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

Abstract

The application discloses a kind of distribution network high resistance ground fault detection method, device, electronic equipment and storage medium.The method comprises: determining target fault zero sequence current signal;The target fault zero sequence current signal is carried out preset fourier transform, and the target discrete signal of target fault zero sequence current signal is obtained, and the target frequency spectrum information of target fault zero sequence current signal is determined according to target discrete signal;According to target frequency spectrum information, the target fault type of target grounding point is determined.The method is transformed according to the result by preset fourier variation to target fault zero sequence current information, judges whether high resistance fault occurs at target grounding point, can be discovered by staff in time when high resistance fault occurs, to prevent the safety hazard such as electric shock and fire caused by long time existence of high resistance fault.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network fault detection, and in particular to a power distribution network high-resistance grounding fault detection method and device, an electronic device and a storage medium. BACKGROUND

[0002] In the power distribution network, the medium and low voltage distribution network has the characteristics of overhead outages and cable mixed outages, numerous branch lines, and complex network topology structure due to its direct facing to power supply 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 operation errors, etc., thereby leading to faults. Among them, single-phase grounding fault is the most common fault type in medium voltage distribution network, accounting for about 50% of the total number of distribution network faults, which poses a serious threat to the safe and stable operation of the distribution network. No matter whether it is a small current grounding or a small resistance grounding system, there is currently a lack of effective detection and protection means for high-resistance faults.

[0003] However, the existing fault detection methods cannot timely discover and handle high-resistance faults, which can easily lead to serious faults in the power distribution network, thereby causing safety hazards such as electric shock and fire. SUMMARY

[0004] The present application provides a power distribution network high-resistance grounding fault detection method, device, electronic device and storage medium to solve the problem of not timely discovering high-resistance faults.

[0005] According to an aspect of the present application, a power distribution network high-resistance grounding fault detection method is provided, comprising:

[0006] determining a target fault zero sequence current signal, the target fault zero sequence current signal being a zero sequence current signal corresponding to a single-phase grounding fault at a target grounding point, the target grounding point being a grounding point in the power distribution network;

[0007] 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 spectral information of the target fault zero sequence current signal according to the target discrete signal, the preset Fourier transform being used for frequency domain conversion of the target fault zero sequence current signal, and a correction factor for eliminating harmonic interference in the target fault zero sequence current signal being introduced in the preset Fourier transform, the target spectral information including first spectral information for representing a current spike of the target grounding point and second spectral information for representing a dissipation condition of the target grounding point;

[0008] determining a target fault type of the target grounding point according to the target spectral information.

[0009] According to another aspect of the present application, there is provided a power distribution network high-resistance grounding fault detection device, comprising:

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

[0011] a spectrum information determination module configured 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 target spectrum information of the target fault zero sequence current signal according to the target discrete signal, the preset Fourier transform being configured to change the target fault zero sequence current signal in a frequency domain, and the preset Fourier transform being configured to introduce a correction factor for eliminating harmonic interference in the target fault zero sequence current signal, the target spectrum information including first spectrum information for characterizing a current peak of the target grounding point and second spectrum information for characterizing a dissipation condition of the target grounding point;

[0012] a fault type determination module configured to determine a target fault type of the target grounding point according to the target spectrum information.

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

[0014] at least one processor; and

[0015] a memory connected to the at least one processor in communication; 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 to enable the at least one processor to perform the power distribution network high-resistance grounding fault detection method according to any one of the embodiments of the present application.

[0017] According to another aspect of the present application, there is provided a computer readable storage medium storing computer instructions for enabling a processor to perform the power distribution network high-resistance grounding fault detection method according to any one of the embodiments of the present application when executed by the processor.

[0018] The technical scheme of the embodiment of the present application determines a target fault zero sequence current signal; performs 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 determines target spectrum information of the target fault zero sequence current signal according to 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 identification of the high-resistance fault; and the target spectrum information is used to determine a target fault type of a target grounding point, and the target spectrum information can be used to distinguish the high-resistance fault and current change, thereby improving the accuracy of high-resistance fault identification. The method can be discovered by the staff in time when the high-resistance fault occurs, so as to prevent the safety hazards such as electric shock and fire caused by the long-time existence of the high-resistance fault.

[0019] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 A flowchart of a high-resistance grounding fault detection method for a power distribution network provided by the embodiment of the present application;

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

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

[0024] Figure 4 Another three-dimensional spectrum diagram of a target fault zero sequence current signal provided by the embodiment of the present application;

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

[0026] Figure 6 A frequency response schematic diagram of a fault outgoing line after 0.3 seconds of high-resistance fault occurrence provided by the embodiment of the present application;

[0027] Figure 7This is a schematic diagram of the frequency response of a non-faulty outgoing line 11 seconds after a high-impedance fault occurs, provided by an embodiment of the present invention.

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

[0029] Figure 9 A schematic diagram of lightning surge response provided in an embodiment of the present invention.

[0030] Figure 10 This is a schematic diagram of the structure of a high-resistance grounding fault detection device for a power distribution network provided in an embodiment of the present invention;

[0031] Figure 11 A schematic diagram of the electronic device used to implement the high-resistance grounding fault detection method for power distribution networks according to embodiments of the present invention. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] Figure 1 This is a flowchart illustrating a method for detecting high-resistance grounding faults in a distribution network, provided by an embodiment of the present invention. This embodiment is applicable to situations where a grounding fault occurs in a distribution network, and the fault type is determined. This method can be executed by a high-resistance grounding fault detection device, which can be implemented in hardware and / or software. This high-resistance grounding fault detection device can be configured in any electronic device with network communication capabilities. 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 at a target grounding point. The single-phase grounding fault can be a low-resistance fault or a high-resistance fault.

[0037] The high-resistance fault includes a high-resistance fault and a current change. The current change can be caused by the start, stop or switching of the power distribution network.

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

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

[0040] Further, the target grounding point is connected to the ground by a neutral grounding strategy. The neutral grounding strategy includes a neutral point ungrounded, resonant grounding and small resistance grounding.

[0041] When the grounding strategy of the target grounding point is neutral point ungrounded, the target fault zero sequence current in the fault outgoing line II in the power distribution network can be represented by the following formula:

[0042]

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

[0044]

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

[0046] Further, 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 power distribution network can be represented by the following formula:

[0047]

[0048] wherein, is the target fault zero sequence current of the fault outgoing line II; is the zero sequence current of the healthy outgoing line in the power distribution network; This represents the inductor current.

[0049] Furthermore, based on the degree of mistuning: 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 C is the capacitance to ground of the first intact outgoing line; 02 The capacitance to ground of the second intact outgoing line; U0 is the zero-sequence voltage; I c ν 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 The capacitance to ground of the kth healthy outgoing line; It is the zero-sequence voltage; R is the sum of the zero-sequence capacitances of all outgoing lines to ground; R is the neutral point grounding resistance; R f The transition resistance at the target grounding point is n; n is the number of complete outgoing lines. The phase voltage before the target grounding point fault.

[0055] The neutral point zero-sequence current is:

[0056]

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

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

[0059]

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

[0061] Specifically, when the current detection device detects a fault transient of the target grounding point, it is considered that the target grounding point may have a high-resistance or low-resistance fault at this moment. At this time, the fault zero sequence current signal of the target grounding point in the preset time range is obtained in the current data acquisition device, and the fault zero sequence current signal obtained is filtered to obtain the target fault zero sequence current signal.

[0062] The fault transient is the instantaneous change of the zero sequence current when the target grounding point is suspected to have a single-phase grounding fault.

[0063] The above step filters the fault zero sequence current signal to eliminate noise signals in the current signal.

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

[0065] For example, assuming that the fault transient of the target grounding point occurring at time A is detected, the fault zero sequence current signal in the t time interval after time A is obtained.

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

[0067] Further, as shown in Figure 3 The three-dimensional spectrum diagram of the normal zero sequence current signal is shown. As can be seen from the diagram, the amplitude of the current 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 that of the normal zero sequence current, and the frequency change range is also greater than that of 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 change the frequency domain of 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 in the preset Fourier transform.

[0070] Further, the correction factor is introduced because there are a large number of nonlinear loads in the power distribution network, or harmonic signals are generated in the process of rectification and inversion. However, when analyzing the target fault zero sequence current signal, it is usually based on the fundamental signal, so the existence of harmonic information will cause deviation in the analysis result.

[0071] The target spectrum information includes first spectrum information for characterizing a current peak of the target grounding point and second spectrum information for characterizing a dispersion condition of the target grounding point.

[0072] Specifically, the target fault zero sequence current signal is subjected to preset Fourier transform, the target fault zero sequence current signal is converted from a time domain signal to a discrete signal in a frequency domain through the preset Fourier transform, and 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 step of performing preset Fourier transform can amplify the fault current signal in the target fault zero sequence current signal in a high frequency band and disperse it in a low frequency band, thereby providing a basis for judging whether the target grounding point has a high resistance fault.

[0074] S130, determining a target fault type of the target grounding point according to the target spectrum information.

[0075] The target fault type includes a high resistance fault or a current change.

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

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

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

[0079] The above step of distinguishing the high resistance fault and the current change according to the target spectrum information is because the current changes of the two are small and the change ranges are similar, and direct judgment is easy to confuse, so it is necessary to distinguish according to the change of the spectrum information to prevent inaccurate detection of the high resistance fault caused by confusion, thereby seriously threatening the safe and stable operation of the power distribution network.

[0080] Optionally, before the target fault zero sequence current signal is subjected to preset Fourier transform, the method further includes steps A1-A3:

[0081] Step A1, determining a reference fault type.

[0082] wherein the reference fault type comprises: a low-resistance fault or a supposed high-resistance fault, and the supposed high-resistance fault comprises: a high-resistance fault or a current change.

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

[0084] Further, when the distribution network has a low-resistance fault, the target fault zero sequence current signal in the fault outgoing line where the target grounding point is located is large; when the distribution network has a high-resistance fault, the target fault zero sequence current signal in the fault outgoing line where the target grounding point is located is weak, and the target fault zero sequence current signal corresponding to the high-resistance fault is different for different grounding strategies. 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 corresponding to the high-resistance fault of 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 detected for a fault transient, and the reference fault type of the target grounding point is judged according to the detection result.

[0087] Step A3, if the reference fault type is a supposed high-resistance fault, a preset Fourier transform needs to be performed on the target fault zero sequence current signal.

[0088] Specifically, if the reference fault type is a supposed high-resistance fault, it is considered that the target grounding point may have a high-resistance fault, so a preset Fourier transform needs to be performed on the target fault zero sequence current signal to further judge whether it is a high-resistance fault.

[0089] The above step of judging whether a preset Fourier transform needs to be performed according to the reference fault type is because when the target grounding point has a low-resistance fault, the fault transient current signal peak in the target fault zero sequence current signal is obvious and can be directly observed, so no frequency domain analysis is needed. However, the fault transient current signal when the high-resistance fault occurs is similar to the current signal generated when the distribution network performs switching action, and it is not easy to distinguish, so frequency domain analysis is needed to distinguish.

[0090] Optionally, determining the reference fault type comprises steps B1-B3:

[0091] Step B1, comparing the target fault zero sequence current signal with a current preset threshold.

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

[0093] Step B2, 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.

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

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

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

[0097] The above steps can provide a basis for determining whether the target fault zero sequence current signal needs to be subjected to a preset Fourier transform according to the reference fault type.

[0098] Optionally, a target discrete signal of the target fault zero sequence current signal is obtained by performing a preset Fourier transform on the target fault zero sequence current signal, including steps C1-C4:

[0099] Step C1, performing a Fourier transform on the target fault zero sequence current signal and expanding the number of sampling points to obtain an expanded fault discrete zero sequence current signal.

[0100] Specifically, performing a short-time Fourier transform on the target fault zero sequence current signal to obtain a fault discrete zero sequence current signal, and expanding the fault discrete zero sequence current signal according to a predicted expansion sampling point number to obtain an expanded fault discrete zero sequence current signal.

[0101] For example, assuming that the target fault zero sequence current signal is h(t), performing a short-time Fourier transform on the target fault zero sequence current signal to obtain a fault discrete zero sequence current signal According to the predicted expansion sampling point number, the number of sampling points is expanded to obtain an expanded fault discrete zero sequence current signal Wherein, n is the frequency sampling point number.

[0102] Step C2, introducing a correction factor into the first window function to obtain a second window function.

[0103] For example, the first window function adopts a Gaussian window, and the first window function can be represented by the following formula:

[0104]

[0105] Wherein, f is the frequency.

[0106] Step C3, frequency sampling point calculation is performed 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 point calculation is performed on the extended fault discrete zero sequence current signal and the second window function according to a preset sampling frequency, and inverse Fourier transform is performed to obtain the target discrete signal of the target fault zero sequence current signal.

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

[0109]

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

[0111] For example, short-time Fourier transform is performed on the target fault zero sequence current signal 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] wherein h(t) is an original signal; g(t-τ) is the first window function; e is the Fourier transform kernel function; f is the frequency; and t is the integral variable. -i2πft

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

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

[0116]

[0117] wherein the width of the Gaussian window is determined by δ, and in order to realize adaptive adjustment of the window width according to the frequency distribution of the signal, δ is defined as:

[0118]

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

[0120]

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

[0122]

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

[0124]

[0125] wherein f a is the optimal recognition frequency of the window function.

[0126] Further, τ→jT, T is a sampling period, then the following can be obtained:

[0127]

[0128] wherein N is the length of the window function; m is the f a corresponding frequency point; n is the frequency sampling point number; f a is the optimal recognition frequency of the window function.

[0129] Further, let then the second window function is:

[0130]

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

[0132]

[0133] Optionally, the target spectrum information of the target fault zero sequence current signal is determined according to the target discrete signal of the target fault zero sequence current signal, including steps D1-D2:

[0134] Step D1, the distribution of the target fault zero sequence current signal in the frequency domain is determined according to the target discrete signal.

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

[0136] Exemplarily, as shown in Figure 4 , the three-dimensional image is intercepted according to the cutoff frequency f1, and a two-dimensional image with the x-axis as the frequency and the y-axis as the amplitude is obtained, as shown in Figure 5As shown in the figure, the red line is the transient response curve 0.1 ms after the fault occurs, the yellow line is the steady-state response curve, and the blue line is the response curve generated at the moment of the target grounding fault. As can be seen from the figure, at 2.5 kHz, the fault current peak amplitude is about 3 dB, the steady-state amplitude is about 1.5 dB, and the transient fault amplitude is less than 1 dB.

[0137] Step D2: According to the distribution, the spectral information corresponding to the region with current peak is taken as the first spectral information, and the spectral information corresponding to the region with spectral dispersion is taken as the second spectral information.

[0138] Specifically, the distribution is analyzed, the spectral information corresponding to the region where the current peak is located is taken as the first spectral information, and the spectral information corresponding to the region where the spectral dispersion occurs is taken as the second spectral information.

[0139] Optionally, the target fault type of the target grounding point is determined according to the target spectral information, including steps E1-E2:

[0140] Step E1: If the first spectral information is greater than or equal to the preset peak, and the second spectral information exists, the target fault type is a high-impedance fault.

[0141] Specifically, if the first spectral information is greater than or equal to the preset peak, and the spectral dispersion exists, i.e., the second spectral information exists, the target fault type is a high-impedance fault.

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

[0143] Specifically, if the first spectral information is less than the preset peak, or the spectral dispersion does not exist, i.e., the second spectral information does not exist, the target fault type is a current change.

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

[0145] Further, as shown in FIG. 7, to make the healthy line frequency response, the blue line is the transient frequency response of the healthy line at 11s after the target grounding fault; the red line is the steady-state response curve of the healthy line. As can be seen from the figure, the steady-state response is the same as the steady-state response curve of the fault line where the target grounding point is located, but the transient response curve amplitude changes, i.e., the current peak is 8.1376 when the frequency is 2.5 kHz. Further, although the transient analysis result exceeds the steady-state threshold value at 11 ms after the fault starts, the steady-state analysis result can always ensure that noise will not be detected as a fault line.

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

[0147] Step F1, determining transient amplitude information and steady-state amplitude information of the target spectrum information.

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

[0149] Step F2, determining a target response degree 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 response degree.

[0151] Further, the target response degree can be represented by the following formula:

[0152]

[0153] Wherein, 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 response degree.

[0155] Wherein, the lightning surge fault includes lightning interference and lightning strike fault. The target response degree can distinguish lightning interference and lightning strike fault.

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

[0157] Wherein, the target sensitivity can distinguish the lightning surge fault and the high resistance fault.

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

[0159]

[0160] Wherein, ω t is a transient filter identification parameter; ω ss is a steady-state filter identification parameter.

[0161] As shown in Figure 8 , the sensitivity of lightning interference and lightning failure is all above 100, indicating that the target grounding point exists lightning surge failure. After the distribution network is struck by lightning, the target fault zero sequence current will have a temporary increase, as shown in Figure 9 , the target response is above 50.

[0162] Further, as shown by the blue line in Figure 9 , the target response temporarily reaches above 50, and after 0.5ms, the target response gradually becomes 0, indicating that the distribution network is temporarily affected by lightning, so the lightning surge failure is lightning interference. As shown by the red line in Figure 9 , the target response temporarily reaches above 50, and at 0.5ms, it decreases to 20, and then continuously increases, indicating that the lightning causes the distribution network to have a short circuit, resulting in a continuous increase in the target fault zero sequence current, so the lightning surge failure is lightning failure.

[0163] The technical scheme of the embodiment determines the target fault zero sequence current signal; performs 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 determines target spectrum information of the target fault zero sequence current signal according to 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 identifying high-resistance faults; the target fault type of the target grounding point is determined according to the target spectrum information, and the target spectrum information can distinguish between high-resistance faults and current changes, thereby improving the accuracy of high-resistance fault identification. The method can be discovered by the staff in time when a high-resistance fault occurs, so as to prevent the safety hazards such as electric shock and fire caused by the long-term existence of the high-resistance fault.

[0164] Figure 10 A structure diagram of a distribution network high-resistance grounding fault detection device provided by the embodiment of the present application. The embodiment can be applicable to the case of determining the fault type when the distribution network has a grounding fault. The distribution network high-resistance grounding fault detection device can be realized in the form of hardware and / or software, and can be configured in any electronic device with network communication function. Figure 10As shown, the device comprises: a fault current signal determination module 210, a spectrum information determination module 220, and a fault type determination module 230, wherein:

[0165] The fault current signal determination module 210 is configured to determine a target fault zero sequence current signal, the target fault zero sequence current signal being a zero sequence current signal corresponding to a single-phase ground fault at a target grounding point in the power distribution network;

[0166] The spectrum information determination module 220 is configured 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 target spectrum information of the target fault zero sequence current signal according to the target discrete signal, the preset Fourier transform being configured to change the target fault zero sequence current signal in the frequency domain, and the preset Fourier transform introducing a correction factor configured to eliminate harmonic interference in the target fault zero sequence current signal, the target spectrum information including: first spectrum information configured to represent a current peak of the target grounding point, and second spectrum information configured to represent a dispersion condition of the target grounding point;

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

[0168] Optionally, the power distribution network high-resistance ground fault detection device further comprises:

[0169] The reference fault type determination module is configured to determine a reference fault type, the reference fault type including: a low-resistance fault or a hypothetical high-resistance fault, the hypothetical high-resistance fault including: a high-resistance fault or a current change;

[0170] The low-resistance fault processing module is configured to continue to determine the reference fault type of the target grounding point if the reference fault type is the low-resistance fault.

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

[0172] Optionally, the reference fault type determination module comprises:

[0173] The comparison unit is configured to compare the target fault zero sequence current signal with a current preset threshold;

[0174] The low-resistance fault determination unit is configured to determine that the reference fault type is the low-resistance fault if the target fault zero sequence current signal is greater than or equal to the current preset threshold.

[0175] The hypothetical high-resistance fault determination unit is configured to determine that the reference fault type is the hypothetical high-resistance fault if the target fault zero sequence current signal is less than the current preset threshold.

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

[0177] The extended fault discrete zero sequence current signal determination unit is configured to perform Fourier transform on the target fault zero sequence current signal, and extend the number of sampling points to obtain an extended fault discrete zero sequence current signal.

[0178] The second window function determination unit is configured to introduce the correction factor into the first window function to obtain a second window function.

[0179] The target discrete signal determination unit is configured to perform 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.

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

[0181] The distribution condition determination unit is configured to determine a distribution condition of the target fault zero sequence current signal in the frequency domain according to the target discrete signal.

[0182] The spectrum information determination unit is configured to take, as the first spectrum information, spectrum information corresponding to a region with current spikes, and take, as the second spectrum information, spectrum information corresponding to a region with spectrum dispersion, according to the distribution condition.

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

[0184] The high-resistance fault determination unit is configured to determine that the target fault type is a high-resistance fault if the first spectrum information is greater than or equal to a preset spike and the second spectrum information exists.

[0185] The current change determination unit is configured to determine that the target fault type is a current change if the first spectrum information is less than the preset spike or the second spectrum information does not exist.

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

[0187] The amplitude information determination module is configured to determine transient amplitude information and steady-state amplitude information of the target spectrum information.

[0188] The target response degree determination module is configured to determine a target response degree according to the transient amplitude information and the steady-state amplitude information.

[0189] The lightning surge fault determination module is configured to determine a lightning surge fault according to the target response degree.

[0190] The power distribution network high-resistance grounding fault detection device provided in the embodiments of the present application can execute the power distribution network high-resistance grounding fault detection method provided in any of the embodiments of the present application, has the corresponding functions and advantages of executing the power distribution network high-resistance grounding fault detection method, and the detailed process can be referred to the related operations of the power distribution network high-resistance grounding fault detection method in the foregoing embodiments.

[0191] Figure 11 The structure schematic diagram of the electronic device for implementing the power distribution network high-resistance grounding fault detection method of the embodiments of the present application. The electronic device is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular telephones, smart phones, wearable devices (such as headsets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be examples only, and are not intended to limit the implementations of the present application described and / or claimed in this document.

[0192] As shown in Figure 11 The electronic device 10 includes at least one processor 11, and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected with the at least one processor 11, wherein the memory stores a computer program which can be executed by the at least one processor. The processor 11 can execute various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or 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 with each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0193] The plurality 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, a loudspeaker, etc.; a storage unit 18, such as a magnetic 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 can be various general and / or special purpose processing components having 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 specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The processor 11 performs various methods and processes described above, such as the power distribution network high resistance ground fault detection method.

[0195] In some embodiments, the power distribution network high resistance ground fault detection method can be implemented as a computer program tangibly embodied in a computer readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded onto the RAM 13 and executed by the processor 11, one or more steps of the power distribution network high resistance ground fault detection method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to perform the power distribution network high resistance ground fault detection method by any other suitable means, such as by means of firmware.

[0196] Various implementations of the systems and techniques described above can be realized in digital electronic circuitry, integrated circuitry, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on a chip (SOC), a programmable logic device (PLD), a computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0197] Computer programs used to implement the methods of the application can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the computer program, when executed, implements the functions / acts specified in the flowcharts and / or block diagrams. The computer program can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0198] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of a machine-readable storage medium will include one or more lines of a program of instructions in a transitory signal, a portable computer diskette, 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 disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0199] To provide for interaction with a user, the systems and techniques described here can 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 a trackball) by which the user can provide input to the electronic device. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0200] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a user computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can 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] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. The server can 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 large management difficulty and weak business scalability in traditional physical host and VPS service.

[0202] It should be understood that the various forms of flow shown above can be reordered, added to, or have steps deleted. For example, the steps described in the present application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, which are not limited herein.

[0203] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting high-resistance grounding faults in a power distribution network, characterized in that, include: Determine the target fault zero-sequence current signal, which is the zero-sequence current signal corresponding to a single-phase ground fault at the target grounding point, and the target grounding point is a grounding point in the 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. The target spectral information of the target fault zero-sequence current signal is determined based on the target discrete signal. The preset Fourier transform is used to perform frequency domain transformation on the target fault zero-sequence current signal. The preset Fourier transform introduces a correction factor to eliminate harmonic interference in the target fault zero-sequence current signal. The target spectral information includes: first spectral information characterizing the current spike of the target grounding point and second spectral information characterizing the dissipation of the target grounding point. The target fault type of the target grounding point is determined based on the target 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, which includes: a low-resistance fault or a assumed high-resistance fault, wherein the assumed high-resistance fault includes: a high-resistance fault or a current change; If the reference fault type is a low-resistance fault, then continue to determine the reference fault type of the target grounding point; If the reference fault type is assumed to be a high-impedance fault, then a preset Fourier transform needs to be performed on the zero-sequence current signal of the target fault.

3. The method according to claim 2, characterized in that, The determination of the reference fault type includes: The target fault zero-sequence current signal is compared with a preset current threshold. If the target fault zero-sequence current signal is greater than or equal to the current preset threshold, then the reference fault type is low resistance fault. If the target fault zero-sequence current signal is less than the current preset threshold, then the reference fault type is assumed to be a high-resistance fault.

4. The method according to claim 1, characterized in that, The step of obtaining the target discrete signal of the target fault zero-sequence current signal by performing a preset Fourier transform on the target fault zero-sequence current signal includes: The target fault zero-sequence current signal is subjected to Fourier transform, and the number of sampling points is expanded to obtain the extended fault discrete zero-sequence current signal. By introducing the correction factor into the first window function, we obtain the second window function; The target discrete signal of the target fault zero-sequence current signal is obtained by calculating the frequency sampling points of the extended fault discrete zero-sequence current signal and the second window function.

5. The method according to claim 1, characterized in that, Determining the target spectrum information of the target fault zero-sequence current signal based on the target discrete signal of the target fault zero-sequence current signal includes: The frequency domain distribution of the target fault zero-sequence current signal is determined based on the target discrete signal; Based on the distribution, the spectral information corresponding to the region with current spikes is taken as the first spectral information; the spectral information corresponding to the region with spectral dissipation is taken as the second spectral information.

6. The method according to claim 1, characterized in that, Determining the target fault type of the target grounding point based on the target spectrum information includes: If the first spectrum information is greater than or equal to a preset peak, and the second spectrum information exists, then the target fault type is a high-impedance fault. If the first spectrum information is less than the preset peak, or if the second spectrum information does not exist, then the target fault type is current change.

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

8. A high-resistance grounding fault detection device for power distribution networks, characterized in that, include: The fault current signal determination module is used to determine the target fault zero-sequence current signal, wherein the target fault zero-sequence current signal is the zero-sequence current signal corresponding to a single-phase ground fault occurring at the target grounding point, and the target grounding point is a grounding point in the distribution network. The 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 to determine the target spectrum information of the target fault zero-sequence current signal based on the target discrete signal. 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 in the preset Fourier transform. 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 dissipation of the target grounding point. The fault type determination module is used to determine the target fault type of the target grounding point based on the target spectrum information.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the distribution network high-resistance grounding fault detection method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the distribution network high-resistance grounding fault detection method according to any one of claims 1-7.

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