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

Abstract

The application discloses a power distribution network grounding fault detection method and device, electronic equipment and storage medium. The method comprises the following steps: reading a target zero sequence current signal corresponding to a target detection point in a 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-yellow transform processing on a part of the zero sequence current signal in the target zero sequence current signal after suppressing a steady-state ripple component; and determining whether a grounding fault occurs at the target detection point according to the target instantaneous energy density level. The scheme realizes real-time detection of the target detection point of the power distribution network, avoids the influence of harmonic components in the target zero sequence current signal on the grounding fault detection, facilitates rapid positioning and removal of the fault, can distinguish the difference between grounding fault transients and load switching transients, and improves the efficiency and accuracy of fault identification.

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 grounding fault detection method and device, an electronic device and a storage medium. BACKGROUND

[0002] At present, as an intermediate link connecting the power system and users, the power distribution network is responsible for distributing the power required for daily life and industrial production, and the safety and stability of the power distribution network is an important prerequisite for ensuring power supply reliability. However, in the power distribution network, the power distribution network covers a wide area and has a complex operating environment, and the line is easy to contact with the ground and other media to cause grounding faults, and the existing line protection device is difficult to identify the grounding fault in the power distribution network, which is easy to cause electric shock and other major safety accidents, and seriously threatens the safe operation of the modern power distribution network. Therefore, how to realize the rapid and accurate identification, positioning and removal of the grounding fault of the power distribution network has become a problem to be solved at present. SUMMARY

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

[0004] According to an aspect of the present application, a power distribution network grounding fault detection method is provided, which comprises:

[0005] reading a target zero sequence current signal corresponding to a target detection point in the power distribution network;

[0006] determining a target instantaneous energy density level of the target zero sequence current signal, the target instantaneous energy density level being obtained by Hilbert transform-Huang transform processing on a partial zero sequence current signal in the target zero sequence current signal that has been subjected to steady-state ripple component suppression;

[0007] determining whether a grounding fault occurs at the target detection point according to the target instantaneous energy density level.

[0008] According to another aspect of the present application, a power distribution network grounding fault detection device is provided, which comprises:

[0009] a target zero sequence current signal reading module for reading a target zero sequence current signal corresponding to a target detection point in the power distribution network;

[0010] a first determination module for determining a target instantaneous energy density level of the target zero sequence current signal, the target instantaneous energy density level being obtained by Hilbert transform-Huang transform processing on a partial zero sequence current signal in the target zero sequence current signal that has been subjected to steady-state ripple component suppression;

[0011] The second determining module is configured to determine whether the target detection point has a ground fault according to the target instantaneous energy density level.

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

[0013] at least one processor; and

[0014] a memory in communication with the at least one processor; wherein

[0015] 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 method for detecting a ground fault of a power distribution network according to any one of the embodiments of the present application.

[0016] According to another aspect of the present application, there is provided a computer readable storage medium storing computer instructions for enabling a processor to implement the method for detecting a ground fault of a power distribution network according to any one of the embodiments of the present application when executed by the processor.

[0017] The technical solution of the embodiments of the present application realizes real-time detection of the target detection point of the power distribution network by reading the target zero sequence current signal corresponding to the target detection point of the power distribution network; determines the target instantaneous energy density level of the target zero sequence current signal, which is obtained by Hilbert transform-Huang transform processing on the part of the zero sequence current signal in the target zero sequence current signal after suppression of the steady-state ripple component, thereby avoiding the influence of the harmonic component in the target zero sequence current signal on the ground fault detection and emphasizing the characteristics of the fault transient state to provide effective data support for subsequent fault judgment; determines whether the target detection point has a ground fault according to the target instantaneous energy density level, which has the characteristic of high sensitivity, so as to facilitate fast positioning and removal of the fault, while being able to distinguish the differences between the ground fault transient state and the load switching transient state, thereby improving the efficiency and accuracy of fault identification.

[0018] 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

[0019] 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 also be obtained by those skilled in the art without creative labor.

[0020] Figure 1A flow chart of a power distribution network grounding fault detection method provided for the embodiment one of the present application;

[0021] Figure 2 A line diagram of a power distribution network system neutral point non-grounding provided for the embodiment one of the present application;

[0022] Figure 3 A line diagram of a power distribution network system neutral point resonance grounding provided for the embodiment one of the present application;

[0023] Figure 4 A line diagram of a power distribution network system neutral point small resistance grounding provided for the embodiment one of the present application;

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

[0025] Figure 6 A original load change signal adding Gaussian white noise corresponding instantaneous energy density level distribution diagram provided for the embodiment one of the present application;

[0026] Figure 7 A structure schematic diagram of a power distribution network grounding fault detection device provided for the embodiment two of the present application;

[0027] Figure 8 A structure schematic diagram of an electronic device for implementing a power distribution network grounding fault detection method provided for the embodiment three of the present application. DETAILED DESCRIPTION

[0028] In order to make the personnel in the art better understand the present application scheme, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0029] It is to be understood that the terminology "first", "second" and the like used in the specification and the claims of the application as well as the foregoing drawings is merely intended to distinguish between similar objects and not necessarily for describing a particular sequential order. It is to be understood that the use of the singular herein includes the plural unless specifically stated otherwise. The use of the term "including", "having" and "comprising" and variations thereof is intended to be inclusive and mean that there are no numerical limitations on the number of objects or steps in the process, method, system, product or apparatus unless otherwise specifically stated or limited by context. Accordingly, "comprising" and "having" are used herein to mean including, but not limited to, that which follows the term.

[0030] Embodiment one

[0031] Figure 1 A flowchart of a power distribution network grounding fault detection method provided by the embodiment one of the application. The embodiment can be applicable to detecting whether a grounding fault occurs in a line of a power distribution network system. The method can be executed by a power distribution network grounding fault detection device, which can be realized in the form of hardware and / or software and can be configured in an electronic device for implementing the power distribution network grounding fault detection method.

[0032] As shown in Figure 1 , the method comprises:

[0033] S101, reading a target zero sequence current signal corresponding to a target detection point in the power distribution network.

[0034] In the embodiment of the application, the target detection point refers to a position in the power distribution network system that is pre-set for detecting whether a grounding fault occurs. The target detection point can be set near a position where a grounding fault occurs in the power distribution network system. The target zero sequence current signal refers to a vector sum of three-phase currents at the target detection point in the power distribution network system. In a normal case, the three-phase currents in the power distribution network system are balanced, i.e., 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 application, due to unbalanced line load or line fault, the three-phase currents are unbalanced, and the vector sum of the three-phase currents is not zero, which will generate a zero sequence current.

[0035] As an option, reading the target zero sequence current signal corresponding to the target detection point in the power distribution network comprises:

[0036] When the power distribution network system adopts a neutral point ungrounded mode, a single-phase grounding fault occurs in the system, and the current distribution is as shown in Figure 2 , wherein the grounding fault occurs at the A phase of the line 2, the zero sequence current of the healthy line 1 is , the zero sequence current of the fault line 2 is , and the zero sequence current of the line 3 is .

[0037] As an option, reading the target detection point in the power distribution network corresponding to the target zero sequence current signal, comprising:

[0038] When the power distribution network system adopts the neutral point resonance grounding mode, when single-phase grounding fault occurs in the system, the current distribution is as shown in Figure 3 , wherein the grounding fault occurs in the A phase of line 2, and the zero sequence current of the healthy line 1 is :

[0039]

[0040] The zero sequence current of the fault line 2 is :

[0041]

[0042] According to the mistuning degree The zero sequence current of the fault line 2 is It can be expressed as:

[0043]

[0044] Wherein, the mistuning degree refers to the arc suppression coil mistuning degree, indicating the degree of deviation from the resonance state, used to describe the compensation degree of the arc suppression coil. If the mistuning degree is negative, it means that the arc suppression coil is overcompensated, and the positive value means that the arc suppression coil is undercompensated.

[0045] As an option, reading the target detection point in the power distribution network corresponding to the target zero sequence current signal, comprising:

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

[0047]

[0048] The neutral point zero sequence current is:

[0049]

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

[0051]

[0052] As Figure 4 shown in the current distribution of the power distribution network system adopting the neutral point small resistance grounding mode, the healthy out line is line 1, and the fault out line is line 2.

[0053] Specifically, according to the different grounding modes of the neutral point of the power distribution network system, the target zero sequence current of the target detection point is calculated by using the corresponding formula.

[0054] As an option, reading the target zero sequence current signal corresponding to the target detection point in the power distribution network comprises the following steps A1-A2:

[0055] Step A1, determine whether a zero sequence current signal is detected at the target detection point in the power distribution network.

[0056] Step A2, if the zero sequence current signal is detected, read the zero sequence current signal at the target detection point in the power distribution network as the target zero sequence current signal.

[0057] Specifically, the target detection point of the power distribution network is detected for the presence of a zero sequence current signal at a preset time interval. If the target detection point is detected for the presence of a zero sequence current signal at the current preset time interval, the zero sequence current signal is read and taken as the target zero sequence current signal. If the target detection point is not detected for the presence of a zero sequence current signal at the current preset time interval, the target detection point of the power distribution network is detected for the presence of a zero sequence current signal in the next preset time interval. 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 pre-set sampling frequency. For example, if the sampling frequency is 10KHz and the sampling window jump length is 8, the sampling time is 0.1ms, the preset time interval is 0.8ms, and the target detection point of the power distribution network can be detected for the presence of a zero sequence current signal by a zero sequence current transformer, three-phase current synthesis, and balanced current, etc.

[0058] S102, determine the target instantaneous energy density level of the target zero sequence current signal, which is obtained by Hilbert-Huang Transform processing on the part of the zero sequence current signal suppressed by the steady-state ripple component in the target zero sequence current signal.

[0059] In the embodiment of the present application, the instantaneous energy density (Instantaneous Energy Density Level, IEDL) refers to the physical quantity of the spectrum energy change with time in a specific frequency range. The instantaneous energy density of the line non-fault transient signal is usually much lower than that when a fault occurs. The steady-state ripple component refers to the periodic steady-state fluctuation of the current signal in the power distribution network system, which is usually caused by the switching action of the power converter and appears at a harmonic frequency in the target zero sequence current signal. The Hilbert-Huang Transform (Hilbert-Huang Transform, HHT) refers to a method for analyzing nonlinear and non-stationary time series, which includes Empirical Mode Decomposition (Empirical Mode Decomposition, EMD) and Hilbert Spectral Analysis (Hilbert Spectral Analysis, HAS).

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

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

[0062] Step B1, determining 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 partial zero sequence current signals in the target zero sequence current signal that can suppress the steady-state ripple component due to the ground fault.

[0063] Step B2, determining reference Hilbert spectrum information associated with the target zero sequence current signal, the reference Hilbert spectrum information being determined according to a Hilbert transform result of a first component of an intrinsic mode function obtained by performing empirical mode decomposition on the target zero sequence current signal.

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

[0065] In the embodiment of the present application, the reference angular frequency range refers to an angular frequency range corresponding to partial zero sequence current signals in the target zero sequence current signal when the power distribution network system has a ground fault, 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 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 same processing is performed on the remainder 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 finally the original signal is decomposed into n intrinsic mode functions and a residual. The 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 Hilbert spectrum information obtained according to the Hilbert transform result.

[0066] Specifically, a range of angular frequencies corresponding to the partial zero sequence current signal capable of suppressing 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.

[0067] As an option, the reference angular frequency range associated with the target zero sequence current signal is determined including the following steps C1-C2.

[0068] Step C1, performing harmonic analysis on the target zero sequence current signal, and determining a starting angular frequency of the reference angular frequency range according to the harmonic analysis result, the starting angular frequency of the reference angular frequency range being capable of avoiding 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 terminal angular frequency of the reference angular frequency range.

[0070] In the embodiment of the present application, since the rectifier circuit draws pulse current from the power grid, these currents do not cancel each other out on the zero line, but superimpose on each other, resulting in a zero line current much larger than the phase line current. When the load of the three-phase power system of the power distribution network is balanced, no current flows through the neutral line of the system, but the actual three-phase power system load is not completely balanced, meaning that the impedances of the phases are not completely the same, and since the current and voltage are vectors, the phase currents are also not the same. When the neutral point is connected, the neutral line will have a current. Nonlinear loads will generate high-frequency harmonic currents under the action of power frequency sinusoidal voltage, usually 3, 5, 7, 9 harmonics, etc., among which 3, 9, 6k-3 harmonics generate zero sequence currents, k is a positive integer, and the superposition in the neutral line will generate a large amount of neutral line current. Therefore, when analyzing the zero sequence current, the harmonic superimposed on the fundamental wave causes an error in measurement, so when setting the reference angular frequency range, the harmonic frequency should be avoided to prevent harmonic interference.

[0071] Specifically, the harmonic state space method, the dynamic phasor method, or the impedance method is used to perform harmonic analysis on the target zero sequence current signal to determine the angular frequency corresponding to the main harmonic component in the target zero sequence current signal. Then, 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 ending angular frequency ω2 of the reference angular frequency range is set to be the sampling frequency of the target zero sequence current signal. For example, after the harmonic analysis on 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 150 Hz, and the main frequency spectrum range of the target zero sequence current signal is greater than 500 Hz, so the starting angular frequency ω1 of the reference angular frequency range is set to be 500 Hz; the sampling frequency of the target zero sequence current signal is 10 KHz, so the ending angular frequency ω2 of the reference angular frequency range is set to be 10 KHz, and the reference angular frequency range is [500 Hz, 10 KHz].

[0072] As an option, the reference Hilbert spectrum information associated with the target zero sequence current signal is determined, including the following steps D1-D2:

[0073] Step D1, performing empirical mode decomposition on the target zero sequence current signal to obtain a first component of an 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 as the reference Hilbert spectrum information.

[0075] In the embodiments of the present application, 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. For example, for a time domain signal x(t), its Hilbert transform y(t) can be defined as:

[0076]

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

[0078] z(t)=x(t)+iy(t)=a(t)e iθ(t)

[0079]

[0080] The instantaneous frequency (Instantaneous Frequency, IF) can be defined as:

[0081]

[0082] The time domain signal x(t) can be expressed in the form of an analysis signal as:

[0083]

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

[0085]

[0086] The contour of the amplitude plotted on the time-frequency plane is the Hilbert spectrum H(ω, t).

[0087] Specifically, the target zero sequence current signal x(t) is subjected to empirical mode decomposition, 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 a 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 Hilbert spectrum of the first intrinsic mode function c1 can be obtained by subjecting the first intrinsic mode function c1 to Hilbert transform, and can be expressed as:

[0088] H1(ω, t) = A(t)cos(∫ω(t)dt)

[0089] Wherein, A(t) is the instantaneous amplitude of the first intrinsic mode function c1 at t, and ω(t) is the instantaneous angular frequency of the first intrinsic mode function c1 at t. Further, the Hilbert spectrum of the first 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 first intrinsic mode function c1 has the advantage of high time-frequency resolution, which can improve the accuracy of ground fault detection. After applying Hilbert spectrum analysis to the first intrinsic mode function c1, the Hilbert spectrum of the first intrinsic mode function c1 is obtained as shown in Figure 5 .

[0090] 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 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 the first component of the intrinsic mode function obtained by subjecting the target zero sequence current signal to empirical mode decomposition is subjected to Hilbert transform, A(t) represents the instantaneous amplitude of the first component of the intrinsic mode function obtained by subjecting the target zero sequence current signal to empirical mode decomposition at t, and ω(t) represents the instantaneous angular frequency of the first component of the intrinsic mode function obtained by subjecting the target zero sequence current signal to empirical mode decomposition at t.

[0094] Specifically, according to the actual calculation result of the power distribution network system, any angular frequency in 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 is taken as the target instantaneous energy density level of the target zero sequence current signal, which can simplify the calculation process of the target instantaneous energy density level and improve the efficiency of the ground fault detection.

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

[0096]

[0097] H1(ω, t) = A(t)cos(∫ω(t)dt)

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

[0099] Specifically, the reference Hilbert spectrum information of the target zero sequence current signal is integrated in the reference angular frequency range to obtain the target instantaneous energy density level of the target zero sequence current signal, which can improve the accuracy of the ground fault detection.

[0100] S103, determining whether the target detection point has a ground fault according to the target instantaneous energy density level.

[0101] Specifically, the target instantaneous energy density level of the target detection point of the power distribution network is determined according to the calculation to determine whether the target detection point has a ground fault. If the target detection point has a ground fault, the ground fault of the target detection point is removed in time to ensure the safety of power supply. If the target detection point does not have a ground fault, the next preset time interval is entered to detect the target detection point of the power distribution network.

[0102] As an option, determining whether the target detection point has a ground fault according to the 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 the target detection point has a ground fault, and the preset instantaneous energy density level is the instantaneous energy density level determined according to the actual power distribution network system, working condition load and rated voltage and current level.

[0104] Step E2, if the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that the target detection point does not have a ground fault.

[0105] In the embodiment of the present application, the preset instantaneous energy density level refers to a threshold for judging whether a grounding fault occurs at the target detection point of the power distribution network system, and is obtained through on-site debugging according to the actual system, working condition load and rated voltage and current level of the power distribution network.

[0106] Specifically, the target instantaneous energy density level of the calculated target zero-sequence current signal is compared with the preset instantaneous energy density level obtained through 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 grounding fault occurs at the target detection point of the power distribution network. If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is considered that no grounding fault occurs at the target detection point of the power distribution network.

[0107] As shown in the example, the background noise will affect the spectral distribution, so the fault detection method based on the frequency domain is susceptible to noise. In view of the interference of noise, the grounding fault detection method should maintain the robustness to noise and filtering. As shown in the example, the Gaussian white noise with a signal-to-noise ratio of 35 decibels is added to the original load change signal, and the corresponding instantaneous energy density value should be kept below 0.04. Figure 6

[0108] The technical scheme of the embodiment of the present application realizes real-time detection of the target detection point of the power distribution network by reading the target zero-sequence current signal corresponding to the target detection point in the power distribution network. The target instantaneous energy density level of the target zero-sequence current signal is determined, which is obtained by Hilbert transform-Huang transform processing on the part of the zero-sequence current signal in the target zero-sequence current signal after suppression of the steady-state ripple component, thereby avoiding the influence of the harmonic component in the target zero-sequence current signal on the grounding fault detection and emphasizing the characteristics of the fault transient state, which provides effective data support for subsequent fault judgment. Whether a grounding fault occurs at the target detection point is determined according to the target instantaneous energy density level, which has the characteristics of high sensitivity, so as to facilitate rapid positioning and removal of the fault, and can distinguish the differences between the grounding fault transient state and the load switching transient state, thereby improving the efficiency and accuracy of fault identification.

[0109] Embodiment two

[0110] Figure 7 A structural schematic diagram of a power distribution network grounding fault detection device provided for the second embodiment of the present application is shown. The present embodiment can be applied to the case of detecting whether a grounding fault occurs in the line of the power distribution network system. The device can be realized in the form of hardware and / or software, and can be configured in an electronic device for implementing the power distribution network grounding fault detection method. As shown in the example, the device comprises: Figure 7

[0111] The target zero-sequence current signal reading module 201 is configured to read the target zero-sequence current signal corresponding to the target detection point in the power distribution network. ​​

[0112] The first determination module 202 is configured to determine a target instantaneous energy density level of the target zero-sequence current signal, the target instantaneous energy density level being obtained by performing Hilbert transform-Huang transform processing on a partial zero-sequence current signal that is inhibited from the target zero-sequence current signal.

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

[0114] As an option, the target zero-sequence current signal at the target detection point in the power distribution network is read, including:

[0115] It is determined whether a zero-sequence current signal is detected at the target detection point in the power distribution network.

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

[0117] As an option, the target instantaneous energy density level of the target zero-sequence current signal is determined, including:

[0118] A reference angular frequency range associated with the target zero-sequence current signal is determined, the reference angular frequency range being an angular frequency range formed by an angular frequency of a partial zero-sequence current signal that is inhibited from the target zero-sequence current signal due to the ground fault.

[0119] Reference Hilbert spectrum information associated with the target zero-sequence current signal is determined, the reference Hilbert spectrum information being determined according to a Hilbert transform result of a first component of an intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal.

[0120] 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.

[0121] As an option, the reference angular frequency range associated with the target zero-sequence current signal is determined, including:

[0122] The target zero-sequence current signal is subjected to harmonic analysis, and a starting angular frequency of the reference angular frequency range is determined according to a result of the harmonic analysis, the starting angular frequency of the reference angular frequency range being able to make the reference angular frequency range avoid an angular frequency corresponding to a main harmonic component from interfering with the zero-sequence current signal.

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

[0124] As an option, the reference Hilbert spectrum information associated with the target zero-sequence current signal is determined, including:

[0125] The first component of the intrinsic mode function is obtained by performing empirical mode decomposition on the target zero sequence current signal;

[0126] The Hilbert spectrum of the first component of the intrinsic mode function is obtained by performing Hilbert transform on the first component of the intrinsic mode function, and is taken as reference Hilbert spectrum information.

[0127] 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, which 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 performing Hilbert transform on 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 can also be calculated in the following manner according to the reference angular frequency range and the reference Hilbert spectrum information:

[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 terminal angular frequency of the reference angular frequency range.

[0135] As an option, whether the target detection point appears ground fault is determined according to the target instantaneous energy density level, which includes:

[0136] If the target instantaneous energy density level is not less than the preset instantaneous energy density level, it is determined that the target detection point appears ground fault, and the preset instantaneous energy density level is the instantaneous energy density level determined by on-site debugging according to the system, working condition load and rated voltage and current level of the actual power distribution network;

[0137] If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that the target detection point does not appear ground fault.

[0138] The technical scheme of the embodiment of the present application realizes real-time detection of the target detection point of the power distribution network by reading the target zero sequence current signal corresponding to the target detection point of the power distribution network; determines the target instantaneous energy density level of the target zero sequence current signal, which 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, avoids the influence of the harmonic component in the target zero sequence current signal on the ground fault detection, emphasizes the characteristics of the fault transient state, and provides effective data support for subsequent fault judgment; determines whether the target detection point has a ground fault according to the target instantaneous energy density level, has the characteristics of high sensitivity, so as to facilitate fast positioning and removal of the fault, and can distinguish the difference between the ground fault transient state and the load switching transient state, thereby improving the efficiency and accuracy of fault identification. The power distribution network ground fault detection device provided in the embodiment of the present application can execute the power distribution network ground fault detection device provided in any embodiment of the present application, has the corresponding function modules and beneficial effects of the execution method.

[0139] Embodiment three

[0140] Figure 8 A structural schematic diagram of an electronic device for implementing a power distribution network ground fault detection method according to Embodiment Three 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 helmets, 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.

[0141] As shown in Figure 8 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 in communication connection with the at least one processor 11, wherein the memory stores a computer program that can be executed by the at least one processor. 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 into 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 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, speakers, 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.

[0143] The processor 11 can be various general and / or special purpose 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 specialized 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 performs various methods and processes described above, such as the power distribution network ground fault detection method.

[0144] In some embodiments, the power distribution network 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 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 ground fault detection method by any other appropriate means, such as by means of firmware.

[0145] 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.

[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, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0147] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0148] To provide interaction with a user, the systems and techniques described herein 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 pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the 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 input, voice input, or tactile input).

[0149] The systems and techniques described herein 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 herein, 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.

[0150] 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. A 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.

[0151] It should be understood that the various forms of flow shown above can be re-ordered, added to, or deleted from without departing from the scope of the present application. For example, the steps recited in the present application can be performed in parallel, in series, or in a different order, without departing from the desired results of the technical solutions of the present application, and this is not limited herein.

[0152] 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 a ground fault in a power distribution network, the method comprising: The method comprises: reading a target zero sequence current signal corresponding to a target detection point in a power distribution network; determining a target instantaneous energy density level of the target zero sequence current signal, the target instantaneous energy density level being obtained by Hilbert transform-Huang transform processing on a partial zero sequence current signal in the target zero sequence current signal after suppression of a steady-state ripple component; determining whether a ground fault occurs at the target detection point according to the target instantaneous energy density level; wherein the determination of the target instantaneous energy density level of the target zero sequence current signal comprises: determining 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 an angular frequency of a partial zero sequence current signal in the target zero sequence current signal that can suppress the steady-state ripple component due to the ground fault; determining reference Hilbert spectrum information associated with the target zero sequence current signal, the reference Hilbert spectrum information being determined according to a Hilbert transform result of a first component of an intrinsic mode function obtained by empirical mode decomposition on the target zero sequence current signal; determining the target instantaneous energy density level of the target zero sequence current signal according to the reference angular frequency range and the reference Hilbert spectrum information; the determination of the reference angular frequency range associated with the target zero sequence current signal comprises: performing harmonic analysis on the target zero sequence current signal, and determining a starting angular frequency of the reference angular frequency range according to a harmonic analysis result, the starting angular frequency of the reference angular frequency range being able to make the reference angular frequency range avoid interference of a main harmonic component on the zero sequence current signal; determining a sampling frequency of the target zero sequence current signal as a terminal angular frequency of the reference angular frequency range.

2. The method of claim 1, wherein, The reading of the target zero sequence current signal corresponding to the target detection point in the power distribution network comprises: determining whether a zero sequence current signal is detected at the target detection point in the power distribution network; if the zero sequence current signal is detected, reading the zero sequence current signal at the target detection point in the power distribution network as the target zero sequence current signal.

3. The method of claim 1, wherein, The determination of the reference Hilbert spectrum information associated with the target zero sequence current signal comprises: performing empirical mode decomposition on the target zero sequence current signal to obtain a first component of an intrinsic mode function; performing Hilbert transform processing on the first component of the intrinsic mode function to obtain a Hilbert spectrum of the first component of the intrinsic mode function, and taking the Hilbert spectrum as the reference Hilbert spectrum information.

4. The method of claim 1, wherein, The determination of the target instantaneous energy density level of the target zero sequence current signal according to the reference angular frequency range and the reference Hilbert spectrum information is 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 a Hilbert spectrum after Hilbert transform on a first component of an intrinsic mode function obtained by empirical mode decomposition on the target zero sequence current signal, A(t) represents an instantaneous amplitude of the first component of the intrinsic mode function at time t obtained by empirical mode decomposition on the target zero sequence current signal, and ω(t) represents an instantaneous angular frequency of the first component of the intrinsic mode function at time t obtained by empirical mode decomposition on the target zero sequence current signal.

5. The method of claim 1, wherein, The method comprises the following steps: If the target instantaneous energy density level is not less than a preset instantaneous energy density level, it is determined that the target detection point has a ground fault, wherein the preset instantaneous energy density level is an instantaneous energy density level determined according to a system, a working condition load and a rated voltage and current level of an actual power distribution network through on-site debugging; If the target instantaneous energy density level is less than the preset instantaneous energy density level, it is determined that the target detection point does not have a ground fault.

6. A power distribution network earth fault detection apparatus characterised by The device comprises: a target zero-sequence current signal reading module configured to read a target zero-sequence current signal corresponding to a target detection point in a power distribution network; a first determination module configured to determine 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 partial zero-sequence current signal in the target zero-sequence current signal that has been subjected to steady-state ripple component suppression; a second determination module configured to determine whether the target detection point has a ground fault according to the target instantaneous energy density level; The determination of the target instantaneous energy density level of the target zero-sequence current signal comprises: determining 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 an angular frequency of a partial zero-sequence current signal in the target zero-sequence current signal that can suppress a steady-state ripple component due to a ground fault; determining reference Hilbert spectrum information associated with the target zero-sequence current signal, wherein the reference Hilbert spectrum information is determined according to a Hilbert transform result of a first component of an intrinsic mode function obtained by performing empirical mode decomposition on the target zero-sequence current signal; determining the target instantaneous energy density level of the target zero-sequence current signal according to the reference angular frequency range and the reference Hilbert spectrum information; The determination of the reference angular frequency range associated with the target zero-sequence current signal comprises: performing harmonic analysis on the target zero-sequence current signal, and determining a starting angular frequency of the reference angular frequency range according to a harmonic analysis result, wherein the starting angular frequency of the reference angular frequency range can make the reference angular frequency range avoid interference of an angular frequency corresponding to a main harmonic component on the zero-sequence current signal; determining a sampling frequency of the target zero-sequence current signal as a terminal angular frequency of the reference angular frequency range.

7. An electronic device, comprising: The electronic device comprises: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores a computer program that can be executed 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 execute the power distribution network ground fault detection method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for enabling the processor to execute the power distribution network ground fault detection method according to any one of claims 1-5 when executed.

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