A Distributed Grounding Line Selection Method and System Based on Phase Current Sudden Changes

Abstract

This invention discloses a distributed ground fault location method and system based on phase current mutation. The method includes: acquiring the three-phase current of the line and calculating the real-time value, derivative, and effective value of the phase current mutation in the three-phase current; determining whether the derivative and effective value of the phase current mutation meet preset phase current mutation activation conditions within a continuous first time period; if the preset phase current mutation activation conditions are met, determining whether the phase current mutation location operation meets preset phase current mutation location operation conditions within a continuous second time period; if the preset phase current mutation location operation conditions are met, determining that a single-phase ground fault exists in the line, and the faulty phase in the line is the phase with the largest current mutation among the three phases. This method can quickly locate single-phase ground fault lines.

Description

Technical Field

[0001] This invention belongs to the field of low-current grounding fault location technology, and particularly relates to a distributed grounding fault location method and system based on phase current mutation. Background Technology

[0002] As a crucial link in power supply, the stable operation of the distribution network plays a key role in ensuring power quality and improving power supply reliability for users. With the continuous advancement of power grid technology, the need for rapid identification and isolation of faulty sections in the distribution network is becoming increasingly urgent. In my country, the neutral point of the distribution network is generally grounded via an arc suppression coil or ungrounded. When a single-phase ground fault occurs, the current flowing through the fault point is very small, hence it is also called a low-current grounding network. In distribution networks where the neutral point is not directly grounded, although short-term operation with the fault is permissible after a single-phase ground fault, the fault location must be determined as quickly as possible to prevent the fault area from expanding further. However, traditional methods of manually searching for faults using guy wires are insufficient to meet the time requirements. For systems where the neutral point is not directly grounded, the fault current is relatively small, posing a significant challenge to the rapid location of the fault section.

[0003] Besides the pull-wire method, current fault location methods include injecting external signals and selecting faults based on the electrical steady-state and transient characteristics generated during a single-phase ground fault. The external signal injection method is limited by the capacity of the voltage transformer, making it unsuitable for scenarios with a large number of power electronic devices. The accuracy of fault location methods based on steady-state characteristics is affected by the compensation effect of the arc suppression coil. Among fault location methods based on transient characteristics, the transient signal components of methods such as the first half-wave method and the zero-sequence energy method are very small, making them susceptible to interference and limiting their effectiveness.

[0004] With the maturation of the low-current grounding line selection principle and the improvement of the device's data processing capabilities, the current grounding line selection device is mainly a centralized grounding line selection device based on the transient quantity line selection principle. However, this type of device has shortcomings such as long secondary cables, complex circuits and maintenance. Summary of the Invention

[0005] This invention provides a distributed grounding fault location method and system based on phase current mutation, which solves the technical problem of being unable to locate line faults quickly and accurately.

[0006] In a first aspect, the present invention provides a distributed grounding line selection method based on phase current abrupt changes, comprising:

[0007] Obtain the three-phase current of the line, and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively;

[0008] Determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within a continuous first time period.

[0009] If the preset phase current surge triggering condition is met, then determine whether the phase current surge line selection action meets the preset phase current surge line selection action condition within the second consecutive time period.

[0010] If the preset phase current change amount line selection action condition is met, it is determined that there is a single-phase ground fault in the line, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

[0011] Secondly, the present invention provides a distributed grounding fault location system based on phase current abrupt changes, comprising:

[0012] The calculation module is configured to acquire the three-phase current of the line and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively.

[0013] The first judgment module is configured to determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start condition within a continuous first time period.

[0014] The second judgment module is configured to determine whether the phase current mutation start condition is met during the second consecutive time period if the preset phase current mutation start condition is met.

[0015] The determination module is configured to determine that if the preset phase current change amount line selection action condition is met, then the line has a single-phase ground fault, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

[0016] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the distributed grounding line selection method based on phase current abrupt changes according to any embodiment of the present invention.

[0017] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the distributed grounding line selection method based on phase current mutation in any embodiment of the present invention.

[0018] This application presents a distributed grounding fault location method and system based on phase current mutation. Based on the phase asymmetry method of three-phase current mutation, it utilizes the transient and steady-state asymmetry of the three-phase currents during a single-phase grounding fault to determine and locate the fault area, thereby quickly locating the single-phase grounding fault line. Subsequently, the grounding fault location function is distributedly integrated into the line protection device, which uses the fault information of this interval to complete the identification and clearing of the grounding fault. This enables section location or graded protection of single-phase grounding faults across the entire 10 kV line. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart of a distributed grounding line selection method based on phase current mutation is provided in an embodiment of the present invention;

[0021] Figure 2 This is a structural block diagram of a distributed grounding line selection system based on phase current mutation, provided in an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1 The diagram shows a flowchart of a distributed grounding line selection method based on phase current mutation.

[0025] like Figure 1 As shown, the distributed grounding line selection method based on phase current abrupt changes specifically includes the following steps:

[0026] Step S101: Obtain the three-phase current of the line, and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively.

[0027] In this step, the expression for calculating the real-time value of the phase current abrupt change is:

[0028]

[0029] In the formula, At time t Real-time value of phase current sudden change. for Real-time value of phase current For time tT Real-time value of phase current sudden change, where T is the power frequency period;

[0030] The expression for calculating the derivative of the phase current abrupt change is:

[0031]

[0032] In the formula, At time t Derivative of phase current mutation For time tT Real-time value of phase current sudden change;

[0033] The expression for calculating the effective value of the phase current mutation is:

[0034]

[0035] In the formula, for The effective value of the phase current surge, where N is the number of sampling points within the power frequency cycle. The nth sampling point within the power frequency cycle Instantaneous value of phase current change.

[0036] Step S102: Determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within the continuous first time period.

[0037] In this step, the expression for the initiation condition of the phase current mutation is:

[0038]

[0039] In the formula, This is the maximum value among the three-phase current abrupt changes. I is the maximum value among the derivatives of the three-phase current surges. QSET The setpoint for the start-up current of the sudden change, I DSET The derivative of the mutation is used to set the starting current.

[0040] In one specific embodiment, after determining whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up condition within a continuous first time period, if the preset phase current mutation start-up condition is not met, the three-phase current of other lines is then acquired.

[0041] Step S103: If the preset phase current mutation start condition is met, then determine whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition during the second consecutive time period.

[0042] In this step, the expression for the line selection condition based on the phase current surge is:

[0043]

[0044] In the formula, ΔI max ΔI med ΔI min These represent the maximum, median, and minimum values ​​of the effective values ​​of the three-phase current surges, respectively. DSET The derivative of the sudden change is the starting current setpoint, Δi max , Δi min K1, K2, and K3 are the maximum and minimum values ​​of the derivatives of the three-phase current mutation, respectively, and are all asymmetry coefficients.

[0045] In one specific embodiment, after determining whether the phase current change amount line selection action meets the preset phase current change amount line selection action condition within a continuous second time period, if the preset phase current change amount line selection action condition is not met, the line is determined to be a normal line.

[0046] Step S104: If the preset phase current change amount line selection action condition is met, it is determined that there is a single-phase ground fault in the line, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

[0047] In summary, the method of this application adaptively filters the collected current to obtain a current of a suitable frequency, thereby increasing the detection capability of high-resistance grounding faults. It uses the phase current mutation and its derivative to determine the fault start-up, allowing the protection device to start quickly during a fault. To prevent the protection device from malfunctioning, a start-up judgment and return logic is set up, and the action judgment is only activated within the time window after the start-up. Based on the asymmetry of the three-phase current mutation during a single-phase grounding fault, the faulty line and the faulty phase are determined.

[0048] Please see Figure 2 The diagram shows a structural block diagram of a distributed grounding line selection system based on phase current mutation.

[0049] like Figure 2As shown, the distributed grounding line selection system 200 includes a calculation module 210, a first judgment module 220, a second judgment module 230, and a determination module 240.

[0050] The calculation module 210 is configured to acquire the three-phase current of the line and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively; the first judgment module 220 is configured to judge whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions in a continuous first time period; the second judgment module 230 is configured to judge whether the phase current mutation line selection action meets the preset phase current mutation line selection action conditions in a continuous second time period if the preset phase current mutation start-up conditions are met; and the determination module 240 is configured to determine that there is a single-phase grounding fault in the line if the preset phase current mutation line selection action conditions are met, and the faulty phase in the line is the phase with the largest current mutation among the three phases.

[0051] It should be understood that Figure 2 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 2 The various modules in the document will not be described in detail here.

[0052] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the distributed grounding line selection method based on phase current mutation in any of the above method embodiments.

[0053] In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows:

[0054] Obtain the three-phase current of the line, and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively;

[0055] Determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within a continuous first time period.

[0056] If the preset phase current surge triggering condition is met, then determine whether the phase current surge line selection action meets the preset phase current surge line selection action condition within the second consecutive time period.

[0057] If the preset phase current change amount line selection action condition is met, it is determined that there is a single-phase ground fault in the line, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

[0058] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the distributed grounding selection system based on phase current abrupt changes, etc. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely located relative to a processor, and this remote memory may be connected to the distributed grounding selection system based on phase current abrupt changes via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0059] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 3 As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 3 Taking a bus connection as an example, memory 320 is the computer-readable storage medium described above. Processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in memory 320, thereby implementing the distributed grounding line selection method based on phase current abrupt changes described in the above method embodiment. Input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the distributed grounding line selection system based on phase current abrupt changes. Output device 340 may include a display screen or other display device.

[0060] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0061] In one implementation, the above-described electronic device is applied to a distributed grounding line selection system based on phase current abrupt changes, for a client, and includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to:

[0062] Obtain the three-phase current of the line, and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively;

[0063] Determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within a continuous first time period.

[0064] If the preset phase current surge triggering condition is met, then determine whether the phase current surge line selection action meets the preset phase current surge line selection action condition within the second consecutive time period.

[0065] If the preset phase current change amount line selection action condition is met, it is determined that there is a single-phase ground fault in the line, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

[0066] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A distributed grounding line selection method based on phase current abrupt change, characterized in that, include: Obtain the three-phase current of the line, and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively; Determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within a continuous first time period. If the preset phase current surge trigger condition is met, then it is determined whether the phase current surge line selection action within the second consecutive time period meets the preset phase current surge line selection action condition, wherein the expression for the phase current surge line selection action condition is: ， In the formula, , , These represent the maximum, median, and minimum values ​​among the effective values ​​of the three-phase current surges. The derivative of the sudden change is used to set the starting current. , These are the maximum and minimum values ​​of the derivatives of the three-phase current surges, respectively. , , All are asymmetric coefficients; If the preset phase current change amount line selection action condition is met, it is determined that there is a single-phase ground fault in the line, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

2. The distributed grounding line selection method based on phase current mutation as described in claim 1, characterized in that, in, The expression for calculating the real-time value of the phase current abrupt change is: ， In the formula, For time t Real-time value of phase current sudden change. for Real-time value of phase current for time Real-time value of phase current sudden change. The power frequency cycle; The expression for calculating the derivative of the phase current abrupt change is: ， In the formula, For time t Derivative of phase current mutation for time Real-time value of phase current sudden change; The expression for calculating the effective value of the phase current mutation is: ， In the formula, for RMS value of phase current sudden change This represents the number of sampling points within the power frequency cycle. The nth sampling point within the power frequency cycle Instantaneous value of phase current change.

3. The distributed grounding line selection method based on phase current mutation as described in claim 1, characterized in that, The expression for the initiation condition of the phase current mutation is: ， ， In the formula, This is the maximum value among the three-phase current abrupt changes. This is the maximum value among the derivatives of the three-phase current abrupt change. Set the starting current value for the sudden change. The derivative of the mutation is used to set the starting current.

4. The distributed grounding line selection method based on phase current mutation as described in claim 1, characterized in that, After determining whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation initiation conditions within a continuous first time period, the method further includes: If the preset phase current surge triggering condition is not met, the three-phase current of other lines will continue to be acquired.

5. The distributed grounding line selection method based on phase current mutation as described in claim 1, characterized in that, After determining whether the phase current surge detection line selection action meets the preset phase current surge detection line selection action conditions within the second consecutive time period, the method further includes: If the preset phase current change amount selection operation condition is not met, the line is determined to be a normal line.

6. A distributed grounding fault location system based on phase current abrupt change, characterized in that, include: The calculation module is configured to acquire the three-phase current of the line and calculate the real-time value of the phase current mutation, the derivative of the phase current mutation, and the effective value of the phase current mutation in the three-phase current respectively. The first judgment module is configured to determine whether the derivative of the phase current mutation and the effective value of the phase current mutation meet the preset phase current mutation start-up conditions within a continuous first time period. The second judgment module is configured to determine whether the phase current surge selection action meets the preset phase current surge action condition if the preset phase current surge activation condition is met within a consecutive second time period. The expression for the phase current surge action condition is: ， In the formula, , , These represent the maximum, median, and minimum values ​​among the effective values ​​of the three-phase current surges. The derivative of the sudden change is used to set the starting current. , These are the maximum and minimum values ​​of the derivatives of the three-phase current surges, respectively. , , All are asymmetric coefficients; The determination module is configured to determine that if the preset phase current change amount line selection action condition is met, then the line has a single-phase ground fault, and the faulty phase in the line is the phase with the largest current change amount among the three phases.

7. An electronic device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method described in any one of claims 1 to 5.

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