Hybrid line fault identification method and system

Abstract

The present invention discloses a hybrid line fault identification method and system, comprising: constructing a three-section hybrid line model; identifying the fault section based on the three-section hybrid line model; and confirming the specific fault location based on the fault section. The present invention uses the voltage modulus difference between the two ends of the line and the trend of the voltage modulus at the measuring end changing with the fault point location as identification indicators. This method can accurately and quickly determine the fault location for any fault point in the hybrid line.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a hybrid line fault identification method and system. Background Art

[0002] Unlike single-material transmission lines with uniform impedance, each section of a "cable-overhead line" hybrid transmission line has a different laying method, resulting in different fault causes and fault natures. Therefore, after a fault occurs, it is necessary to quickly determine the fault point in the line section. This is crucial for improving inspection and line inspection efficiency, increasing the success rate of automatic reclosing, quickly restoring power, and maintaining grid stability. In "cable-overhead line" hybrid transmission lines, the significant difference in impedance angles between the cable and overhead line results in virtually no uniform impedance across the entire hybrid line, making it difficult to accurately determine the fault location. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a hybrid line fault identification method and system, which can accurately determine the hybrid line fault location.

[0004] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] In a first aspect, a hybrid line fault identification method is provided, comprising:

[0006] Construct a three-section hybrid circuit model;

[0007] Confirm the fault section based on the three-section hybrid line model;

[0008] Confirm the specific location of the fault according to the section where the fault is located.

[0009] In combination with the first aspect, further, the three-section hybrid circuit model includes:

[0010] The M-terminal model of the hybrid line is shown in formula (1):

[0011]

[0012] The N-terminal model of the hybrid circuit is shown in formula (2):

[0013]

[0014] in are the voltage and current at terminal M of the hybrid circuit respectively; They are the current at terminal M, positive sequence current, and zero sequence current respectively; They represent the zero-sequence current compensation coefficients of the first, second, and third sections of the line, respectively. x is the distance from the fault point to the measuring end. L1, L2, and L3 are the lengths of the first section of cable, the overhead line, and the second section of overhead line, respectively. are the positive sequence impedance per unit length of the first, second and third sections of the line, R F is the grounding equivalent resistance at the fault point, y(F i ) is the fault point F i The actual distance from the sampling point.

[0015] In combination with the first aspect, further, confirming the fault section according to the three-section hybrid line model includes:

[0016] If f(x) < 0 and g(x) < a, the fault point is located at the first section of the line; when f(x) > 0, the fault point is located at the second section of the line; when f(x) < 0 and g(x) > a, the fault point is located at the third section of the line; when f(x) does not exist and g(x) < a, the fault point is located at the junction of the first and second sections of the line; when f(x) does not exist and g(x) > a, the fault point is located at the junction of the second and third sections of the line, and a represents the limit value.

[0017] In combination with the first aspect, further, confirming the specific location of the fault according to the section where the fault is located includes:

[0018]

[0019] Among them, Im represents the imaginary part, For I. mA1 The complex conjugate of

[0020] According to the determined fault section, the distance x from the measurement end point of the fault section to the fault point to the measurement end is the specific location of the fault point.

[0021] In a second aspect, a hybrid line fault identification system is provided, comprising:

[0022] Modeling module, used to build a three-section hybrid circuit model;

[0023] The fault section determination module is used to confirm the section where the fault is located based on the three-section hybrid line model;

[0024] The fault location determination module is used to confirm the specific location of the fault based on the section where the fault is located.

[0025] In a third aspect, a hybrid line fault identification system is provided, comprising a memory and a processor;

[0026] The memory is used to store instructions;

[0027] The processor is configured to operate according to the instructions to execute the steps of any one of the methods of the first aspect.

[0028] Beneficial effects of the present invention: The present invention uses the voltage modulus difference at both ends of the line and the trend of the voltage modulus at the measuring end changing with the position of the fault point as discrimination indicators, and can accurately determine the fault location of any fault point in the hybrid line quickly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of the present invention;

[0030] Figure 2 Schematic diagram of the model of the hybrid circuit in the present invention. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In order to better understand the present invention, the relevant technologies in the technical solution of the present invention are described below.

[0033] like Figure 1-2 As shown, the present invention is based on the "cable-overhead line-cable" hybrid line model, the line model consists of power supply systems at both ends and It consists of two sections of cable and one section of overhead line, where Z M and Z N The three lines are connected through two segmentation points J1 and J2 respectively. The first segment is a cable line with a length of L1, the second segment is an overhead line with a length of L2, and the third segment is a cable line with a length of L3.

[0034] Example 1

[0035] like Figure 1 As shown, the present invention discloses a hybrid line fault identification method, comprising the following steps:

[0036] Step 1: Build a three-section hybrid circuit model

[0037] The hybrid model includes:

[0038] The M-terminal model of the hybrid line is shown in formula (1):

[0039]

[0040] The N-terminal model of the series-parallel circuit is as shown in Equation (2).

[0041]

[0042] Where are the voltage and current at the M-terminal of the series-parallel circuit respectively; are the current, positive-sequence current, and zero-sequence current at the M-terminal respectively; respectively represent the zero-sequence current compensation coefficients of the first, second, and third lines. x is the distance from the fault point to the measurement end, and L1, L2, and L3 are the lengths of the first cable section, overhead line, and second overhead line respectively. are the positive-sequence impedances per unit length of the first, second, and third lines respectively, and R F is the grounding equivalent resistance at the fault point, and F i is the fault point.

[0043] Step 2: Confirm the section where the fault is located according to the three-section series-parallel circuit model

[0044] Record the length from the actual fault point to the M-terminal of the measurement end as x. The derivative of the modulus value of the phasor is f(x). The difference between the modulus values of the phasors is g(x), and the boundary value a is 12.99. When the fault point is located in the first line (cable section), f(x) < 0 and g(x) < a; when the fault point is located in the second line (overhead line), f(x) > 0, and there is no need to calculate g(x); when the fault point is located in the third line (cable section), f(x) < 0 and g(x) > a; when the fault point is located at the first and second sectional points, f(x) does not exist, g(x) < a and f(x) does not exist, g(x) > a respectively.

[0045] Step 3: Confirm the specific location of the fault according to the section where the fault is located

[0046]

[0047] Among them, Im represents taking the imaginary part. is the conjugate complex number of;

[0048] According to the determined fault section, take the distance x from the measurement end point of the fault section to the fault point to the measurement end as the specific location of the fault point.

[0049] Embodiment 2

[0050] The present invention also provides a series-parallel circuit fault identification system, including:

[0051] A modeling module for constructing a three-section series-parallel circuit model;

[0052] The fault section determination module is used to confirm the section where the fault is located based on the three-section hybrid line model;

[0053] The fault location determination module is used to confirm the specific location of the fault based on the section where the fault is located.

[0054] Example 3

[0055] The present invention also provides a hybrid line fault identification system, comprising a memory and a processor;

[0056] The memory is used to store instructions;

[0057] The processor is configured to operate according to the instruction to execute the steps of any one of the methods for identifying a fault in a parallel-parallel transmission line.

[0058] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0059] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0060] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0061] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

Claims

1. A hybrid line fault identification method, characterized in that: include: Construct a three-section hybrid circuit model; Confirm the fault section based on the three-section hybrid line model; Confirm the specific location of the fault according to the section where the fault is located; The three-section hybrid circuit model includes: The M-terminal model of the hybrid line is shown in formula (1): The N-terminal model of the hybrid circuit is shown in formula (2): in are the voltage and current at terminal M of the hybrid circuit respectively; They are the current at terminal M, positive sequence current, and zero sequence current respectively; They represent the zero-sequence current compensation coefficients of the first, second, and third sections of the line, respectively. x is the distance from the fault point to the measuring end. L1, L2, and L3 are the lengths of the first section of cable, the overhead line, and the second section of overhead line, respectively. are the positive sequence impedance per unit length of the first, second and third sections of the line, R F is the grounding equivalent resistance at the fault point, y(F i ) is the fault point F i The actual distance from the sampling point.

2. A hybrid line fault identification method according to claim 1, characterized in that: The confirming of the fault section according to the three-section hybrid line model includes: If f(x) < 0 and g(x) < a, the fault point is located at the first section of the line; when f(x) > 0, the fault point is located at the second section of the line; when f(x) < 0 and g(x) > a, the fault point is located at the third section of the line; when f(x) does not exist and g(x) < a, the fault point is located at the junction of the first and second sections of the line; when f(x) does not exist and g(x) > a, the fault point is located at the junction of the second and third sections of the line, and a represents the limit value.

3. A hybrid line fault identification method according to claim 2, characterized in that: Confirming the specific location of the fault according to the section where the fault is located includes: Among them, Im represents the imaginary part, For I. mA1 The complex conjugate of According to the determined fault section, the distance x from the measurement end point of the fault section to the fault point to the measurement end is the specific location of the fault point.

4. A hybrid line fault identification system, characterized in that: include: Modeling module, used to build a three-section hybrid circuit model; The fault section determination module is used to confirm the section where the fault is located based on the three-section hybrid line model; Fault location determination module, used to confirm the specific location of the fault according to the section where the fault is located; The three-section hybrid circuit model includes: The M-terminal model of the hybrid line is shown in formula (1): The N-terminal model of the hybrid circuit is shown in formula (2): in are the voltage and current at terminal M of the hybrid circuit respectively; They are the current at terminal M, positive sequence current, and zero sequence current respectively; They represent the zero-sequence current compensation coefficients of the first, second, and third sections of the line, respectively. x is the distance from the fault point to the measuring end. L1, L2, and L3 are the lengths of the first section of cable, the overhead line, and the second section of overhead line, respectively. are the positive sequence impedance per unit length of the first, second and third sections of the line, R F is the grounding equivalent resistance at the fault point, y(F i ) is the fault point F i The actual distance from the sampling point.

5. A hybrid line fault identification system, characterized in that: including memory and processor; The memory is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 3.

Images