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

Abstract

The invention discloses a power distribution network ground fault detection method and device, electronic equipment and a storage medium. The method comprises the following steps: reading a target zero-sequence current signal corresponding to a target detection point in the power distribution network; determining a target instantaneous energy density level of the target zero-sequence current signal, wherein the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a part of zero-sequence current signal subjected to steady-state ripple component suppression in the target zero-sequence current signal; and determining whether the target detection point has a ground fault according to the target instantaneous energy density level. According to the scheme, the target detection point of the power distribution network is detected in real time, the influence of the harmonic component in the target zero-sequence current signal on ground fault detection is avoided, the fault can be quickly positioned and removed, meanwhile, the difference between the ground fault transient state and the load switching transient state can be distinguished, and the efficiency and accuracy of fault recognition are improved.

Description

Technical Field

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

[0002] At present, the distribution network is the intermediate link between the power system and users. It is responsible for distributing the electric energy required for daily life and industrial production. The safety and stability of the distribution network is an important prerequisite for ensuring the reliability of power supply. However, in the distribution network, the distribution network covers a wide area and the operating environment is complex. The line is easy to contact with the ground and other media to cause grounding faults. The existing line protection device is difficult to identify the grounding fault in the distribution network, which is easy to cause major safety accidents such as electric shock, and seriously threatens the safe operation of modern distribution networks. Therefore, how to quickly and accurately identify, locate and remove the grounding fault of the distribution network has become a problem that needs to be solved urgently. Summary of the invention

[0003] The present invention provides a distribution network grounding fault detection method, device, electronic equipment and storage medium to solve the problem that when a grounding fault occurs in a distribution network system, it is difficult to be accurately identified by an existing line protection device.

[0004] According to one aspect of the present invention, a method for detecting a ground fault in a power distribution network is provided, the method comprising:

[0005] Read the target zero-sequence current signal corresponding to the target detection point in the distribution network;

[0006] Determine a target instantaneous energy density level of a target zero-sequence current signal, where the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal that has undergone steady-state ripple component suppression in the target zero-sequence current signal;

[0007] Whether a ground fault occurs at a target detection point is determined according to a target instantaneous energy density level.

[0008] According to another aspect of the present invention, a distribution network grounding fault detection device is provided, the device comprising:

[0009] A target zero-sequence current signal reading module is used to read a target zero-sequence current signal corresponding to a target detection point in a distribution network;

[0010] A first determination module is used to determine a target instantaneous energy density level of a target zero-sequence current signal, where the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal that has undergone steady-state ripple component suppression in the target zero-sequence current signal;

[0011] The second determination module is used to determine whether a ground fault occurs at the target detection point according to a target instantaneous energy density level.

[0012] According to another aspect of the present invention, there is provided an electronic device, the electronic device comprising:

[0013] at least one processor; and

[0014] a memory communicatively connected to at least one processor; wherein,

[0015] The memory stores a computer program that can be executed by at least one processor. The computer program is executed by at least one processor so that the at least one processor can execute the distribution network grounding fault detection method according to any embodiment of the present invention.

[0016] According to another aspect of the present invention, a computer-readable storage medium is provided, which stores computer instructions for enabling a processor to implement the distribution network grounding fault detection method according to any embodiment of the present invention when the computer instructions are executed.

[0017] The technical solution of the embodiment of the present invention realizes real-time detection of the target detection point of the distribution network by reading the target zero-sequence current signal corresponding to the target detection point in the distribution network; determines the target instantaneous energy density level of the target zero-sequence current signal, and the target instantaneous energy density level is obtained by Hilbert transform-Huang transform processing on the partial zero-sequence current signal of the target zero-sequence current signal after the steady-state ripple component is suppressed, thereby avoiding the influence of the harmonic component in the target zero-sequence current signal on the ground fault detection, emphasizing the characteristics of the fault transient, and providing effective data support for subsequent fault judgment; determines whether a ground fault occurs at the target detection point according to the target instantaneous energy density level, and has the characteristics of high sensitivity, so as to facilitate rapid positioning and removal of the fault, and can distinguish the difference between the ground fault transient and the load switching transient, thereby improving the efficiency and accuracy of fault identification.

[0018] 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

[0019] 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.

[0020] Figure 1A flow chart of a method for detecting ground faults in a distribution network provided in Embodiment 1 of the present invention;

[0021] Figure 2 A circuit diagram of a distribution network system with an ungrounded neutral point provided in Embodiment 1 of the present invention;

[0022] Figure 3 A circuit diagram of neutral point resonant grounding of a distribution network system provided in Embodiment 1 of the present invention;

[0023] Figure 4 A circuit diagram of a distribution network system with a low-resistance neutral point grounding provided in the first embodiment of the present invention;

[0024] Figure 5 A Hilbert spectrum diagram of a first intrinsic mode function of a target zero-sequence current signal provided in the first embodiment of the present invention;

[0025] Figure 6 A distribution diagram of instantaneous energy density level corresponding to adding Gaussian white noise to an original load change signal provided in the first embodiment of the present invention;

[0026] Figure 7 A schematic diagram of the structure of a distribution network grounding fault detection device provided in Embodiment 2 of the present invention;

[0027] Figure 8 A schematic diagram of the structure of an electronic device for implementing a method for detecting grounding faults in a distribution network provided in a third embodiment of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] Embodiment 1

[0031] Figure 1 A flow chart of a distribution network ground fault detection method provided in Embodiment 1 of the present invention. This embodiment can be applied to detecting whether a ground fault occurs in a line in a distribution network system. The method can be performed by a distribution network ground fault detection device, which can be implemented in the form of hardware and / or software and can be configured in an electronic device that implements the distribution network ground fault detection method.

[0032] like Figure 1 As shown, the method includes:

[0033] S101. Read a target zero-sequence current signal corresponding to a target detection point in a distribution network.

[0034] In an embodiment of the present invention, a target detection point refers to a position in the distribution network system that is pre-set for detecting whether a ground fault occurs. The target detection point can be set near the position where the ground fault occurs in the distribution network system. The target zero-sequence current signal refers to the vector sum of the three-phase currents at the target detection point in the distribution network system. Under normal circumstances, the three-phase currents in the distribution network system are balanced, that is, the three-phase current amplitudes are equal, the phase difference is 120 degrees, and the vector sum of the three-phase currents is zero. In actual applications, due to unbalanced line load or line faults, the three-phase currents are unbalanced, the vector sum of the three-phase currents is not zero, and a zero-sequence current will be generated.

[0035] As an optional method, a target zero-sequence current signal corresponding to a target detection point in the distribution network is read, including:

[0036] When the distribution network system adopts the method of ungrounded neutral point, when a single-phase grounding fault occurs in the system, the current distribution is as follows: Figure 2 As shown in the figure, the ground fault occurs in phase A of line 2, and the zero-sequence current of line 1 is for: Zero sequence current of fault line 2 for:

[0037] As an optional method, a target zero-sequence current signal corresponding to a target detection point in the distribution network is read, including:

[0038] When the distribution network system adopts the neutral point resonant grounding method, when a single-phase grounding fault occurs in the system, the current distribution is as follows: Figure 3 As shown in the figure, the ground fault occurs in phase A of line 2, and the zero-sequence current of line 1 is for:

[0039]

[0040] Zero sequence current of fault line 2 for:

[0041]

[0042] According to the detuning Zero sequence current of fault line 2 It can be expressed as:

[0043]

[0044] Among them, the detuning degree refers to the detuning degree of the arc extinguishing coil, which indicates the degree of deviation from the resonant state and is used to describe the compensation degree of the arc extinguishing coil. If the detuning degree is a negative value, it means that the arc extinguishing coil is over-compensated, and a positive value means that the arc extinguishing coil is under-compensated.

[0045] As an optional method, a target zero-sequence current signal corresponding to a target detection point in the distribution network is read, including:

[0046] When the distribution network system adopts the method of neutral point small resistance grounding, when a single-phase grounding fault occurs in the system, the zero-sequence current of each healthy outgoing line is:

[0047]

[0048] The neutral point zero sequence current is:

[0049]

[0050] The zero-sequence current of the fault line is:

[0051]

[0052] like Figure 4 In the current distribution of the distribution network system shown, the neutral point is grounded with small resistance, the healthy outgoing line is line 1, and the faulty outgoing line is line 2.

[0053] Specifically, according to different grounding modes of the neutral point of the distribution network system, a corresponding formula is used to calculate the target zero-sequence current of the target detection point.

[0054] As an optional method, reading a target zero-sequence current signal corresponding to a target detection point in a distribution network includes the following steps A1-A2:

[0055] Step A1: Determine whether a zero-sequence current signal is detected at a target detection point in the distribution network.

[0056] Step A2: If a zero-sequence current signal is detected, the zero-sequence current signal at the target detection point in the distribution network is read and used as the target zero-sequence current signal.

[0057] Specifically, detect whether there is a zero-sequence current signal at the target detection point of the distribution network according to the preset time interval. If the zero-sequence current signal is detected at the target detection point in the current preset time interval, the zero-sequence current signal is read and used as the target zero-sequence current signal. If the zero-sequence current signal is not detected at the target detection point in the current preset time interval, enter the next preset time interval to perform zero-sequence current signal detection on the target detection point of the distribution network. Among them, the preset time interval is determined by the product of the sampling time and the sampling window jump length, and the sampling time is determined by the preset sampling frequency. Exemplarily, if the sampling frequency is 10KHz and the sampling window jump length is 8, the sampling time is 0.1ms, and the preset time interval is 0.8ms. Detecting whether there is a zero-sequence current signal at the target detection point of the distribution network can be done by zero-sequence current transformer, three-phase current synthesis, and balanced current.

[0058] S102, determining a target instantaneous energy density level of a target zero-sequence current signal, where the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal whose steady-state ripple component has been suppressed in the target zero-sequence current signal.

[0059] In an embodiment of the present invention, instantaneous energy density (IEDL) refers to the physical quantity of the change of spectral energy over time within a specific frequency range. Usually, the instantaneous energy density of a non-fault transient signal of a line is much lower than the instantaneous energy density when a fault occurs. The steady-state ripple component refers to the periodic steady-state fluctuation of the current signal in the distribution network system, which is usually caused by the switching action of the power converter and appears as a harmonic frequency in the target zero-sequence current signal. Hilbert-Huang Transform (HHT) refers to a method for analyzing nonlinear and non-stationary time series, including empirical mode decomposition (EMD) and Hilbert Spectral Analysis (HAS).

[0060] Specifically, when a target zero-sequence current signal is detected at a target detection point in the distribution network system, the target zero-sequence current signal is subjected to HHT processing. Further, the spectral energy of the target zero-sequence current signal within the frequency range of suppressing the steady-state ripple component after the HHT transformation is obtained as the target instantaneous energy density level of the target zero-sequence current signal.

[0061] As an optional method, determining a target instantaneous energy density level of a target zero-sequence current signal includes the following steps B1-B3:

[0062] Step B1, determining a reference angular frequency range associated with a target zero-sequence current signal, the reference angular frequency range being an angular frequency range formed by angular frequencies corresponding to a portion of the zero-sequence current signal in the target zero-sequence current signal that can suppress a steady-state ripple component due to a ground fault.

[0063] Step B2: determining reference Hilbert spectrum information associated with the target zero-sequence current signal. The reference Hilbert spectrum information is determined based on the Hilbert transform result of the first component of the intrinsic mode function obtained after performing empirical mode decomposition on the target zero-sequence current signal.

[0064] Step B3: determining a target instantaneous energy density level of a target zero-sequence current signal according to the reference angular frequency range and the reference Hilbert spectrum information.

[0065] In an embodiment of the present invention, the reference angular frequency range refers to the angular frequency range corresponding to part of the zero-sequence current signal in the target zero-sequence current signal when a ground fault occurs in the distribution network system, which can suppress the influence of the steady-state ripple component in the target zero-sequence current signal on the ground fault detection. Empirical mode decomposition refers to repeatedly subtracting the average value of the upper envelope and the lower envelope of the original signal from the original signal until the first intrinsic mode function (IMF) is obtained, and the remainder is processed in the same way to obtain the second intrinsic mode function. When the residual becomes a monotonic function or is less than a set value, the screening process stops, and the original signal is finally decomposed into n intrinsic mode functions and a residual. Reference Hilbert spectrum information refers to performing Hilbert transform on the first intrinsic mode function after performing empirical mode decomposition on the target zero-sequence current signal, and determining the obtained Hilbert spectrum information according to the Hilbert transform result.

[0066] Specifically, the angular frequency range corresponding to the partial zero-sequence current signal in the target zero-sequence current signal that can suppress the steady-state ripple component in the target zero-sequence current signal is determined as the reference angular frequency range associated with the target zero-sequence current signal. The reference Hilbert spectrum information associated with the target zero-sequence current signal is determined by HHT. The spectrum energy of the reference Hilbert spectrum information associated with the target zero-sequence current signal within the reference angular frequency range is calculated as the target instantaneous energy density level of the target zero-sequence current signal.

[0067] As an optional method, determining a reference angular frequency range associated with a target zero-sequence current signal includes the following steps C1-C2:

[0068] Step C1, perform harmonic analysis on the target zero-sequence current signal, and determine the starting angular frequency of the reference angular frequency range according to the harmonic analysis result, wherein the starting angular frequency of the reference angular frequency range can avoid the interference of the angular frequency corresponding to the main harmonic component on the zero-sequence current signal.

[0069] Step C2: determining the sampling frequency of the target zero-sequence current signal as the end angular frequency of the reference angular frequency range.

[0070] In the embodiment of the present invention, since the rectifier circuit draws pulse current from the power grid, these currents will not cancel each other out on the neutral line, but will be superimposed on each other, resulting in the neutral line current being much larger than the phase line current. When the load of the three-phase power system of the distribution network is balanced, no current will flow through the system neutral line, and the actual three-phase power system load will not be completely balanced, which means that the impedance of each phase will not be exactly the same. At the same time, since the current and voltage are both vectors, the currents of each phase are also different. When the neutral point is connected, current will appear in the neutral line. Under the action of the industrial frequency sinusoidal voltage, nonlinear loads will generate high-frequency harmonic currents, usually 3rd, 5th, 7th, 9th harmonics, etc., among which 3rd, 9th, 6k-3rd harmonics generate zero-sequence currents, k is a positive integer, and superposition in the neutral line will generate a large amount of neutral line currents. Therefore, when analyzing the zero-sequence current, the harmonics are superimposed on the fundamental wave, which causes errors in the measurement. When setting the reference angular frequency range, the harmonic frequencies should be avoided to prevent interference from harmonics.

[0071] Specifically, the target zero-sequence current signal is harmonically analyzed by the harmonic state space method, the dynamic phasor method, or the impedance method to determine the angular frequency corresponding to the main harmonic component in the target zero-sequence current signal. Furthermore, the starting angular frequency ω1 of the reference angular frequency range is set to be greater than the angular frequency corresponding to the main harmonic component in the target zero-sequence current signal, so that the influence of the main harmonic component in the target zero-sequence current signal can be avoided. The end angular frequency ω2 of the reference angular frequency range is set to the sampling frequency of the target zero-sequence current signal. For example, after the harmonic analysis of the target zero-sequence current signal, it is determined that the angular frequency corresponding to the main harmonic component of the target zero-sequence current signal is 150Hz, and the main spectrum range of the target zero-sequence current signal is greater than 500Hz, then the starting angular frequency ω1 of the reference angular frequency range is set to 500Hz; the sampling frequency of the target zero-sequence current signal is 10KHz, then the end angular frequency ω2 of the reference angular frequency range is set to 10KHz, then the reference angular frequency range is [500Hz, 10KHz].

[0072] As an optional method, determining reference Hilbert spectrum information associated with the target zero-sequence current signal includes the following steps D1-D2:

[0073] Step D1, performing empirical mode decomposition on the target zero-sequence current signal to obtain the first component of the intrinsic mode function.

[0074] Step D2: Performing Hilbert transform processing on the first component of the intrinsic mode function to obtain the Hilbert spectrum of the first component of the intrinsic mode function, and using it as reference Hilbert spectrum information.

[0075] In the embodiment of the present invention, the Hilbert transform refers to an analytical signal used to generate a time domain signal, and the instantaneous frequency and instantaneous amplitude of the time domain signal can be calculated. Exemplarily, for a time domain signal x(t), its Hilbert transform y(t) can be defined as:

[0076]

[0077] The analytical signal z(t) is defined as:

[0078] z(t)=x(t)+iy(t)=a(t)e iθ(t)

[0079]

[0080] Then the instantaneous frequency (IF) can be defined as:

[0081]

[0082] x(t) can be expressed in the form of analytical signal as:

[0083]

[0084] The real part of x(t) can be expressed as:

[0085]

[0086] The contour lines of the amplitude are drawn on the time-frequency plane, and the time-frequency distribution of the amplitude is the Hilbert spectrum H(ω, t).

[0087] Specifically, empirical mode decomposition is performed on the target zero-sequence current signal x(t), and the target zero-sequence current signal is repeatedly subtracted from the average of the upper envelope extreme value and the lower envelope extreme value of the target zero-sequence current signal to obtain the first intrinsic mode function c1. The first intrinsic mode function c1 contains the highest frequency oscillation of the target zero-sequence current signal, and using it for fault detection can improve efficiency and accuracy. The intrinsic mode function c1 is Hilbert transformed, and the Hilbert spectrum of the intrinsic mode function c1 can be expressed as:

[0088] H1(ω,t)=A(t)cos(∫ω(t)dt)

[0089] Wherein, A(t) is the instantaneous amplitude of the intrinsic mode function c1 at time t, and ω(t) is the instantaneous angular frequency of the intrinsic mode function c1 at time t. Then, the Hilbert spectrum of the intrinsic mode function c1 is used as the reference Hilbert spectrum information associated with the target zero-sequence current signal. The Hilbert spectrum of the intrinsic mode function c1 has the advantage of high time-frequency resolution, which can improve the accuracy of ground fault detection. Exemplarily, after applying Hilbert spectrum analysis to the intrinsic mode function c1, the Hilbert spectrum of the intrinsic mode function c1 is obtained as follows: Figure 5 shown.

[0090] As an option, the target instantaneous energy density level of the target zero-sequence current signal is determined based on the reference angular frequency range and the reference Hilbert spectrum information, and is calculated in the following manner:

[0091]

[0092] H1(ω,t)=A(t)cos(∫ω(t)dt)

[0093] Wherein, [ω1, ω2] represents the reference angular frequency range, H1(ω, t) represents the Hilbert spectrum after Hilbert transform of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal, A(t) represents the instantaneous amplitude of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t, and ω(t) represents the instantaneous angular frequency of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t.

[0094] Specifically, according to the actual calculation results of the distribution network system, any angular frequency within the reference angular frequency range can be selected, and the square value of the reference Hilbert spectrum information of the target zero-sequence current signal corresponding to any angular frequency can be used as the target instantaneous energy density level of the target zero-sequence current signal, which can be used to simplify the calculation process of the target instantaneous energy density level and improve the efficiency of ground fault detection.

[0095] As an option, the target instantaneous energy density level of the target zero-sequence current signal is determined according to the reference angular frequency range and the reference Hilbert spectrum information, and can also be calculated in the following manner:

[0096]

[0097] H1(ω,t)=A(t)cos(∫ω(t)dt)

[0098] Wherein, ω1 is the starting angular frequency of the reference angular frequency range, and ω2 is the ending angular frequency of the reference angular frequency range.

[0099] Specifically, the reference Hilbert spectrum information of the target zero-sequence current signal is integrated within a reference angular frequency range to obtain a target instantaneous energy density level of the target zero-sequence current signal, thereby improving the accuracy of ground fault detection.

[0100] S103: Determine whether a ground fault occurs at the target detection point according to the target instantaneous energy density level.

[0101] Specifically, it is determined whether a ground fault occurs at the target detection point according to the target instantaneous energy density level of the target detection point of the distribution network. If a ground fault occurs at the target detection point, the ground fault at the target detection point is promptly removed to ensure power supply safety. If no ground fault occurs at the target detection point, the next preset time interval is entered to perform fault detection on the target detection point of the distribution network.

[0102] As an option, determining whether a ground fault occurs at a target detection point according to a target instantaneous energy density level includes the following steps E1-E2:

[0103] Step E1: If the target instantaneous energy density level is not less than the preset instantaneous energy density level, it is determined that a ground fault occurs at the target detection point. The preset instantaneous energy density level is the instantaneous energy density level determined by on-site debugging based on the system, operating load and rated voltage and current level of the actual distribution network.

[0104] Step E2: If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that no ground fault occurs at the target detection point.

[0105] In an embodiment of the present invention, the preset instantaneous energy density level refers to a threshold for determining whether a ground fault occurs at a target detection point of the distribution network system, and is obtained by on-site debugging based on the actual system, operating load and rated voltage and current levels of the distribution network.

[0106] Specifically, the target instantaneous energy density level of the target zero-sequence current signal obtained by calculation is compared with the preset instantaneous energy density level obtained according to the on-site debugging. If the target instantaneous energy density level is equal to or greater than the preset instantaneous energy density level, it is considered that a ground fault occurs at the target detection point of the distribution network. If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is considered that no ground fault occurs at the target detection point of the distribution network.

[0107] For example, since background noise affects the spectrum distribution, the fault detection method based on the frequency domain is easily affected by noise. For noise interference, the ground fault detection method should maintain robustness to noise and filtering. Figure 6 As shown, when Gaussian white noise with a signal-to-noise ratio of 35 dB is added to the original load change signal, the corresponding instantaneous energy density value should be kept below 0.04.

[0108] The technical solution of the embodiment of the present invention realizes real-time detection of the target detection point of the distribution network by reading the target zero-sequence current signal corresponding to the target detection point in the distribution network; determines the target instantaneous energy density level of the target zero-sequence current signal, and the target instantaneous energy density level is obtained by Hilbert transform-Huang transform processing on the partial zero-sequence current signal of the target zero-sequence current signal after the steady-state ripple component is suppressed, thereby avoiding the influence of the harmonic component in the target zero-sequence current signal on the ground fault detection, emphasizing the characteristics of the fault transient, and providing effective data support for subsequent fault judgment; determines whether a ground fault occurs at the target detection point according to the target instantaneous energy density level, and has the characteristics of high sensitivity, so as to facilitate rapid positioning and removal of the fault, and can distinguish the difference between the ground fault transient and the load switching transient, thereby improving the efficiency and accuracy of fault identification.

[0109] Embodiment 2

[0110] Figure 7 This is a schematic diagram of the structure of a distribution network grounding fault detection device provided in the second embodiment of the present invention. This embodiment can be applied to detecting whether a grounding fault occurs in a line in a distribution network system. The device can be implemented in the form of hardware and / or software, and can be configured in an electronic device that implements a distribution network grounding fault detection method. Figure 7 As shown, the device comprises:

[0111] A target zero-sequence current signal reading module 201 is used to read a target zero-sequence current signal corresponding to a target detection point in the distribution network;

[0112] A first determination module 202 is used to determine a target instantaneous energy density level of a target zero-sequence current signal, where the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal that has been subjected to steady-state ripple component suppression in the target zero-sequence current signal;

[0113] The second determination module 203 is used to determine whether a ground fault occurs at the target detection point according to the target instantaneous energy density level.

[0114] As an optional method, a target zero-sequence current signal corresponding to a target detection point in the distribution network is read, including:

[0115] determining whether a zero-sequence current signal is detected at a target detection point in the distribution network;

[0116] If a zero-sequence current signal is detected, the zero-sequence current signal at the target detection point in the distribution network is read and used as the target zero-sequence current signal.

[0117] As an option, determining a target instantaneous energy density level of a target zero-sequence current signal includes:

[0118] Determine a reference angular frequency range associated with the target zero-sequence current signal, the reference angular frequency range being an angular frequency range formed by angular frequencies corresponding to a portion of the zero-sequence current signal in the target zero-sequence current signal that can suppress a steady-state ripple component due to a ground fault;

[0119] Determine reference Hilbert spectrum information associated with the target zero-sequence current signal, where the reference Hilbert spectrum information is determined based on a Hilbert transform result of a first component of an intrinsic mode function obtained after performing empirical mode decomposition on the target zero-sequence current signal;

[0120] A target instantaneous energy density level of a target zero-sequence current signal is determined according to a reference angular frequency range and reference Hilbert spectrum information.

[0121] As an option, determining a reference angular frequency range associated with a target zero-sequence current signal includes:

[0122] Performing harmonic analysis on the target zero-sequence current signal, and determining the starting angular frequency of the reference angular frequency range according to the harmonic analysis result, wherein the starting angular frequency of the reference angular frequency range can enable the reference angular frequency range to avoid interference of the angular frequency corresponding to the main harmonic component on the zero-sequence current signal;

[0123] The sampling frequency of the target zero-sequence current signal is determined as the end angular frequency of the reference angular frequency range.

[0124] As an optional method, determining reference Hilbert spectrum information associated with the target zero-sequence current signal includes:

[0125] Performing empirical mode decomposition on the target zero-sequence current signal to obtain the first component of the intrinsic mode function;

[0126] The first component of the intrinsic mode function is subjected to Hilbert transform processing to obtain the Hilbert spectrum of the first component of the intrinsic mode function, and the Hilbert spectrum is used as reference Hilbert spectrum information.

[0127] As an option, the target instantaneous energy density level of the target zero-sequence current signal is determined based on the reference angular frequency range and the reference Hilbert spectrum information, and is calculated in the following manner:

[0128]

[0129] H1(ω,t)=A(t)cos(∫ω(t)dt)

[0130] Wherein, [ω1, ω2] represents the reference angular frequency range, H1(ω, t) represents the Hilbert spectrum after Hilbert transform of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal, A(t) represents the instantaneous amplitude of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t, and ω(t) represents the instantaneous angular frequency of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t.

[0131] As an option, the target instantaneous energy density level of the target zero-sequence current signal is determined according to the reference angular frequency range and the reference Hilbert spectrum information, and can also be calculated in the following manner:

[0132]

[0133] H1(ω,t)=A(t)cos(∫ω(t)dt)

[0134] Wherein, ω1 is the starting angular frequency of the reference angular frequency range, and ω2 is the ending angular frequency of the reference angular frequency range.

[0135] As an option, determining whether a ground fault occurs at a target detection point according to a target instantaneous energy density level includes:

[0136] If the target instantaneous energy density level is not less than the preset instantaneous energy density level, it is determined that a ground fault occurs at the target detection point, and the preset instantaneous energy density level is the instantaneous energy density level determined by on-site debugging based on the system, operating load and rated voltage and current level of the actual distribution network;

[0137] If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that no ground fault occurs at the target detection point.

[0138] The technical solution of the embodiment of the present invention realizes real-time detection of the target detection point of the distribution network by reading the target zero-sequence current signal corresponding to the target detection point in the distribution network; determines the target instantaneous energy density level of the target zero-sequence current signal, and the target instantaneous energy density level is obtained by Hilbert transform-Huang transform processing of the partial zero-sequence current signal in the target zero-sequence current signal after the steady-state ripple component is suppressed, thereby avoiding the influence of the harmonic component in the target zero-sequence current signal on the ground fault detection, emphasizing the characteristics of the fault transient, and providing effective data support for subsequent fault judgment; determines whether a ground fault occurs at the target detection point according to the target instantaneous energy density level, and has the characteristics of high sensitivity, so as to facilitate rapid positioning and removal of the fault, and can distinguish the difference between the ground fault transient and the load switching transient, thereby improving the efficiency and accuracy of fault identification. The distribution network ground fault detection device provided by the embodiment of the present invention can execute the distribution network ground fault detection device provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0139] Embodiment 3

[0140] Figure 8 A schematic diagram of the structure of an electronic device for implementing a distribution network ground fault detection method provided in Embodiment 3 of the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, 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 required herein.

[0141] like Figure 8 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.

[0142] 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.

[0143] 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 distribution network ground fault detection method.

[0144] In some embodiments, the distribution network ground fault detection method 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 distribution network ground fault detection method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to execute the distribution network ground fault detection method in any other appropriate manner (e.g., by means of firmware).

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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).

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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 ground faults in a distribution network, characterized in that: The method comprises: Read the target zero-sequence current signal corresponding to the target detection point in the distribution network; Determining a target instantaneous energy density level of a target zero-sequence current signal, wherein the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal whose steady-state ripple component has been suppressed in the target zero-sequence current signal; Whether a ground fault occurs at the target detection point is determined according to the target instantaneous energy density level.

2. The method according to claim 1, characterized in that Read the target zero-sequence current signal corresponding to the target detection point in the distribution network, including: determining whether a zero-sequence current signal is detected at a target detection point in the distribution network; If a zero-sequence current signal is detected, the zero-sequence current signal at the target detection point in the distribution network is read and used as the target zero-sequence current signal.

3. The method according to claim 1, characterized in that Determine a target instantaneous energy density level of a target zero-sequence current signal, including: Determine a reference angular frequency range associated with the target zero-sequence current signal, wherein the reference angular frequency range is an angular frequency range formed by angular frequencies corresponding to a portion of the zero-sequence current signal that can suppress a steady-state ripple component in the target zero-sequence current signal due to a ground fault; Determine reference Hilbert spectrum information associated with the target zero-sequence current signal, wherein the reference Hilbert spectrum information is determined based on a Hilbert transform result of a first component of an intrinsic mode function obtained after performing empirical mode decomposition on the target zero-sequence current signal; A target instantaneous energy density level of a target zero-sequence current signal is determined according to the reference angular frequency range and the reference Hilbert spectrum information.

4. The method according to claim 3, characterized in that Determine the reference angular frequency range associated with the target zero-sequence current signal, including: Performing harmonic analysis on the target zero-sequence current signal, and determining the starting angular frequency of the reference angular frequency range according to the harmonic analysis result, wherein the starting angular frequency of the reference angular frequency range can enable the reference angular frequency range to avoid interference of the angular frequency corresponding to the main harmonic component on the zero-sequence current signal; The sampling frequency of the target zero-sequence current signal is determined as the end angular frequency of the reference angular frequency range.

5. The method according to claim 3, characterized in that: Determine the reference Hilbert spectrum information associated with the target zero-sequence current signal, including: Performing empirical mode decomposition on the target zero-sequence current signal to obtain the first component of the intrinsic mode function; The first component of the intrinsic mode function is subjected to Hilbert transform processing to obtain the Hilbert spectrum of the first component of the intrinsic mode function, and the Hilbert spectrum is used as reference Hilbert spectrum information.

6. The method according to claim 3, characterized in that According to the reference angular frequency range and the reference Hilbert spectrum information, the target instantaneous energy density level of the target zero-sequence current signal is determined and calculated in the following manner: H1(ω,t)=A(t)cos(∫ω(t)dt) Wherein, [ω1, ω2] represents the reference angular frequency range, H1(ω, t) represents the Hilbert spectrum after Hilbert transform of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal, A(t) represents the instantaneous amplitude of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t, and ω(t) represents the instantaneous angular frequency of the first component of the intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal at time t.

7. The method according to claim 1, characterized in that Determining whether a ground fault occurs at a target detection point according to the target instantaneous energy density level includes: If the target instantaneous energy density level is not less than a preset instantaneous energy density level, it is determined that a ground fault occurs at the target detection point, and the preset instantaneous energy density level is an instantaneous energy density level determined by on-site debugging according to the system, operating load and rated voltage and current level of the actual power distribution network; If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that no ground fault occurs at the target detection point.

8. A distribution network grounding fault detection device, characterized in that: The device comprises: A target zero-sequence current signal reading module is used to read a target zero-sequence current signal corresponding to a target detection point in a distribution network; A first determination module is used to determine a target instantaneous energy density level of a target zero-sequence current signal, wherein the target instantaneous energy density level is obtained by performing Hilbert transform-Huang transform processing on a portion of the zero-sequence current signal whose steady-state ripple component has been suppressed in the target zero-sequence current signal; The second determination module is used to determine whether a ground fault occurs at the target detection point according to the target instantaneous energy density level.

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 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 distribution network grounding fault detection method according to any one of claims 1 to 7 when executed.

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