A method and system for filtering out singular points of partial discharge signals

Abstract

The present invention discloses a method and system for filtering out singular points of partial discharge signals, comprising: obtaining a partial discharge signal sequence; obtaining the median, lower quartile and upper quartile of the partial discharge signal sequence; obtaining the average value and standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile, judging the interval distribution between the upper quartile and the lower quartile according to the average value, standard deviation and median, and updating the upper quartile and the lower quartile according to the judgment result; obtaining the upper threshold value and the lower threshold value according to the updated lower quartile and upper quartile, and determining the singular points to be filtered out. Aiming at the problem of collecting an indefinite number of extreme values ​​when sampling partial discharge data, the problem of extreme value data affecting the accuracy of selecting valid data segments is effectively solved by updating the positions of the upper and lower quartiles of the quartile method.

Description

Technical Field

[0001] The present invention relates to the technical field of partial discharge processing, and in particular to a method and system for filtering singular points of partial discharge signals. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] High-voltage cables are used as energy transmission media in power systems. Air gaps and harmful impurities often exist in the insulation structure due to difficulties in processing technology or impure raw materials. Local discharge is very likely to occur at the tips of these air gaps and impurities. Partial discharge is the main manifestation of early insulation failure in high-voltage cable lines. It is not only the main cause of insulation aging, but also the main characteristic parameter to characterize the insulation condition. In order to accurately analyze and identify insulation defects in cable lines and accessories, it is necessary not only to accurately measure high-frequency partial discharge signals, but also to effectively identify and filter out singular points caused by interference from the surrounding environment.

[0004] However, since the local discharge signal will collect different amounts of extreme data during the sampling process, and a single sampling with a large amount of extreme data will cause the quartile interval divided by the quartile method to be inaccurate, and if the quartile interval is inaccurate, it will affect the determination of the upper and lower thresholds for singular point filtering, leading to misjudgment of singular points. In addition, when the local discharge signal obeys characteristics such as bimodal distribution, filtering out singular points may cause the local discharge signal to lose some of its original characteristics, affecting the integrity of the local discharge signal. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a method and system for filtering singular points of partial discharge signals. In view of the problem of collecting an indefinite number of extreme values ​​when sampling partial discharge data, the upper and lower quartiles of the quartile method are updated to effectively solve the problem that extreme value data affects the accuracy of selecting valid data segments.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for filtering singular points of a partial discharge signal, comprising:

[0008] Acquiring a partial discharge signal sequence;

[0009] Obtain the median, lower quartile and upper quartile of the partial discharge signal sequence;

[0010] The average value and standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile are calculated, and the interval distribution between the upper quartile and the lower quartile is determined according to the average value, standard deviation and median, and the upper quartile and the lower quartile are updated according to the determination result;

[0011] According to the updated lower quartile and upper quartile, the upper threshold value and the lower threshold value are obtained, and the singular points to be filtered out are determined accordingly.

[0012] As an optional implementation, the process of determining the interval distribution between the upper quartile and the lower quartile includes:

[0013] If |bM|≤δ, the interval between the upper quartile and the lower quartile is evenly distributed;

[0014] If bM>δ, the interval distribution between the upper quartile and the lower quartile is uneven, the median is close to the lower quartile, and the upper quartile and the lower quartile are updated;

[0015] If bM<-δ, the interval distribution between the upper quartile and the lower quartile is uneven, and the median is close to the upper quartile; update the upper quartile and the lower quartile;

[0016] Among them, b is the median, M is the mean, and δ is the standard deviation.

[0017] As an optional implementation, the specific process of updating the upper quartile and the lower quartile includes:

[0018] When the median is close to the lower quartile, both the upper and lower quartiles are moved forward by 1 position;

[0019] When the median is close to the upper quartile, both the upper and lower quartiles are moved back by 1 position;

[0020] Until |bM|≤δ is satisfied or the maximum number of iterations is reached.

[0021] As an optional implementation, the upper threshold value is: c+(ca)*3; the lower threshold value is: a-(ca)*3;

[0022] Among them, a is the lower quartile, b is the median, and c is the upper quartile.

[0023] As an optional implementation, the process of determining the singular point is that if the digital value of the partial discharge signal is greater than an upper threshold value or less than a lower threshold value, the location of the digital value of the partial discharge signal is the singular point.

[0024] As an optional implementation, the method for filtering out singular points of partial discharge signals further includes:

[0025] Initialize the singularity counter and set the value of the singularity counter to zero;

[0026] After determining the singularity points according to the upper threshold value and the lower threshold value, increment the value of the singularity counter by 1;

[0027] Judge whether to filter out the singularity points according to the comparison result between the value of the singularity counter and the number of partial discharge signals.

[0028] As an alternative implementation, if the value n of the singularity counter and the number N of partial discharge signals satisfy n < N * 10%, then filter out the singularity points; otherwise, retain the singularity points.

[0029] In a second aspect, the present invention provides a system for filtering singularity points of partial discharge signals, including:

[0030] A partial discharge acquisition module configured to obtain a partial discharge signal sequence;

[0031] A quartile division module configured to obtain the median, the lower quartile, and the upper quartile of the partial discharge signal sequence;

[0032] An update module configured to calculate the average value and the standard deviation of the digital quantity of the partial discharge signals between the upper quartile and the lower quartile, judge the interval distribution between the upper quartile and the lower quartile according to the average value, the standard deviation, and the median, and update the upper quartile and the lower quartile according to the judgment result;

[0033] A singularity point determination module configured to obtain the upper threshold value and the lower threshold value according to the updated lower quartile and upper quartile, and determine the singularity points to be filtered out based on this.

[0034] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in the first aspect is completed.

[0035] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the method described in the first aspect is completed.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] The present invention provides a method and a system for filtering singularity points of partial discharge signals. Aiming at the problem of collecting an indefinite number of extreme values when sampling partial discharge data, the positions of the upper and lower quartiles of the quartile method are updated, which can effectively solve the problem that the extreme value data affects the accuracy of selecting the effective data segment.

[0038] The present invention provides a method and system for filtering singular points of a partial discharge signal, which can judge the validity of the singular points based on the number of singular points and the number of discharge data, and can retain the original characteristics of the partial discharge to the maximum extent.

[0039] The present invention provides an adaptive high-frequency partial discharge signal singular point filtering method. For the singular points generated by interference in different environments, different parameters or thresholds can be adaptively adjusted according to different environments without targeting specific scenes, so as to achieve adaptation to different environments. The method has good filtering effect, simple algorithm, small memory occupation and high processing efficiency, and can achieve real-time online processing of multiple terminals.

[0040] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0042] Figure 1 This is a schematic diagram of a method for filtering singular points of partial discharge signals provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0044] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0045] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0047] Example 1

[0048] like Figure 1 As shown, this embodiment provides a method for filtering singular points of partial discharge signals, comprising:

[0049] S1: Acquire partial discharge signal sequence;

[0050] S2: Get the median, lower quartile and upper quartile of the partial discharge signal sequence;

[0051] S3: Calculate the average value and standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile, determine the interval distribution between the upper quartile and the lower quartile according to the average value, standard deviation and median, and update the upper quartile and the lower quartile according to the determination result;

[0052] S4: According to the updated lower quartile and upper quartile, an upper threshold value and a lower threshold value are obtained, and singular points to be filtered out are determined accordingly.

[0053] In this embodiment, step S1 includes: acquiring a high-frequency partial discharge signal; and sorting the high-frequency partial discharge signals of a single channel in ascending order to obtain a high-frequency partial discharge signal sequence.

[0054] Specifically:

[0055] S1-1: Setting parameters for a partial discharge acquisition terminal, so that the partial discharge acquisition terminal acquires high-frequency partial discharge signals;

[0056] In this embodiment, the parameter equipment includes: terminal number, channel trigger threshold, cumulative number of reports, working mode, etc.

[0057] In this embodiment, the partial discharge acquisition terminal supports the synchronous acquisition of three 100M high-frequency signals and one industrial frequency phase signal.

[0058] In this embodiment, the background data processing module verifies the numbers of the partial discharge acquisition terminals, and the partial discharge acquisition terminals with registered numbers can log in normally and complete subsequent partial discharge acquisition services.

[0059] As an optional implementation method, the background data processing module can also manage the partial discharge acquisition terminal, including: login verification, parameter configuration, connection control, acquisition control, singular point filtering and data storage.

[0060] S1-2: The PD acquisition terminal acquires and reports high-frequency PD signals by means of timing triggering or threshold triggering;

[0061] In this embodiment, in the partial discharge acquisition terminal, a channel trigger threshold is preset, and the channel trigger threshold is used as a trigger condition. If a channel is triggered, the partial discharge acquisition terminal will synchronously collect signals from all channels once; when the cumulative number exceeds the preset cumulative reporting number threshold, a trigger report is performed; if all channels are not triggered or the number of triggered items does not exceed the trigger reporting number within a period of time, a timed reporting method is adopted.

[0062] In this embodiment, the acquisition frequency of a single high-frequency partial discharge signal acquisition channel of the partial discharge acquisition terminal is 100M, so the time difference between two consecutive acquisition values ​​is 1 / 100M=10 nanoseconds.

[0063] In this embodiment, the partial discharge acquisition terminal continuously collects 5 microseconds of data from three high-frequency signal acquisition channels and one power frequency phase channel, and uploads the data as a packet of discharge data, wherein the number of data points is: 5*1000 / 10=500 points.

[0064] In this embodiment, the partial discharge acquisition terminal continuously acquires multiple discharge data to form a complete partial discharge signal acquisition; and the number of acquisitions is limited by the "accumulated number of reports".

[0065] In this embodiment, a complete frame of high-frequency partial discharge signal data represents discharge data synchronously collected by multiple channels after a threshold is triggered.

[0066] S1-3: Sort the high-frequency partial discharge signals of a single channel in ascending order from small to large to obtain a partial discharge signal sequence, which is AD[1] to AD[N], where N is the number of discharge data and has a value range of [1,500].

[0067] In this embodiment, in step S2, the specific process of obtaining the median, upper quartile and lower quartile of the partial discharge signal sequence is:

[0068] The median b is: the AD value corresponding to the position of (1+N) / 2;

[0069] The lower quartile a is: the AD value corresponding to the position of (1+N) / 4;

[0070] The upper quartile c is: the AD value corresponding to the position of (1+N) / 4*3.

[0071] As an optional implementation, the above division operation needs to be rounded off.

[0072] In this embodiment, in step S3, the average value M and the standard deviation δ of the digital quantity of the partial discharge signal between the upper quartile c and the lower quartile a are calculated, and whether the interval distribution between the upper quartile c and the lower quartile a is balanced is judged according to the average value M, the standard deviation δ and the median b, and the upper quartile c and the lower quartile a are iteratively updated according to the judgment result to correct the positions of the upper quartile c and the lower quartile a;

[0073] in,

[0074] Specifically, (1) when |bM|≤δ, it means that the upper quartile c and the lower quartile a are evenly distributed, and the current upper quartile c and the lower quartile a can accurately filter out singular points;

[0075] (2) When bM>δ, it means that the median b is closer to the lower quartile a;

[0076] (3) When bM<-δ, it means that the median b is closer to the upper quartile c.

[0077] When situation (2-3) occurs, it means that the current distribution of the upper quartile c and the lower quartile a is unbalanced, and the position of the distribution of the upper quartile c and the lower quartile a needs to be corrected.

[0078] In this embodiment, in step S3, the specific process of updating the upper quartile and the lower quartile includes:

[0079] (1) When the median b is closer to the lower quartile a, the positions of the upper quartile c and the lower quartile a are both moved forward by 1, and the values ​​of the lower quartile a, median b, and upper quartile c are updated at the same time;

[0080] (2) When the median b is closer to the upper quartile c, the positions of the upper quartile c and the lower quartile a are both moved backward by 1, and the values ​​of the lower quartile a, median b, and upper quartile c are updated at the same time;

[0081] (3) Set the maximum number of iterations until |bM|≤δ or the maximum number of iterations is reached, then exit the iteration loop and complete the update of the positions of the upper quartile c and the lower quartile a.

[0082] Since the partial discharge data will collect different amounts of extreme data during the sampling process, and when the amount of extreme data is large in a single sampling, the effect of the quartile method will deteriorate, affecting the effectiveness of the singular point filtering threshold. Therefore, in response to this problem, this embodiment corrects the quartile method, and by iteratively updating and correcting the positions of the upper quartile c and the lower quartile a, the purpose of extracting the effective upper and lower quartile intervals can be achieved, so that the calculated upper and lower limits of the threshold can more accurately filter out singular points.

[0083] In this embodiment, in step S4, according to the updated lower quartile a and upper quartile c, the upper threshold value and the lower threshold value of the partial discharge signal sequence are obtained. The specific process is as follows:

[0084] The upper threshold value is: c+(c - a)*3;

[0085] The lower threshold value is: a–(c - a)*3.

[0086] In this embodiment, the method for filtering singular points of the partial discharge signal further includes:

[0087] Initialize the singular point counter, and set the singular point counter, i.e., n = 0;

[0088] After determining the singular points according to the upper threshold value and the lower threshold value, increment the singular point counter n by 1;

[0089] Compare the singular point counter n with the number of discharge data N. If n < N*10%, filter the singular points and output the result; otherwise, retain the singular points and output the result.

[0090] As an alternative embodiment, if the AD value is greater than the upper threshold value or the AD value is less than the lower threshold value, the position where the AD value is located is a singular point.

[0091] As an alternative embodiment, the actual value of the singular point is the value of the previous 1 point.

[0092] As an alternative embodiment, if the first point is a singular point, take the mean value of the valid data of this discharge as the value of the first point. The valid data refers to the values corresponding to non-singular points.

[0093] Although the above filtering method can effectively filter the singular points in the signal, when the partial discharge signal follows characteristics such as a bimodal distribution, this filtering method may lose some of the original characteristics of the signal. Therefore, in this embodiment, an analysis and judgment on the effectiveness of the singular points is carried out to maximize the retention of the original characteristics of the partial discharge.

[0094] In this embodiment, the partial discharge signal data after filtering the singular points is stored to provide basic data for subsequent analysis and processing.

[0095] Embodiment 2

[0096] This embodiment provides a system for filtering singular points of a partial discharge signal, including:

[0097] A partial discharge acquisition module configured to obtain a partial discharge signal sequence;

[0098] A quartile division module is configured to obtain a median, a lower quartile, and an upper quartile of a partial discharge signal sequence;

[0099] An updating module is configured to obtain an average value and a standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile, determine the interval distribution between the upper quartile and the lower quartile according to the average value, the standard deviation and the median, and update the upper quartile and the lower quartile according to the determination result;

[0100] The singular point determination module is configured to obtain an upper threshold value and a lower threshold value according to the updated lower quartile and upper quartile, and thereby determine the singular point to be filtered out.

[0101] It should be noted that the above modules correspond to the steps described in Example 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the contents disclosed in the above Example 1. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer executable instructions.

[0102] In further embodiments, there is also provided:

[0103] An electronic device includes a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method described in Embodiment 1 is performed. For the sake of brevity, it will not be described in detail here.

[0104] It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0105] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0106] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the method described in Example 1 is completed.

[0107] The method in Example 1 can be directly embodied as a hardware processor, or a combination of hardware and software modules in the processor. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it is not described in detail here.

[0108] Those skilled in the art will appreciate that the units, i.e., algorithm steps, of the various examples described in conjunction with this embodiment can be implemented in electronic hardware or in a combination of 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.

[0109] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for filtering singular points of partial discharge signals, characterized in that: include: Acquiring a partial discharge signal sequence; Obtain the median, lower quartile and upper quartile of the partial discharge signal sequence; The average value and standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile are calculated, and the interval distribution between the upper quartile and the lower quartile is determined according to the average value, standard deviation and median, and the upper quartile and the lower quartile are updated according to the determination result; The quartile method is modified by iteratively updating the positions of the upper and lower four scores; The specific process of updating the upper quartile and the lower quartile includes: (1) When the median is closer to the lower quartile, the positions of the upper quartile and the lower quartile are moved forward by 1, and the values ​​of the lower quartile, median, and upper quartile are updated at the same time; (2) When the median is closer to the upper quartile, the upper quartile and the lower quartile are both moved back by 1, and the values ​​of the lower quartile, median, and upper quartile are updated at the same time; (3) Set the maximum number of iterations until Or when the maximum number of iterations is reached, exit the iteration loop and complete the update of the upper quartile and lower quartile positions; According to the updated lower quartile and upper quartile, the upper threshold value and the lower threshold value are obtained, and the singular points to be filtered out are determined accordingly; The process of determining the interval distribution between the upper quartile and the lower quartile includes: like , then the interval distribution between the upper quartile and the lower quartile is balanced; like , then the interval distribution between the upper quartile and the lower quartile is uneven, the median is close to the lower quartile, and the upper quartile and the lower quartile are updated; like , the interval distribution between the upper quartile and the lower quartile is uneven, and the median is close to the upper quartile; update the upper quartile and the lower quartile; Among them, b is the median, M is the mean, is the standard deviation.

2. A method for filtering singular points of partial discharge signals as claimed in claim 1, characterized in that: The upper threshold value is: c + (c - a) * 3; the lower threshold value is: a - (c - a) * 3; Among them, a is the lower quartile, b is the median, and c is the upper quartile.

3. A method for filtering singular points of partial discharge signals as claimed in claim 1, characterized in that: The process of determining the singular point is that if the digital value of the partial discharge signal is greater than the upper threshold value or less than the lower threshold value, the location of the digital value of the partial discharge signal is the singular point.

4. A method for filtering singular points of partial discharge signals as claimed in claim 1, characterized in that: The method for filtering out singular points of partial discharge signals also includes: Initialize the singular point counter and set the value of the singular point counter to zero; After the singular point is determined according to the upper threshold value and the lower threshold value, the value of the singular point counter is increased by 1; According to the comparison result between the value of the singular point counter and the number of partial discharge signals, it is determined whether to filter out the singular point.

5. A method for filtering singular points of partial discharge signals as claimed in claim 4, characterized in that: If the value n of the singular point counter and the number N of partial discharge signals satisfy n < N * 10%, the singular point is filtered out, otherwise the singular point is retained.

6. A partial discharge signal singular point filtering system, characterized in that: include: A partial discharge acquisition module is configured to acquire a partial discharge signal sequence; A quartile division module is configured to obtain a median, a lower quartile, and an upper quartile of a partial discharge signal sequence; An updating module is configured to obtain an average value and a standard deviation of the digital quantity of the partial discharge signal between the upper quartile and the lower quartile, determine the interval distribution between the upper quartile and the lower quartile according to the average value, the standard deviation and the median, and update the upper quartile and the lower quartile according to the determination result; The quartile method is modified by iteratively updating the positions of the upper and lower four scores; The specific process of updating the upper quartile and the lower quartile includes: (1) When the median is closer to the lower quartile, the positions of the upper quartile and the lower quartile are moved forward by 1, and the values ​​of the lower quartile, median, and upper quartile are updated at the same time; (2) When the median is closer to the upper quartile, the upper quartile and the lower quartile are both moved back by 1, and the values ​​of the lower quartile, median, and upper quartile are updated at the same time; (3) Set the maximum number of iterations until Or when the maximum number of iterations is reached, exit the iteration loop and complete the update of the upper quartile and lower quartile positions; A singular point determination module is configured to obtain an upper threshold value and a lower threshold value according to the updated lower quartile and upper quartile, and thereby determine the singular point to be filtered out; The process of determining the interval distribution between the upper quartile and the lower quartile includes: like , then the interval distribution between the upper quartile and the lower quartile is balanced; like , then the interval distribution between the upper quartile and the lower quartile is uneven, the median is close to the lower quartile, and the upper quartile and the lower quartile are updated; like , the interval distribution between the upper quartile and the lower quartile is uneven, and the median is close to the upper quartile; update the upper quartile and the lower quartile; Among them, b is the median, M is the mean, is the standard deviation.

7. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method according to any one of claims 1 to 5 is completed.

8. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the method described in any one of claims 1 to 5.

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