CN117269703B - Screening method for measuring partial discharge signals by ultra-high frequency method - Google Patents
Screening method for measuring partial discharge signals by ultra-high frequency method Download PDFInfo
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- 238000005259 measurement Methods 0.000 abstract description 5
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The invention discloses a screening method for measuring partial discharge signals by an ultrahigh frequency method, which comprises the steps of setting a plurality of main window areas for receiving signals converted into digital signals, wherein each main window area is divided into a front fixed window, a main fixed window and a rear fixed window, and two adjacent main window areas are partially overlapped; a sliding window is arranged in each main window area; screening the data in the window by single pulse peak value, and screening the screened data as partial discharge signals if the absolute value of the difference value between the screened data and other data in the sliding window is larger than ERR when the screened data moves to the middle position of the sliding window; based on the different characteristics of the partial discharge signal and the communication modulation signal under the excitation of the power frequency voltage source, the invention sets a plurality of partially overlapped main window areas aiming at the received signal converted into the digital signal, sets a sliding window in each main window area, screens out the partial discharge signal by combining a single-pulse peak screening mode, reduces the cost of a test system and can accurately filter out the communication modulation signal interference in the partial discharge measurement process.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a screening method for measuring partial discharge signals by an ultrahigh frequency method.
Background
The ultra-high frequency method (UHF method) is to receive the ultra-high frequency electromagnetic wave radiated in the partial discharge process through an ultra-high frequency signal sensor, so as to realize the detection of the partial discharge.
In the process of measuring the partial discharge signal by using the power frequency power supply as an excitation source by the ultra-high frequency method, the frequency range, the amplitude range and the waveform of the partial discharge signal are similar to those of the communication modulation signal in the space, and the frequency band of the communication modulation signal in the space is wide, so that the partial discharge signal and the spatial modulation signal are difficult to identify by the traditional filtering measure.
In the prior art, as shown in fig. 1, a physical shielding method is used to separate a communication modulation signal E from a partial discharge signal D, so that a receiving antenna can only receive the partial discharge signal, and the specific scheme is as follows: and placing the sample A and the receiving antenna B in the shielding shell C to completely isolate the sample A and the receiving antenna B from the outside, and after the power frequency high voltage is applied to the sample, receiving the generated partial discharge signal D by the receiving antenna, and converting the partial discharge signal D into digital quantity through the logarithmic detector and the analog-to-digital converter to be input into the FPGA. However, the shielding shell has high cost and large volume, high pressure is applied to the inside of the shielding shell to cause potential safety hazard, and the volume of the sample cannot exceed the allowable size of the shielding shell.
Disclosure of Invention
The invention aims to provide a screening method for measuring partial discharge signals by an ultrahigh frequency method, which cancels the existing mode of dividing communication modulation signals and partial discharge signals by adopting physical shielding, receives mixed signals containing the communication modulation signals and partial discharge signals of a sample through an ultrahigh frequency antenna, screens out the partial discharge signals by adopting a single-pulse peak screening mode, reduces the cost of a test system and can accurately filter out communication modulation signal interference in the partial discharge measurement process.
The invention is realized by adopting the following technical scheme:
the screening method for measuring partial discharge signals by an ultrahigh frequency method comprises the following steps:
s1, setting a plurality of main window areas for a received signal converted into a digital signal, wherein each main window area is divided into a front fixed window, a main fixed window and a rear fixed window; the adjacent two main window areas are partially overlapped, so that the main fixed window of the next main window area is continuous with the main fixed window of the previous main window area in front and back; the window length of the front fixed window is equal to that of the rear fixed window;
s2, setting a sliding window with the length of 2LA-1 in each main window area; LA is the window length of the front/rear fixed window;
s3, when the main window area is activated, screening single pulse peak values of data in the window;
and S4, when the screened data moves to the middle position of the sliding window, screening the data to be a partial discharge signal if the absolute values of the difference values of the screened data and other data in the sliding window are larger than ERR.
In some embodiments of the present invention, the window length of the pre/post fixed window is greater than the time interval between two adjacent pulses of the same group of communication modulated signals.
In some embodiments of the present invention, the window length of the main fixed window is set according to the display resolution, so that at least one pixel point can display whether partial discharge occurs in the corresponding time range of the main fixed window.
In some embodiments of the present invention, the single pulse peak screening of the data in the window in S3 includes:
s31, setting a single-pulse peak value register MaxImp to be in a reset state;
s32, entering a screening state when the digital quantity input value Ui (k) is larger than a set threshold value TH;
s33, in the screening state, assigning Ui (k) to MaxImp if and only if Ui (k) > MaxImp;
s34, when Ui (k) is less than or equal to TH, the state is switched to an end state, the current MaxImp value is recorded in a main window history peak register, and S31 is returned.
Compared with the prior art, the invention has the advantages and positive effects that: the screening method for measuring the partial discharge signals by the ultra-high frequency method is based on the different characteristics of the partial discharge signals and the communication modulation signals under the excitation of a power frequency voltage source, a plurality of partially overlapped main window areas are arranged for the received signals converted into the digital signals, sliding windows are arranged in each main window area, the partial discharge signals are screened out by combining a single-pulse peak screening mode, the cost of a testing system is reduced, and meanwhile, the communication modulation signal interference in the partial discharge measurement process can be accurately filtered.
Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention, without limitation to the invention. It is evident that the figures in the following description are only examples, from which other figures can be obtained, without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a measurement structure for measuring partial discharge signals by using an existing ultra-high frequency method;
FIG. 2 is a schematic diagram of a measurement structure for measuring partial discharge signals by an ultra-high frequency method according to the present invention;
FIG. 3 is a schematic illustration of received clutter signals when partial discharge signals are measured using an ultra-high frequency method;
FIG. 4 is a schematic diagram of the steps performed in the screening method for measuring partial discharge signals by the ultra-high frequency method according to the present invention;
FIG. 5 is a schematic view of the structure of the main window area in the present invention;
FIG. 6 is a schematic view of a main window area and a sliding window structure according to the present invention;
FIG. 7 is a single pulse peak screening status schematic in accordance with the present invention;
FIG. 8 is a schematic illustration of a single pulse peak screening step in accordance with the present invention;
FIG. 9 is a schematic illustration of screening of communication modulated signals in a sliding window;
FIG. 10 is an illustration of partial discharge signal screening within a sliding window;
fig. 11 is an illustration of single pulse peak data screening within a sliding window.
It should be noted that these drawings and the written description are not intended to limit the scope of the inventive concept in any way, but to illustrate the inventive concept to those skilled in the art by referring to the specific embodiments.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention, and the following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.
The communication modulation signal E and the partial discharge signal D are difficult to distinguish in frequency amplitude, but the occurrence frequencies of the communication modulation signal E and the partial discharge signal D are obviously different under the excitation of a power frequency voltage source. The communication modulation signal E is represented in shape as a single-peak pulse signal, and the communication modulation signal E always appears in groups, as shown in fig. 2, that is, the frequency of occurrence is more in a certain time range, the peak value of each pulse in the time range is less different, and the maximum between the maximum value and the minimum value of the single-pulse peak values appearing in the same group does not exceed the tolerance ERR. The partial discharge signal D under the power frequency excitation does not have the characteristics.
Based on the above-mentioned thought, the invention provides a screening method for measuring partial discharge signals by an ultra-high frequency method, which cancels the existing mode of dividing communication modulation signals E and partial discharge signals D by adopting physical shielding, as shown in fig. 3, the partial discharge signals D of a sample A excited by a power frequency voltage source are mixed with the communication modulation signals E to be received by an ultra-high frequency receiving antenna B, the ultra-high frequency small signals are converted into voltage signals which can be received by an analog-to-digital converter (ADC, analog to Digital Convertor) through a logarithmic detector, the synchronous clock period of the digital output of the ADC is CLK, and after the digital output of the analog-to-digital converter is input into a field programmable logic gate array (FPGA, field Programmable Gate Array), the FPGA performs further screening processing, retains the partial discharge signals D, and shields or eliminates the communication modulation signals E.
The specific screening method, as shown in fig. 4, includes:
s1: setting a plurality of main window areas, wherein each main window area is divided into a front fixed window, a main fixed window and a rear fixed window; the adjacent two main window areas are partially overlapped, so that the main fixed window of the next main window area is continuous with the main fixed window of the previous main window area in front and back; the window length of the front fixed window is equal to that of the rear fixed window, denoted as LA, (unit: CLK) and is greater than the time interval between two adjacent pulses of the same group of communication modulation signals.
As shown in fig. 5 and 6, windowing is performed on the input digital quantity in the FPGA by taking time as a horizontal axis, and a plurality of main window areas are adjacently arranged, wherein each main window area is divided into a front fixed window, a main fixed window and a rear fixed window; the adjacent two main window areas are partially overlapped, and the overlapping condition is that the main fixed window of the next main window area is continuous with the main fixed window of the previous main window area, and as shown in the figure, the main fixed window of the A1 main window area is adjacent to the main fixed window of the A2 main window area in front and back.
The front fixed window is arranged to avoid misjudging the communication modulation signal E as the partial discharge signal D when the test is started, and the rear fixed window is arranged to misjudging the communication modulation signal E as the partial discharge signal D when the test is ended.
The window lengths of the front fixed window and the rear fixed window are equal, denoted as LA (unit: CLK), and the length is larger than the time interval between two adjacent pulses of the same group of communication modulation signals E, so that the communication modulation signals E are in the screening range when the single pulse peak screening of the partial discharge signals D is carried out later.
The window length of the main fixed window is LM (unit: CLK); the length of the main fixed window LM depends on the resolution of the user display, and the higher the display resolution is, the smaller the window length of the main fixed window is, specifically, for example, the time of power frequency sine excitation is Xms, and assuming that Y pixel points are located on the horizontal axis under the applicable display resolution, the corresponding time length of each point in the Y pixel points is Xms/Y, and only one pixel can display whether partial discharge occurs in the time of Xms/Y. That is, in the present application, the length of the main window area describes a time range that at least one pixel point on the display interface can be represented, and by screening the single pulse peak value in the main window area, the partial discharge that does not occur in the time period is displayed by using at least one pixel point.
S2: a sliding window of length 2LA-1 is provided in each main window area.
The specific hardware structure is a shift register with depth of 2LA-1, which is marked as SR [0 ]: 2LA-1], in which the sliding window slides when the main window area is activated, as shown in fig. 6.
S3: and when the main window area is activated, single pulse peak screening is carried out on the data in the window.
The main window regions may be activated sequentially one by one, or may be activated sequentially in a group (comprising at least two adjacent main window regions).
The state transition diagram for single pulse peak screening is shown in fig. 7: in the reset state (IDLE), the single-pulse peak register MaxImp is in the reset state, and enters the screening state (FILTER) after the digital quantity input value Ui (k) is greater than the set threshold TH, in which state, as shown in connection with fig. 8, maximp=ui (k) if and only if Ui (k) > MaxImp; in the FILTER state and when Ui (k) is less than or equal to TH, the state is switched to an END state (END), the MaxImp value at the moment is recorded in the history peak registers HisPeak_A1 and HisPeak_A2 of the main window, and the state is returned to an IDLE state after the state is switched to the END state depending on the main window area activated at the moment; the value in the main window history peak register is reset when the corresponding main window is disabled.
S4: when the screened data moves to the middle position of the sliding window, if the absolute values of the differences between the screened data and other data in the sliding window are larger than the tolerance ERR, screening the screened data as partial discharge signal peak value information.
As shown in fig. 9 to 11, when the output value hispeak_a1 (A2) moves to the middle position of the sliding window, that is, SR [ LA ] =hispeak_a1 (A2), as shown in fig. 10, if the absolute values of the differences between the data in SR [ 0:la-1 ] and SR [ la+1:2 LA-1] and SR [ LA ] are both greater than the tolerance ERR, as shown in fig. 11, the data in SR [ LA ] is the partial discharge signal D, and if the absolute values of the differences between the data in SR [ 0:la-1 ] and SR [ la+1:2 LA-1] and SR [ LA ] are both within the tolerance ERR, as shown in fig. 9, the data in SR [ LA ] is the communication modulation signal E.
It can be seen that the present invention aims to screen the maximum peak partial discharge signal D from the communication modulation signals E appearing in groups in a single pulse screening manner, and thus, the depth setting of 2LA-1 is such that the first data after the front fixed window and the last data before the rear fixed window in one main window area can be moved to the middle position of the sliding window, so that the data can be screened by the sliding window. Therefore, the main fixed window of the next main window area and the main fixed window of the previous main window area defined in the step S1 are continuously arranged in order to ensure the data allowance in the sliding window, and ensure that effective data exists in SR [ 0:LA-1 ] and SR [ LA+1:2LA-1 ] to ensure screening.
It should be noted that, in the specific implementation process, the control portion is implemented by a computer execution instruction in a software form stored in the FPGA execution memory, which is not repeated herein, and the program corresponding to the action executed by the control circuit may be stored in a software form in an FPGA readable storage medium of the system, so that the FPGA may call and execute the operations corresponding to the above modules.
The computer readable storage medium above may include volatile memory, such as random access memory; but may also include non-volatile memory such as read-only memory, flash memory, hard disk, or solid state disk; combinations of the above types of memories may also be included.
The processor referred to above may be a general term for a plurality of processing elements. For example, the processor may be a central processing unit, or may be other general purpose processors, digital signal processors, application specific integrated circuits, field programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or may be any conventional processor or the like, but may also be a special purpose processor.
It should be noted that the above description is not intended to limit the invention, but rather the invention is not limited to the above examples, and that variations, modifications, additions or substitutions within the spirit and scope of the invention will be within the scope of the invention.
Claims (3)
1. The screening method for measuring partial discharge signals by using an ultrahigh frequency method is characterized by comprising the following steps of:
s1, setting a plurality of main window areas for a received signal converted into a digital signal, wherein each main window area is divided into a front fixed window, a main fixed window and a rear fixed window; the adjacent two main window areas are partially overlapped, so that the main fixed window of the next main window area is continuous with the main fixed window of the previous main window area in front and back; the window length of the front fixed window is equal to that of the rear fixed window;
s2, setting a sliding window with the length of 2LA-1 in each main window area; LA is the window length of the front/rear fixed window;
s3, when the main window area is activated, single pulse peak value screening is carried out on the data in the window, and the method comprises the following steps: when in a reset state, the single-pulse peak value register MaxImp is in a reset state, and enters a screening state after the digital quantity input value Ui (k) is larger than a set threshold value TH; in the screening state, maximp=ui (k) if and only if Ui (k) > MaxImp; when the Ui (k) is less than or equal to TH in the screening state, switching the state to an ending state, recording the MaxImp value in a main window history peak value register, and returning to a reset state; resetting the value in the history peak register of the main window when the corresponding main window area is disabled;
and S4, when the screened data moves to the middle position of the sliding window, screening the data to be a partial discharge signal if the absolute values of the difference values of the screened data and other data in the sliding window are larger than ERR.
2. The method of claim 1, wherein the window length of the pre/post fixed window is greater than the time interval between two adjacent pulses of the same group of communication modulated signals.
3. The screening method for measuring partial discharge signals by an ultrahigh frequency method according to claim 1, wherein the window length of the main fixed window is set according to the display resolution, so that at least one pixel point can display whether partial discharge occurs in the corresponding time range of the main fixed window.
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CN116298741A (en) * | 2023-03-14 | 2023-06-23 | 青岛艾诺仪器有限公司 | Insulator partial discharge detection method |
KR102547467B1 (en) * | 2022-12-23 | 2023-06-26 | 주식회사 솔라리치 | Distribution board with partial discharge diagnosis function using ultra high frequency signal |
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CN1834669A (en) * | 2006-04-19 | 2006-09-20 | 重庆大学 | On-line detecting and positioning device for local discharging of electrical insulated combined electrical appliance, and positioning method thereof |
CN110244199A (en) * | 2019-05-16 | 2019-09-17 | 上海金艺检测技术有限公司 | Partial discharge pulse's statistical method based on time domain reconstruction |
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