A method and device for extracting grounding grid signal

Abstract

The present invention provides a grounding grid signal extraction method and device, which relate to the field of signal processing. The method comprises: establishing a grounding grid current-carrying model, establishing its derivative waveforms of various orders through a magnetic field differential method, realizing a comb filter in the frequency domain by digital averaging, and filtering the measured signal to obtain an average result of the magnetic field differential output signal after filtering; if it is determined that the measured signal satisfies the magnetic field differential signal corresponding to each order derivative waveform, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then the measured signal is digitally accumulated and averaged; according to the average result of the magnetic field differential output signal after filtering and the result of the digital accumulated and averaged calculation, the signal is extracted. The device executes the above method. The grounding grid signal extraction method and device provided in the embodiment of the present invention can effectively extract the weak magnetic field signal of the grounding grid to improve the accuracy of the measurement system.

Description

Technical Field

[0001] The present invention relates to the technical field of signal processing, and in particular to a method and device for extracting grounding grid signals. Background Art

[0002] Power safety plays a pivotal role in the power industry. With the advancement of modern technology, the demand for the power industry is increasing. Among them, the substation grounding grid is an important part of the power system to maintain the stable operation of the power system and ensure the safety of operation and maintenance personnel and power equipment. When the electrical device is struck by lightning or a short circuit occurs in the power system, the fault current can be quickly discharged through the grounding grid and the ground potential rise can be effectively reduced. Therefore, the performance of the grounding grid is of great significance to the safety of the power system.

[0003] Since the power equipment of the substation is connected to the grounding grid through the grounding down conductor, it is difficult to determine the direction and topological distribution of the grounding grid below the surface. In addition, some substations were built a long time ago, and the grounding grid design drawings may be damaged or lost, making it difficult to upgrade and detect corrosion of the grounding grid. In addition, due to the limited construction level of some substations, there is a problem that the actual down conductor of the grounding grid does not correspond to the topological structure of the design drawings or the topological data of the grounding grid is lost, which will bring more complicated processing methods and higher costs to the subsequent work. At the same time, the traditional topological detection method uses wired data transmission or data transmission through routers. These methods are not only slow but also have low portability and operability on site, which increases the complexity of grounding grid topology detection and subsequent work. The magnetic field differential method is a method for locating the conductor of the grounding grid. The differential method is applied to the magnetic field method measurement. Since the measurement environment is easily affected by the electromagnetic interference around the substation, the weak signal used for detection is often interfered by random noise and cannot obtain satisfactory measurement results, thereby reducing the overall signal-to-noise ratio of the measurement system. Summary of the invention

[0004] In view of the problems in the prior art, an embodiment of the present invention provides a grounding grid signal extraction method and device, which can at least partially solve the problems in the prior art.

[0005] On the one hand, the present invention provides a grounding grid signal extraction method, comprising:

[0006] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0007] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0008] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0009] The filtering of the measured signal to obtain an average result of the filtered magnetic field differential output signal includes:

[0010] The average result of the magnetic field differential output signal after filtering is expressed according to the following formula:

[0011]

[0012] Where A(t) is the average result of the differential output signal of the magnetic field after filtering, N is the total number of samples, i is the i-th sampling, x(t) is the measured signal, t represents time, T is the period of the measured signal, and h(t) is the impulse response function of the filtering system.

[0013] Wherein, the digital cumulative average calculation of the measured signal includes:

[0014] The measured signal is digitally accumulated and averaged according to the following formula:

[0015]

[0016] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, x is the j-th sample, ij =s j +n ij , where s j is the sampling value of the jth channel, n ij is the substation interference noise signal sampled for the i-th time in the j-th channel.

[0017] Wherein, after the step of performing signal extraction according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result, the grounding grid signal extraction method further includes:

[0018] The signal extraction process is represented by the following expression of the digital averaging process:

[0019]

[0020] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, t jis the sampling time of the jth channel, T is the period of the measured signal, and M is the total number of sampling channels.

[0021] Wherein, the ground grid signal extraction method further includes:

[0022] The cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation is calculated.

[0023] The calculation of the cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation includes:

[0024] Obtaining N accumulation results; the N accumulation results include a first accumulation item corresponding to the magnetic field differential signal and a second accumulation item corresponding to the substation interference noise signal;

[0025] Calculating the root mean square value of the substation interference noise signal according to the second accumulated sub-item, and calculating the signal-to-noise ratio of the accumulated output magnetic field differential signal according to the sampled value of the magnetic field differential signal, the root mean square value and N;

[0026] The ratio of the signal-to-noise ratio of the accumulated output magnetic field differential signal to the signal-to-noise ratio of the magnetic field differential signal corresponding to each sampling period is taken as the cumulative average improved system signal-to-noise ratio multiple.

[0027] In one aspect, the present invention provides a grounding grid signal extraction device, comprising:

[0028] The filtering unit is used to establish a grounding grid current-carrying model, establish its derivative waveforms of various orders by means of magnetic field differentiation, implement a comb filter in the frequency domain by means of digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering;

[0029] A calculation unit, configured to perform digital cumulative average calculation on the measured signal if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal;

[0030] The extraction unit is used to extract the signal according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0031] In another aspect, an embodiment of the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the following method when executing the computer program:

[0032] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0033] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0034] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0035] An embodiment of the present invention provides a computer-readable storage medium, including:

[0036] The computer readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0037] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0038] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0039] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0040] The embodiment of the present invention further provides a computer program product, the computer program product comprising a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0041] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0042] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0043] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0044] The grounding grid signal extraction method and device provided in the embodiment of the present invention establish a grounding grid current-carrying model, establish its various-order derivative waveforms through the magnetic field differentiation method, implement a comb filter in the frequency domain by digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering; if it is determined that the measured signal satisfies the magnetic field differential signal corresponding to each order derivative waveform, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal, then the measured signal is digitally accumulated and averaged; according to the average result of the magnetic field differential output signal after filtering and the digital accumulated and averaged calculation result, signal extraction is performed, which can effectively extract the weak magnetic field signal of the grounding grid to improve the accuracy of the measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0046] Figure 1 It is a flow chart of a ground grid signal extraction method provided in one embodiment of the present invention.

[0047] Figure 2 Schematic diagram for explaining the establishment of the current-carrying model of the grounding grid.

[0048] Figure 3 It is a sinusoidal current signal of the mixed substation background noise before comb filtering is adopted in the present invention.

[0049] Figure 4 This is a sinusoidal current signal of the mixed substation background noise before comb filtering in the present invention.

[0050] Figure 5 The magnetic induction intensity B at the straight line y=8m of the present invention y (x).

[0051] Figure 6 The magnetic induction intensity B at the straight line y=8m of the present invention y (x) Second-order differential processing results.

[0052] Figure 7 The present invention uses the extracted weak signal to restore and construct the grounding grid topology.

[0053] Figure 8 It is a structural schematic diagram of a ground grid signal extraction device provided by an embodiment of the present invention.

[0054] Fig. 9 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0056] Figure 1 FIG. 1 is a flow chart of a grounding grid signal extraction method provided by an embodiment of the present invention. Figure 1 As shown, the ground grid signal extraction method provided by the embodiment of the present invention includes:

[0057] Step S1: Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation, implement a comb filter in the frequency domain using digital averaging, and filter the measured signal to obtain the average result of the filtered magnetic field differential output signal.

[0058] Step S2: If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, a digital cumulative average calculation is performed on the measured signal.

[0059] Step S3: performing signal extraction according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0060] In the above step S1, the device establishes a grounding grid current model, establishes its derivative waveforms of various orders by magnetic field differentiation, realizes a comb filter in the frequency domain by digital averaging, and performs filtering on the measured signal to obtain the average result of the magnetic field differential output signal after filtering. The device can be a computer device that executes the method, such as a server. The acquisition, storage, use, and processing of data in the technical solution of this application are in compliance with relevant regulations. Figure 2 As shown, the current I is injected into the grounding grid conductor, and then the magnetic field signal generated by the grounding grid current is measured. According to the Ampere loop theorem: the y-axial component B of the magnetic induction intensity parallel to the ground generated by the current-carrying conductor at point P y (y) is:

[0061]

[0062] in, h represents the buried depth of the grounding grid branch, y represents the component length of the measured magnetic induction intensity in the horizontal direction, L1 represents the length of one part of the conductor, L2 represents the length of the other part of the conductor, and μ represents the magnetic permeability.

[0063] Find B y The second and fourth order derivatives of (y) are ignored. When y→0, That is, when y = 0, ignore right and impact.

[0064] therefore, and The main peak position of is the same as that of the current-carrying conductor, and both are at y = 0, so the y-axial component of the magnetic induction intensity B y The main peak position of the second-order derivative or fourth-order derivative of (y) can determine the location of the grounding grid branch in the measurement area, and then draw the grounding grid topology.

[0065]

[0066]

[0067] Higher-order differential functions | B y (y)| and There is a main peak characteristic, and the conductor position is determined using the main peak coordinates.

[0068] The measured signal x(t) is converted into the frequency domain by Fourier transform. The i-th sample x(t-iT) is the convolution result of x(t) and δ(t-iT), that is, x(t-iT)×x(t)*δ(t-iT). The further digital average frequency domain result can be expressed as: Substituting x(t-iT)=x(t)*δ(t-iT) yields:

[0069]

[0070] Among them, A(t) is the average result of the magnetic field differential output signal after filtering, N is the total number of samples, i is the i-th sampling, x(t) is the measured signal, t represents time, T is the period of the measured signal, h(t) is the impulse response function of the filter system, δ(t-iT) is the impulse function, and h(t) is obtained by frequency domain transformation of the impulse response function of the magnetic field differential filter system:

[0071]

[0072] Its amplitude-frequency characteristics are:

[0073]

[0074] According to the limit theorem:

[0075]

[0076] When N>1, the transmission characteristic of h(t) is that of a comb filter implemented in the frequency domain by digital averaging.

[0077] In the above step S2, if the device determines that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be divided into the substation non-interference noise signal and the substation interference noise signal, the measured signal is digitally accumulated and averaged. In order to further improve the signal-to-noise ratio of the measurement system, it is assumed that the measured signal x(t) satisfies x(t)=s(t)+n(t).

[0078] Where s(t) is the non-interference noise signal of the substation, and n(t) is the interference noise signal of the substation. Assume that the number of sampling channels in each signal cycle is j=1,2,3,...,M, the sampling interval is Δt, and the number of repetitions is i=1,2,3,...,N-1. The sampling value of the jth channel at the i-th time can be expressed as:

[0079] x(t i + jΔt) = s(t i +jΔt)+n(t i +jΔt)

[0080] Where, t i is the moment when the sampling of the magnetic field signal starts in the i-th sampling period. y (y)|, To determine the signal, for different sampling periods i, the sampling values ​​of the jth channel are basically the same, and s j Indicates that the noise n(t) is a random value whose value depends on i and j, so x(t i + jΔt) = s(t i +jΔt)+n(t i +jΔt) is written as x ij =s j +n ij , the calculation formula for the digital cumulative average of the measured signal is:

[0081]

[0082] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, x is the j-th sample, ij =sj +n ij , where s j is the sampling value of the jth channel, n ij is the substation interference noise signal sampled for the i-th time in the j-th channel.

[0083] In the above step S3, the device extracts the signal according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result. The waveforms of the differential functions of each order after digital averaging are obtained by digital averaging, and the sampling process is triggered at the beginning of each cycle. The sampling is uniformly performed M times in each cycle, and the sampling time interval is Δt.

[0084] For the j-th sampling signal, the digital averaging operation process can be expressed as:

[0085]

[0086] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, t j is the sampling time of the jth channel, T is the period of the measured signal, and M is the total number of sampling channels. That is, T can be |B y (y)|, The period of the signal.

[0087] For j = 1, 2, 3, ..., M, the corresponding digital average values ​​are calculated respectively, and A(j) is output in sequence after digital-to-analog conversion, so that |B after digital averaging can be obtained y (y)|,

[0088] The ground grid signal extraction method further includes:

[0089] The cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation is calculated.

[0090] The calculation of the cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation includes:

[0091] Obtaining N accumulation results; the N accumulation results include a first accumulation item corresponding to the magnetic field differential signal and a second accumulation item corresponding to the substation interference noise signal;

[0092] Calculating the root mean square value of the substation interference noise signal according to the second accumulated sub-item, and calculating the signal-to-noise ratio of the accumulated output magnetic field differential signal according to the sampled value of the magnetic field differential signal, the root mean square value and N;

[0093] The ratio of the signal-to-noise ratio of the accumulated output magnetic field differential signal to the signal-to-noise ratio of the magnetic field differential signal corresponding to each sampling period is taken as the cumulative average improved system signal-to-noise ratio multiple.

[0094] The calculation process of digital cumulative average of the differential signal of the substation grounding grid magnetic field is analyzed, and the cumulative average of N sampling values ​​at different times is obtained to improve the system signal-to-noise ratio multiple, so as to effectively suppress the random noise interference in the measurement process.

[0095] The result after N accumulations is where s j is the sampling value of the jth channel. After N accumulations, the amplitude will increase by N times. The mean square value of the noise after sampling and accumulation is:

[0096]

[0097] It represents the sum of squares of each sampling value of the magnetic field differential signal. It represents the mathematical expectation of the sum of the two-way multiplication of the sampling values ​​of the substation noise at different times.

[0098] The signal-to-noise ratio of the output magnetic field differential signal after accumulation is Improve the signal-to-noise ratio SNIR to σ n is the RMS value of the substation interference noise signal. Take the square root and you get .

[0099] The cumulative average of N sampling values ​​at different times can improve the signal-to-noise ratio When detecting weak signals, the signal-to-noise ratio can be improved by digitally averaging the repeated signals.

[0100] The grounding grid signal extraction method provided by the embodiment of the present invention uses a digital averaging method to achieve the following beneficial effects:

[0101] 1. Effectively improve the signal-to-noise ratio of weak magnetic field signal measurement. Compared with the technology without digital averaging, the signal-to-noise ratio is improved. times.

[0102] 2. The non-periodic background magnetic field noise generated by the substation power equipment during the grounding grid conductor positioning magnetic field measurement process is suppressed.

[0103] 3. Effectively improve the waveform shape of AC magnetic field measurement, making it closer to the excitation current signal waveform generated by the excitation source.

[0104] like Figure 3 As shown, it is the sinusoidal current signal of the hybrid substation background noise before the comb filtering is adopted in the present invention.

[0105] like Figure 4 As shown, it is a sinusoidal current signal of the mixed substation background noise before comb filtering according to the present invention.

[0106] like Figure 5 As shown, it is the magnetic induction intensity B at the straight line y=8m of the present invention. y (x).

[0107] like Figure 6 As shown, the magnetic induction intensity B at the straight line y=8m of the present invention y (x) Second-order differential processing results.

[0108] like Figure 7 As shown, the grounding grid topology structure restored and constructed by the present invention using the extracted weak signal.

[0109] The grounding grid signal extraction method provided in the embodiment of the present invention establishes a grounding grid current-carrying model, establishes its various-order derivative waveforms through the magnetic field differentiation method, realizes a comb filter in the frequency domain by digital averaging, and performs filtering processing on the measured signal to obtain the average result of the magnetic field differential output signal after filtering; if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the various-order derivative waveforms respectively, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal, then the measured signal is digitally accumulated and averaged; according to the average result of the magnetic field differential output signal after filtering and the digital accumulated and averaged calculation result, signal extraction is performed, which can effectively extract the weak magnetic field signal of the grounding grid to improve the accuracy of the measurement system.

[0110] Furthermore, the filtering process is performed on the measured signal to obtain an average result of the filtered magnetic field differential output signal, including:

[0111] The average result of the magnetic field differential output signal after filtering is expressed according to the following formula:

[0112]

[0113] Wherein, A(t) is the average result of the differential output signal of the magnetic field after filtering, N is the total number of samples, i is the i-th sampling, x(t) is the measured signal, t represents time, T is the period of the measured signal, and h(t) is the impulse response function of the filtering system. The above-mentioned embodiment can be referred to for explanation and will not be repeated here.

[0114] Furthermore, the digital cumulative average calculation of the measured signal includes:

[0115] The measured signal is digitally accumulated and averaged according to the following formula:

[0116]

[0117] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, x is the j-th sample, ij =s j +n ij , where s j is the sampling value of the jth channel, n ij is the substation interference noise signal sampled at the i-th time in the j-th channel. The above description can be referred to, and will not be repeated here.

[0118] Furthermore, after the step of performing signal extraction according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result, the grounding grid signal extraction method further includes:

[0119] The signal extraction process is represented by the following expression of the digital averaging process:

[0120]

[0121] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, t j is the sampling time of the jth channel, T is the period of the measured signal, and M is the total number of sampling channels. The above description can be referred to and will not be repeated here.

[0122] Furthermore, the ground grid signal extraction method further includes:

[0123] The cumulative average improvement of the system signal-to-noise ratio of the N sampling values ​​at different times during the digital average operation is calculated. The above-mentioned embodiment can be referred to for explanation and will not be described in detail.

[0124] Furthermore, the calculation of the cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation includes:

[0125] Obtain N accumulation results; the N accumulation results include a first accumulation item corresponding to the magnetic field differential signal and a second accumulation item corresponding to the substation interference noise signal; the above embodiment can be referred to for description and will not be repeated here.

[0126] The root mean square value of the substation interference noise signal is calculated according to the second accumulated sub-item, and the signal-to-noise ratio of the accumulated output magnetic field differential signal is calculated according to the sampling value of the magnetic field differential signal, the root mean square value and N; the description can be made with reference to the above embodiment and will not be repeated here.

[0127] The ratio of the signal-to-noise ratio of the accumulated output magnetic field differential signal to the signal-to-noise ratio of the magnetic field differential signal corresponding to each sampling period is taken as the cumulative average improved system signal-to-noise ratio multiple.

[0128] Figure 8 FIG. 1 is a schematic diagram of the structure of a grounding grid signal extraction device provided by an embodiment of the present invention. Figure 8 As shown, the grounding grid signal extraction device provided by the embodiment of the present invention includes a filtering unit 801, a calculating unit 802 and an extracting unit 803, wherein:

[0129] The filtering unit 801 is used to establish a current-carrying model of the grounding grid, establish its derivative waveforms of various orders through the magnetic field differentiation method, implement a comb filter in the frequency domain by digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering; the calculation unit 802 is used to perform digital cumulative average calculation on the measured signal if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of various orders, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal; the extraction unit 803 is used to extract the signal according to the average result of the magnetic field differential output signal after filtering and the digital cumulative average calculation result.

[0130] Specifically, the filtering unit 801 in the device is used to establish a current-carrying model of the grounding grid, establish its various-order derivative waveforms through the magnetic field differentiation method, implement a comb filter in the frequency domain by digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering; the calculation unit 802 is used to perform digital cumulative averaging calculation on the measured signal if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the various-order derivative waveforms respectively, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal; the extraction unit 803 is used to extract the signal according to the average result of the magnetic field differential output signal after filtering and the digital cumulative averaging calculation result.

[0131] The grounding grid signal extraction device provided in the embodiment of the present invention establishes a grounding grid current-carrying model, establishes its various-order derivative waveforms through the magnetic field differentiation method, realizes a comb filter in the frequency domain by digital averaging, and performs filtering processing on the measured signal to obtain the average result of the magnetic field differential output signal after filtering; if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the various-order derivative waveforms respectively, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal, then the measured signal is digitally accumulated and averaged; according to the average result of the magnetic field differential output signal after filtering and the digital accumulated and averaged calculation result, signal extraction is performed, which can effectively extract the weak magnetic field signal of the grounding grid to improve the accuracy of the measurement system.

[0132] Furthermore, the filtering unit 801 is specifically used for:

[0133] The average result of the magnetic field differential output signal after filtering is expressed according to the following formula:

[0134]

[0135] Where A(t) is the average result of the differential output signal of the magnetic field after filtering, N is the total number of samples, i is the i-th sampling, x(t) is the measured signal, t represents time, T is the period of the measured signal, and h(t) is the impulse response function of the filtering system.

[0136] Further, the calculating unit 802 is specifically used for:

[0137] The measured signal is digitally accumulated and averaged according to the following formula:

[0138]

[0139] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, x is the j-th sample, ij =s j +n ij , where s j is the sampling value of the jth channel, n ij is the substation interference noise signal sampled for the i-th time in the j-th channel.

[0140] Furthermore, after the step of performing signal extraction according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result, the grounding grid signal extraction device is further used to:

[0141] The signal extraction process is represented by the following expression of the digital averaging process:

[0142]

[0143] Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, t j is the sampling time of the jth channel, T is the period of the measured signal, and M is the total number of sampling channels.

[0144] Furthermore, the ground grid signal extraction device is also specifically used for:

[0145] The cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation is calculated.

[0146] Furthermore, the ground grid signal extraction device is also specifically used for:

[0147] Obtaining N accumulation results; the N accumulation results include a first accumulation item corresponding to the magnetic field differential signal and a second accumulation item corresponding to the substation interference noise signal;

[0148] Calculating the root mean square value of the substation interference noise signal according to the second accumulated sub-item, and calculating the signal-to-noise ratio of the accumulated output magnetic field differential signal according to the sampled value of the magnetic field differential signal, the root mean square value and N;

[0149] The ratio of the signal-to-noise ratio of the accumulated output magnetic field differential signal to the signal-to-noise ratio of the magnetic field differential signal corresponding to each sampling period is taken as the cumulative average improved system signal-to-noise ratio multiple.

[0150] The embodiment of the ground grid signal extraction device provided in the embodiment of the present invention can be specifically used to execute the processing flow of the above-mentioned method embodiments. Its functions are not described in detail here, and reference can be made to the detailed description of the above-mentioned method embodiments.

[0151] Fig. 9 A schematic diagram of the physical structure of a computer device provided in an embodiment of the present invention is shown in FIG. Fig. 9 As shown, the computer device includes: a memory 901, a processor 902, and a computer program stored in the memory 901 and executable on the processor 902. When the processor 902 executes the computer program, the following method is implemented:

[0152] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0153] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0154] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0155] This embodiment discloses a computer program product, the computer program product including a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0156] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0157] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0158] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0159] This embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0160] Establish a grounding grid current-carrying model, establish its derivative waveforms of various orders through magnetic field differentiation method, realize comb filter in frequency domain by digital averaging, filter the measured signal, and obtain the average result of magnetic field differential output signal after filtering;

[0161] If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal;

[0162] Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

[0163] Compared with the technical solutions in the prior art, the embodiments of the present invention establish a grounding grid current-carrying model, establish its various-order derivative waveforms through the magnetic field differentiation method, implement a comb filter in the frequency domain by digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering; if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the various-order derivative waveforms respectively, and the measured signal can be divided into a substation non-interference noise signal and a substation interference noise signal, then the measured signal is digitally accumulated and averaged; according to the average result of the magnetic field differential output signal after filtering and the digital accumulated and averaged calculation result, signal extraction is performed, which can effectively extract the weak magnetic field signal of the grounding grid to improve the accuracy of the measurement system.

[0164] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0165] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0166] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0168] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0169] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A grounding grid signal extraction method, characterized in that: include: The grounding grid current-carrying model is established, and its derivative waveforms of various orders are established by magnetic field differential method. The comb filter is realized in the frequency domain by digital averaging, and the measured signal is filtered to obtain the average result of the magnetic field differential output signal after filtering. If it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal, then a digital cumulative average calculation is performed on the measured signal; Signal extraction is performed based on the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

2. The grounding grid signal extraction method according to claim 1, characterized in that: The filtering process is performed on the measured signal to obtain an average result of the filtered magnetic field differential output signal, including: The average result of the magnetic field differential output signal after filtering is expressed according to the following formula: Where A(t) is the average result of the differential output signal of the magnetic field after filtering, N is the total number of samples, i is the i-th sampling, x(t) is the measured signal, t represents time, T is the period of the measured signal, and h(t) is the impulse response function of the filtering system.

3. The grounding grid signal extraction method according to claim 1, characterized in that: The digital cumulative average calculation of the measured signal comprises: The measured signal is digitally accumulated and averaged according to the following formula: Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, x is the j-th sample, ij =s j +n ij , where s j is the sampling value of the jth channel, n ij is the substation interference noise signal sampled for the i-th time in the j-th channel.

4. The grounding grid signal extraction method according to claim 1, characterized in that: After the step of performing signal extraction according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result, the grounding grid signal extraction method further includes: The signal extraction process is represented by the following expression of the digital averaging process: Where A(j) is the result of digital cumulative average calculation, N is the total number of samples, i is the i-th sample, j is the j-th sample, t j is the sampling time of the jth channel, T is the period of the measured signal, and M is the total number of sampling channels.

5. The grounding grid signal extraction method according to claim 4, characterized in that: The ground grid signal extraction method further includes: The cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation is calculated.

6. The grounding grid signal extraction method according to claim 5, characterized in that: The calculation of the cumulative average improvement of the system signal-to-noise ratio multiple of the sampling values ​​at N different times during the digital averaging operation includes: Obtaining N accumulation results; the N accumulation results include a first accumulation item corresponding to the magnetic field differential signal and a second accumulation item corresponding to the substation interference noise signal; Calculating the root mean square value of the substation interference noise signal according to the second accumulated sub-item, and calculating the signal-to-noise ratio of the accumulated output magnetic field differential signal according to the sampled value of the magnetic field differential signal, the root mean square value and N; The ratio of the signal-to-noise ratio of the accumulated output magnetic field differential signal to the signal-to-noise ratio of the magnetic field differential signal corresponding to each sampling period is taken as the cumulative average improved system signal-to-noise ratio multiple.

7. A grounding grid signal extraction device, characterized in that: include: The filtering unit is used to establish a grounding grid current-carrying model, establish its derivative waveforms of various orders by means of magnetic field differentiation, implement a comb filter in the frequency domain by means of digital averaging, and filter the measured signal to obtain the average result of the magnetic field differential output signal after filtering; A calculation unit, configured to perform digital cumulative average calculation on the measured signal if it is determined that the measured signal satisfies the magnetic field differential signals corresponding to the derivative waveforms of each order, and the measured signal can be split into a substation non-interference noise signal and a substation interference noise signal; The extraction unit is used to extract the signal according to the average result of the filtered magnetic field differential output signal and the digital cumulative average calculation result.

8. A computer 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 computer program, the method according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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