CN115308533A - High-resistance grounding fault line distinguishing method and related device - Google Patents
High-resistance grounding fault line distinguishing method and related device Download PDFInfo
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The application discloses a high-resistance grounding fault line distinguishing method and a related device, wherein the method comprises the following steps: acquiring zero-sequence voltage at a bus, and acquiring zero-sequence current of each line when the zero-sequence voltage is smaller than a preset threshold value; extracting characteristic frequency band signals of zero sequence current of each line through S transformation; establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix; and calculating the directional energy ratio of each line based on the directional energy matrix, and judging whether the line is a fault line according to the directional energy ratio. Compared with the prior art, the high-resistance grounding fault line distinguishing method enlarges the traditional S transformation energy criterion, overcomes the defect of insufficient applicability of a single line selection method, can be suitable for distinguishing the single-phase grounding fault of the resonance grounding system under different fault conditions, particularly has a good effect on the high-resistance grounding fault distinguishing aspect, and has strong applicability.
Description
Technical Field
The application relates to the technical field of high-resistance ground fault line selection detection of a power distribution network, in particular to a high-resistance ground fault line distinguishing method and a related device.
Background
When single-phase earth fault occurs in resonance grounding, due to the compensation effect of the arc suppression coil, the fault current in the system is very weak, so that many scholars refer to a signal characteristic extraction method to solve the problem.
For example, based on an energy ratio method of S conversion or wavelet packets, the method mainly judges a fault line by calculating the energy ratio of characteristic frequency band signals of each line, wherein a line with high energy is a fault line, but the method only utilizes an energy criterion of the characteristic frequency band signals, has a single criterion, and has the condition of low criterion margin when judging the high-resistance grounding fault. The correlation coefficient rule based on wavelet packet transformation is to use the waveform difference of characteristic frequency band signals of each line to carry out fault line selection, and then to judge a fault line by using the principle of signal polarity.
The judgment rule based on information fusion is to utilize multi-source information to judge faults, but the method needs to provide a large amount of historical data as support, and the multi-source signals have characteristic overlapping, so that the judgment margin is improved, and the fault boundary is defined.
Disclosure of Invention
The application provides a high-resistance grounding fault line distinguishing method and a related device, which are used for solving the technical problems of single criterion and low criterion margin in the prior art.
In view of the above, a first aspect of the present application provides a method for determining a high resistance ground fault line, where the method includes:
acquiring zero sequence voltage at a bus, and acquiring zero sequence current of each line when the zero sequence voltage is smaller than a preset threshold value;
extracting characteristic frequency band signals of zero sequence current of each line through S transformation;
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix;
and calculating the direction energy ratio of each line based on the direction energy matrix, and judging whether the line is a fault line according to the direction energy ratio.
Optionally, the establishing a directional energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the directional energy formula to obtain a directional energy matrix specifically includes:
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix A;
wherein the directional energy formula is:
in the formula, theta (i, j) xy Sampling point S for characteristic frequency band signal of line x zero sequence current x Sampling point S of characteristic frequency band signal of (i, j) and line y zero sequence current y Phase angle difference of (i, j), a xy For x-comparison of the linesThe energy in the direction of the line y, i.e. the sum of squares, real (S) of the product of the amplitude of each sampling point of the line x minus the amplitude of the corresponding sampling point of the line y and the cosine of the phase angle difference between the two signals x (i,j))、angle(S x (i, j)) respectively representing the amplitude and phase angle of S (i, j) sampling points in the complex matrix;
the directional energy matrix A is:
wherein q is the number of system outgoing lines, and the x-th line can be represented as the directional energy vector A of the line x x Where the major diagonal elements are all 0.
Optionally, the calculating a directional energy proportion of each line based on the directional energy matrix, and determining whether the line is a faulty line according to the directional energy proportion includes:
constructing a criterion formula based on the direction energy matrix, calculating the direction energy ratio of the line according to the criterion formula, and judging the line as a fault line when the direction energy ratio is greater than a preset threshold value;
wherein the criterion formula is as follows:
in the formula, ω x Is the ratio of the directional energy of the line x.
Optionally, the extracting, by using S transform, the characteristic frequency band signal of the zero sequence current of each line specifically includes:
transforming the zero-sequence current through S transformation to obtain a discrete form formula of the zero-sequence current, transforming the discrete form formula to obtain a complex matrix, and extracting a characteristic frequency band signal of the zero-sequence current based on the complex matrix;
wherein the discrete form formula is:
in the formula, N is the number of sampling points, T is the sampling interval, l is a time parameter, and N is a frequency parameter;
the complex matrix is:
wherein S (i, j) is the jth sampling point at the ith frequency.
A second aspect of the present application provides a high resistance ground fault line discrimination system, the system including:
the acquisition unit is used for acquiring zero sequence voltage at a bus, and acquiring zero sequence current of each line when the zero sequence voltage is smaller than a preset threshold value;
the extraction unit is used for extracting characteristic frequency band signals of the zero sequence current of each line through S transformation;
the calculation unit is used for establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix;
and the judging unit is used for calculating the directional energy proportion of each line based on the directional energy matrix and judging whether the line is a fault line according to the directional energy proportion.
Optionally, the computing unit is specifically configured to:
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix A;
wherein the directional energy formula is:
in the formula, theta (i, j) xy Sampling point S of characteristic frequency band signal for line x zero sequence current x (i, j) and line ySampling point S of characteristic frequency band signal of zero sequence current y Phase angle difference of (i, j), a xy The energy of line x in the direction of line y is calculated by subtracting the sum of squares, real (S) of the product of the amplitude of sampling point of line y and the cosine of the phase angle difference between two signals from the amplitude of each sampling point of line x x (i,j))、angle(S x (i, j)) respectively representing the amplitude and phase angle of S (i, j) sampling points in the complex matrix;
the directional energy matrix a is:
wherein q is the number of system outgoing lines, and the x-th line can be represented as the energy vector A of the line x in the direction x Where the major diagonal elements are all 0.
Optionally, the determining unit is specifically configured to:
constructing a criterion formula based on the direction energy matrix, calculating the direction energy ratio of the line according to the criterion formula, and judging the line as a fault line when the direction energy ratio is greater than a preset threshold value;
wherein the criterion formula is as follows:
in the formula, omega x Is the ratio of the directional energy of the line x.
Optionally, the extracting unit is specifically configured to:
transforming the zero-sequence current through S transformation to obtain a discrete form formula of the zero-sequence current, transforming the discrete form formula to obtain a complex matrix, and extracting a characteristic frequency band signal of the zero-sequence current based on the complex matrix;
wherein the discrete form formula is:
in the formula, N is the number of sampling points, T is the sampling interval, l is a time parameter, and N is a frequency parameter;
the complex matrix is:
where S (i, j) is the jth sample point at the ith frequency.
A third aspect of the present application provides a high resistance ground fault line discrimination apparatus, including a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the steps of the method for determining a high impedance ground fault line according to the first aspect.
A fourth aspect of the present application provides a computer-readable storage medium for storing a program code for executing the method for determining a high impedance ground fault line according to the first aspect.
According to the technical scheme, the method has the following advantages:
the application provides a high-resistance grounding fault line distinguishing method, which comprises the following steps: acquiring zero sequence voltage at a bus, and acquiring zero sequence current of each line when the zero sequence voltage is smaller than a preset threshold value; extracting characteristic frequency band signals of zero sequence current of each line through S transformation; establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix; and calculating the directional energy ratio of each line based on the directional energy matrix, and judging whether the line is a fault line according to the directional energy ratio. Compared with the prior art, the high-resistance grounding fault line distinguishing method enlarges the traditional S transformation energy criterion, overcomes the defect of insufficient applicability of a single line selection method, can be suitable for distinguishing the single-phase grounding fault of the resonance grounding system under different fault conditions, particularly has a good effect on the high-resistance grounding fault distinguishing aspect, and has strong applicability.
Drawings
Fig. 1 is a schematic flowchart of an embodiment of a method for determining a high resistance ground fault line provided in an embodiment of the present application;
fig. 2 is a schematic structural diagram of an embodiment of a high resistance ground fault line identification system provided in an embodiment of the present application;
FIG. 3 is a diagram of a simulation model provided in an embodiment of the present application;
fig. 4 is a distribution diagram of each line band provided in the embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, a method for determining a high resistance ground fault line provided in an embodiment of the present application includes:
it should be noted that, first, the zero sequence voltage U at the bus is obtained 0 Zero sequence voltage U if single-phase earth fault occurs 0 And extracting zero sequence current of each line when the rated system voltage Um is less than 0.15 time.
102, extracting characteristic frequency band signals of zero sequence current of each line through S transformation;
it should be noted that S transform is a powerful signal feature extraction method, which can extract not only amplitude information but also phase angle information of a signal.
If the original continuous signal x (t) is present, its discrete form can be obtained by S transformation as follows:
in the formula, N is the number of sampling points, T is the sampling interval, l is the time parameter, and N is the frequency parameter.
Further processing of the above equation yields a complex matrix as follows:
in the complex matrix, S (i, j) is the jth sampling point at the ith frequency, and if the whole complex matrix is subjected to triangular matrix transformation, amplitude sequence information and phase angle sequence information of each frequency can be resolved.
The frequency band with the maximum energy in all the frequency signals is a characteristic frequency band, and therefore the characteristic frequency band of the zero-sequence current of each line, and corresponding amplitude sequence information and phase angle sequence information can be extracted.
103, establishing a directional energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the directional energy formula to obtain a directional energy matrix;
it should be noted that, when a single-phase earth fault occurs in the system, the transient zero-sequence current directions of the fault line and the healthy line are opposite, the amplitude of the fault line is much larger than that of the healthy line, the transient zero-sequence current characteristics of each healthy line are approximately the same, and the characteristic frequency band signal extracted after S conversion has corresponding properties.
Assuming the ith frequency as the characteristic frequency band, the amplitude sequence of the zero sequence current characteristic frequency band signal of the line can be expressed as { real (S) x (i,1)),real(S x (i,2)),…,real(S x (i, N)) }, the sequence of phase angles of the line zero-sequence current characteristic frequency band signal can be represented as { angle (S) } x (i,1)),angle(S x (i,2)),…,angle(S x (i, N)) }, where real (S) x (i,j))、angle(S x (i, j)) respectively represent a complex matrixAmplitude and phase angle of the middle S (i, j) sampling point.
Because the amplitude of the zero-sequence current characteristic frequency band of the fault line is far larger than that of the healthy current, and the directions of the zero-sequence current characteristic frequency band and the healthy current are approximately opposite, and the direction of the signals of the zero-sequence current characteristic frequency band of the healthy line is the same, the amplitude difference is not large, in order to fuse the direction and the amplitude characteristic and improve the fault boundary, the concept of directional energy is provided, and the specific formula is as follows:
θ(i,j) xy ＝angle(S x (i,j))-angle(S y (i,j))
in the formula, theta (i, j) xy For line x zero sequence current characteristic frequency band sampling point S x (i, j) and line y zero sequence current characteristic frequency band sampling point S y Phase angle difference of (i, j), a xy The energy of the line x in the direction of comparing the line y is obtained, namely the sum of squares of the amplitude of each sampling point of the line x minus the product of the amplitude of the corresponding sampling point of the line y and the cosine of the phase angle difference of the two signals.
The directional energy matrix a can then be obtained as follows:
wherein q is the number of system outgoing lines, and the x-th line can be represented as the energy vector A of the line x in the direction x Where the major diagonal elements are all 0.
And 104, calculating the directional energy ratio of each line based on the directional energy matrix, and judging whether the line is a fault line according to the directional energy ratio.
It should be noted that, because the cosine of the phase angle difference between the faulty line and the healthy line is close to-1, and the cosine of the phase angle difference between the healthy lines is close to 1, it can be known that the minimum value except 0 element in the directional energy vector of the faulty line is improved to a certain extent compared with the traditional energy, and the healthy line is reduced compared with the traditional energy, and the former is much larger than the latter, so that the faulty line can be determined by using the magnitude of the directional energy ratio, and the criterion formula is as follows:
in the formula of omega x Is the ratio of the directional energy of the line x.
According to the above formula, it can be known that the direction energy ratio of the fault line is close to 1, and the healthy line is close to 0, if a threshold value ω is set set When the system has single-phase earth fault, then omega set <ω x The line x can be judged to be a fault line, otherwise, the line x is a sound line, and therefore, a fault boundary can be well defined.
The following is a brief description of the embodiment of the present application taking a 10kV distribution network resonance grounding system model as an example:
the arc suppression coil comprises 5 outgoing lines, the types, the lengths and the line parameters of the outgoing lines are respectively shown in tables 1 and 2, wherein the arc suppression coil adopts an overcompensation mode, the compensation degree is 8%, the sampling frequency is 10kHz, and a specific simulation model diagram is shown in FIG. 2.
TABLE 1 System model line parameters
| Type of feed line | R 1 /Ω | L 1 /mH | C 1 /uF | R 0 /Ω | L 0 /mH | C 0 /uF |
| Overhead line | 0.175 | 1.210 | 0.01 | 0.23 | 5.478 | 0.008 |
| Cable with a protective layer | 0.270 | 0.354 | 0.339 | 2.70 | 1.019 | 0.280 |
TABLE 2 detailed line length and load conditions
| Line length | L 1 | L 2 | L 3 | L 4 | L 5 |
| Overhead line (Km) | 12 | 5 | 0 | 0 | 20 |
| Cable (Km) | 0 | 5 | 10 | 15 | 0 |
The existing simulation line 1 has single-phase earth fault with earth resistance of 2000 omega and fault closing angle of 90 degrees at 50%. The zero sequence current of each line is subjected to S transformation to obtain an amplitude sequence and a phase angle sequence of each frequency, wherein the energy distribution of each frequency band of the lines 1 to 4 is shown in fig. 4. The energy distribution map shows that the energy of the second frequency band is maximum, so the second frequency band is used as a characteristic frequency band.
Now, the direction energy matrix can be calculated according to the formula by using the amplitude sequence and the phase angle sequence of each line characteristic frequency band as follows:
according to the direction energy matrix, the main diagonal element is 0, and the minimum value except 0 element in the fault line direction energy vector is far larger than the minimum value except 0 element in the healthy line direction energy vector. And then calculating the directional energy ratio of each line as [0.858,0.030,0.040,0.042 and 0.030], wherein the directional energy ratio of each line can indicate that the directional energy ratio of the line 1, namely the fault line, is close to 1, and all the other lines, namely the healthy lines, are close to 0, so that a protection criterion is formed, and the criterion provided by the text can clearly define a fault boundary relatively, and can well distinguish the fault line from the healthy lines.
In order to further verify the applicability of the protection criterion proposed herein, especially the effect of high-impedance grounding, single-phase high-impedance grounding faults under different fault conditions are analyzed, and the specific fault conditions and the energy accounts for each corresponding line direction are shown in table 3.
TABLE 3 energy ratio results for each line direction under different fault conditions
As can be seen from the results of the energy ratios of the directions of the lines in table 3, no matter under which fault condition the single-phase ground fault occurs, the energy ratio of the direction corresponding to the fault line is close to 1, and the energy ratio of the direction of the healthy line is close to 0, that is, the energy ratio of the direction of the fault line is much greater than that of the direction of the healthy line, so that the fault line can be better distinguished without being affected by various fault conditions, and the method has a better application prospect.
The above is a method for determining a high-resistance ground fault line provided in the embodiment of the present application, and the following is a system for determining a high-resistance ground fault line provided in the embodiment of the present application.
Referring to fig. 2, a high resistance ground fault line identification system provided in an embodiment of the present application includes:
the obtaining unit 201 is configured to obtain a zero-sequence voltage at a bus, and when the zero-sequence voltage is smaller than a preset threshold, obtain a zero-sequence current of each line;
an extracting unit 202, configured to extract a characteristic frequency band signal of the zero sequence current of each line through S transformation;
the calculation unit 203 is configured to establish a directional energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transform the directional energy formula to obtain a directional energy matrix;
and a judging unit 204, configured to calculate a directional energy ratio of each line based on the directional energy matrix, and determine whether the line is a faulty line according to the directional energy ratio.
Further, an embodiment of the present application further provides a high resistance ground fault line distinguishing device, where the device includes a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is used for executing the high-resistance earth fault line judgment method according to the method embodiment according to the instructions in the program codes
Further, an embodiment of the present application also provides a computer-readable storage medium, where the computer-readable storage medium is used to store program codes, and the program codes are used to execute the method for determining a high-resistance ground fault line according to the above-mentioned method embodiment.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The terms "first," "second," "third," "fourth," and the like in the description of the application and the above-described figures, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the application described herein may be implemented, for example, in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b and c may be single or plural.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present application.
Claims (10)
1. A high-resistance ground fault line discrimination method is characterized by comprising the following steps:
acquiring zero sequence voltage at a bus, and acquiring zero sequence current of each line when the zero sequence voltage is smaller than a preset threshold value;
extracting characteristic frequency band signals of zero sequence current of each line through S transformation;
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix;
and calculating the directional energy ratio of each line based on the directional energy matrix, and judging whether the line is a fault line according to the directional energy ratio.
2. The method according to claim 1, wherein the establishing a directional energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the directional energy formula to obtain a directional energy matrix specifically comprises:
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix A;
wherein the directional energy formula is:
in the formula, theta (i, j) xy Sampling point S for characteristic frequency band signal of line x zero sequence current x Sampling point S of characteristic frequency band signal of zero sequence current of (i, j) and line y y Phase angle difference of (i, j), a xy Comparing the direction energy of the line x with the direction energy of the line y, namely subtracting the square sum, real (S) of the product of the amplitude of the sampling point of the corresponding line y and the cosine of the phase angle difference of the two signals from the amplitude of each sampling point of the line x x (i,j))、angle(S x (i, j)) respectively representing the amplitude and phase angle of S (i, j) sampling points in the complex matrix;
the directional energy matrix A is:
wherein q is the number of system outgoing lines, and the x-th line can be represented as the directional energy vector A of the line x x Where the major diagonal elements are all 0.
3. The method according to claim 2, wherein the calculating a directional energy ratio of each line based on the directional energy matrix and determining whether a line is a faulty line according to the directional energy ratio includes:
constructing a criterion formula based on the direction energy matrix, calculating the direction energy ratio of the line according to the criterion formula, and judging the line as a fault line when the direction energy ratio is greater than a preset threshold value;
wherein the criterion formula is as follows:
in the formula, ω x Is the ratio of the directional energy of the line x.
4. The method for identifying a high resistance ground fault line according to claim 1, wherein the extracting the characteristic frequency band signal of the zero sequence current of each line through S transformation specifically comprises:
the method comprises the steps of converting zero-sequence current through S conversion to obtain a discrete form formula of the zero-sequence current, converting the discrete form formula to obtain a complex matrix, and extracting a characteristic frequency band signal of the zero-sequence current based on the complex matrix;
wherein the discrete form formula is:
in the formula, N is the number of sampling points, T is the sampling interval, l is a time parameter, and N is a frequency parameter;
the complex matrix is:
where S (i, j) is the jth sample point at the ith frequency.
5. A high-resistance ground fault line discrimination system is characterized by comprising:
the acquisition unit is used for acquiring zero sequence voltage at a bus, and acquiring zero sequence current of each line when the zero sequence voltage is smaller than a preset threshold value;
the extraction unit is used for extracting characteristic frequency band signals of the zero sequence current of each line through S transformation;
the calculation unit is used for establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix;
and the judging unit is used for calculating the directional energy ratio of each line based on the directional energy matrix and judging whether the line is a fault line according to the directional energy ratio.
6. The high impedance ground fault line discrimination system of claim 5, wherein the calculation unit is specifically configured to:
establishing a direction energy formula according to the amplitude sequence and the phase angle sequence of the characteristic frequency band signal, and transforming the direction energy formula to obtain a direction energy matrix A;
wherein the directional energy formula is:
in the formula, theta (i, j) xy Sampling point S for characteristic frequency band signal of line x zero sequence current x Sampling point S of characteristic frequency band signal of zero sequence current of (i, j) and line y y Phase angle difference of (i, j), a xy The energy of line x in the direction of line y is calculated by subtracting the sum of squares, real (S) of the product of the amplitude of sampling point of line y and the cosine of the phase angle difference between two signals from the amplitude of each sampling point of line x x (i,j))、angle(S x (i, j)) respectively represents the amplitude and phase of S (i, j) sampling point in complex matrixAn angle;
the directional energy matrix A is:
wherein q is the number of system outgoing lines, and the x-th line can be represented as the energy vector A of the line x in the direction x Where the major diagonal elements are all 0.
7. The high impedance ground fault line discrimination system of claim 6, wherein the discrimination unit is specifically configured to:
constructing a criterion formula based on the direction energy matrix, calculating the direction energy ratio of the line according to the criterion formula, and judging the line as a fault line when the direction energy ratio is greater than a preset threshold value;
wherein the criterion formula is as follows:
in the formula, ω x Is the ratio of the directional energy of the line x.
8. The high impedance ground fault line discrimination system of claim 5, wherein the extraction unit is specifically configured to:
transforming the zero-sequence current through S transformation to obtain a discrete form formula of the zero-sequence current, transforming the discrete form formula to obtain a complex matrix, and extracting a characteristic frequency band signal of the zero-sequence current based on the complex matrix;
wherein the discrete form formula is:
in the formula, N is the number of sampling points, T is the sampling interval, l is a time parameter, and N is a frequency parameter;
the complex matrix is:
wherein S (i, j) is the jth sampling point at the ith frequency.
9. A high resistance ground fault line discrimination apparatus, characterized in that the apparatus comprises a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is configured to execute the method according to any one of claims 1 to 4 according to instructions in the program code.
10. A computer-readable storage medium for storing program code for executing the high resistance ground fault line discrimination method according to any one of claims 1 to 4.
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