

[0072] As a preferred embodiment of this embodiment, in the operation module, the specific method for constructing a characteristic function representing capacitive current according to the system voltage decomposition signal is:

[0073]

[0074] where \(D\) is a non-zero constant.

[0075] As a preferred embodiment of this embodiment, in the output module, the formula for calculating the resistive component of the arrester leakage current according to the ratio of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically:

[0076] I R (t)=I(t - t0)-CI c1 (t);

[0077] where \(I R (t)\) is the resistive component of the arrester leakage current, \(t0\) is the characteristic time, \(I c1 (t)\) is the characteristic current signal, and \(C\) is the ratio of the leakage current signal to the amplitude of the characteristic current signal.

[0078] Embodiment 3:

[0079] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method for extracting the resistive component of the arrester leakage current as described in any embodiment of the present invention.

[0080] Embodiment 4:

[0081] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the method for extracting the resistive component of the arrester leakage current as described in any embodiment of the present invention.

[0082] In the embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent the situations of A existing alone, A and B existing simultaneously, and B existing alone. Wherein A and B may be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one of the following" and its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c may represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c may be single or plural.

[0083] Those of ordinary skill in the art can realize that the units and algorithm steps described in the embodiments disclosed herein can be implemented by a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present application.

[0084] 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 foregoing method embodiments and will not be elaborated herein.

[0085] In several embodiments provided by 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 such understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art or a part of this technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (hereinafter referred to as ROM), random access memories (hereinafter referred to as RAM), magnetic disks, or optical discs that can store program codes.

[0086] The above are only the embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for extracting the resistive component of the leakage current of a lightning arrester, characterized in that, It includes the following steps: Synchronously collect the arrester leakage current signal and the system voltage signal for at least one cycle; Perform Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal; Construct a characteristic function representing capacitive current based on the system voltage decomposition signal; Calculate the characteristic current signal based on the characteristic function representing capacitive current, and calculate the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal, as well as the characteristic time when the amplitude moment of the leakage current signal leads the amplitude moment of the characteristic current signal; Calculate the resistive component of the arrester leakage current according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time.

2. The method for extracting the resistive component of the leakage current of a lightning arrester according to claim 1, wherein, The specific process of performing Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal is to decompose the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically: where k is the harmonic order, U k is the amplitude of each harmonic, ω is the fundamental angular frequency, and is the initial phase angle of each harmonic.

3. A method for extracting the resistive component of the leakage current of a lightning arrester according to claim 2, characterized in that, The specific process of constructing a characteristic function representing capacitive current based on the system voltage decomposition signal is: where D is a non-zero constant.

4. A method for extracting the resistive component of the leakage current of a lightning arrester according to claim 1, characterized in that, The formula for calculating the resistive component of the arrester leakage current according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically: I R I(t) = I(t - t0) - CI c1 I(t); Among them, I R (t) is the resistive component of the arrester leakage current, t0 is the characteristic time, I c1 (t) is the characteristic current signal, and C is the ratio of the leakage current signal to the amplitude of the characteristic current signal.

5. A system for extracting the resistive component of the leakage current of a lightning arrester, characterized in that, It includes: A signal acquisition module for synchronously collecting the arrester leakage current signal and the system voltage signal for at least one cycle; An operation module for performing Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal; constructing a characteristic function representing capacitive current based on the system voltage decomposition signal; calculating the characteristic current signal based on the characteristic function representing capacitive current, and calculating the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal, as well as the characteristic time when the amplitude moment of the leakage current signal leads the amplitude moment of the characteristic current signal; An output module for calculating and outputting the resistive component of the arrester leakage current according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time.

6. The extraction system for the resistive component of the lightning arrester leakage current according to claim 1, characterized in that In the operation module, the specific process of performing Fourier transform decomposition on the system voltage signal to obtain the system voltage decomposition signal is to decompose the system voltage signal into the sum of the fundamental wave and higher harmonics, specifically: where k is the harmonic order, U k is the amplitude of each harmonic, ω is the fundamental angular frequency, is the initial phase angle of each harmonic.

7. An extraction system for the resistive component of the leakage current of a lightning arrester according to claim 6, characterized in that, In the operation module, the specific process of constructing a characteristic function representing capacitive current based on the system voltage decomposition signal is: where D is a non-zero constant.

8. An extraction system for the resistive component of the leakage current of a lightning arrester according to claim 5, characterized in that In the output module, the formula for calculating the resistive component of the arrester leakage current according to the ratio of the amplitude of the leakage current signal to the amplitude of the characteristic current signal and the characteristic time is specifically: I R I(t) = I(t - t0) - CI c1 I(t); Among them, I R (t) is the resistive component of the arrester leakage current, t0 is the characteristic time, I c1 (t) is the characteristic current signal, and C is the ratio of the leakage current signal amplitude to the characteristic current signal amplitude.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method for extracting the resistive component of the arrester leakage current according to any one of claims 1 to 4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method for extracting the resistive component of the arrester leakage current according to any one of claims 1 to 4.

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