CN113687267B - High-resistance ground fault direction detection method, system, equipment and storage medium - Google Patents
High-resistance ground fault direction detection method, system, equipment and storage medium Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The utility model discloses a high-resistance ground fault direction detection method, a system, equipment and a storage medium, which relate to the technical field of ground fault detection of a low-current ground mode distribution network, and the method is characterized in that fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current fed back by detection points are obtained, zero sequence voltage polarization phasors are constructed by using the zero sequence voltage and the fault phase voltage through Hilbert transformation, so that the fault phase voltage can be subjected to phase transformation, and the zero sequence voltage is in phase with the zero sequence voltage, so that the fault characteristics are amplified, the sensitivity of fault identification is improved, the low-current ground fault direction is positioned through calculating the correlation coefficient between the zero sequence voltage polarization phasors and the zero sequence current, and the detection accuracy in the direction of positioning the low-current ground fault is improved.
Description
Technical Field
The application relates to the technical field of ground fault detection of a low-current ground mode power distribution network, in particular to a high-resistance ground fault direction detection method, a system, equipment and a storage medium.
Background
High resistance ground faults refer to direct contact between a bare live wire and a non-ideal conductor, including wire breakage, falling to ground, grounding through a tree barrier, and the like. As the transition resistance of the fault point can reach kiloohms or even higher, the fault signal is extremely weak and the detection difficulty is extremely high. And high resistance ground faults are liable to cause serious personal injury and great social influence. Therefore, when a high-resistance ground fault occurs, it is required to quickly locate the fault section and make corresponding isolation measures.
At present, when a low-resistance grounding fault occurs in a low-current grounding system (including a non-grounding system and a resonance grounding system), a large number of detection (such as line selection and positioning) methods utilize the characteristics of a high-frequency transient component to position a fault grounding point, but when the fault grounding resistance is increased, the characteristics of fault electric quantity on a line are also changed, and the specific expression is as follows: the highest frequency of the transient component is only slightly higher than the power frequency, and the influence of the arc suppression coil on the transient cannot be ignored; the polarity relationship between the transient currents upstream and downstream of the fault point will not be determinable; the amplitude of the transient current is smaller; the zero sequence voltage amplitude is reduced along with the increase of the transition resistance, and when the zero sequence voltage is lower than 5% of the rated phase voltage, the conventional voltage Transformer (TV) cannot accurately transfer the zero sequence voltage. Therefore, the detection sensitivity of the method in the direction of positioning the low-current high-resistance ground fault is obviously reduced, and the detection accuracy of the method in the direction of positioning the low-current ground fault is lower.
Disclosure of Invention
The application provides a high-resistance ground fault direction detection method, a system, equipment and a storage medium, which are used for solving the technical problem that the detection accuracy of the method in the direction of positioning the low-current ground fault is low.
In view of this, the first aspect of the present application provides a high-resistance ground fault direction detection method, including the following steps:
acquiring corresponding fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current when a preset detection point on a feed line feeds back a grounding fault of a grounding system;
constructing a zero sequence voltage polarization phasor by utilizing the zero sequence voltage and the fault phase voltage based on Hilbert transform;
calculating a correlation coefficient between the zero sequence voltage polarization phasor and the zero sequence current by using a preset formula;
judging the fault direction according to whether the correlation coefficient is larger than zero, if the correlation coefficient is smaller than zero, judging that the fault point with the ground fault is positioned in the upstream section of the preset detection point, and if the correlation coefficient is larger than zero, judging that the fault point with the ground fault is positioned in the downstream section of the preset detection point.
Optionally, before the step of obtaining the fault occurrence time, the zero sequence voltage, the fault phase voltage and the zero sequence current, which correspond to the case that the preset detection point feedback grounding system on the feeder line has the grounding fault, the step of obtaining the fault phase voltage and the zero sequence current comprises the following steps:
and regularly collecting the zero sequence voltage instantaneous value and the zero sequence current instantaneous abrupt change of the preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero sequence voltage instantaneous value exceeds a preset zero sequence voltage threshold value or the zero sequence current instantaneous abrupt change exceeds a preset zero sequence current threshold value.
Optionally, the step of constructing a zero sequence voltage polarization phasor by using the zero sequence voltage and the fault phase voltage based on hilbert transformation specifically includes:
acquiring the system type of a grounding system, wherein the system type comprises an ungrounded system, a resonant grounding system in an under-compensation state and a resonant grounding system in an over-compensation state;
according to the system type, based on Hilbert transform, constructing zero sequence voltage polarization phasors by using the zero sequence voltage and the fault phase voltage, specifically comprising:
for an ungrounded system or an under-compensated state resonant grounded system, based on a hilbert transform, the zero sequence voltage polarization phasor constructed using the zero sequence voltage and the fault phase voltage is expressed as:
t∈[0，T] τ∈[0，T]
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing the voltage of the fault phase, wherein T is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensated state, the zero-sequence voltage polarization phasors constructed using the zero-sequence voltage and the fault phase voltage based on the hilbert transform are expressed as:
t∈[0，T] τ∈[0，T]。
optionally, the preset formula is:
wherein δ represents a correlation coefficient, i 0 And (t) represents zero sequence current.
In a second aspect, the present invention further provides a high-resistance ground fault direction detection system, including:
the acquisition module is used for acquiring fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current corresponding to the situation that the preset detection point on the feed line feeds back the grounding fault of the grounding system;
the phasor construction module is used for constructing zero-sequence voltage polarization phasors by utilizing the zero-sequence voltage and the fault phase voltage based on Hilbert transformation;
the correlation coefficient calculation module is used for calculating the correlation coefficient between the zero sequence voltage polarization phasor and the zero sequence current by using a preset formula;
and the position judging module is used for judging the fault direction according to whether the correlation coefficient is larger than zero, judging that the fault point with the ground fault is positioned in the upstream section of the preset detection point if the correlation coefficient is smaller than zero, and judging that the fault point with the ground fault is positioned in the downstream section of the preset detection point if the correlation coefficient is larger than zero.
Optionally, the system further comprises:
the fault detection module is used for periodically collecting the zero-sequence voltage instantaneous value and the zero-sequence current instantaneous abrupt change of the preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero-sequence voltage instantaneous value exceeds a preset zero-sequence voltage threshold value or the zero-sequence current instantaneous abrupt change exceeds a preset zero-sequence current threshold value.
Optionally, the phasor construction module specifically includes:
the system comprises a type acquisition module, a compensation module and a compensation module, wherein the type acquisition module is used for acquiring the system type of a grounding system, and the system type comprises an ungrounded system, a resonant grounding system in an under-compensation state and a resonant grounding system in an over-compensation state;
the phase calculation operator module is configured to construct a zero-sequence voltage polarization phasor by using the zero-sequence voltage and the fault phase voltage based on hilbert transformation according to the system type, and specifically includes:
for an ungrounded system or an under-compensated state resonant grounded system, based on a hilbert transform, the zero sequence voltage polarization phasor constructed using the zero sequence voltage and the fault phase voltage is expressed as:
t∈[0，T] τ∈[0，T]
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing faulty phase voltageT is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensated state, the zero-sequence voltage polarization phasors constructed using the zero-sequence voltage and the fault phase voltage based on the hilbert transform are expressed as:
t∈[0，T] τ∈[0，T]。
in a third aspect, the present invention also provides an electronic device, including: the device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory are communicated with each other through the communication bus;
the memory stores a computer program that, when executed by the processor, causes the processor to perform the above-described high-resistance ground fault direction detection step.
In a fourth aspect, the present invention also provides a computer readable storage medium storing a computer program executable by an electronic device, which when run on the electronic device, causes the electronic device to perform the above-described step of high-resistance ground fault direction detection.
From the above technical scheme, the invention has the following advantages:
the invention constructs zero-sequence voltage polarization phasors by acquiring zero-sequence voltage, fault phase voltage and zero-sequence current at fault occurrence time fed back by detection points and utilizing the zero-sequence voltage and the fault phase voltage through Hilbert transformation, so that the fault phase voltage can be subjected to phase transformation to be in phase with the zero-sequence voltage to amplify the zero-sequence voltage, thereby amplifying fault characteristics, overcoming the problems that the amplitude of the zero-sequence voltage is too small and the transmission error of a zero-sequence voltage transformer is large and can not be reliably detected when high-resistance grounding is carried out, improving the sensitivity of fault identification, and further positioning the grounding fault direction of the small current through calculating the correlation coefficient between the zero-sequence voltage polarization phasors and the zero-sequence current and positioning the detection accuracy in the grounding fault direction of the small current through the positive-negative number relation of the correlation coefficient.
Drawings
Fig. 1 is a flowchart of a high-resistance ground fault direction detection method provided in an embodiment of the present application;
fig. 2 is a block diagram of a high-resistance ground fault direction detection system according to an embodiment of the present application.
Detailed Description
In order to make the present application solution better understood by those skilled in the art, the following description will clearly and completely describe the technical solution in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
For easy understanding, please refer to fig. 1, the method for detecting a high-resistance ground fault direction provided by the present invention includes the following steps:
s1, acquiring corresponding fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current when a preset detection point on a feed line feeds back a ground fault of a ground system.
It should be noted that the zero-sequence voltage, the fault phase voltage and the zero-sequence current all include a power frequency period and a transient component. The starting point of the time interval is the fault occurrence time, and the range of the time interval is a plurality of complete power frequency periods after the fault occurrence time.
S2, constructing zero-sequence voltage polarization phasors by utilizing zero-sequence voltage and fault phase voltage based on Hilbert transformation.
In practical application, the zero-sequence voltage amplitude is large and the fault phase voltage amplitude is small when the low-resistance ground fault is caused, and the zero-sequence voltage amplitude is small and the fault phase voltage amplitude is large when the high-resistance ground fault is caused. The traditional methods all use zero sequence voltage, and the zero sequence voltage transformer has large transmission error when the high resistance is grounded, so that the high resistance detection sensitivity and reliability are lower. According to the embodiment, the phase transformation is carried out on the fault phase voltage through Hilbert transformation, the fault phase voltage is in the same phase with the zero sequence voltage under the condition of unchanged amplitude, and the fault phase voltage and the zero sequence voltage phasors are combined to form zero sequence voltage polarization phasors so as to amplify the zero sequence voltage, thereby amplifying fault characteristics and improving the sensitivity of fault identification.
And S3, calculating a correlation coefficient between the zero-sequence voltage polarization phasor and the zero-sequence current by using a preset formula.
S4, judging the fault direction according to whether the correlation coefficient is larger than zero, if the correlation coefficient is smaller than zero, judging that the fault point with the ground fault is located in the upstream section of the preset detection point, and if the correlation coefficient is larger than zero, judging that the fault point with the ground fault is located in the downstream section of the preset detection point.
It should be noted that, in the zero sequence network, energy is generated by a virtual power supply of a fault point, for the downstream of the fault point, the reference direction of the current transformer CT is the same as the actual flow direction of the energy, that is, the energy is positive, the correlation coefficient is also positive, and for the upstream line of the fault point, the reference direction of the current transformer CT is opposite to the actual flow direction of the energy, so that the energy is negative, and the correlation coefficient is also negative. Therefore, the fault direction can be judged by whether the correlation coefficient is greater than zero.
In a specific embodiment, a plurality of detection points are disposed on the feeder, a detection section may be formed between adjacent detection points, if a fault point occurs in an upstream section of one detection point a, each detection point may be traversed in sequence along the direction of the upstream section of the detection point a until a fault point occurs in a downstream section corresponding to a certain detection point F, and the fault point may be considered to be on the feeder between the detection point a and the detection point F.
In this embodiment, the fault occurrence time, the zero sequence voltage, the fault phase voltage and the zero sequence current fed back by the detection point are obtained, and the zero sequence voltage polarization phasor is constructed by using the zero sequence voltage and the fault phase voltage through hilbert transformation, so that the fault phase voltage can be subjected to phase transformation to be in phase with the zero sequence voltage, so as to amplify the zero sequence voltage, thereby amplifying the fault characteristic, improving the sensitivity of fault identification, further positioning the small current grounding fault direction through calculating the correlation coefficient between the zero sequence voltage polarization phasor and the zero sequence current and positioning the small current grounding fault direction through the positive-negative number relation of the correlation coefficient, and further improving the detection accuracy in the positioning of the small current grounding fault direction.
The following is a specific description of an embodiment of a high-resistance ground fault direction detection method provided by the present invention.
The invention provides a high-resistance ground fault direction detection method, which comprises the following steps:
and S100, periodically collecting a zero-sequence voltage instantaneous value and a zero-sequence current instantaneous abrupt change of a preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero-sequence voltage instantaneous value exceeds a preset zero-sequence voltage threshold value or the zero-sequence current instantaneous abrupt change exceeds a preset zero-sequence current threshold value.
And S200, acquiring corresponding fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current when a preset detection point on the feed line feeds back the ground fault of the grounding system.
It should be noted that the zero-sequence voltage, the fault phase voltage and the zero-sequence current all include a power frequency period and a transient component.
S300, constructing zero-sequence voltage polarization phasors by utilizing zero-sequence voltages and fault phase voltages based on Hilbert transformation.
In practical application, because the amplitude of the zero sequence voltage and the fault phase voltage is smaller, the embodiment performs phase transformation on the fault phase voltage through Hilbert transformation, and makes the zero sequence voltage and the zero sequence voltage in the same phase under the condition of unchanged amplitude so as to amplify the zero sequence voltage, thereby amplifying the fault characteristics and improving the sensitivity of fault identification.
In this embodiment, step S300 specifically includes:
s301, acquiring a system type of a grounding system, wherein the system type comprises an ungrounded system, a resonance grounding system in an under compensation state and a resonance grounding system in an over compensation state;
s302, constructing zero-sequence voltage polarization phasors by utilizing zero-sequence voltages and fault phase voltages based on Hilbert transformation according to the system type, wherein the method specifically comprises the following steps of:
for an ungrounded system or a resonant grounded system in an under-compensated state, based on the hilbert transform, a zero-sequence voltage polarization phasor constructed by using a zero-sequence voltage and a fault phase voltage is expressed as:
t∈[0，T] τ∈[0，T]
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing the voltage of the fault phase, wherein T is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensation state, based on Hilbert transform, a zero-sequence voltage polarization phasor constructed by using a zero-sequence voltage and a fault phase voltage is expressed as follows:
s400, calculating a correlation coefficient between the zero-sequence voltage polarization phasor and the zero-sequence current by using a preset formula.
In this embodiment, the preset formula is:
wherein δ represents a correlation coefficient, i 0 And (t) represents zero sequence current.
S500, judging the fault direction according to whether the correlation coefficient is larger than zero, if the correlation coefficient is smaller than zero, judging that the fault point with the ground fault is positioned in the upstream section of the preset detection point, and if the correlation coefficient is larger than zero, judging that the fault point with the ground fault is positioned in the downstream section of the preset detection point.
It should be noted that, in the zero sequence network, energy is generated by a virtual power supply of a fault point, for the downstream of the fault point, the reference direction of the current transformer CT is the same as the actual flow direction of the energy, that is, the energy is positive, the correlation coefficient is also positive, and for the upstream line of the fault point, the reference direction of the current transformer CT is opposite to the actual flow direction of the energy, so that the energy is negative, and the correlation coefficient is also negative. Therefore, the fault direction can be judged by whether the correlation coefficient is greater than zero.
The above is a detailed description of an embodiment of a high-resistance ground fault direction detection method provided by the present invention, and the following is a detailed description of an embodiment of a high-resistance ground fault direction detection system provided by the present invention.
For easy understanding, referring to fig. 2, the present invention provides a high-resistance ground fault direction detection system, which includes:
the acquisition module 100 is configured to acquire a fault occurrence time, a zero-sequence voltage, a fault phase voltage and a zero-sequence current corresponding to a preset detection point on a feeder line when the feedback grounding system has a grounding fault;
the phasor construction module 200 is configured to construct a zero-sequence voltage polarization phasor using the zero-sequence voltage and the fault phase voltage based on the hilbert transformation;
the correlation coefficient calculating module 300 is configured to calculate a correlation coefficient between the zero-sequence voltage polarization phasor and the zero-sequence current by using a preset formula;
in this embodiment, the preset formula is:
wherein δ represents a correlation coefficient, i 0 And (t) represents zero sequence current.
The position determining module 400 is configured to determine the fault direction according to whether the correlation coefficient is greater than zero, if the correlation coefficient is less than zero, determine that the fault point with the ground fault is located in an upstream section of the preset detection point, and if the correlation coefficient is greater than zero, determine that the fault point with the ground fault is located in a downstream section of the preset detection point.
Further, the system further comprises:
the fault detection module is used for periodically collecting the zero-sequence voltage instantaneous value and the zero-sequence current instantaneous abrupt change of the preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero-sequence voltage instantaneous value exceeds a preset zero-sequence voltage threshold value or the zero-sequence current instantaneous abrupt change exceeds a preset zero-sequence current threshold value.
Further, the phasor construction module specifically includes:
the type acquisition module is used for acquiring the system type of the grounding system, wherein the system type comprises an ungrounded system, a resonant grounding system in an under-compensation state and a resonant grounding system in an over-compensation state;
the phase calculation operator module is used for constructing zero sequence voltage polarization phasors by utilizing zero sequence voltage and fault phase voltage based on Hilbert transformation according to the system type, and specifically comprises the following steps:
for an ungrounded system or a resonant grounded system in an under-compensated state, based on the hilbert transform, a zero-sequence voltage polarization phasor constructed by using a zero-sequence voltage and a fault phase voltage is expressed as:
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing the voltage of the fault phase, wherein T is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensation state, based on Hilbert transform, a zero-sequence voltage polarization phasor constructed by using a zero-sequence voltage and a fault phase voltage is expressed as follows:
t∈[0，T] τ∈[0，T]。
it should be noted that, the working process of the high-resistance ground fault direction detection system provided in this embodiment is consistent with the flow of the high-resistance ground fault direction detection method in the foregoing embodiment, and will not be described herein.
The system constructs zero-sequence voltage polarization phasors by acquiring fault occurrence time, zero-sequence voltage, fault phase voltage and zero-sequence current fed back by detection points and utilizing the zero-sequence voltage and the fault phase voltage through Hilbert transformation, so that the fault phase voltage can be subjected to phase transformation, and is in phase with the zero-sequence voltage to amplify the zero-sequence voltage, thereby amplifying fault characteristics to improve the sensitivity of fault identification, and further, the direction of the small-current grounding fault is positioned through calculating the correlation coefficient between the zero-sequence voltage polarization phasors and the zero-sequence current and the positive-negative number relation of the correlation coefficient, thereby improving the detection accuracy in the direction of positioning the small-current grounding fault.
The invention also provides an electronic device, comprising: the device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory are communicated with each other through the communication bus;
the memory stores a computer program that, when executed by the processor, causes the processor to perform the above-described high-resistance ground fault direction detection step.
The present invention also provides a computer-readable storage medium storing a computer program executable by an electronic device, which when run on the electronic device causes the electronic device to perform the above-described step of high-resistance ground fault direction detection.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown 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 may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution in the form of a software product stored in a storage medium, including several instructions to execute all or part of the steps of the methods described in the embodiments of the present application by a computer device (which may be a personal computer, a server, or a network device, etc.). And the aforementioned storage medium includes: u disk, mobile hard disk, read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), magnetic disk or optical disk, etc.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (6)
1. The high-resistance ground fault direction detection method is characterized by comprising the following steps of:
acquiring corresponding fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current when a preset detection point on a feed line feeds back a grounding fault of a grounding system;
based on Hilbert transformation, constructing a zero-sequence voltage polarized phasor by utilizing the zero-sequence voltage and the fault phase voltage, wherein the fault phase voltage is subjected to phase transformation by Hilbert transformation, is in phase with the zero-sequence voltage under the condition of unchanged amplitude, and is combined with the zero-sequence voltage phasor to form the zero-sequence voltage polarized phasor so as to amplify the zero-sequence voltage, and the method specifically comprises the following steps of:
acquiring the system type of a grounding system, wherein the system type comprises an ungrounded system, a resonant grounding system in an under-compensation state and a resonant grounding system in an over-compensation state;
according to the system type, based on Hilbert transform, constructing zero sequence voltage polarization phasors by using the zero sequence voltage and the fault phase voltage, specifically comprising:
for an ungrounded system or an under-compensated state resonant grounded system, based on a hilbert transform, the zero sequence voltage polarization phasor constructed using the zero sequence voltage and the fault phase voltage is expressed as:
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing the voltage of the fault phase, wherein T is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensated state, the zero-sequence voltage polarization phasors constructed using the zero-sequence voltage and the fault phase voltage based on the hilbert transform are expressed as:
calculating a correlation coefficient between the zero sequence voltage polarization phasor and the zero sequence current by using a preset formula, wherein the preset formula is as follows:
wherein δ represents a correlation coefficient, i 0 (t) represents zero sequence current;
judging the fault direction according to whether the correlation coefficient is larger than zero, if the correlation coefficient is smaller than zero, judging that the fault point with the ground fault is positioned in the upstream section of the preset detection point, and if the correlation coefficient is larger than zero, judging that the fault point with the ground fault is positioned in the downstream section of the preset detection point.
2. The method for detecting a high-resistance ground fault direction according to claim 1, wherein the step of obtaining the fault occurrence time, the zero-sequence voltage, the fault phase voltage and the zero-sequence current corresponding to the occurrence of the ground fault of the feedback ground system at the preset detection point on the feeder line comprises:
and regularly collecting the zero sequence voltage instantaneous value and the zero sequence current instantaneous abrupt change of the preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero sequence voltage instantaneous value exceeds a preset zero sequence voltage threshold value or the zero sequence current instantaneous abrupt change exceeds a preset zero sequence current threshold value.
3. A high resistance ground fault direction detection system, comprising:
the acquisition module is used for acquiring fault occurrence time, zero sequence voltage, fault phase voltage and zero sequence current corresponding to the situation that the preset detection point on the feed line feeds back the grounding fault of the grounding system;
the phasor construction module is used for constructing zero-sequence voltage polarized phasors by utilizing the zero-sequence voltage and the fault phase voltage based on Hilbert transformation, wherein the fault phase voltage is subjected to phase transformation through Hilbert transformation, is in phase with the zero-sequence voltage under the condition of unchanged amplitude, and is combined with the zero-sequence voltage phasors to form the zero-sequence voltage polarized phasors so as to amplify the zero-sequence voltage;
the phasor construction module specifically includes:
the system comprises a type acquisition module, a compensation module and a compensation module, wherein the type acquisition module is used for acquiring the system type of a grounding system, and the system type comprises an ungrounded system, a resonant grounding system in an under-compensation state and a resonant grounding system in an over-compensation state;
the phase calculation operator module is configured to construct a zero-sequence voltage polarization phasor by using the zero-sequence voltage and the fault phase voltage based on hilbert transformation according to the system type, and specifically includes:
for an ungrounded system or an under-compensated state resonant grounded system, based on a hilbert transform, the zero sequence voltage polarization phasor constructed using the zero sequence voltage and the fault phase voltage is expressed as:
wherein u is j0 (t) represents zero sequence voltage polarization phasors, u 0 (t) represents zero sequence voltage, u pf Representing the voltage of the fault phase, wherein T is the time length, and the value of T is T 0 ×K，T 0 For the power frequency period, K is a positive integer, and t and τ both represent time;
for a resonant grounding system in an overcompensated state, the zero-sequence voltage polarization phasors constructed using the zero-sequence voltage and the fault phase voltage based on the hilbert transform are expressed as:
the correlation coefficient calculation module is used for calculating the correlation coefficient between the zero sequence voltage polarization phasor and the zero sequence current by using a preset formula, wherein the preset formula is as follows:
wherein δ represents a correlation coefficient, i 0 (t) represents zero sequence current;
and the position judging module is used for judging the fault direction according to whether the correlation coefficient is larger than zero, judging that the fault point with the ground fault is positioned in the upstream section of the preset detection point if the correlation coefficient is smaller than zero, and judging that the fault point with the ground fault is positioned in the downstream section of the preset detection point if the correlation coefficient is larger than zero.
4. The high resistance ground fault direction detection system of claim 3, further comprising:
the fault detection module is used for periodically collecting the zero-sequence voltage instantaneous value and the zero-sequence current instantaneous abrupt change of the preset detection point according to a preset period, and judging that the grounding system has a grounding fault if the zero-sequence voltage instantaneous value exceeds a preset zero-sequence voltage threshold value or the zero-sequence current instantaneous abrupt change exceeds a preset zero-sequence current threshold value.
5. An electronic device, comprising: the device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory are communicated with each other through the communication bus;
the memory has stored therein a computer program which, when executed by the processor, causes the processor to perform the high resistance ground fault direction detection steps of any one of claims 1-2.
6. A computer readable storage medium, characterized in that it stores a computer program executable by an electronic device, which when run on the electronic device, causes the electronic device to perform the high-resistance ground fault direction detection steps of any one of claims 1-2.
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