Distributed grounding line selection method and system based on phase current break variable

Abstract

The invention discloses a distributed grounding line selection method and system based on phase current abrupt change, and the method comprises the steps: obtaining three-phase current of a line, and calculating a phase current abrupt change real-time value, a phase current abrupt change derivative and a phase current abrupt change effective value in the three-phase current; judging whether the phase current break variable derivative and the phase current break variable effective value meet a preset phase current break variable starting condition or not in a continuous first time period; if the preset phase current abrupt change starting condition is met, whether the phase current abrupt change line selection action in a continuous second time period meets a preset phase current abrupt change line selection action condition or not is judged; and if a preset phase current break variable line selection action condition is met, determining that the line has a single-phase earth fault and the fault phase in the line is the phase with the maximum current break variable in the three phases. And a single-phase earth fault line can be quickly positioned.

Description

Technical Field

[0001] The present invention belongs to the technical field of small current grounding line selection, and in particular relates to a distributed grounding line selection method and system based on phase current mutation quantity. Background Art

[0002] As an important part of power supply, the stable operation of the distribution network plays a key role in ensuring the quality of power supply to users and improving the reliability of power supply. With the continuous advancement of power grid technology, the demand for the distribution network to quickly identify and isolate the fault section is becoming more and more urgent. The neutral point of my country's distribution network is generally grounded or ungrounded through an arc suppression coil. When a single-phase grounding fault occurs, the current flowing through the fault point is very small, so it is also called a small current grounding grid. After a single-phase grounding fault occurs in a distribution network where the neutral point is not directly grounded, although short-term operation with faults is allowed, in order to prevent the scope of the fault from further expanding, the fault point section must be located as soon as possible. However, the traditional wire pulling method uses manual fault finding, which is difficult to meet the time limit requirements. For systems where the neutral point is not directly grounded, the fault current is small, and there are great challenges in quickly selecting and locating the fault section.

[0003] In addition to the wire pulling method, current line selection methods include line selection by injecting external signals and line selection based on the electrical steady-state and transient characteristic quantities generated when a single-phase grounding fault occurs. The line selection method of injecting external signals is limited by the capacity of the voltage transformer, which is not conducive to application in scenarios with a large number of power electronic equipment. The line selection method based on the steady-state characteristic quantity when a fault occurs is affected by the compensation effect of the arc suppression coil, and the line selection accuracy is affected. Among the line selection methods based on the transient characteristic quantity when a fault occurs, the transient signal components of the first half-wave method, the zero-sequence energy method, and other methods are very small, easily interfered, and have limitations.

[0004] With the maturity of the small current grounding line selection principle and the improvement of the data processing capability of the device, the current grounding line selection device is mainly a centralized grounding line selection device based on the transient quantity selection principle. However, this type of device has shortcomings such as long secondary cables, complex loops and operation and maintenance. Summary of the invention

[0005] The present invention provides a distributed grounding line selection method and system based on phase current mutation quantity, which are used to solve the technical problem that line faults cannot be located relatively quickly and accurately.

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

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

[0008] Determine whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition in a continuous first time period;

[0009] If the preset phase current mutation start condition is met, then determining whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a second continuous time period;

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

[0011] In a second aspect, the present invention provides a distributed grounding line selection system based on phase current mutation, comprising:

[0012] A calculation module is configured to obtain the three-phase current of the line, and respectively calculate the real-time value of the phase current mutation amount, the derivative of the phase current mutation amount, and the effective value of the phase current mutation amount in the three-phase current;

[0013] A first judgment module is configured to judge whether the derivative of the phase current mutation amount and the effective value of the phase current mutation amount meet a preset phase current mutation amount starting condition within a continuous first time period;

[0014] A second judgment module is configured to judge whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a continuous second time period if the preset phase current mutation start condition is met;

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

[0016] According to a third aspect, 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, and the instructions are executed by the at least one processor so that the at least one processor can perform the steps of the distributed grounding line selection method based on phase current mutation quantity according to any embodiment of the present invention.

[0017] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor executes the steps of a distributed grounding line selection method based on phase current mutation quantity according to any embodiment of the present invention.

[0018] The distributed grounding line selection method and system based on phase current mutation quantity of the present application is based on the phase asymmetry method of three-phase current mutation quantity, and utilizes the transient and steady-state asymmetry characteristics of the three-phase current when a single-phase grounding fault occurs to judge and locate the fault area, thereby quickly locating the single-phase grounding fault line, and subsequently the grounding line selection function is distributedly integrated into the line protection device, and the line protection device uses the fault information of this interval to complete the judgment and removal of the grounding fault, which can realize the section positioning or hierarchical protection of single-phase grounding faults in the entire 10 kV line. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0021] Figure 2 A structural block diagram of a distributed grounding line selection system based on phase current mutation provided by an embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1 , which shows a flow chart of a distributed grounding line selection method based on phase current mutation quantity of the present application.

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

[0026] Step S101, obtaining the three-phase current of the line, and respectively calculating the real-time value of the phase current mutation amount, the derivative of the phase current mutation amount, and the effective value of the phase current mutation amount in the three-phase current.

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

[0028]

[0029] In the formula, is time t Real-time value of phase current mutation, for Phase current real-time value, tT time Real-time value of phase current mutation, T is the power frequency period;

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

[0031]

[0032] In the formula, is time t The derivative of the phase current mutation, tT time Real-time value of phase current mutation;

[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 mutation, N is the number of sampling points within the power frequency cycle, is the nth sampling point in the power frequency cycle The instantaneous value of phase current mutation.

[0036] Step S102, determining whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition within a first continuous time period.

[0037] In this step, the expression of the phase current sudden change starting condition is:

[0038]

[0039] In the formula, is the maximum value of the three-phase current mutation. is the maximum value of the derivative of the three-phase current mutation, I QSET is the starting current constant of the sudden change, I DSET It is the starting current constant of the sudden change derivative.

[0040] In a specific embodiment, after determining whether the derivative of the phase current mutation amount and the effective value of the phase current mutation amount meet the preset phase current mutation amount starting condition in a continuous first time period, if the preset phase current mutation amount starting condition is not met, continue to obtain the three-phase currents of other lines.

[0041] Step S103: if the preset phase current mutation start condition is met, it is determined whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a second continuous time period.

[0042] In this step, the expression of the phase current sudden change line selection action condition is:

[0043]

[0044] In the formula, ΔI max , ΔI med , ΔI min are the maximum, middle and minimum values ​​of the effective values ​​of the three-phase current mutation, I DSET is the starting current constant of the sudden change derivative, Δi max , Δi min They are respectively the maximum and minimum values ​​of the derivatives of the three-phase current mutation quantities, and K1, K2, and K3 are all asymmetric coefficients.

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

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

[0047] In summary, the method of the present application performs adaptive filtering on the collected current to obtain a current of a suitable frequency, thereby increasing the ability to detect high-resistance grounding faults, and makes fault start judgments through phase current mutations and derivatives of phase current mutations. In the event of a fault, the protection device can be quickly started. In order to prevent misoperation of the protection device, a start judgment and return logic are set, and the action judgment is only enabled in the time window after startup. The fault line and fault phase are judged based on the asymmetry of the three-phase current mutations in the event of a single-phase grounding fault.

[0048] See also Figure 2 , which shows a structural block diagram of a distributed grounding line selection system based on phase current mutation quantity of the present application.

[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] Among them, the calculation module 210 is configured to obtain the three-phase current of the line, and respectively calculate the real-time value of the phase current mutation amount, the derivative of the phase current mutation amount and the effective value of the phase current mutation amount in the three-phase current; the first judgment module 220 is configured to judge whether the derivative of the phase current mutation amount and the effective value of the phase current mutation amount meet the preset phase current mutation amount starting condition in a continuous first time period; the second judgment module 230 is configured to judge whether the phase current mutation amount line selection action meets the preset phase current mutation amount line selection action condition in a continuous second time period if the preset phase current mutation amount starting condition is met; the determination module 240 is configured to determine that a single-phase grounding fault exists in the line if the preset phase current mutation amount line selection action condition is met, and the fault phase in the line is the phase with the largest current mutation amount among the three phases.

[0051] It should be understood that Figure 2 Modules and references documented in Figure 1 Therefore, the operations and features described above for the method and the corresponding technical effects are also applicable to Figure 2 The modules in it will not be described in detail here.

[0052] In some other embodiments, the embodiments of the present invention further provide a computer-readable storage medium, on which a computer program is stored, and when the program instructions are executed by a processor, the processor executes the distributed grounding line selection method based on phase current mutation amount in any of the above method embodiments;

[0053] As an implementation mode, the computer-readable storage medium of the present invention stores computer-executable instructions, and the computer-executable instructions are configured as follows:

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

[0055] Determine whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition in a continuous first time period;

[0056] If the preset phase current mutation start condition is met, then determining whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a second continuous time period;

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

[0058] The computer-readable storage medium may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required by at least one function; the data storage area may store data created according to the use of a distributed grounding line selection system based on phase current mutation, etc. In addition, the computer-readable storage medium may include a high-speed random access memory, and may also include a memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the distributed grounding line selection system based on phase current mutation through a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0059] Figure 3 is a schematic diagram of the structure of an electronic device provided by an 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, the memory 320, the input device 330 and the output device 340 may be connected via a bus or other means. Figure 3 In the example, the connection through the bus is taken as an example. The memory 320 is the above-mentioned computer-readable storage medium. The processor 310 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory 320, that is, the distributed grounding line selection method based on the phase current mutation quantity of the above-mentioned method embodiment is implemented. The input device 330 can receive input digital or character information, and generate key signal input related to user settings and function control of the distributed grounding line selection system based on the phase current mutation quantity. The output device 340 may include display devices such as display screens.

[0060] The electronic device can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0061] As an implementation mode, the electronic device is applied to a distributed grounding line selection system based on phase current mutation, and is used for a client, and includes: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor, so that the at least one processor can:

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

[0063] Determine whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition in a continuous first time period;

[0064] If the preset phase current mutation start condition is met, then determining whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a second continuous time period;

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

[0066] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or some parts of the embodiment.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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 mutation, characterized in that: include: Obtain the three-phase current of the line, and respectively calculate the real-time value of the phase current mutation amount, the derivative of the phase current mutation amount, and the effective value of the phase current mutation amount in the three-phase current; Determine whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition in a continuous first time period; If the preset phase current mutation start condition is met, then determining whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a second continuous time period; If the preset phase current mutation line selection action condition is met, it is determined that a single-phase grounding fault exists in the line, and the faulty phase in the line is the phase with the largest current mutation among the three phases.

2. A distributed grounding line selection method based on phase current mutation according to claim 1, characterized in that: in, The expression for calculating the real-time value of the phase current mutation amount is: In the formula, is time t Real-time value of phase current mutation, for Phase current real-time value, tT time Real-time value of phase current mutation, T is the power frequency period; The expression for calculating the derivative of the phase current sudden change is: In the formula, is time t The derivative of the phase current mutation, tT time Real-time value of phase current mutation; The expression for calculating the effective value of the phase current mutation is: In the formula, for The effective value of the phase current mutation, N is the number of sampling points within the power frequency cycle, is the nth sampling point in the power frequency cycle The instantaneous value of phase current mutation.

3. A distributed grounding line selection method based on phase current mutation according to claim 1, characterized in that: The expression of the phase current sudden change starting condition is: In the formula, is the maximum value of the three-phase current mutation. is the maximum value of the derivative of the three-phase current mutation, I QSET is the starting current constant of the sudden change, I DSET It is the starting current constant of the sudden change derivative.

4. A distributed grounding line selection method based on phase current mutation according to claim 1, characterized in that: After determining whether the phase current sudden change derivative and the phase current sudden change effective value meet a preset phase current sudden change start condition within a continuous first time period, the method further includes: If the preset phase current mutation start condition is not met, continue to obtain the three-phase currents of other lines.

5. The distributed grounding line selection method based on phase current mutation according to claim 1 is characterized in that: The expression of the phase current sudden change line selection action condition is: In the formula, ΔI max , ΔI med , ΔI min are the maximum, middle and minimum values ​​of the effective values ​​of the three-phase current mutation, I DSET is the starting current constant of the sudden change derivative, Δi max ′、Δi min ′ are the maximum and minimum values ​​of the derivatives of the three-phase current mutation, and K1, K2, and K3 are all asymmetric coefficients.

6. A distributed grounding line selection method based on phase current mutation according to claim 1, characterized in that: After determining whether the phase current sudden change line selection action meets the preset phase current sudden change line selection action condition within the second continuous time period, the method further includes: If the preset phase current sudden change line selection action condition is not met, the line is determined to be a normal line.

7. A distributed grounding line selection system based on phase current mutation, characterized in that: include: A calculation module is configured to obtain the three-phase current of the line, and respectively calculate the real-time value of the phase current mutation amount, the derivative of the phase current mutation amount, and the effective value of the phase current mutation amount in the three-phase current; A first judgment module is configured to judge whether the derivative of the phase current mutation amount and the effective value of the phase current mutation amount meet a preset phase current mutation amount starting condition within a continuous first time period; A second judgment module is configured to judge whether the phase current mutation line selection action meets the preset phase current mutation line selection action condition within a continuous second time period if the preset phase current mutation start condition is met; The determination module is configured to determine that a single-phase grounding fault exists in the line if a preset phase current mutation amount line selection action condition is met, and the faulty phase in the line is the phase with the largest current mutation amount among the three phases.

8. 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, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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