Power distribution network high-resistance grounding fault detection method and device, electronic equipment and storage medium

Abstract

The invention discloses a power distribution network high-resistance grounding fault detection method and device, electronic equipment and a storage medium. The method comprises the following steps: determining a target fault zero-sequence current signal; performing preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and determining target frequency spectrum information of the target fault zero-sequence current signal according to the target discrete signal; and determining a target fault type of the target grounding point according to the target spectrum information. According to the method, the target fault zero-sequence current information is subjected to the preset Fourier transform, whether the target grounding point has the high-resistance fault is judged according to the transform result, and the high-resistance fault can be found by workers in time when the high-resistance fault occurs, so that potential safety hazards such as electric shock and fire caused by long-time existence of the high-resistance fault are prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault detection, and in particular to a distribution network high-resistance grounding fault detection method, device, electronic equipment and storage medium. Background Art

[0002] In the distribution network, the medium and low voltage distribution network has the characteristics of overhead and cable mixed outgoing lines, numerous branch lines, and complex network topology due to its direct orientation to power users and proximity to load centers. These characteristics make the medium voltage distribution network more susceptible to various factors during operation, such as natural disasters, equipment aging, human operational errors, etc., which lead to the occurrence of faults. Among them, single-phase grounding faults are the most common type of faults in medium voltage distribution networks, accounting for about the total number of distribution network faults, posing a serious threat to the safe and stable operation of distribution networks. Whether it is a low current grounding or a low resistance grounding system, there is currently a lack of effective detection and protection methods for high resistance faults.

[0003] However, existing fault detection methods cannot detect and handle high-resistance faults in a timely manner, which can easily lead to serious faults in the distribution network, thus causing safety hazards such as electric shock and fire. Summary of the invention

[0004] The present invention provides a method, device, electronic equipment and storage medium for detecting high-resistance grounding faults in a distribution network, so as to solve the problem that high-resistance faults are not discovered in time.

[0005] According to one aspect of the present invention, a method for detecting a high-resistance grounding fault in a distribution network is provided, comprising:

[0006] Determine a target fault zero-sequence current signal, where the target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault occurring at a target grounding point, where the target grounding point is a grounding point in a distribution network;

[0007] A preset Fourier transform is performed on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and target spectrum information of the target fault zero-sequence current signal is determined according to the target discrete signal, wherein the preset Fourier transform is used to perform frequency domain changes on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform, and the target spectrum information includes: first spectrum information for characterizing the current spike of the target grounding point and second spectrum information for characterizing the dispersion of the target grounding point;

[0008] A target fault type of a target grounding point is determined according to the target frequency spectrum information.

[0009] According to another aspect of the present invention, a device for detecting high-resistance grounding faults in a power distribution network is provided, comprising:

[0010] A fault current signal determination module is used to determine a target fault zero-sequence current signal, wherein the target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault occurring at a target grounding point, wherein the target grounding point is a grounding point in a distribution network;

[0011] A spectrum information determination module is used to perform a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and determine the target spectrum information of the target fault zero-sequence current signal according to the target discrete signal, wherein the preset Fourier transform is used to perform a frequency domain change on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform, and the target spectrum information includes: first spectrum information for characterizing the current spike of the target grounding point and second spectrum information for characterizing the dispersion of the target grounding point;

[0012] The fault type determination module is used to determine a target fault type of a target grounding point according to the target frequency spectrum information.

[0013] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0014] at least one processor; and

[0015] a memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for detecting high-resistance grounding faults in a distribution network described in any embodiment of the present invention.

[0017] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method for detecting high-resistance grounding faults in a distribution network as described in any embodiment of the present invention when executed.

[0018] The technical solution of the embodiment of the present invention determines the target fault zero-sequence current signal; performs a preset Fourier transform on the target fault zero-sequence current signal to obtain the target discrete signal of the target fault zero-sequence current signal, and determines the target spectrum information of the target fault zero-sequence current signal based on the target discrete signal. The preset Fourier transform can amplify the fault current signal in the target fault zero-sequence current signal, so that the obtained target spectrum information can provide a basis for the identification of high-resistance faults; the target fault type of the target grounding point is determined based on the target spectrum information, and the high-resistance fault and current change can be distinguished through the target spectrum information, thereby improving the accuracy of high-resistance fault identification. This method can be discovered by staff in a timely manner when a high-resistance fault occurs, so as to prevent safety hazards such as electric shock and fire caused by the long-term existence of the high-resistance fault.

[0019] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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.

[0021] Figure 1 A flow chart of a method for detecting a high-resistance grounding fault in a distribution network provided by an embodiment of the present invention;

[0022] Figure 2 A three-dimensional spectrum diagram of a target fault zero-sequence current signal provided by an embodiment of the present invention;

[0023] Figure 3 A three-dimensional spectrum diagram of a normal zero-sequence current signal provided by an embodiment of the present invention;

[0024] Figure 4 A three-dimensional spectrum diagram of another target fault zero-sequence current signal provided by an embodiment of the present invention;

[0025] Figure 5 A two-dimensional spectrum diagram of a target fault zero-sequence current signal provided by an embodiment of the present invention;

[0026] Figure 6 A frequency response diagram of a faulty outgoing line 0.3 seconds after a high-resistance fault occurs provided by an embodiment of the present invention;

[0027] Figure 7A frequency response diagram of a non-faulty outgoing line 11 seconds after a high-resistance fault occurs provided by an embodiment of the present invention;

[0028] Figure 8 A schematic diagram of a lightning surge sensitivity response provided by an embodiment of the present invention;

[0029] Fig. 9 A schematic diagram of a lightning surge response provided by an embodiment of the present invention

[0030] Fig.10 A schematic diagram of the structure of a distribution network high-resistance grounding fault detection device provided by an embodiment of the present invention;

[0031] Fig.11 A schematic diagram of the structure of an electronic device for implementing the method for detecting high-resistance grounding faults in a distribution network according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] Figure 1 This is a flow chart of a method for detecting a high-resistance grounding fault in a distribution network provided by an embodiment of the present invention. This embodiment is applicable to the case where the type of fault is determined when a grounding fault occurs in a distribution network. This method can be performed by a high-resistance grounding fault detection device for a distribution network. The high-resistance grounding fault detection device for a distribution network can be implemented in the form of hardware and / or software. The high-resistance grounding fault detection device for a distribution network can be configured in any electronic device with a network communication function. Figure 1 As shown, the method includes:

[0035] S110. Determine a target fault zero-sequence current signal.

[0036] The target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault occurring at the target grounding point. The single-phase grounding fault may be: a low-resistance fault or an assumed high-resistance fault.

[0037] It is assumed that the high-resistance fault includes: high-resistance fault and current change. The current change can be the current change caused by the start, stop or switch change of the distribution network.

[0038] Furthermore, the current change is caused by the change of zero-sequence current when the distribution network performs a specific action, and the change state is similar to the change of zero-sequence current of a high-resistance fault, so it will be mistaken for a high-resistance fault. Therefore, it is assumed that a high-resistance fault includes: a high-resistance fault and a current change.

[0039] The target grounding point is a grounding point in the distribution network.

[0040] Furthermore, the target grounding point adopts a neutral grounding strategy to connect the distribution network to the earth. The neutral grounding strategies include: neutral point ungrounded, resonant grounding and low resistance grounding.

[0041] Among them, when the grounding strategy of the target grounding point is that the neutral point is not grounded, the target fault zero-sequence current in the fault outgoing line II in the distribution network can be expressed by the following formula:

[0042]

[0043] in, is the zero-sequence current of the healthy outgoing line Ⅰ in the distribution network, is the target fault zero-sequence current of the faulty outgoing line II, where the faulty outgoing line is the line where the target grounding point is located; the zero-sequence current I of the sound outgoing line I 01 It can be expressed by the following formula:

[0044]

[0045] in, They are the capacitive currents of the healthy outgoing line Ⅰ in phases A, B and C respectively.

[0046] Furthermore, when the grounding strategy of the target grounding point is resonant grounding, the target fault zero-sequence current in the fault outgoing line II in the distribution network can be expressed by the following formula:

[0047]

[0048] in, is the target fault zero-sequence current of fault outgoing line II; It is the zero-sequence current of the healthy outgoing line in the distribution network; is the inductor current.

[0049] Furthermore, according to the detuning degree: The target fault zero-sequence current can be expressed as:

[0050]

[0051] Where j is the imaginary unit; ω is the angular frequency; C 01 is the capacitance of the first healthy outgoing line to ground; C 02 is the capacitance to ground of the second healthy outgoing line; U0 is the zero-sequence voltage; I c is the capacitor current; v is the detuning degree.

[0052] Furthermore, when the grounding strategy of the target grounding point is low resistance grounding, the zero-sequence current of each healthy outgoing line is:

[0053]

[0054] Where j is the imaginary unit; ω is the angular frequency; C 0k is the capacitance to ground of the kth healthy outgoing line; is the zero sequence voltage; is the sum of the zero-sequence capacitance of all outgoing lines to ground; R is the neutral point grounding resistance; R f is the transition resistance of the target grounding point; n is the number of healthy outgoing lines; is the phase voltage before the fault at the target grounding point.

[0055] The neutral point zero sequence current is:

[0056]

[0057] Where R is the neutral point grounding resistance; R f is the target grounding point transition resistance; is the phase voltage before the fault at the target grounding point; It is the sum of the zero-sequence capacitance of all outgoing lines to ground.

[0058] Furthermore, the target fault zero-sequence current in the faulty outgoing line in the distribution network is:

[0059]

[0060] in, is the zero-sequence current of the neutral point grounding resistance, is the target fault zero-sequence current, is the phase voltage before the target grounding point fault, ω is the angular frequency, R is the neutral point grounding resistance, R f is the target grounding point transition resistance, is the sum of the zero-sequence capacitance of all healthy outgoing lines to ground, It is the sum of the zero-sequence capacitance of all outgoing lines to ground.

[0061] Specifically, if the current detection device detects a transient fault at the target grounding point, it is considered that a high-resistance or low-resistance fault may occur at the target grounding point at this moment. At this time, the current data acquisition device obtains the fault zero-sequence current signal of the target grounding point within a preset time range, filters the acquired fault zero-sequence current signal, and uses the filtered fault zero-sequence current signal as the target fault zero-sequence current signal.

[0062] Among them, the fault transient is the instantaneous change of the zero-sequence current when a single-phase grounding fault is suspected to occur at the target grounding point.

[0063] In the above steps, filtering the fault zero-sequence current signal is performed to eliminate the noise signal in the current signal.

[0064] Furthermore, the target fault zero-sequence current signal can also be calculated according to the target fault zero-sequence current expression corresponding to the grounding strategy according to the current grounding strategy when the fault transient of the target grounding point is detected.

[0065] Exemplarily, assuming that a fault transient is detected at the target grounding point at time A, a fault zero-sequence current signal within a time interval t after time A is acquired.

[0066] For example, Figure 2 As shown, it is a three-dimensional spectrum diagram of the zero-sequence current signal of the target fault. It can be seen from the figure that the amplitude of the current is between 0-12dB and the frequency is between 0-1500Hz.

[0067] Furthermore, if Figure 3 As shown in Figure 1, it is a three-dimensional spectrum diagram of the normal zero-sequence current signal. It can be seen from the figure that the current amplitude is between 0-2dB and the frequency is between 0-500Hz. The current amplitude of the target fault zero-sequence current is significantly higher than the normal zero-sequence current, and the frequency variation range is also greater than the normal zero-sequence current.

[0068] S120, performing a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and determining target frequency spectrum information of the target fault zero-sequence current signal according to the target discrete signal.

[0069] The preset Fourier transform is used to perform frequency domain transformation on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform.

[0070] Furthermore, the correction factor is introduced because there are a large number of nonlinear loads in the distribution network, or harmonic signals are generated during rectification and inversion. However, when analyzing the zero-sequence current signal of the target fault, it is usually based on the fundamental signal. Therefore, the presence of harmonic information will lead to deviations in the analysis results.

[0071] The target frequency spectrum information includes: first frequency spectrum information for characterizing the current peak of the target grounding point and second frequency spectrum information for characterizing the dissipation of the target grounding point.

[0072] Specifically, a preset Fourier transform is performed on the target fault zero-sequence current signal, and the target fault zero-sequence current signal is converted from a time domain signal into a discrete signal in the frequency domain through the preset Fourier transform. A three-dimensional spectrum image is generated according to the obtained discrete signal, and the target spectrum information of the target fault zero-sequence current signal is determined from the three-dimensional spectrum image.

[0073] The above steps perform a preset Fourier transform, which can amplify the fault current signal in the target fault zero-sequence current signal in the high frequency band and dissipate it in the low frequency band, thereby providing a basis for determining whether a high-resistance fault occurs at the target grounding point.

[0074] S130. Determine a target fault type of a target grounding point according to target frequency spectrum information.

[0075] The target fault types include: high resistance fault or current change.

[0076] Specifically, the target frequency spectrum information is judged according to preset conditions, and the target fault type of the target grounding point is determined according to the obtained judgment result.

[0077] Furthermore, the preset condition may be that the first spectrum information is greater than or equal to a preset peak, and the second spectrum information exists.

[0078] Further, if the target frequency spectrum information meets the preset conditions, the target fault type of the target grounding point is a high resistance fault; if the target frequency spectrum information does not meet the preset conditions, the target fault type of the target grounding point is a current change.

[0079] The above steps distinguish high-resistance faults and current changes based on the target spectrum information because the current changes generated by the two are small and the change range is similar. Direct judgment is easy to cause confusion. Therefore, it is necessary to distinguish them based on the changes in the spectrum information to prevent inaccurate high-resistance fault detection caused by confusion, which poses a serious threat to the safe and stable operation of the distribution network.

[0080] Optionally, before performing a preset Fourier transform on the target fault zero-sequence current signal, steps A1-A3 are also included:

[0081] Step A1: Determine the reference fault type.

[0082] The reference fault types include: low resistance fault or assumed high resistance fault, and the assumed high resistance fault includes: high resistance fault or current change.

[0083] Specifically, the reference fault type is determined according to the target fault zero-sequence current signal and a current preset threshold.

[0084] Furthermore, when a low-resistance fault occurs in the distribution network, the target fault zero-sequence current signal in the fault outgoing line where the target grounding point is located is large; when a high-resistance fault occurs in the distribution network, the target fault zero-sequence current signal in the fault outgoing line where the target grounding point is located is weak, and different grounding strategies have different target fault zero-sequence current signals corresponding to high-resistance faults. Therefore, the grounding strategy needs to be considered when setting the current preset threshold, that is, the current preset threshold is determined according to the change of the target fault zero-sequence current signal of the high-resistance fault corresponding to the grounding strategy.

[0085] Step A2: If the reference fault type is a low-resistance fault, continue to judge the reference fault type of the target grounding point.

[0086] Specifically, if the reference fault type is a low-resistance fault, a low-resistance fault warning is performed, and the zero-sequence current of the target grounding point is continuously tested for fault transients, and the reference fault type of the target grounding point is judged based on the test results.

[0087] Step A3: If the reference fault type is an assumed high-resistance fault, it is necessary to perform a preset Fourier transform on the target fault zero-sequence current signal.

[0088] Specifically, if the reference fault type is an assumed high-resistance fault, it is considered that a high-resistance fault may occur at the target grounding point, so it is necessary to perform a preset Fourier transform on the target fault zero-sequence current signal to further determine whether it is a high-resistance fault.

[0089] The above steps determine whether a preset Fourier transform is required based on the reference fault type because when a low-resistance fault occurs at the target grounding point, the fault transient current signal peak in the target fault zero-sequence current signal is obvious and can be observed intuitively, so there is no need for frequency domain analysis. However, the fault transient current signal when a high-resistance fault occurs is similar to the current signal generated when the distribution network performs a switching action, and it is difficult to distinguish, so frequency domain analysis is required to distinguish them.

[0090] Optionally, determining a reference fault type includes steps B1-B3:

[0091] Step B1: Compare the target fault zero-sequence current signal with a preset current threshold.

[0092] Specifically, the current peak signal in the target fault zero-sequence current signal is compared with a preset current threshold.

[0093] Step B2: If the target fault zero-sequence current signal is greater than or equal to the preset current threshold, the reference fault type is a low-resistance fault.

[0094] Specifically, if there is a current spike signal greater than or equal to a preset current threshold in the target fault zero-sequence current signal, it is considered that the fault of the target grounding point is a low-resistance fault, so the reference fault type is a low-resistance fault.

[0095] Step B3: If the target fault zero-sequence current signal is less than the preset current threshold, the reference fault type is an assumed high-resistance fault.

[0096] Specifically, if there is a current spike signal less than a preset current threshold in the target fault zero-sequence current signal, it is considered that the zero-sequence current of the target grounding point has changed, so the reference fault type is an assumed high-resistance fault.

[0097] The above steps, with reference to the determination of the fault type, can provide a basis for determining whether it is necessary to perform a preset Fourier transform on the target fault zero-sequence current signal.

[0098] Optionally, performing a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal includes steps C1-C4:

[0099] Step C1, perform Fourier transform on the target fault zero-sequence current signal, and expand the number of sampling points to obtain an extended fault discrete zero-sequence current signal.

[0100] Specifically, a short-time Fourier transform is performed on the target fault zero-sequence current signal to obtain a fault discrete zero-sequence current signal. According to the predicted number of extended sampling points, the fault discrete zero-sequence current signal is expanded to obtain an extended fault discrete zero-sequence current signal.

[0101] For example, assuming that the target fault zero-sequence current signal is h(t), a short-time Fourier transform is performed on the target fault zero-sequence current signal to obtain a fault discrete zero-sequence current signal The sampling points are expanded according to the predicted extended sampling points to obtain the extended fault discrete zero-sequence current signal Where n is the number of frequency sampling points.

[0102] Step C2: Introduce the correction factor into the first window function to obtain the second window function.

[0103] Exemplarily, the first window function adopts a Gaussian window, and the first window function can be expressed by the following formula:

[0104]

[0105] Where f is the frequency.

[0106] Step C3: performing frequency sampling point calculation on the extended fault discrete zero-sequence current signal and the second window function to determine a target discrete signal of the target fault zero-sequence current signal.

[0107] Specifically, frequency sampling points are calculated for the extended fault discrete zero-sequence current signal and the second window function according to a preset sampling frequency, and an inverse Fourier transform is performed to obtain a target discrete signal of the target fault zero-sequence current signal.

[0108] Furthermore, the target discrete signal of the target fault zero-sequence current signal can be expressed by the following formula:

[0109]

[0110] Among them, N is the length of the window function; T is the sampling period; m is f a The corresponding frequency point; n is the number of frequency sampling points; v is the correction factor; f a is the optimal recognition frequency of the window function.

[0111] Exemplarily, the target fault zero-sequence current signal is subjected to short-time Fourier transform to obtain a fault discrete zero-sequence current signal. The fault discrete zero-sequence current signal can be expressed by the following formula:

[0112]

[0113] Where h(t) is the original signal; g(t-τ) is the first window function; e -i2πft is the kernel function of Fourier transform; f is the frequency, and t is the integral variable.

[0114] Furthermore, due to the weighting effect of g(t) on h(t) at t = τ, the signal is preserved near τ and suppressed away from τ. Therefore, the frequency distribution of h(t) can be expressed as t = τ.

[0115] Furthermore, if the first window function is selected as a Gaussian window, the corresponding fault discrete zero-sequence current signal can be written as:

[0116]

[0117] The width of the Gaussian window is determined by δ. In order to achieve adaptive adjustment of the window width according to the frequency distribution of the signal, δ is defined as:

[0118]

[0119] Furthermore, in the continuous domain, the fault discrete zero-sequence current signal whose window width is inversely proportional to the signal frequency is:

[0120]

[0121] Furthermore, the fault discrete zero-sequence current signal is also written as the operation of the Fourier spectrum H(f) of h(t):

[0122]

[0123] Furthermore, the correction factor is introduced into the first window function to obtain the second window function:

[0124]

[0125] Among them, f a is the optimal recognition frequency of the window function.

[0126] Further, τ→jT, T is the sampling period, then we can get:

[0127]

[0128] Among them, N is the length of the window function; m is f a The corresponding frequency point; n is the number of frequency sampling points; f a is the optimal recognition frequency of the window function.

[0129] Furthermore, Then the second window function is:

[0130]

[0131] Furthermore, the target discrete signal of the target fault zero-sequence current signal is obtained as:

[0132]

[0133] Optionally, determining target frequency spectrum information of a target fault zero-sequence current signal according to a target discrete signal of the target fault zero-sequence current signal includes steps D1-D2:

[0134] Step D1: determining the distribution of the target fault zero-sequence current signal in the frequency domain according to the target discrete signal.

[0135] Specifically, a three-dimensional distribution of a target fault zero-sequence current signal in the frequency domain is generated according to the target discrete signal.

[0136] For example, Figure 4 As shown in the figure, it is the distribution of the target discrete signal in the frequency domain. It can be seen from the figure that the zero-sequence current changes around 3s, and the amplitude is around 20dB. The three-dimensional image is intercepted according to the cutoff frequency f1 to obtain a two-dimensional image with the x-axis as the frequency and the y-axis as the amplitude, as shown in Figure 5As shown in the figure, the red line is the transient response curve 0.1ms after the fault occurs, the yellow line is the steady-state response curve; the blue line is the response curve generated at the moment the target grounding point fails. It can be seen from the figure that at 2.5kHz, the fault current peak amplitude is about 3dB, the steady-state amplitude is about 1.5dB, and the transient fault amplitude is less than 1dB.

[0137] Step D2: according to the distribution, the frequency spectrum information corresponding to the area with the current peak is used as the first frequency spectrum information; the frequency spectrum information corresponding to the area with the spectrum dispersion is used as the second frequency spectrum information.

[0138] Specifically, the distribution is analyzed, and the spectrum information corresponding to the area where the current peak is located is used as the first spectrum information; and the spectrum information corresponding to the area where the spectrum dispersion occurs is used as the second spectrum information.

[0139] Optionally, determining a target fault type of a target grounding point according to target spectrum information includes steps E1-E2:

[0140] Step E1: If the first frequency spectrum information is greater than or equal to a preset peak value and there is second frequency spectrum information, the target fault type is a high resistance fault.

[0141] Specifically, if the first spectrum information is greater than or equal to a preset peak value and there is spectrum dispersion, that is, there is second spectrum information, then the target fault type is a high-resistance fault.

[0142] Step E2: If the first spectrum information is smaller than a preset peak value, or the second spectrum information does not exist, the target fault type is a current change.

[0143] Specifically, if the first spectrum information is smaller than a preset peak, or there is no spectrum dispersion, that is, there is no second spectrum information, then the target fault type is current change.

[0144] For example, Figure 6 As shown in the figure, the blue line is the transient frequency response of the high-resistance fault 0.3s after the fault occurs; the red line is the steady-state response curve. It can be seen from the figure that although the addition of noise causes a certain degree of spectrum distortion, the high-resistance fault can still be detected 0.3ms after the fault begins; the current spike of the high-resistance fault is 4.2166, the frequency is 2.5kHz, and the amplitude of the steady-state response at the corresponding frequency is 3.2732.

[0145] Furthermore, as shown in Figure 7, the blue line is the transient frequency response of the healthy outgoing line 11s after the target grounding point fault, and the red line is the steady-state response curve of the healthy outgoing line. As can be seen from the figure, the steady-state response is the same as the steady-state response curve of the faulty outgoing line where the target grounding point is located, but the amplitude of the transient response curve has changed, that is, when the frequency is 2.5kHz, the current peak is 8.1376. Furthermore, although the transient analysis result exceeds the steady-state threshold 11ms after the fault starts, the steady-state analysis result can always ensure that the noise will not be detected as a faulty outgoing line.

[0146] Optionally, after determining the target fault type of the target grounding point according to the target spectrum information and preset conditions, steps F1-F3 are also included:

[0147] Step F1: Determine transient amplitude information and steady-state amplitude information of target spectrum information.

[0148] Specifically, transient amplitude information and steady-state amplitude information are obtained from the target spectrum information.

[0149] Step F2: determining the target responsiveness according to the transient amplitude information and the steady-state amplitude information.

[0150] Specifically, the ratio of the transient amplitude information to the steady-state amplitude information is calculated to obtain the target responsiveness.

[0151] Furthermore, the target responsiveness can be expressed by the following formula:

[0152]

[0153] Among them, m t is the transient amplitude information; m ss is the steady-state amplitude information.

[0154] Step F3: determining a lightning surge fault according to the target responsiveness.

[0155] Among them, lightning surge faults include: lightning interference and lightning faults. The target responsivity can distinguish between lightning interference and lightning faults.

[0156] Specifically, the target sensitivity is determined according to the target spectrum information. If the target sensitivity is greater than the preset sensitivity, a lightning surge fault occurs at the target grounding point. Further, if the target responsiveness is greater than the preset responsiveness, the lightning surge fault is a lightning strike fault; if the target responsiveness is less than the preset responsiveness, the lightning surge fault is lightning interference. If the target sensitivity is less than the preset sensitivity, only a high-resistance fault occurs at the target grounding point.

[0157] Among them, the target sensitivity can distinguish between lightning surge faults and high-resistance faults.

[0158] Furthermore, the target sensitivity can be expressed by the following formula:

[0159]

[0160] Among them, ω t is the transient filter identification parameter; ω ss Identify parameters for the steady-state filter.

[0161] For example, Figure 8 As shown in the figure, the sensitivity of lightning interference and lightning fault is above 100, which indicates that there is a lightning surge fault at the target grounding point. After the distribution network is struck by lightning, the zero-sequence current of the target fault will temporarily increase, such as Fig. 9 As shown, the target responsiveness is above 50.

[0162] Furthermore, if Fig. 9 As shown by the blue line in the middle, the target response degree briefly reaches above 50, and after 0.5ms, the target response degree gradually changes to 0, indicating that the distribution network was briefly affected by lightning, so the lightning surge fault is lightning interference. Fig. 9 As shown by the red line, the target responsiveness briefly reaches above 50, and then drops to 20 at 0.5ms, and then continues to increase, indicating that lightning has caused a short circuit in the distribution network, resulting in a continuous increase in the target fault zero-sequence current, so the lightning surge fault is a lightning fault.

[0163] The technical solution of this embodiment determines the target fault zero-sequence current signal; performs a preset Fourier transform on the target fault zero-sequence current signal to obtain the target discrete signal of the target fault zero-sequence current signal, and determines the target spectrum information of the target fault zero-sequence current signal based on the target discrete signal. The preset Fourier transform can amplify the fault current signal in the target fault zero-sequence current signal, so that the obtained target spectrum information can provide a basis for the identification of high-resistance faults; the target fault type of the target grounding point is determined based on the target spectrum information, and the high-resistance fault and current change can be distinguished through the target spectrum information, thereby improving the accuracy of high-resistance fault identification. This method can be discovered by staff in a timely manner when a high-resistance fault occurs, so as to prevent safety hazards such as electric shock and fire caused by the long-term existence of the high-resistance fault.

[0164] Fig.10 The present invention provides a schematic diagram of the structure of a high-resistance grounding fault detection device for a distribution network. This embodiment is applicable to the case where the type of a grounding fault occurs in a distribution network and the fault type is determined. The distribution network high-resistance grounding fault detection device can be implemented in the form of hardware and / or software, and the distribution network high-resistance grounding fault detection device can be configured in any electronic device with a network communication function. Fig.10As shown, the device includes: a fault current signal determination module 210, a spectrum information determination module 220 and a fault type determination module 230, wherein:

[0165] Fault current signal determination module 210: used to determine a target fault zero-sequence current signal, where the target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault at a target grounding point, where the target grounding point is a grounding point in the distribution network;

[0166] The spectrum information determination module 220 is used to perform a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and determine the target spectrum information of the target fault zero-sequence current signal according to the target discrete signal, wherein the preset Fourier transform is used to perform a frequency domain change on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform, and the target spectrum information includes: first spectrum information for characterizing the current peak of the target grounding point and second spectrum information for characterizing the dispersion of the target grounding point;

[0167] The fault type determination module 230 is used to determine the target fault type of the target grounding point according to the target frequency spectrum information.

[0168] Optionally, the distribution network high-resistance grounding fault detection device further includes:

[0169] A reference fault type determination module is used to determine a reference fault type, where the reference fault type includes: a low resistance fault or an assumed high resistance fault, where the assumed high resistance fault includes: a high resistance fault or a current change;

[0170] A low resistance fault processing module, used for continuing to judge the reference fault type of the target grounding point if the reference fault type is a low resistance fault;

[0171] The high-resistance fault processing module is used to perform a preset Fourier transform on the target fault zero-sequence current signal if the reference fault type is an assumed high-resistance fault.

[0172] Optionally, a reference fault type determination module includes:

[0173] Comparison unit: used to compare the target fault zero-sequence current signal with the current preset threshold value;

[0174] A low resistance fault determination unit: used for determining that the reference fault type is a low resistance fault if the target fault zero sequence current signal is greater than or equal to a current preset threshold value;

[0175] Assumed high-resistance fault determination unit: used for determining that if the target fault zero-sequence current signal is less than a preset current threshold, the reference fault type is an assumed high-resistance fault.

[0176] Optionally, the spectrum information determination module 220 includes:

[0177] Extended fault discrete zero-sequence current signal determination unit: used for performing Fourier transform on the target fault zero-sequence current signal and expanding the number of sampling points to obtain an extended fault discrete zero-sequence current signal;

[0178] A second window function determination unit: used for introducing a correction factor into the first window function to obtain a second window function;

[0179] Target discrete signal determination unit: used to calculate the frequency sampling points of the extended fault discrete zero-sequence current signal and the second window function to determine the target discrete signal of the target fault zero-sequence current signal.

[0180] Optionally, the spectrum information determination module 220 includes:

[0181] A distribution determination unit: used to determine the distribution of the target fault zero-sequence current signal in the frequency domain according to the target discrete signal;

[0182] The spectrum information determining unit is used to determine the spectrum information corresponding to the area with the current peak as the first spectrum information according to the distribution situation; and determine the spectrum information corresponding to the area with the spectrum dispersion as the second spectrum information.

[0183] Optionally, the fault type determination module 230 includes:

[0184] A high-resistance fault determination unit: used to determine that if the first spectrum information is greater than or equal to a preset peak and there is second spectrum information, the target fault type is a high-resistance fault;

[0185] A current change determination unit is used to determine that if the first spectrum information is smaller than a preset peak value, or if the second spectrum information does not exist, the target fault type is a current change.

[0186] Optionally, the distribution network high-resistance grounding fault detection device further includes:

[0187] Amplitude information determination module: used to determine transient amplitude information and steady-state amplitude information of target spectrum information;

[0188] Target responsiveness determination module: used to determine the target responsiveness according to transient amplitude information and steady-state amplitude information;

[0189] Lightning surge fault determination module: used to determine lightning surge fault according to target responsiveness.

[0190] The distribution network high-resistance grounding fault detection device provided in the embodiment of the present invention can execute the distribution network high-resistance grounding fault detection method provided in any of the above-mentioned embodiments of the present invention, and has the corresponding functions and beneficial effects of executing the distribution network high-resistance grounding fault detection method. For detailed process, please refer to the relevant operations of the distribution network high-resistance grounding fault detection method in the above-mentioned embodiment.

[0191] Fig.11 A schematic diagram of the structure of an electronic device for implementing the method for detecting high-resistance ground faults in a distribution network according to an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0192] like Fig.11 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0193] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0194] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a method for detecting a high-resistance grounding fault in a distribution network.

[0195] In some embodiments, the method for detecting a high-resistance grounding fault in a distribution network may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for detecting a high-resistance grounding fault in a distribution network described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to execute the method for detecting a high-resistance grounding fault in a distribution network by any other appropriate means (e.g., by means of firmware).

[0196] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0197] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0198] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0199] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0200] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0201] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0202] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0203] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting high-resistance grounding faults in a distribution network, characterized in that: include: Determine a target fault zero-sequence current signal, where the target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault occurring at a target grounding point, where the target grounding point is a grounding point in a distribution network; A preset Fourier transform is performed on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and target spectrum information of the target fault zero-sequence current signal is determined according to the target discrete signal, wherein the preset Fourier transform is used to perform frequency domain changes on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform, and the target spectrum information includes: first spectrum information for characterizing the current spike of the target grounding point and second spectrum information for characterizing the dispersion of the target grounding point; A target fault type of a target grounding point is determined according to the target frequency spectrum information.

2. The method according to claim 1, characterized in that: Before performing a preset Fourier transform on the target fault zero-sequence current signal, the method further includes: Determine a reference fault type, the reference fault type includes: a low resistance fault or an assumed high resistance fault, the assumed high resistance fault includes: a high resistance fault or a current change; If the reference fault type is a low-resistance fault, continue to judge the reference fault type of the target grounding point; If the reference fault type is an assumed high-resistance fault, it is necessary to perform a preset Fourier transform on the target fault zero-sequence current signal.

3. The method according to claim 2, characterized in that The determining of the reference fault type comprises: Comparing the target fault zero-sequence current signal with a preset current threshold; If the target fault zero-sequence current signal is greater than or equal to the current preset threshold, the reference fault type is a low-resistance fault; If the target fault zero-sequence current signal is less than the preset current threshold, the reference fault type is an assumed high-resistance fault.

4. The method according to claim 1, characterized in that: The method of performing a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal includes: Perform Fourier transform on the target fault zero-sequence current signal and expand the number of sampling points to obtain an extended fault discrete zero-sequence current signal; Introducing the correction factor into the first window function to obtain the second window function; The frequency sampling points of the extended fault discrete zero-sequence current signal and the second window function are calculated to obtain a target discrete signal of the target fault zero-sequence current signal.

5. The method according to claim 1, characterized in that The step of determining target frequency spectrum information of a target fault zero-sequence current signal according to a target discrete signal of the target fault zero-sequence current signal comprises: Determine the distribution of the target fault zero-sequence current signal in the frequency domain according to the target discrete signal; According to the distribution, the frequency spectrum information corresponding to the area with the current peak is used as the first frequency spectrum information; and the frequency spectrum information corresponding to the area with the spectrum dispersion is used as the second frequency spectrum information.

6. The method according to claim 1, characterized in that The determining a target fault type of a target grounding point according to the target spectrum information includes: If the first spectrum information is greater than or equal to a preset peak value and the second spectrum information exists, the target fault type is a high resistance fault; If the first frequency spectrum information is smaller than a preset peak value, or the second frequency spectrum information does not exist, the target fault type is a current change.

7. The method according to claim 1, characterized in that After determining the target fault type of the target grounding point according to the target spectrum information and the preset conditions, the method further includes: Determining transient amplitude information and steady-state amplitude information of the target spectrum information; determining a target responsiveness according to the transient amplitude information and the steady-state amplitude information; A lightning surge fault is determined according to the target responsiveness.

8. A distribution network high-resistance grounding fault detection device, characterized in that: include: A fault current signal determination module is used to determine a target fault zero-sequence current signal, wherein the target fault zero-sequence current signal is a zero-sequence current signal corresponding to a single-phase grounding fault occurring at a target grounding point, wherein the target grounding point is a grounding point in a distribution network; A spectrum information determination module is used to perform a preset Fourier transform on the target fault zero-sequence current signal to obtain a target discrete signal of the target fault zero-sequence current signal, and determine the target spectrum information of the target fault zero-sequence current signal according to the target discrete signal, wherein the preset Fourier transform is used to perform a frequency domain change on the target fault zero-sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero-sequence current signal is introduced into the preset Fourier transform, and the target spectrum information includes: first spectrum information for characterizing the current spike of the target grounding point and second spectrum information for characterizing the dispersion of the target grounding point; The fault type determination module is used to determine a target fault type of a target grounding point according to the target frequency spectrum information.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the distribution network high-resistance grounding fault detection method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method for detecting high-resistance grounding faults in a distribution network according to any one of claims 1 to 7 when executed.

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