Ground fault judgment method and system of distribution line grounding system, storage medium, electronic equipment and computer program product

Abstract

The invention discloses a grounding fault judgment method and system of a distribution line grounding system, a storage medium, electronic equipment and a computer program product. According to the ground fault judgment method, the ground fault judgment system determines a zero-sequence voltage abrupt change value and a zero-sequence voltage amplitude according to the collected zero-sequence voltage of the distribution line; under the condition that the zero-sequence voltage abrupt change value meets a preset zero-sequence voltage abrupt change value condition, determining a transient grounding judgment result and a zero-sequence admittance value according to the collected zero-sequence current and zero-sequence voltage of the distribution line; determining the classification condition of the zero-sequence admittance value according to the transient grounding judgment result; under the condition that the zero-sequence voltage amplitude meets a preset zero-sequence voltage amplitude condition, determining a zero-sequence admittance judgment result according to the classification condition of the zero-sequence admittance value and the zero-sequence admittance value; determining a grounding comprehensive result according to the transient grounding judgment result and the zero-sequence admittance judgment result; and determining a grounding fault condition of the distribution line according to the grounding comprehensive result and a preset grounding result condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power control, in particular to a grounding fault discrimination method and system of a distribution line grounding system, a storage medium, an electronic device and a computer program product. BACKGROUND

[0002] The medium-voltage distribution network in China is mainly a small-current grounding system, i.e., a distribution network neutral point ungrounded system or a distribution network neutral point grounded system through an arc suppression coil. In the operation of the distribution network, single-phase grounding fault discrimination is an important link.

[0003] The steady-state fault characteristics of the fault line and the non-fault line after single-phase grounding in a small-current grounding system, especially a neutral point grounded system through an arc suppression coil, are not obvious, and the zero-sequence current of the fault line is even smaller than that of the non-fault line sometimes. The accuracy of conventional steady-state algorithms such as the zero-sequence current ratio amplitude method, the fifth harmonic method, and the zero-sequence admittance method is limited.

[0004] Since the transient line selection method is not affected by the neutral point operation mode, it has relatively high applicability and relatively high sensitivity. At present, the grounding fault discrimination method for a small-current grounding system is mainly the transient line selection method. However, the present inventors have found that the current common grounding fault discrimination method has the following problems:

[0005] (1) The transient discrimination method based on zero-sequence current and zero-sequence voltage, for example, the transient zero-sequence power direction method, the transient amplitude ratio method, and the transient phase ratio method. These methods mainly use the phase or amplitude relationship between the transient zero-sequence current and the transient zero-sequence voltage after the fault occurs to judge the grounding fault, and have high accuracy. However, these methods are easily affected by unbalanced current, and the transient characteristic frequency of the zero-sequence current and the zero-sequence voltage is uncertain, the transient duration is very short (generally less than half a cycle), and the sensitivity to high-resistance grounding is insufficient.

[0006] (2) The transient discrimination method based on three-phase current, for example, the three-phase current transient phase asymmetry method and the three-phase transient amplitude ratio method. These methods mainly use the difference between the transient amplitude and the transient direction of the fault phase and the non-fault phase current after the fault occurs to discriminate. Similarly, these methods are easily affected by load current and impact current, and the transient characteristic frequency of the zero-sequence current and the zero-sequence voltage is uncertain, the transient duration is very short, and the sensitivity to high-resistance grounding is insufficient. SUMMARY

[0007] According to an aspect of the present application, the present application provides a grounding fault discrimination method of a power distribution line grounding system. The grounding fault discrimination method includes the following steps. A grounding fault discrimination system determines a zero sequence voltage mutation value and a zero sequence voltage amplitude value according to a zero sequence voltage of a power distribution line. In a case where the zero sequence voltage mutation value meets a preset zero sequence voltage mutation value condition, the grounding fault discrimination system determines a transient grounding judgment result and a zero sequence admittance value according to a zero sequence current and the zero sequence voltage of the power distribution line. The grounding fault discrimination system determines a classification condition of the zero sequence admittance value according to the transient grounding judgment result. In a case where the zero sequence voltage amplitude value meets a preset zero sequence voltage amplitude value condition, the grounding fault discrimination system determines a zero sequence admittance judgment result according to the classification condition of the zero sequence admittance value and the zero sequence admittance value. The grounding fault discrimination system determines a grounding comprehensive result according to the transient grounding judgment result and the zero sequence admittance judgment result. The grounding fault discrimination system determines a grounding fault condition of the power distribution line according to the grounding comprehensive result and a preset grounding result condition.

[0008] According to an aspect of the present application, the present application provides a grounding fault discrimination system of a power distribution line grounding system. The grounding fault discrimination system includes an acquisition module and a processing module. The acquisition module acquires a zero sequence voltage and a zero sequence current of a power distribution line. The processing module determines a zero sequence voltage mutation value and a zero sequence voltage amplitude value according to the zero sequence voltage. In a case where the zero sequence voltage mutation value meets a preset zero sequence voltage mutation value condition, the processing module determines a transient grounding judgment result and a zero sequence admittance value according to the zero sequence voltage and the zero sequence current. The processing module determines a classification condition of the zero sequence admittance value according to the transient grounding judgment result. In a case where the zero sequence voltage amplitude value meets a preset zero sequence voltage amplitude value condition, the processing module determines a zero sequence admittance judgment result according to the classification condition of the zero sequence admittance value and the zero sequence admittance value. The processing module determines a grounding comprehensive result according to the transient grounding judgment result and the zero sequence admittance judgment result. The processing module determines a grounding fault condition of the power distribution line according to the grounding comprehensive result.

[0009] According to another aspect of the present application, the present application further provides a non-volatile computer readable storage medium having stored thereon a computer program, which, when executed by a processor, enables the grounding fault discrimination method of the power distribution line grounding system as described above.

[0010] According to another aspect of the present application, the present application further provides an electronic device, including: one or more processors; a storage device configured to store one or more programs, which, when executed by the one or more processors, enable the one or more processors to implement the grounding fault discrimination method of the power distribution line grounding system as described above.

[0011] According to another aspect of the present application, the present application further provides a computer program product, including: a computer program stored on a computer readable storage medium; the computer program including program instructions, which, when executed by a computer, cause the computer to perform the grounding fault discrimination method of the power distribution line grounding system as described above.

[0012] The application can determine the zero sequence voltage mutation value and the zero sequence voltage amplitude value through the collected zero sequence voltage. The application can determine the transient ground judgment result and the zero sequence admittance value through the collected zero sequence voltage, the zero sequence circuit and the calculated zero sequence voltage mutation value. The application can determine the zero sequence admittance ground result through the transient ground judgment result and the zero sequence admittance value. The application can determine the grounding fault condition of the power distribution line through the grounding comprehensive result. The application can determine the grounding fault condition of the power distribution line through the transient ground judgment result and the zero sequence admittance judgment result, so that the requirement of hardware sampling can be reduced. The technical solution of the application does not completely depend on the transient characteristics of the grounding moment, so that the problem of capturing the transient characteristics due to the short duration of the transient state in the transient method can be avoided. The application avoids the problem that the steady-state characteristics of the fault line and the non-fault line are difficult to distinguish in the conventional steady-state algorithm, and thus the sensitivity of judging the high-resistance grounding fault of the power distribution line is improved.

[0013] The application can determine the grounding fault condition of the power distribution line through the transient ground judgment result and the zero sequence admittance judgment result, so that the requirement of hardware sampling can be reduced. The technical solution of the application does not completely depend on the transient characteristics of the grounding moment, so that the problem of capturing the transient characteristics due to the short duration of the transient state in the transient method can be avoided. The application avoids the problem that the steady-state characteristics of the fault line and the non-fault line are difficult to distinguish in the conventional steady-state algorithm, and thus the sensitivity of judging the high-resistance grounding fault of the power distribution line is improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0015] Figure 1 Fig. 1 shows a flowchart of a grounding fault discrimination method 1000 of a power distribution line grounding system according to an embodiment of the application;

[0016] Figure 2 Fig. 2 shows a flowchart of step S200 according to an embodiment of the application;

[0017] Figure 3 Fig. 3 shows a flowchart of step S300 according to an embodiment of the application;

[0018] Figure 4 Fig. 4 shows a flowchart of step S400 according to an embodiment of the application;

[0019] Figure 5 Fig. 5 shows a flowchart of step S500 according to an embodiment of the application;

[0020] Figure 6 Fig. 6 shows a flowchart of step S600 according to an embodiment of the application;

[0021] Figure 7Fig. 1 shows a structural schematic diagram of a ground fault discrimination system of a power distribution line grounding system according to an embodiment of the present application.

[0022] Reference signs:

[0023] Ground fault discrimination system 700; power transmission and distribution network 800; power distribution line 810; other power distribution line 820; acquisition module 710; processing module 720; zero sequence voltage transformer 711; zero sequence current transformer 712; line switch 801. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] According to an aspect of the present application, the present application provides a ground fault discrimination method 1000 of a power distribution line grounding system. The ground fault discrimination method 1000 comprises steps S100-S600. Figure 1 The ground fault discrimination method 1000 can be executed by a ground fault discrimination system.

[0026] Exemplarily, the ground fault discrimination system can be a client device (such as a host computer, etc.) with data processing capability.

[0027] In step S100, the ground fault discrimination system determines a zero sequence voltage mutation value and a zero sequence voltage amplitude value according to the acquired zero sequence voltage of the power distribution line.

[0028] According to an example embodiment, the power distribution line can be a three-phase power distribution line in a power transmission and distribution network. The zero sequence voltage is the vector sum of the three-phase voltages in the three-phase power distribution line. The zero sequence current is the vector sum of the three-phase currents in the three-phase power distribution line.

[0029] According to an example embodiment, the ground fault discrimination system can acquire the zero sequence current of the power distribution line through a zero sequence current transformer. The ground fault discrimination system can acquire the zero sequence voltage of the power distribution line through a zero sequence voltage transformer.

[0030] For example, in step S100, the ground fault discrimination system can determine the zero sequence voltage mutation value and the zero sequence voltage amplitude value according to the zero sequence voltage.

[0031] According to an example embodiment, the mutation value of the zero sequence voltage can be the sudden change value of the zero sequence voltage relative to the normal operating state in the case of a ground fault or other unbalanced state occurring in the power distribution line. The amplitude of the zero sequence voltage can be the maximum value of the zero sequence voltage.

[0032] For example, in order to avoid the influence of the fixed interference in the unbalanced voltage, unbalanced current, zero sequence current transformer and zero sequence voltage transformer sampling link of the power distribution line, the grounding fault discrimination system can first perform differential filtering on the sampled zero sequence voltage and zero sequence current. The differential period is a multiple of the power frequency period. For example, the differential period can take 2-10 power frequency periods of zero sequence voltage data for differential processing. After differential processing, the grounding fault discrimination system can calculate the zero sequence voltage sudden change value and the zero sequence voltage amplitude by Fourier formula, full-wave integration, half-wave integration and the like.

[0033] For example, the differential period can take 8 power frequency periods for differential processing.

[0034] In step S200, the grounding fault discrimination system determines the transient ground judgment result and the zero sequence admittance value according to the collected zero sequence current and zero sequence voltage of the power distribution line when the zero sequence voltage sudden change value meets the preset zero sequence voltage sudden change value condition.

[0035] According to an example embodiment, the preset zero sequence voltage sudden change value condition can be that the calculated zero sequence voltage sudden change value is greater than a zero sequence voltage sudden change value threshold. The zero sequence voltage sudden change value threshold can be a critical value of the zero sequence voltage sudden change value. The zero sequence voltage sudden change value threshold can be determined according to the zero sequence voltage value of the power distribution line in the case of single-phase metallic grounding of the power distribution line.

[0036] According to an example embodiment, the value range of the zero sequence voltage sudden change value threshold can be 5%U e ≤ΔU set ≤95%U e . Wherein, ΔU set is the zero sequence voltage sudden change value threshold, U e is the zero sequence voltage value of the power distribution line in the case of single-phase metallic grounding of the power distribution line.

[0037] For example, for a 10kV ungrounded power distribution line, U e may be 5774V, and the grounding fault discrimination system can pre-set the value of this U e .

[0038] For example, the value of the zero sequence voltage sudden change value threshold can be ΔU set = 10%U e .

[0039] For example, in step S200, the grounding fault discrimination system determines the transient ground judgment result according to the collected zero sequence current and zero sequence voltage of the power distribution line when the zero sequence voltage sudden change value is greater than the zero sequence voltage sudden change value threshold.

[0040] According to an example embodiment, the transient ground judgment result can be a result of assigning a value to the power distribution line according to the collected zero sequence voltage and zero sequence current. The transient ground judgment result includes a first transient ground judgment result and a second transient ground judgment result. The first transient ground judgment result and the second transient ground judgment result can be classified according to a fault condition of the power distribution line derived from the collected zero sequence current and zero sequence voltage.

[0041] In a case where the zero sequence current and the zero sequence voltage of the power distribution line collected by the ground fault discrimination system determine that the power distribution line is a non-fault line, the transient ground judgment result is the first transient ground judgment result.

[0042] In a case where the zero sequence current and the zero sequence voltage of the power distribution line collected by the ground fault discrimination system determine that the power distribution line is a fault line, the transient ground judgment result is the second transient ground judgment result.

[0043] According to an example embodiment, the zero sequence conductance value can be a response capability of the power system to the zero sequence current. The zero sequence conductance value is the inverse of the impedance. In a case where the ground fault discrimination system determines that the zero sequence voltage mutation value is greater than the zero sequence voltage threshold value in step S200, the zero sequence conductance value is calculated according to the collected zero sequence current and zero sequence voltage of the power distribution line.

[0044] In step S300, the ground fault discrimination system determines the classification of the zero sequence conductance value according to the transient ground judgment result.

[0045] According to an example embodiment, after the ground fault discrimination system calculates the zero sequence conductance value, the ground fault discrimination system can classify the zero sequence conductance value according to the transient ground judgment result.

[0046] The zero sequence conductance value can be classified into a first zero sequence conductance value and a second zero sequence conductance value according to the transient ground judgment result.

[0047] In step S400, the ground fault discrimination system determines the zero sequence conductance judgment result according to the classification of the zero sequence conductance value and the zero sequence conductance value in a case where the zero sequence voltage amplitude satisfies a preset zero sequence voltage amplitude condition.

[0048] According to an example embodiment, the preset zero sequence voltage amplitude condition can be that the calculated zero sequence voltage amplitude is greater than a zero sequence voltage amplitude threshold value. The zero sequence voltage amplitude threshold value can be a critical value of the zero sequence voltage amplitude. The zero sequence voltage amplitude threshold value can also be determined according to the zero sequence voltage value (U e ) of the power distribution line in a case where the power distribution line has a single-phase metallic ground.

[0049] According to an example embodiment, the zero sequence voltage amplitude threshold value can be in the range of 5%U e ≤U set ≤95%U e . Wherein, U set is the zero sequence voltage amplitude threshold value.

[0050] Exemplarily, the zero sequence voltage amplitude threshold value can be U set = 15%U e .

[0051] For example, in step S400, when the ground fault discrimination system determines that the zero sequence voltage amplitude is greater than the zero sequence voltage amplitude threshold value, the zero sequence admittance judgment result is determined according to the classification of the zero sequence admittance value and the zero sequence admittance value.

[0052] According to an example embodiment, the zero sequence admittance judgment result can be the result of assigning the zero sequence admittance judgment result of the distribution line according to the classification of the zero sequence admittance value and the zero sequence admittance value. The zero sequence admittance judgment result includes a first zero sequence admittance judgment result, a second zero sequence admittance judgment result, and a third zero sequence admittance judgment result. The first zero sequence admittance judgment result, the second zero sequence admittance judgment result, and the third zero sequence admittance judgment result can be classified according to the calculated zero sequence admittance value, the first zero sequence admittance value, and the second zero sequence admittance value.

[0053] In step S500, the ground fault discrimination system determines the ground comprehensive result according to the transient ground judgment result and the zero sequence admittance judgment result.

[0054] According to an example embodiment, the ground fault discrimination system can assign weights to the transient ground judgment result and the zero sequence admittance judgment result according to the size of the zero sequence voltage amplitude. In the case of a larger zero sequence voltage amplitude, the weight of the transient ground judgment result is larger, and the weight of the zero sequence admittance judgment result is smaller; in the case of a smaller zero sequence voltage amplitude, the weight of the transient ground judgment result is smaller, and the weight of the zero sequence admittance judgment result is larger. Then, the ground fault discrimination system determines the ground comprehensive result according to the transient ground judgment result and the zero sequence admittance judgment result.

[0055] In step S600, the ground fault discrimination system determines the ground fault condition of the distribution line according to the ground comprehensive result and the preset ground result condition.

[0056] According to an example embodiment, the preset ground result condition can be that the value of the ground comprehensive result is greater than or equal to the ground comprehensive result threshold value. The ground comprehensive result threshold value can be a critical value of the ground comprehensive result.

[0057] The ground comprehensive result threshold value can be determined according to the zero sequence voltage value (U e ) of the distribution line in the case of single-phase metallic ground of the distribution line.

[0058] For example, in the step S600, in the case that the grounding integrated result is greater than or equal to the grounding integrated result threshold, the grounding fault discrimination system determines that the grounding fault condition of the power distribution line is that the power distribution line is a grounding fault line.

[0059] Through the above embodiment, the grounding fault discrimination method provided by the application can determine the zero sequence voltage mutation value and the zero sequence voltage amplitude value through the collected zero sequence voltage. The application can determine the transient grounding judgment result and the zero sequence admittance value through the collected zero sequence voltage, the zero sequence circuit and the calculated zero sequence voltage mutation value. The application can determine the zero sequence admittance grounding result through the transient grounding judgment result and the zero sequence admittance value. The application can determine the grounding integrated result through the transient grounding judgment result and the zero sequence admittance judgment result. The application can determine the grounding fault condition of the power distribution line through the grounding integrated result.

[0060] The grounding fault discrimination method provided by the application can determine the grounding fault condition of the power distribution line through the transient grounding judgment result and the zero sequence admittance judgment result of the power distribution line, which can reduce the requirement of hardware sampling. The technical solution of the application does not completely depend on the transient characteristics of the grounding moment, thereby avoiding the problem of transient method that the transient characteristics are difficult to capture because of the short duration of the transient state. The application avoids the problem that the steady-state characteristics of the fault line and the non-fault line are difficult to distinguish in the conventional steady-state algorithm, thereby improving the sensitivity of the judgment of the high-resistance grounding fault of the power distribution line.

[0061] Optionally, referring to Figure 2 , the step S200 can include the step S210 and the step S220.

[0062] In the step S210, in the case that the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition, the grounding fault discrimination system determines the transient grounding judgment result through the transient grounding algorithm according to the zero sequence voltage and the zero sequence current.

[0063] According to the example embodiment, the grounding fault discrimination system can also determine the transient grounding judgment result through the algorithm based on the Hilbert-Huang Transform (HHT) transient method, the artificial intelligence recognition-based transient method, etc. According to the example embodiment, the grounding fault discrimination system can determine the transient grounding judgment result through the grounding transient algorithm to be the first transient grounding judgment result or the second transient grounding judgment result.

[0064] For example, in the case that the grounding fault discrimination system determines that the power distribution line is a non-fault line, the grounding fault discrimination system determines that flg1=a.

[0065] For example, in the case that the ground fault discrimination system determines that the power distribution line is a fault line, the ground fault discrimination system determines that flgl = b.

[0066] Wherein, flgl is a transient ground judgment result; a is a first transient ground judgment result; b is a second transient ground judgment result.

[0067] Optionally, referring to Figure 2 , the step S210 can include steps S211-S214.

[0068] In step S211, the ground fault discrimination system respectively performs n-layer wavelet packet decomposition on the zero sequence current and the zero sequence voltage through the transient zero sequence power algorithm of wavelet packet transform, to obtain 2 n frequency band of zero sequence current data and 2 n frequency band of zero sequence voltage data, wherein n is a natural number greater than 1.

[0069] According to an example embodiment, the ground fault discrimination system can cache at least 2 cycles of zero sequence current data and at least 2 cycles of zero sequence voltage data in real time. In the case that the ground fault discrimination system determines that the zero sequence voltage mutation value is greater than the zero sequence voltage mutation value threshold, the ground fault discrimination system starts the transient ground algorithm. In order to avoid the error caused by the asynchronization between the starting time of the transient ground algorithm and the fault occurrence time, the ground fault discrimination system caches the zero sequence voltage data and the zero sequence current data of each cycle before and after the mutation of the zero sequence voltage when starting the transient ground algorithm.

[0070] Illustratively, the ground fault discrimination system caches 2 cycles of zero sequence current data and 2 cycles of zero sequence voltage data. For a power distribution system with a working frequency of 50Hz, the ground fault discrimination system caches 2 cycles (i.e. 40ms) of zero sequence current data and 2 cycles (i.e. 40ms) of zero sequence voltage data.

[0071] The ground fault discrimination system performs n-layer wavelet packet decomposition on the cached zero sequence current data of each cycle before and after the starting time of the transient ground algorithm based on the transient ground algorithm of wavelet packet transform, to obtain 2 n frequency band of zero sequence current data, and performs n-layer wavelet packet decomposition on the cached zero sequence voltage data of each cycle before and after the starting time of the transient zero sequence power algorithm, to obtain 2 n frequency band of zero sequence voltage data.

[0072] The frequency band range of the transient ground algorithm of wavelet packet transform is large, which can cover more frequency bands of zero sequence current data and zero sequence voltage data.

[0073] Optionally, in step S211, the grounding fault discrimination system can take n as 4. The grounding fault discrimination system carries out 4-layer wavelet packet decomposition on the zero sequence current and the zero sequence voltage respectively by the transient zero sequence power algorithm of the compactly supported orthonormal wavelet basis DB10 wavelet transform, to obtain the data of the zero sequence current in 16 frequency bands and the data of the zero sequence voltage in 16 frequency bands.

[0074] According to the example embodiment, the grounding fault discrimination system carries out 4-layer wavelet packet decomposition on the zero sequence current data of each 20 ms before and after the starting time of the cached transient grounding algorithm based on the transient grounding algorithm of the compactly supported orthonormal wavelet basis DB10 wavelet transform, to obtain the data of the zero sequence current in 16 frequency bands.

[0075] For example, the 40 ms zero sequence current data cached by the grounding fault discrimination system is N, and the DB10 wavelet packet transform is used on the N zero sequence current data to carry out 4-layer wavelet packet decomposition to obtain the data of the zero sequence current in 16 frequency bands as w (m)(j).

[0076] Wherein, m is the mth frequency band in the 16 frequency bands, 1≤m≤16, and m is an integer; j is the jth data in the N data, 1≤j≤N, and j is an integer; I w (m) is the basic wavelet of the zero sequence current in the mth frequency band; I w (m)(j) is the jth data in the N data of the zero sequence current in the mth frequency band.

[0077] According to the example embodiment, the grounding fault discrimination system carries out 4-layer wavelet packet decomposition on the zero sequence voltage data of each 20 ms before and after the starting time of the cached transient grounding algorithm based on the transient grounding algorithm of the compactly supported orthonormal wavelet basis DB10 wavelet transform, to obtain the data of the zero sequence voltage in 16 frequency bands.

[0078] For example, the 40 ms zero sequence voltage data cached by the grounding fault discrimination system is also N, and the DB10 wavelet packet transform is used on the N zero sequence voltage data to carry out 4-layer wavelet packet decomposition to obtain the data of the zero sequence voltage in 16 frequency bands as w (m)(j).

[0079] Wherein, m is the mth frequency band in the 16 frequency bands, 1≤m≤16, and m is an integer; j is the jth data in the N data, 1≤j≤N, and j is an integer; U w (m) is the basic wavelet of the zero sequence voltage in the mth frequency band; U w (m)(j) is the jth data in the N data of the zero sequence voltage in the mth frequency band.

[0080] In step S212, the grounding fault discrimination system compares 2 nThe data of zero-sequence current in each frequency band can be used to obtain the characteristic frequency band of zero-sequence current.

[0081] According to an example embodiment, the characteristic frequency band of the zero-sequence current may be 2 n Among the zero-sequence current data of the frequency bands, the frequency band with the largest and most concentrated characteristic energy is 2 n The frequency band in which the average amplitude of the zero-sequence current data is the largest.

[0082] The ground fault identification system can calculate the average amplitude of the zero-sequence current data in the mth frequency band according to the following formula:

[0083]

[0084] Among them, EI w (m) is the average amplitude of the zero-sequence current data in the m-th frequency band.

[0085] For example, the ground fault identification system can compare and obtain the average amplitude of the zero-sequence current data in 16 frequency bands, and determine the frequency band with the largest average amplitude of the zero-sequence current data in the 16 frequency bands as the characteristic frequency band of the zero-sequence current.

[0086] In step S213 , the ground fault identification system determines the zero-sequence reactive power within the characteristic frequency band of the zero-sequence current according to the characteristic frequency band of the zero-sequence current and the frequency band data of the zero-sequence voltage corresponding to the characteristic frequency band of the zero-sequence current.

[0087] According to an example embodiment, the zero-sequence reactive power is reactive power generated due to three-phase imbalance.

[0088] According to an example embodiment, after determining the characteristic frequency band of the zero-sequence current, the ground fault identification system may determine the frequency band of the zero-sequence voltage corresponding to the characteristic frequency band of the zero-sequence current based on the characteristic frequency band of the zero-sequence current.

[0089] For example, after comparing and obtaining the average amplitude of the zero-sequence current data in 16 frequency bands, the ground fault judgment system determines that the characteristic frequency band of the zero-sequence current is the i-th frequency band (1≤i≤16, and i is an integer), and the frequency band of the zero-sequence voltage corresponding to the characteristic frequency band of the zero-sequence current is the i-th frequency band.

[0090] According to an exemplary embodiment, within the characteristic frequency band of zero-sequence current, the ground fault identification system multiplies the basic wavelet of zero-sequence current data with the basic wavelet of zero-sequence voltage data to calculate the zero-sequence reactive power of the basic wavelet within the characteristic frequency band.

[0091] For example, the ground fault identification system multiplies the basic wavelet of the zero-sequence current data of the i-th frequency band with the basic wavelet of the zero-sequence voltage data of the i-th frequency band to calculate the zero-sequence reactive power of the basic wavelet in the i-th frequency band.

[0092] In step S214, the ground fault discrimination system determines the transient ground fault judgment result as the first transient ground fault result or the second transient ground fault result according to the preset zero sequence reactive power condition and the zero sequence reactive power.

[0093] According to an example embodiment, the preset zero sequence reactive power condition is a zero sequence reactive power threshold. The zero sequence reactive power threshold can be a critical value of the zero sequence reactive power preset according to the maximum negative reactive power of the power distribution line in the power distribution system under normal operation.

[0094] According to an example embodiment, the zero sequence reactive power threshold has a value range of Q set <0, and Q set <Q max . Wherein, Q set is the zero sequence reactive power threshold; Q max is the maximum negative reactive power of the power distribution line in the power distribution system under normal operation, i.e., the maximum negative reactive power that can occur due to three-phase imbalance under normal operation of the power distribution line.

[0095] The preset zero sequence reactive power condition includes a first preset zero sequence reactive power condition and a second preset zero sequence reactive power condition.

[0096] The first preset zero sequence reactive power condition can be that the calculated zero sequence reactive power is less than the zero sequence reactive power threshold.

[0097] The second preset zero sequence reactive power condition can be that the calculated zero sequence reactive power is greater than or equal to the zero sequence reactive power threshold.

[0098] In the case where the zero sequence reactive power meets the first preset zero sequence reactive power condition, the ground fault discrimination system determines that the current power distribution line is a non-fault line, and the ground fault discrimination system determines that flg1=a.

[0099] In the case where the zero sequence reactive power meets the second preset zero sequence reactive power condition, the ground fault discrimination system determines that the current power distribution line is a fault line, and the ground fault discrimination system determines that flg1=b.

[0100] For example, a can take 0, and b can take 1.

[0101] For example, the ground fault discrimination system can determine the transient ground fault judgment result according to the following formula:

[0102]

[0103] For example, if the maximum negative reactive power of the power distribution line in the power distribution system under normal operation can be Q max= -100 VA, the grounding fault determination system presets Q set = -120 VA.

[0104] In step S220, the grounding fault determination system determines the zero sequence admittance value according to the zero sequence voltage and the zero sequence current after a preset delay time.

[0105] According to an example embodiment, the preset delay time can be a preset waiting time for the zero sequence admittance value to stabilize. Since the zero sequence admittance value is a steady-state value, while the determination of the transient ground fault is a transient process. The grounding fault determination system can avoid the transient process by a preset delay time, and take a cross-sectional zero sequence admittance value, which is a relatively stable value.

[0106] For example, the preset delay time can be 5 cycles, i.e. the preset delay time is 100 ms. If the preset delay time is too short, the transient process may not end, and if the preset delay time is too long, the fault switching condition of the power distribution line can become more complex, thereby affecting the determination of the zero sequence admittance value by the grounding fault determination system.

[0107] For example, the grounding fault determination system can calculate the zero sequence admittance value by the following formula:

[0108]

[0109] Wherein, I0 is the collected zero sequence current; U0 is the collected zero sequence voltage; Y0 is the zero sequence admittance value.

[0110] Optionally, referring to Figure 3 , step S300 can include step S310 and step S320.

[0111] In step S310, the grounding fault determination system determines the zero sequence admittance value as a first zero sequence admittance value in a case where the transient ground fault determination result is a first transient ground fault determination result. That is, the transient ground fault algorithm determines that the power distribution line is a non-fault line, and the grounding fault determination system stores the first zero sequence admittance value in a first group of storage modules.

[0112] In step S320, the grounding fault determination system determines the zero sequence admittance value as a second zero sequence admittance value in a case where the transient ground fault determination result is a second transient ground fault determination result. That is, the transient ground fault algorithm determines that the power distribution line is a fault line, and the grounding fault determination system stores the second zero sequence admittance value in a second group of storage modules.

[0113] The first group of storage modules and the second group of storage modules can be a database, and can also be different databases.

[0114] The first group of storage modules can include a plurality of first zero sequence admittance values. The plurality of first zero sequence admittance values can be calculated from the collected zero sequence current and zero sequence voltage, and can also be determined by methods such as the external capacitance method and the external voltage method, or can be obtained from empirical values or theoretical calculations. The zero sequence admittance values obtained from empirical values or theoretical calculations are set as preset first zero sequence admittance values.

[0115] The second group of storage modules can include a plurality of second zero sequence admittance values. The plurality of second zero sequence admittance values can be calculated from the collected zero sequence current and zero sequence voltage.

[0116] Optionally, referring to Figure 4 , step S400 can include step S410 and step S420.

[0117] In step S410, the ground fault discrimination system determines the zero sequence admittance value difference according to the zero sequence admittance value and the first zero sequence admittance value when the zero sequence voltage amplitude meets the preset zero sequence voltage amplitude condition.

[0118] For example, when the ground fault discrimination system determines that the zero sequence voltage amplitude is greater than the zero sequence voltage amplitude threshold, the zero sequence admittance value difference can be calculated according to the following formula:

[0119] ΔY = |Y0-Y1 mid |;

[0120] or ΔY = |Y0-Y1 set |;

[0121] wherein ΔY is the zero sequence admittance value difference, i.e., the absolute value of the difference between the zero sequence admittance value and the first zero sequence admittance value; Y0 is the zero sequence admittance value; Y1 mid is the median of the plurality of first zero sequence admittance values in the first group of storage modules; and Y1 set is the preset first zero sequence admittance value.

[0122] In step S420, the ground fault discrimination system determines the zero sequence admittance judgment result to be the first zero sequence admittance result, the second zero sequence admittance result, or the third zero sequence admittance result according to the preset zero sequence admittance value difference condition and the zero sequence admittance value difference.

[0123] According to an example embodiment, the preset zero sequence admittance value difference condition can be a zero sequence admittance value difference threshold. The zero sequence admittance value difference threshold is a critical value of the zero sequence admittance value difference.

[0124] The zero sequence admittance value difference threshold can be determined as a first zero sequence admittance value difference threshold and a second zero sequence admittance value difference threshold according to the first zero sequence admittance value and the second zero sequence admittance value.

[0125] For example, the ground fault discrimination system can calculate the absolute value of the difference between the first zero sequence admittance value and the second zero sequence admittance value by the following formula:

[0126] ΔY mid = |Y2 mid - Y1 mid |;

[0127] wherein, ΔY mid is the absolute value of the difference between the first zero sequence admittance value and the second zero sequence admittance value; Y1 mid is the median of the plurality of first zero sequence admittance values in the first group of storage modules; Y2 mid is the median of the plurality of second zero sequence admittance values in the second group of storage modules.

[0128] For example, the first zero sequence admittance value difference threshold value can have a value range of 50% ΔY mid ≤ ΔY1 set ≤ 95% ΔY mid . Wherein, ΔY1 set is the first zero sequence admittance value difference threshold value.

[0129] For example, the second zero sequence admittance value difference threshold value can have a value range of 105% ΔY mid ≤ ΔY2 set ≤ 200% ΔY mid . Wherein, ΔY2 set is the second zero sequence admittance value difference threshold value.

[0130] Preferably, ΔY1 set = 80% ΔY mid ; ΔY2 set = 120% ΔY mid .

[0131] According to an example embodiment, the ground fault discrimination system can divide the preset zero sequence admittance value difference condition into a first preset zero sequence admittance value difference condition, a second preset zero sequence admittance value difference condition, and a third preset zero sequence admittance value difference condition according to the first zero sequence admittance value difference threshold value and the second zero sequence admittance value difference threshold value.

[0132] For example, the first preset zero sequence admittance value condition can be that the zero sequence admittance value difference is less than the first zero sequence admittance value difference threshold value.

[0133] The first preset zero sequence admittance value condition can be that the zero sequence admittance value difference is less than the second zero sequence admittance value difference threshold value, and the zero sequence admittance value difference is greater than or equal to the first zero sequence admittance value difference threshold value.

[0134] The third preset zero sequence admittance value condition can be that the zero sequence admittance value difference is greater than or equal to the first zero sequence admittance value difference threshold value.

[0135] In a case where the difference between the zero sequence admittance values meets a first preset difference between zero sequence admittance values condition, the ground fault discrimination system determines that the zero sequence admittance determination result is a first zero sequence admittance determination result.

[0136] In a case where the difference between the zero sequence admittance values meets a second preset difference between zero sequence admittance values condition, the ground fault discrimination system determines that the zero sequence admittance determination result is a second zero sequence admittance determination result.

[0137] In a case where the difference between the zero sequence admittance values meets a third preset difference between zero sequence admittance values condition, the ground fault discrimination system determines that the zero sequence admittance determination result is a third zero sequence admittance determination result.

[0138] The first zero sequence admittance result is less than the second zero sequence admittance result, and the second zero sequence admittance result is less than the third zero sequence admittance result.

[0139]

[0140] The first zero sequence admittance result is less than the second zero sequence admittance result, and the second zero sequence admittance result is less than the third zero sequence admittance result.

[0141] For example, c can be 0, d can be 1, and e can be 2.

[0142] For example, the ground fault discrimination system can determine the zero sequence admittance determination result according to the following formula:

[0143]

[0144] Optionally, referring to Figure 5 , the step S500 can include a step S510.

[0145] In the step S510, the ground fault discrimination system determines the ground comprehensive result according to the preset zero sequence voltage parameter, the transient ground determination result, a preset coefficient corresponding to the transient ground determination result, the zero sequence admittance determination result, a preset coefficient corresponding to the zero sequence admittance determination result, and the transient ground determination result.

[0146] According to an example embodiment, the preset zero sequence voltage parameter can be a zero sequence voltage value (U e ) of the distribution line in a case where a single-phase metallic ground fault occurs in the distribution line.

[0147] The preset coefficient corresponding to the transient ground determination result can be a weight coefficient determined according to a zero sequence voltage amplitude and according to a transient ground algorithm sensitivity.

[0148] The preset coefficient corresponding to the zero sequence admittance determination result can be a weight coefficient determined according to a zero sequence voltage amplitude and according to a transient ground algorithm sensitivity.

[0149] For example, the ground fault discrimination system can determine the ground comprehensive result according to the following formula:

[0150] Flg=kxU0xFlg1+(1-k)x(U e -U0)xFlg2;

[0151] Wherein, Flg is the ground comprehensive result; k is a preset coefficient corresponding to the zero sequence admittance judgment result, 0 e k<1; Flg1 is the transient ground judgment result; U

[0152] For example, for a 10kV ungrounded distribution line, the ground fault discrimination system presets: U e =5774V, k=0.6, then the ground fault discrimination system can determine the ground comprehensive result according to the following formula:

[0153] Flg=0.6xU0xFlg1+0.4x(5774-U0)xFlg2.

[0154] The ground fault discrimination system can determine the relationship between Flg and U0 in combination with the possible cases of Flg1 and Flg2 values:

[0155] In the case of Flg1=0, Flg2=0, the ground fault discrimination system calculates Flg=0;

[0156] In the case of Flg1=0, Flg2=1, the ground fault discrimination system calculates Flg=

[0157] 0.4x(5774-U0);

[0158] In the case of Flg1=0, Flg2=2, the ground fault discrimination system calculates Flg=

[0159] 0.8x(5774-U0);

[0160] In the case of Flg1=1, Flg2=0, the ground fault discrimination system calculates Flg=0.6xU0;

[0161] In the case of Flg1=1, Flg2=1, the ground fault discrimination system calculates Flg=5774;

[0162] In the case of Flg1=1, Flg2=2, the ground fault discrimination system calculates Flg=8083.6-0.4xU0.

[0163] Optionally, referring to Figure 6 , step S600 can include step S610.

[0164] In step S610, the grounding fault discrimination system determines, according to the preset grounding result condition and the grounding comprehensive result, that the grounding fault condition of the power distribution line is that the power distribution line is a non-grounding fault line or a grounding fault line.

[0165] The preset grounding result condition can include a first preset grounding result condition and a second preset grounding result condition.

[0166] For example, the first preset grounding result condition can be that the comprehensive grounding result is less than a grounding comprehensive result threshold. The second preset grounding result condition can be that the comprehensive grounding result is greater than or equal to the grounding comprehensive result threshold.

[0167] If the grounding comprehensive result satisfies the first preset grounding result condition, the grounding fault discrimination system determines that the grounding fault condition of the power distribution line is that the power distribution line is a non-grounding fault line.

[0168] If the grounding comprehensive result satisfies the second preset grounding result condition, the grounding fault discrimination system determines that the grounding fault condition of the power distribution line is that the power distribution line is a grounding fault line.

[0169] According to an example embodiment, the grounding comprehensive result threshold can be set to a fixed value or dynamically adjusted according to the grounding condition of the power distribution line. In the case where the grounding comprehensive result threshold is set to a fixed value, the value range of the grounding comprehensive result threshold can be 5%U e ≤flg set ≤95%U e , wherein flg set is the grounding comprehensive result threshold.

[0170] Exemplarily, the value of the grounding comprehensive result threshold can be flg set = 20%U e .

[0171] For example, for a 10kV non-grounding power distribution line, the grounding fault discrimination system presets that U e = 5774V, k = 0.6, flg set = 1144.8V, then in the case where flg < 1154.8V, the grounding fault discrimination system determines that the grounding fault condition of the power distribution line is that the power distribution line is a non-grounding fault line. In the case where flg ≥ 1154.8V, the grounding fault discrimination system determines that the grounding fault condition of the power distribution line is that the power distribution line is a grounding fault line.

[0172] The ground fault discrimination system can determine the ground fault condition of the distribution line in combination with the possible conditions of Flgl, Flg2 and the value range of U0.

[0173] In the case of Flgl=0, Flg2=0, the ground fault discrimination system calculates Flg=0, and the ground fault condition of the distribution line is that the distribution line is a non-ground fault line.

[0174] In the case of Flgl=0, Flg2=1, the ground fault discrimination system calculates Flg=0.4×(5774-U0), and in the case of U0≤2887V, the ground fault condition of the distribution line is that the distribution line is a ground fault line.

[0175] In the case of Flgl=0, Flg2=2, the ground fault discrimination system calculates Flg=0.8×(5774-U0), and in the case of U0≤4330.5V, the ground fault condition of the distribution line is that the distribution line is a ground fault line.

[0176] In the case of Flgl=1, Flg2=0, the ground fault discrimination system calculates Flg=0.6×U0, and in the case of U0≥1924.67V, the ground fault condition of the distribution line is that the distribution line is a ground fault line.

[0177] In the case of Flgl=1, Flg2=1, the ground fault discrimination system calculates Flg=5774, and the ground fault condition of the distribution line is that the distribution line is a ground fault line.

[0178] In the case of Flgl=1, Flg2=2, the ground fault discrimination system calculates Flg=8083.6-0.4×U0, and the ground fault condition of the distribution line is that the distribution line is a ground fault line.

[0179] It can be understood that for some ground faults, such as broken wire of overhead line or discharge of cable insulation deterioration, the initial ground resistance can be as high as tens of thousands of ohms, and the change process of zero sequence voltage is slow, and it is difficult to identify the occurrence of the fault only by the transient discrimination method due to small transient component. The application can effectively identify the ground fault with small transient component by determining the zero sequence admittance ground result based on the transient ground judgment result and the zero sequence admittance value, and improve the sensitivity of judging the high resistance ground fault of the distribution line.

[0180] According to an aspect of the application, the application provides a ground fault discrimination system 700 of a distribution line 810 grounding system. Referring to Figure 7 , the ground fault discrimination system 700 comprises an acquisition module 710 and a processing module 720.

[0181] According to an example embodiment, the acquisition module 710 acquires the zero sequence voltage and the zero sequence current of the power distribution line 810. Referring to Figure 7 The acquisition module 710 includes a zero sequence voltage transformer 711 and a zero sequence current transformer 712.

[0182] According to an example embodiment, the power distribution line 810 can be a three-phase power distribution line 810 in the power transmission and distribution network 800. Referring to Figure 7 The power transmission and distribution network 800 can include the power distribution line 810 and other power distribution lines 820. This application describes the case of judging the ground fault of the power distribution line 810. The power distribution line 810 and the other power distribution lines 820 can both be provided with a line switch 801, which can be a protective switch for ground fault.

[0183] The zero sequence voltage is the vector sum of the three-phase voltage in the three-phase power distribution line 810. The zero sequence current is the vector sum of the three-phase current in the three-phase power distribution line 810.

[0184] The zero sequence voltage transformer 711 can be arranged on the power distribution line 810 to acquire the zero sequence voltage of the power distribution line 810. The zero sequence voltage transformer 711 transmits the acquired zero sequence voltage to the processing module 720. The zero sequence current transformer 712 can be arranged on the power distribution line 810 to acquire the zero sequence current of the power distribution line 810. The zero sequence current transformer 712 transmits the acquired zero sequence current to the processing module 720.

[0185] According to an example embodiment, the processing module 720 determines the zero sequence voltage mutation value and the zero sequence voltage amplitude value according to the zero sequence voltage.

[0186] According to an example embodiment, the mutation value of the zero sequence voltage can be the sudden change value of the zero sequence voltage relative to the normal operating state in the case of ground fault or other unbalanced state in the power distribution line 810. The amplitude of the zero sequence voltage can be the maximum value of the zero sequence voltage.

[0187] For example, in order to avoid the influence of the fixed interference in the unbalanced voltage, unbalanced current, zero sequence current transformer and zero sequence voltage transformer sampling link of the power distribution line 810, the processing module 720 can first perform differential filtering on the sampled zero sequence voltage and zero sequence current. The differential period is a multiple of the power frequency period. For example, the differential period can take 2-10 power frequency periods of zero sequence voltage data for differential processing. After differential processing, the processing module 720 can calculate the zero sequence voltage mutation value and the zero sequence voltage amplitude value by Fourier formula, full-wave integration, half-wave integration, etc.

[0188] Exemplarily, the differential period can take a value of 8 power frequency periods, and the value of the cycle is differential processed.

[0189] According to the example embodiment, in a case where the zero sequence voltage sudden change value meets the preset zero sequence voltage sudden change value condition, the processing module 720 determines the zero sequence admittance value according to the zero sequence voltage and the zero sequence current transient ground judgment result.

[0190] According to the example embodiment, the preset zero sequence voltage sudden change value condition can be that the calculated zero sequence voltage sudden change value is greater than a zero sequence voltage sudden change value threshold. The zero sequence voltage sudden change value threshold can be a critical value of the zero sequence voltage sudden change value. The zero sequence voltage sudden change value threshold can be determined according to the zero sequence voltage value of the power distribution line 810 in a case where the power distribution line 810 has a single-phase metallic ground.

[0191] According to the example embodiment, the value range of the zero sequence voltage sudden change value threshold can be 5%U e ≤ΔU set ≤95%U e . Wherein, ΔU set is the zero sequence voltage sudden change value threshold, and U e is the zero sequence voltage value of the power distribution line 810 in a case where the power distribution line 810 has a single-phase metallic ground.

[0192] For example, for a 10kV ungrounded power distribution line 810, U e may be 5774V, and the processing module 720 can pre-set the value of this U e .

[0193] Exemplarily, the value of the zero sequence voltage sudden change value threshold can be ΔU set = 10%U e .

[0194] For example, in a case where the processing module 720 judges that the zero sequence voltage sudden change value is greater than the zero sequence voltage sudden change value threshold, the transient ground judgment result is determined according to the collected zero sequence current and zero sequence voltage of the power distribution line 810.

[0195] According to the example embodiment, the transient ground judgment result can be a result of assigning the transient ground judgment result of the power distribution line 810 according to the collected zero sequence voltage and zero sequence current. The transient ground judgment result includes a first transient ground judgment result and a second transient ground judgment result. The first transient ground judgment result and the second transient ground judgment result can be classified according to the fault condition of the power distribution line 810 derived from the collected zero sequence current and zero sequence voltage.

[0196] In a case where the zero sequence current and zero sequence voltage of the power distribution line 810 collected by the processing module 720 determine that the power distribution line 810 is a non-fault line, the transient ground judgment result is the first transient ground judgment result.

[0197] In a case where the processing module 720 determines that the zero sequence current and the zero sequence voltage of the power distribution line 810 indicate that the power distribution line 810 is a fault line, the transient ground determination result is a second transient ground determination result.

[0198] According to an example embodiment, the zero sequence conductance value can be a response capability of the power system to the zero sequence current. The zero sequence conductance value is the inverse of the impedance. In a case where the processing module 720 determines that the zero sequence voltage mutation value is greater than the zero sequence voltage threshold value, the zero sequence conductance value is calculated according to the collected zero sequence current and the zero sequence voltage of the power distribution line 810.

[0199] According to an example embodiment, the processing module 720 determines the classification of the zero sequence conductance value according to the transient ground determination result.

[0200] According to an example embodiment, after calculating the zero sequence conductance value, the processing module 720 can classify the zero sequence conductance value according to the transient ground determination result.

[0201] The zero sequence conductance value can be classified into a first zero sequence conductance value and a second zero sequence conductance value according to the transient ground determination result.

[0202] According to an example embodiment, in a case where the zero sequence voltage amplitude satisfies a preset zero sequence voltage amplitude condition, the processing module 720 determines a zero sequence conductance determination result according to the classification of the zero sequence conductance value and the zero sequence conductance value.

[0203] According to an example embodiment, the preset zero sequence voltage amplitude condition can be that the calculated zero sequence voltage amplitude is greater than a zero sequence voltage amplitude threshold value. The zero sequence voltage amplitude threshold value can be a critical value of the zero sequence voltage amplitude. The zero sequence voltage amplitude threshold value can also be determined according to the zero sequence voltage value (U e ) of the power distribution line 810 in a case where the power distribution line 810 has a single-phase metallic ground.

[0204] According to an example embodiment, the value range of the zero sequence voltage amplitude threshold value can be 5%U e ≤U set ≤95%U e . Wherein U set is the zero sequence voltage amplitude threshold value.

[0205] For example, the value of the zero sequence voltage amplitude threshold value can be U set = 15%U e .

[0206] For example, in a case where the processing module 720 determines that the zero sequence voltage amplitude is greater than the zero sequence voltage amplitude threshold value, the zero sequence conductance determination result is determined according to the classification of the zero sequence conductance value and the zero sequence conductance value.

[0207] According to an example embodiment, the zero sequence admittance judgment result can be a result of assigning the zero sequence admittance judgment result of the power distribution line 810 according to the classification of the zero sequence admittance value and the zero sequence admittance value. The zero sequence admittance judgment result includes a first zero sequence admittance judgment result, a second zero sequence admittance judgment result, and a third zero sequence admittance judgment result. The first zero sequence admittance judgment result, the second zero sequence admittance judgment result, and the third zero sequence admittance judgment result can be classified according to the calculated zero sequence admittance value, the first zero sequence admittance value, and the second zero sequence admittance value.

[0208] According to an example embodiment, the processing module 720 determines the grounding comprehensive result according to the transient ground judgment result and the zero sequence admittance judgment result.

[0209] According to an example embodiment, the processing module 720 can assign weights to the transient ground judgment result and the zero sequence admittance judgment result according to the size of the zero sequence voltage amplitude. In the case of a larger zero sequence voltage amplitude, the weight of the transient ground judgment result is larger, and the weight of the zero sequence admittance judgment result is smaller; in the case of a smaller zero sequence voltage amplitude, the weight of the transient ground judgment result is smaller, and the weight of the zero sequence admittance judgment result is larger. Then, the processing module 720 determines the grounding comprehensive result according to the transient ground judgment result and the zero sequence admittance judgment result.

[0210] According to an example embodiment, the processing module 720 determines the grounding fault condition of the power distribution line 810 according to the grounding comprehensive result and the preset grounding result condition.

[0211] According to an example embodiment, the preset grounding result condition can be that the value of the grounding comprehensive result is greater than or equal to the grounding comprehensive result threshold value. The grounding comprehensive result threshold value can be a critical value of the grounding comprehensive result.

[0212] The grounding comprehensive result threshold value can be determined according to the zero sequence voltage value (U e ) of the power distribution line 810 in the single-phase metallic grounding condition of the power distribution line 810.

[0213] In the case that the processing module 720 determines that the value of the grounding comprehensive result is greater than or equal to the grounding comprehensive result threshold value, the processing module 720 determines that the grounding fault condition of the power distribution line 810 is that the power distribution line 810 is a grounding fault line.

[0214] Through the above embodiments, the application can determine the zero sequence voltage mutation value and the zero sequence voltage amplitude value through the collected zero sequence voltage. The application can determine the transient ground judgment result and the zero sequence admittance value through the collected zero sequence voltage, the zero sequence circuit and the calculated zero sequence voltage mutation value. The application can determine the zero sequence admittance ground result through the transient ground judgment result and the zero sequence admittance value. The application can determine the grounding fault condition of the power distribution line 810 through the grounding comprehensive result. The application can determine the grounding fault condition of the power distribution line 810 through the transient ground judgment result and the zero sequence admittance judgment result, which can reduce the requirement of hardware sampling. The technical solution of the application does not completely depend on the transient characteristics of the grounding moment, thereby avoiding the problem of transient method because of the short transient duration and transient feature capture. The application avoids the problem that the steady-state characteristics of the fault line and the non-fault line are difficult to distinguish in the conventional steady-state algorithm, thereby improving the sensitivity of determining the high resistance ground fault of the power distribution line 810.

[0215] The application can determine the grounding fault condition of the power distribution line 810 through the transient ground judgment result and the zero sequence admittance judgment result, which can reduce the requirement of hardware sampling. The technical solution of the application does not completely depend on the transient characteristics of the grounding moment, thereby avoiding the problem of transient method because of the short transient duration and transient feature capture. The application avoids the problem that the steady-state characteristics of the fault line and the non-fault line are difficult to distinguish in the conventional steady-state algorithm, thereby improving the sensitivity of determining the high resistance ground fault of the power distribution line 810.

[0216] Optionally, the processing module 720 determines the transient ground judgment result through the transient ground algorithm according to the zero sequence voltage and the zero sequence current in the case that the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition.

[0217] According to an example embodiment, the processing module 720 can also determine the transient ground judgment result through the algorithm based on the Hilbert-Huang Transform (HHT) transient method, the artificial intelligence recognition-based transient method, etc. According to an example embodiment, the processing module 720 can determine the transient ground judgment result as the first transient ground judgment result or the second transient ground judgment result through the grounding transient algorithm.

[0218] For example, in the case that the processing module 720 determines that the power distribution line 810 is a non-fault line, the processing module 720 determines that flg1=a.

[0219] For example, in the case that the processing module 720 determines that the power distribution line 810 is a fault line, the processing module 720 determines that flg1=b.

[0220] Wherein, flg1 is the transient ground judgment result; a is the first transient ground judgment result; b is the second transient ground result.

[0221] The processing module 720 respectively performs n-layer wavelet packet decomposition on the zero sequence current and the zero sequence voltage through the transient zero sequence power algorithm of the wavelet packet transform, to obtain the data of the zero sequence current of 2 n frequency bands and the data of the zero sequence voltage of 2 nwherein n is a natural number greater than 1.

[0222] According to an example embodiment, the processing module 720 can cache data of zero sequence current of at least 2 cycles and data of zero sequence voltage of at least 2 cycles in real time. When the processing module 720 determines that the zero sequence voltage sudden change value is greater than the zero sequence voltage sudden change value threshold, the processing module 720 starts the transient ground algorithm. In order to avoid the error caused by the asynchronization between the starting time of the transient ground algorithm and the fault occurrence time, the processing module 720 caches the data of zero sequence voltage and the data of zero sequence current of each cycle before and after the sudden change of the zero sequence voltage when starting the transient ground algorithm.

[0223] For example, the processing module 720 caches 2 cycles of data of zero sequence current and 2 cycles of data of zero sequence voltage. For a power distribution system with a working frequency of 50 Hz, the processing module 720 caches 2 cycles (i.e. 40 ms) of data of zero sequence current and 2 cycles (i.e. 40 ms) of data of zero sequence voltage.

[0224] The processing module 720 performs n-layer wavelet packet decomposition on the cached data of zero sequence current of each cycle before and after the starting time of the transient ground algorithm based on the transient ground algorithm of wavelet packet transform, to obtain 2n frequency bands of data of zero sequence current. n The processing module 720 performs n-layer wavelet packet decomposition on the cached data of zero sequence voltage of each cycle before and after the starting time of the transient ground algorithm based on the transient ground algorithm of wavelet packet transform, to obtain 2n frequency bands of data of zero sequence voltage. n

[0225] The frequency band range of the transient ground algorithm of wavelet packet transform is large, which can cover more frequency bands of data of zero sequence current and more frequency bands of data of zero sequence voltage.

[0226] Optionally, the processing module 720 can take n as 4. The processing module 720 performs 4-layer wavelet packet decomposition on the zero sequence current and the zero sequence voltage respectively by the transient ground algorithm of wavelet packet transform of the compactly supported orthogonal wavelet basis DB10, to obtain 16 frequency bands of data of zero sequence current and 16 frequency bands of data of zero sequence voltage.

[0227] According to an example embodiment, the processing module 720 performs 4-layer wavelet packet decomposition on the cached data of zero sequence current of each 20 ms before and after the starting time of the transient ground algorithm based on the transient ground algorithm of wavelet packet transform of the compactly supported orthogonal wavelet basis DB10, to obtain 16 frequency bands of data of zero sequence current.

[0228] For example, the 40 ms data of zero sequence current cached by the processing module 720 is N, and the 4-layer wavelet packet decomposition of DB10 wavelet packet transform on the N data of zero sequence current obtains 16 frequency bands of data of zero sequence current I(m)(j). w (m)(j).​

[0229] wherein m is the mth frequency band of the 16 frequency bands, 1≤m≤16, and m is an integer; j is the jth data of the N data, 1≤j≤N, and j is an integer; U w (m) is the basic wavelet of the zero sequence current in the mth frequency band; and w (m)(j) is the jth data of the N data of the zero sequence current in the mth frequency band.

[0230] According to the example embodiment, the processing module 720 performs 4-layer wavelet packet decomposition on the zero sequence voltage data of each of the 20 ms before and after the starting time of the transient earth algorithm cached by the processing module 720 based on the transient earth algorithm of the compactly supported orthogonal wavelet basis DB10 wavelet transform, to obtain the data of the zero sequence voltage in the 16 frequency bands.

[0231] For example, the 40 ms zero sequence voltage data cached by the processing module 720 is also N, and the 4-layer wavelet packet decomposition of the N zero sequence voltage data using the DB10 wavelet packet transform obtains the data of the zero sequence voltage in the 16 frequency bands as U w (m)(j).

[0232] wherein m is the mth frequency band of the 16 frequency bands, 1≤m≤16, and m is an integer; j is the jth data of the N data, 1≤j≤N, and j is an integer; U w (m) is the basic wavelet of the zero sequence voltage in the mth frequency band; and w (m)(j) is the jth data of the N data of the zero sequence voltage in the mth frequency band.

[0233] The processing module 720 compares the data of the zero sequence current in the 2 n frequency bands to obtain the characteristic frequency band of the zero sequence current.

[0234] According to the example embodiment, the characteristic frequency band of the zero sequence current can be one of the 2 n frequency bands with the largest characteristic energy, i.e., the frequency band with the largest average amplitude of the data of the zero sequence current in the 2 n frequency bands.

[0235] The processing module 720 can calculate the average amplitude of the data of the zero sequence current in the mth frequency band according to the following formula:

[0236]

[0237] wherein E w (m) is the average amplitude of the data of the zero sequence current in the mth frequency band.

[0238] For example, the processing module 720 can compare the average amplitude of the data of the zero sequence current in the 16 frequency bands, and determine the frequency band with the largest average amplitude of the data of the zero sequence current as the characteristic frequency band of the zero sequence current.

[0239] Optionally, the processing module 720 determines the zero sequence reactive power in the characteristic frequency band of the zero sequence current according to the characteristic frequency band of the zero sequence current and the frequency band data of the zero sequence voltage corresponding to the characteristic frequency band of the zero sequence current.

[0240] According to an example embodiment, the zero sequence reactive power is the reactive power generated due to three-phase imbalance.

[0241] According to an example embodiment, after determining the characteristic frequency band of the zero sequence current, the processing module 720 can determine the frequency band of the zero sequence voltage corresponding to the characteristic frequency band of the zero sequence current according to the characteristic frequency band of the zero sequence current.

[0242] For example, after comparing the average amplitude of the data of the zero sequence current in the 16 frequency bands, the processing module 720 determines that the characteristic frequency band of the zero sequence current is the i-th frequency band (1≤i≤16, and i is an integer), and the frequency band of the zero sequence voltage corresponding to the characteristic frequency band of the zero sequence current is the i-th frequency band.

[0243] According to an example embodiment, in the characteristic frequency band of the zero sequence current, the processing module 720 multiplies the basic wavelet of the zero sequence current data and the basic wavelet of the zero sequence voltage data to calculate the zero sequence reactive power of the basic wavelet in the characteristic frequency band.

[0244] For example, the processing module 720 multiplies the basic wavelet of the zero sequence current data in the i-th frequency band and the basic wavelet of the zero sequence voltage data in the i-th frequency band to calculate the zero sequence reactive power of the basic wavelet in the i-th frequency band.

[0245] Optionally, the processing module 720 determines the transient ground fault judgment result as the first transient ground fault result or the second transient ground fault result according to the preset zero sequence reactive power condition and the zero sequence reactive power.

[0246] According to an example embodiment, the preset zero sequence reactive power condition is a zero sequence reactive power threshold. The zero sequence reactive power threshold can be a critical value of the zero sequence reactive power preset according to the maximum negative reactive power of the power distribution line 810 in the power distribution system under normal operation.

[0247] According to an example embodiment, the value range of the zero sequence reactive power threshold is Q set <0, and Q set <Q max . Wherein, Q set is the zero sequence reactive power threshold; Q maxThe maximum negative reactive power of the power distribution line 810 in the power distribution system under normal operation is the maximum negative reactive power that can occur due to three-phase imbalance under normal operation of the power distribution line 810.

[0248] The preset zero sequence reactive power condition includes a first preset zero sequence reactive power condition and a second preset zero sequence reactive power condition.

[0249] The first preset zero sequence reactive power condition can be that the calculated zero sequence reactive power is less than a zero sequence reactive power threshold.

[0250] The second preset zero sequence reactive power condition can be that the calculated zero sequence reactive power is greater than or equal to the zero sequence reactive power threshold.

[0251] If the zero sequence reactive power meets the first preset zero sequence reactive power condition, the processing module 720 determines that the power distribution line 810 is a non-fault line, and the processing module 720 determines that flg1=a.

[0252] If the zero sequence reactive power meets the second preset zero sequence reactive power condition, the processing module 720 determines that the power distribution line 810 is a fault line, and the processing module 720 determines that flg1=b.

[0253] For example, a can be 0 and b can be 1.

[0254] For example, the processing module 720 can determine the transient ground judgment result according to the following formula:

[0255]

[0256] For example, if the maximum negative reactive power of the power distribution line 810 in the power distribution system under normal operation is Q max =-100 VA, the processing module 720 presets Q set =-120 VA.

[0257] Optionally, the processing module 720 determines the zero sequence admittance value according to the zero sequence voltage and the zero sequence current after a preset delay time.

[0258] According to an example embodiment, the preset delay time can be a preset waiting time for the zero sequence admittance value to stabilize. Since the zero sequence admittance value is a steady-state value, and the determination of the transient ground judgment structure is a transient process. The processing module 720 can avoid the transient process by a preset delay time to take a cross-sectional zero sequence admittance value, which is a relatively stable value.

[0259] For example, the preset delay time can be 5 cycles, that is, the preset delay time is 100ms. If the preset delay time is too short, the transient process may not end. If the preset delay time is too long, the fault conversion of the distribution line 810 may become more complicated, thereby affecting the processing module 720's determination of the zero-sequence admittance value.

[0260] For example, the processing module 720 can calculate the zero-sequence admittance value by the following formula:

[0261]

[0262] Among them, I0 is the collected zero-sequence current; U0 is the collected zero-sequence voltage; Y0 is the zero-sequence admittance value.

[0263] Optionally, when the transient ground fault determination result is a first transient ground fault result, processing module 720 determines the zero-sequence admittance value as a first zero-sequence admittance value. That is, the transient ground fault algorithm determines that distribution line 810 is a non-fault line, and the ground fault determination system stores the first zero-sequence admittance value in the first group of storage modules.

[0264] Optionally, when the transient ground fault determination result is a second transient ground fault result, processing module 720 determines the zero-sequence admittance value as a second zero-sequence admittance value. That is, the transient ground fault algorithm determines that distribution line 810 is a fault line, and processing module 720 stores the second zero-sequence admittance value in the second group of storage modules.

[0265] The first group of storage modules and the second group of storage modules may be one database or different databases.

[0266] The first group of storage modules may include multiple first zero-sequence admittance values. The multiple first zero-sequence admittance values ​​may be calculated using the collected zero-sequence current and zero-sequence voltage, or may be zero-sequence admittance values ​​determined using methods such as an applied capacitance method or an applied voltage method for the distribution line 810, or may be zero-sequence admittance values ​​derived from empirical values ​​or theoretical calculations. The zero-sequence admittance value derived from the empirical value or theoretical calculation is set as the preset first zero-sequence admittance value.

[0267] The second group of storage modules may include a plurality of second zero-sequence admittance values, which may be calculated from the collected zero-sequence current and zero-sequence voltage.

[0268] Optionally, when the zero-sequence voltage amplitude satisfies a preset zero-sequence voltage amplitude condition, the processing module 720 determines a zero-sequence admittance value difference according to the zero-sequence admittance value and the first zero-sequence admittance value.

[0269] For example, when the processing module 720 determines that the zero sequence voltage amplitude is greater than the zero sequence voltage amplitude threshold value, the zero sequence admittance value difference can be calculated according to the following formula:

[0270] ΔY = |Y0-Y1 mid |;

[0271] or ΔY = |Y0-Y1 set |;

[0272] wherein, ΔY is the zero sequence admittance value difference, i.e., the absolute value of the difference between the zero sequence admittance value and the first zero sequence admittance value; Y0 is the zero sequence admittance value; Y1 mid is the median of the plurality of first zero sequence admittance values in the first group of storage modules; Y1 set is the preset first zero sequence admittance value.

[0273] Optionally, the processing module 720 determines the zero sequence admittance judgment result to be the first zero sequence admittance result, the second zero sequence admittance result, or the third zero sequence admittance result according to the preset zero sequence admittance value difference condition and the zero sequence admittance value difference.

[0274] According to an example embodiment, the preset zero sequence admittance value difference condition can be a zero sequence admittance value difference threshold value. The zero sequence admittance value difference threshold value is a critical value of the zero sequence admittance value difference.

[0275] The zero sequence admittance value difference threshold value can be determined as a first zero sequence admittance value difference threshold value and a second zero sequence admittance value difference threshold value according to the first zero sequence admittance value and the second admittance value.

[0276] For example, the processing module 720 can calculate the absolute value of the difference between the first zero sequence admittance value and the second zero sequence admittance value according to the following formula:

[0277] ΔY mid = |Y2 mid -Y1 mid |;

[0278] wherein, ΔY mid is the absolute value of the difference between the first zero sequence admittance value and the second zero sequence admittance value; Y1 mid is the median of the plurality of first zero sequence admittance values in the first group of storage modules; Y2 mid is the median of the plurality of second zero sequence admittance values in the second group of storage modules.

[0279] For example, the first zero sequence admittance value difference threshold value can have a value range of 50% ΔY mid ≤ ΔY1 set ≤ 95% ΔY mid . Wherein, ΔY1 set is the first zero sequence admittance value difference threshold value.

[0280] Exemplarily, the second zero sequence admittance value difference threshold value can be in the range of 105% ΔY mid ≤ ΔY2 set ≤ 200% ΔY mid , wherein ΔY2 set is the second zero sequence admittance value difference threshold value.

[0281] Preferably, ΔY1 set = 80% ΔY mid ; and ΔY2 set = 120% ΔY mid .

[0282] According to an example embodiment, the processing module 720 can divide the preset zero sequence admittance value difference condition into a first preset zero sequence admittance value difference condition, a second preset zero sequence admittance value difference condition and a third preset zero sequence admittance value difference condition according to the first zero sequence admittance value difference threshold value and the second zero sequence admittance value difference threshold value.

[0283] For example, the first preset zero sequence admittance value condition can be that the zero sequence admittance value difference is less than the first zero sequence admittance value difference threshold value.

[0284] The first preset zero sequence admittance value condition can be that the zero sequence admittance value difference is less than the second zero sequence admittance value difference threshold value, and the zero sequence admittance value difference is greater than or equal to the first zero sequence admittance value difference threshold value.

[0285] The third preset zero sequence admittance value condition can be that the zero sequence admittance value difference is greater than or equal to the first zero sequence admittance value difference threshold value.

[0286] In the case that the zero sequence admittance value difference satisfies the first preset zero sequence admittance value difference condition, the processing module 720 determines that the zero sequence admittance judgment result is a first zero sequence admittance judgment result.

[0287] In the case that the zero sequence admittance value difference satisfies the second preset zero sequence admittance value difference condition, the processing module 720 determines that the zero sequence admittance judgment result is a second zero sequence admittance judgment result.

[0288] In the case that the zero sequence admittance value difference satisfies the third preset zero sequence admittance value difference condition, the processing module 720 determines that the zero sequence admittance judgment result is a third zero sequence admittance judgment result.

[0289] , wherein the first zero sequence admittance result is less than the second zero sequence admittance result, and the second zero sequence admittance result is less than the third zero sequence admittance result.

[0290]

[0291] , wherein Flg2 is the zero sequence admittance judgment result; c is the first zero sequence admittance result; d is the second zero sequence admittance result; e is the third zero sequence admittance result; and c < d < e.

[0292] For example, c can be 0, d can be 1, and e can be 2.

[0293] For example, the processing module 720 can determine the zero sequence admittance judgment result according to the following formula:

[0294]

[0295] Optionally, the processing module 720 determines the grounding comprehensive result according to the preset zero sequence voltage parameter, the transient ground judgment result, a preset coefficient corresponding to the transient ground judgment result, the zero sequence admittance judgment result, a preset coefficient corresponding to the zero sequence admittance judgment result, and the transient ground judgment result.

[0296] According to an example embodiment, the preset zero sequence voltage parameter can be a zero sequence voltage value (U e ) of the power distribution line 810 in a single-phase metallic grounding case of the power distribution line 810.

[0297] The preset coefficient corresponding to the transient ground judgment result can be a weight coefficient determined according to the zero sequence voltage amplitude and according to the sensitivity of the transient ground algorithm.

[0298] The preset coefficient corresponding to the zero sequence admittance judgment result can be a weight coefficient determined according to the zero sequence voltage amplitude and according to the sensitivity of the transient ground algorithm.

[0299] For example, the processing module 720 can determine the grounding comprehensive result according to the following formula:

[0300] Flg = k × U0 × Flg1 + (1-k) × (U e -U0) × Flg2;

[0301] Wherein, Flg is the grounding comprehensive result; k is the preset coefficient corresponding to the zero sequence admittance judgment result, 0 < k < 1; Flg1 is the transient ground judgment result; U e is the zero sequence voltage value of the power distribution line 810 in a single-phase metallic grounding case of the power distribution line 810; U0 is the collected zero sequence voltage of the power distribution line 810; and Flg2 is the zero sequence admittance judgment result.

[0302] For example, for a 10kV ungrounded power distribution line 810, the processing module 720 presets: U e =5774V, k=0.6, then the processing module 720 can determine the grounding comprehensive result according to the following formula:

[0303] Flg = 0.6 × U0 × Flg1 + 0.4 × (5774-U0) × Flg2.

[0304] Optionally, the processing module 720 determines, according to the preset grounding result condition and the grounding comprehensive result, that the grounding fault condition of the power distribution line 810 is that the power distribution line 810 is a non-grounding fault line or a grounding fault line.

[0305] The preset grounding result condition can include a first preset grounding result condition and a second preset grounding result condition.

[0306] For example, the first preset grounding result condition can be that the comprehensive grounding result is less than a grounding comprehensive result threshold. The second preset grounding result condition can be that the comprehensive grounding result is greater than or equal to the grounding comprehensive result threshold.

[0307] When the grounding comprehensive result is determined to satisfy the first preset grounding result condition, the processing module 720 determines that the grounding fault condition of the power distribution line 810 is that the power distribution line 810 is a non-grounding fault line.

[0308] When the grounding comprehensive result is determined to satisfy the second preset grounding result condition, the processing module 720 determines that the grounding fault condition of the power distribution line 810 is that the power distribution line 810 is a grounding fault line.

[0309] According to an example embodiment, the grounding comprehensive result threshold can be set to a fixed value or dynamically adjusted according to the grounding condition of the power distribution line 810. In the case where the grounding comprehensive result threshold is set to a fixed value, the value range of the grounding comprehensive result threshold can be 5%U e ≤ flg set ≤ 95%U e , wherein flg set is the grounding comprehensive result threshold.

[0310] For example, the value of the grounding comprehensive result threshold can be flg set = 20%U e .

[0311] It can be understood that for some grounding faults, such as broken wire of overhead line or discharge of cable insulation deterioration, the initial grounding resistance can be as high as tens of thousands of ohms, and the change process of the zero sequence voltage is slow, and it is difficult to identify the occurrence of the fault only by the transient state discrimination method due to the small transient component. The application can effectively identify the grounding fault with small transient component by determining the zero sequence admittance grounding result based on the transient grounding judgment result and the weight dynamic change, and improve the sensitivity of judging the high resistance grounding fault of the power distribution line.

[0312] According to another aspect of the application, the application also provides a non-volatile computer readable storage medium having a computer program stored thereon, which can implement the grounding fault discrimination method of the power distribution line grounding system as described above when executed by a processor.

[0313] According to another aspect of the present application, the present application also provides an electronic device, comprising: one or more processors; a storage device configured to store one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the grounding fault discrimination method of the grounding system of the power distribution line as described above.

[0314] According to another aspect of the present application, the present application also provides a computer program product, comprising: a computer program stored on a computer readable storage medium; the computer program comprises program instructions, when the program instructions are executed by a computer, the computer executes the grounding fault discrimination method of the grounding system of the power distribution line as described above.

[0315] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. 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 of ground fault discrimination for a power distribution line grounding system, comprising: The ground fault discrimination method comprises: According to the collected zero sequence voltage of the distribution line, determine the zero sequence voltage mutation value and the zero sequence voltage amplitude value; In the case where the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition, determine the transient ground judgment result and the zero sequence admittance value according to the collected zero sequence current and the zero sequence voltage of the distribution line; According to the transient ground judgment result, determine the classification of the zero sequence admittance value; In the case where the zero sequence voltage amplitude value meets the preset zero sequence voltage amplitude value condition, determine the zero sequence admittance judgment result according to the classification of the zero sequence admittance value and the zero sequence admittance value; According to the transient ground judgment result and the zero sequence admittance judgment result, determine the ground comprehensive result; According to the ground comprehensive result and the preset ground result condition, determine the ground fault condition of the distribution line.

2. The ground fault discrimination method of claim 1, wherein, The determination of the transient ground judgment result and the zero sequence admittance value according to the collected zero sequence current and the zero sequence voltage of the distribution line comprises: In the case where the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition, determine the transient ground judgment result according to the zero sequence voltage and the zero sequence current through the transient ground algorithm; After a preset delay time, determine the zero sequence admittance value according to the zero sequence voltage and the zero sequence current.

3. The ground fault discrimination method of claim 2, wherein, The determination of the transient ground judgment result according to the zero sequence voltage and the zero sequence current in the case where the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition comprises: The zero-sequence current and the zero-sequence voltage are decomposed by n-layer wavelet packets using the transient zero-sequence power algorithm of wavelet packet transform to obtain 2 n The zero sequence current data of the frequency band and 2 n The zero-sequence voltage data of frequency bands, wherein n is a natural number greater than 1; comparing the data of the zero sequence current of the two n frequency bands to obtain a characteristic frequency band of the zero sequence current; According to the characteristic frequency band of the zero sequence current and the frequency band data of the zero sequence voltage corresponding to the characteristic frequency band of the zero sequence current, determine the zero sequence reactive power in the characteristic frequency band of the zero sequence current; According to the preset zero sequence reactive power condition and the zero sequence reactive power, determine that the transient ground judgment result is the first transient ground result or the second transient ground result.

4. The ground fault discrimination method of claim 3, wherein, The transient zero-sequence power algorithm using wavelet packet transform performs n-layer wavelet packet decomposition on the zero-sequence current and the zero-sequence voltage to obtain 2 n The zero sequence current data of the frequency band and 2 n The zero-sequence voltage data of each frequency band includes: The transient zero sequence power algorithm through the compactly supported orthogonal wavelet basis DB10 wavelet transform is used to perform 4-layer wavelet packet decomposition on the zero sequence current and the zero sequence voltage respectively, so as to obtain the data of the zero sequence current in 16 frequency bands and the data of the zero sequence voltage in 16 frequency bands.

5. The ground fault discrimination method according to claim 3 or 4, characterized in that, The determination of the classification of the zero sequence admittance value according to the transient ground judgment result comprises: In the case where the transient ground judgment result is the first transient ground result, determine the zero sequence admittance value as the first zero sequence admittance value; In the case where the transient ground judgment result is the second transient ground result, determine the zero sequence admittance value as the second zero sequence admittance value.

6. The ground fault discrimination method of claim 5, wherein, The determination of the zero sequence admittance judgment result according to the classification of the zero sequence admittance value and the zero sequence admittance value in the case where the zero sequence voltage amplitude value meets the preset zero sequence voltage amplitude value condition comprises: In the case where the zero sequence voltage amplitude value meets the preset zero sequence voltage amplitude value condition, determine the zero sequence admittance value difference according to the first zero sequence admittance value and the zero sequence admittance value; According to the preset zero sequence admittance value difference condition and the zero sequence admittance difference, determine that the zero sequence admittance judgment result is the first zero sequence admittance result, the second zero sequence admittance result or the third zero sequence admittance result.

7. The ground fault discrimination method of claim 6, wherein, The determining the grounding comprehensive result according to the transient grounding judgment result and the zero sequence admittance judgment result comprises: The determining the grounding comprehensive result according to the transient grounding judgment result and the zero sequence admittance judgment result comprises:

8. The ground fault discrimination method of claim 7, wherein, The determining the grounding fault condition of the power distribution line according to the grounding comprehensive result comprises: The determining the grounding fault condition of the power distribution line according to the grounding comprehensive result and the preset grounding result condition comprises that the grounding fault condition of the power distribution line is determined as that the power distribution line is a non-grounding fault line or a grounding fault line.

9. A ground fault discrimination system for a power distribution line grounding system, comprising: The grounding fault discrimination system comprises: The acquisition module acquires the zero sequence voltage and the zero sequence current of the power distribution line; The processing module determines the zero sequence voltage mutation value and the zero sequence voltage amplitude according to the zero sequence voltage; The processing module determines the zero sequence admittance value according to the zero sequence voltage and the zero sequence current transient grounding judgment result in the case that the zero sequence voltage mutation value meets the preset zero sequence voltage mutation value condition; The processing module determines the classification condition of the zero sequence admittance value according to the transient grounding judgment result; The processing module determines the zero sequence admittance judgment result according to the classification condition of the zero sequence admittance value and the zero sequence admittance value in the case that the zero sequence voltage amplitude meets the preset zero sequence voltage amplitude condition; The processing module determines the grounding comprehensive result according to the transient grounding judgment result and the zero sequence admittance judgment result; The processing module determines the grounding fault condition of the power distribution line according to the grounding comprehensive result and the preset grounding result condition.

10. A non-transitory computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the grounding fault discrimination method of the grounding system of the power distribution line according to any one of claims 1-8.

11. An electronic device, comprising: Comprise: One or more processors; Storage devices for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors realize the grounding fault discrimination method of the grounding system of the power distribution line according to any one of claims 1-8.

12. A computer program product, characterised in that, The computer program comprises program instructions stored on a computer readable storage medium, when the program instructions are executed by a computer, the computer executes the grounding fault discrimination method of the grounding system of the power distribution line according to any one of claims 1-8.

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