Live-line measurement method for zero-sequence distribution parameters of four-circuit non-whole-line parallel transmission line under asymmetric simplified model

Abstract

The invention provides a live-line measurement method for zero-sequence distribution parameters of four-circuit non-whole-line parallel power transmission lines under an asymmetric simplified model, and the method comprises the steps: firstly, respectively measuring the head-end zero-sequence electrical parameters and the tail-end zero-sequence electrical parameters of each power transmission line in eight connection modes; and determining the relationship between the head and tail end electrical parameters of the four-circuit line part and the relationship between the head and tail end electrical parameters of the double-circuit line part. Then, the impedance parameters and the admittance parameters of the four-circuit line part can be determined according to the matrix, and the impedance parameters and the admittance parameters of the double-circuit line part are obtained according to the intermediate variables in the double-circuit relation matrix. Finally, the zero-sequence parameter of the four-circuit non-whole-line parallel transmission line can be measured based on the impedance parameter and the admittance parameter of the four-circuit part and the impedance parameter and the admittance parameter of the double-circuit part. Therefore, the technical effect of effectively solving the zero-sequence parameters of the four-circuit non-whole-line parallel power transmission line can be realized, and more accurate zero-sequence distribution parameters can be obtained.

Description

Technical Field

[0001] The present application relates to the technical field of power system measurement, and in particular to a live measurement method for zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model. Background Art

[0002] Under the three-phase symmetrical operation conditions of the power system, the equivalent circuit of the overhead transmission line can be simplified to a single-phase circuit, which is composed of the resistance, reactance (i.e. inductance) of the conductor, and the conductance and susceptance (i.e. capacitance) to the ground. The resistance mainly represents the loss of active power, the reactance is related to the magnetic field effect generated by the current-carrying conductor, and the susceptance reflects the electric field effect around the current-carrying conductor. The conductivity parameters of the transmission line are usually small, mainly affected by leakage and corona along the insulator, but in actual line design, the lines designed to avoid corona phenomena ensure that the conductance value is extremely small, which is often ignored. These power frequency parameters constitute the cornerstone of the power system model, and are crucial to the accuracy of power flow calculation, relay protection setting, transient stability analysis and fault location, highlighting the importance of obtaining accurate transmission line parameters for the safe and stable operation of the power grid. Therefore, when building a modern power system, the accuracy of measuring transmission line parameters cannot be ignored.

[0003] With the acceleration of urbanization and rapid economic growth, the demand for electricity supply has risen sharply, and industrial and commercial expansion has prompted the large-scale construction of transmission lines and towers. At the same time, the restriction of the land area required for the transmission line corridor has become increasingly prominent, causing tension between the construction of power infrastructure and the use of land resources. Therefore, balancing the development of the national economy with the construction of the power grid and improving the utilization efficiency of the transmission corridor have become urgent issues to be solved. In this context, increasing the transmission capacity of the line is one of the solutions. By constructing multiple transmission lines on the same tower, that is, adopting the same tower multi-circuit transmission technology, it can not only increase the power supply capacity, but also save land resources and reduce investment costs, thus bringing significant social and economic benefits. However, the complex electromagnetic coupling phenomenon in the multi-circuit transmission line makes it a technical challenge to accurately measure its zero-sequence parameters.

[0004] In the design of power transmission systems, four-circuit transmission lines on the same tower are widely used due to their obvious advantages in optimizing the use of line corridors, improving transmission efficiency and reducing construction costs. This type of transmission line has many types, such as 500 kV / 220 kV, 275 kV / 132 kV, 220 kV / 110 kV, etc., and is widely used. However, the complex electromagnetic coupling relationship of the four-circuit line on the same tower makes the measurement of zero-sequence parameters challenging, especially the measurement of zero-sequence distributed parameters of four non-full-line parallel transmission lines.

[0005] In the field implementation, due to the diversity of factors such as the materials, specifications, and installation methods used in the transmission lines, as well as the different degrees of aging of different transmission circuits over time, the balance of line parameters will be affected. At present, many theoretical studies are based on the assumption that the transmission line parameters are completely symmetrical. However, in actual engineering applications, this assumption is often not applicable. In the existing methods, it is often required that the transmission lines are symmetrically distributed in pairs, especially for the asymmetric installation of four-circuit transmission lines on the vertical plane, that is, when the line parameters are asymmetric, how to measure their zero-sequence parameters has not yet been formed. An effective method. Summary of the invention

[0006] The purpose of this application is to solve at least one of the above-mentioned technical defects, especially the technical defect that the prior art cannot effectively determine the zero-sequence parameters of four-circuit non-full-line parallel transmission lines under an asymmetric simplified model.

[0007] In the first aspect, the embodiment of the present application provides a method for measuring zero-sequence distribution parameters of four-circuit non-full-line parallel transmission lines under an asymmetric simplified model, wherein the four-circuit non-full-line parallel transmission lines include a four-circuit line portion and a double-circuit line portion, wherein the four-circuit line portion is composed of a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line, and the length of the four-circuit line portion is l1; the double-circuit line portion is composed of a third transmission line and a fourth transmission line, and the length of the double-circuit line portion is l2; the method includes:

[0008] Respectively measure the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in a first connection mode, a second connection mode, a third connection mode, a fourth connection mode, a fifth connection mode, a sixth connection mode, a seventh connection mode, and an eighth connection mode;

[0009] According to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode, respectively calculate the four-loop relationship matrix m1 and the double-loop relationship matrix m2; wherein the four-loop relationship matrix m1 is used to reflect the relationship between the head-end electrical parameters of the four-loop part, including the first intermediate matrix A; the double-loop relationship matrix m2 is used to reflect the relationship between the head-end electrical parameters of the double-loop part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2;

[0010] Determine a first impedance parameter and a first admittance parameter of the four-loop portion based on the first intermediate matrix A;

[0011] Based on the first intermediate variable A1 and the second intermediate variable A2, the first double-return characteristic root r is calculated. aand the second double characteristic root r b ;

[0012] According to the first double characteristic root r a , the second double characteristic root r b , a third intermediate variable B1 and a fourth intermediate variable B2, to determine a second impedance parameter and a second admittance parameter of the double loop portion;

[0013] Determine zero-sequence distribution parameters of four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distribution parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance;

[0014] Wherein: the first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0015] The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0016] The third connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0017] The fourth connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the first transmission line, the third transmission line and the fourth transmission line are all normally energized and operated;

[0018] The fifth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0019] The sixth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0020] The seventh connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally;

[0021] The eighth connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally.

[0022] In a second aspect, an embodiment of the present application provides an energized measurement device for zero-sequence distribution parameters of four-circuit non-full-line parallel transmission lines under an asymmetric simplified model, wherein the four-circuit non-full-line parallel transmission lines include a four-circuit line portion and a double-circuit line portion, wherein the four-circuit line portion is composed of a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line, and the length of the four-circuit line portion is l1; the double-circuit line portion is composed of a third transmission line and a fourth transmission line, and the length of the double-circuit line portion is l2; the device includes:

[0023] A zero-sequence electrical parameter measurement module is used to measure the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode, respectively;

[0024] A relationship matrix calculation module is used to calculate the four-circuit relationship matrix m1 and the double-circuit relationship matrix m2 according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode; wherein the four-circuit relationship matrix m1 is used to reflect the relationship between the head-end electrical parameters of the four-circuit part, including the first intermediate matrix A; the double-circuit relationship matrix m2 is used to reflect the relationship between the head-end electrical parameters of the double-circuit part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2;

[0025] A first impedance-admittance parameter determination module, used to determine a first impedance parameter and a first admittance parameter of a four-loop part based on a first intermediate matrix A;

[0026] A double-pass characteristic root determination module is used to calculate the first double-pass characteristic root r based on the first intermediate variable A1 and the second intermediate variable A2. a and the second double characteristic root r b ;

[0027] The second impedance and admittance parameter determination module is used to determine the impedance and admittance parameters according to the first double-loop characteristic root r a , the second double characteristic root r b , a third intermediate variable B1 and a fourth intermediate variable B2, to determine a second impedance parameter and a second admittance parameter of the double loop portion;

[0028] A zero-sequence distribution parameter determination module is used to determine the zero-sequence distribution parameters of the four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distribution parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance;

[0029] Wherein: the first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0030] The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0031] The third connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0032] The fourth connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the first transmission line, the third transmission line and the fourth transmission line are all normally energized and operated;

[0033] The fifth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0034] The sixth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0035] The seventh connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally;

[0036] The eighth connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally.

[0037] In a third aspect, an embodiment of the present application provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, causes the one or more processors to execute the steps of the energized measurement method for zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model of any of the above-mentioned embodiments.

[0038] In a fourth aspect, an embodiment of the present application provides a computer device, the computer device comprising: one or more processors, and a memory;

[0039] The memory stores computer-readable instructions, which, when executed by one or more processors, execute the steps of the method for live measurement of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model of any of the above-mentioned embodiments.

[0040] In the live measurement method and related device of zero-sequence distribution parameters of four-circuit non-full-line parallel transmission lines under the asymmetric simplified model provided in some embodiments of the present application, the four-circuit non-full-line parallel transmission lines can be divided into a four-circuit line part and a double-circuit line part. In the process of measuring the zero-sequence distribution parameters, the zero-sequence electrical parameters of the head end and the zero-sequence electrical parameters of the end of each transmission line under eight connection modes can be measured respectively, and the relationship between the electrical parameters of the head and end of the four-circuit line part (i.e., the four-circuit relationship matrix) and the relationship between the electrical parameters of the head and end of the double-circuit line part (i.e., the double-circuit relationship matrix) can be determined accordingly. Then, the present application can determine the impedance parameters and admittance parameters of the four-circuit line part according to the first intermediate matrix in the four-circuit relationship matrix, and obtain the impedance parameters and admittance parameters of the double-circuit line part according to the first intermediate variable, the second intermediate variable, the third intermediate variable and the fourth intermediate variable in the double-circuit relationship matrix. Finally, the present application can measure the zero-sequence parameters of the four-circuit non-full-line parallel transmission lines based on the impedance parameters and admittance parameters of the four-circuit line part and the impedance parameters and admittance parameters of the double-circuit line part. In this way, the technical effect of effectively solving the zero-sequence parameters of four non-full-line parallel transmission lines can be achieved, thereby solving the technical problem of being unable to effectively solve the line parameters of multiple non-full-line parallel transmission lines under an asymmetric simplified model, and then obtaining more accurate zero-sequence distribution parameters of four non-full-line parallel transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 One of the flow charts of a method for live measurement of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model in one embodiment;

[0043] Figure 2 2 is a flow chart of a method for live measurement of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model in an embodiment;

[0044] Figure 3 A schematic diagram of a tower structure of four non-full-line parallel transmission lines in one embodiment;

[0045] Figure 4 A schematic diagram of a physical model of four non-full-line parallel transmission lines in one embodiment;

[0046] Figure 5A schematic diagram of a distributed parameter model of a four-circuit portion of a four-circuit non-full-line parallel transmission line in one embodiment;

[0047] Figure 6 A schematic diagram of a distributed parameter model of a double-circuit part of a four-circuit non-full-line parallel transmission line in one embodiment;

[0048] Figure 7 A schematic diagram of a simulation model of four non-full-line parallel transmission lines in one embodiment;

[0049] Figure 8 is a schematic diagram of a comparison of measurement errors of a conventional method when the length of a transmission line changes in an embodiment;

[0050] Fig. 9 FIG. 1 is a diagram of the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] Embodiment 1:

[0053] In some embodiments, Figure 1 As shown, the present application provides a method for measuring zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model. Figure 3 and Figure 4 As shown, the four-circuit non-full-line parallel transmission line may include a four-circuit line section and a double-circuit line section. The four-circuit line section is composed of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line, and the length of the four-circuit line section is l1. That is, the four-circuit line section includes a first transmission line with a length of l1, a second transmission line with a length of l1, a third transmission line with a length of l1 and a fourth transmission line with a length of l1.

[0054] The double-circuit section is composed of the third transmission line and the fourth transmission line, and the length of the double-circuit section is l2. That is, the double-circuit section includes the third transmission line with a length of l2 and the fourth transmission line with a length of l2. It can be determined that the total length of the first transmission line is l1, the total length of the second transmission line is l1, the total length of the third transmission line is l1+l2, and the total length of the fourth transmission line is l1+l2.

[0055] In some optional implementations, the four non-full-line parallel transmission lines may be four non-full-line parallel transmission lines on the same tower.

[0056] The following embodiments are described by taking the method applied to a computer device with data processing function as an example. Figure 1 As shown, the method provided by the present application may include the following steps:

[0057] S102: respectively measuring the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in a first connection mode, a second connection mode, a third connection mode, a fourth connection mode, a fifth connection mode, a sixth connection mode, a seventh connection mode, and an eighth connection mode.

[0058] Among them, the first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all normally energized and operated.

[0059] The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally.

[0060] The third connection mode is that the first transmission line is normally energized and operated, the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the third transmission line and the fourth transmission line are both normally energized and operated.

[0061] The fourth connection mode is that the first transmission line is normally energized and operated, the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the third transmission line and the fourth transmission line are both normally energized and operated.

[0062] The fifth connection mode is that both the first transmission line and the second transmission line are normally energized and operated, the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the fourth transmission line is normally energized and operated.

[0063] The sixth connection mode is that the first transmission line and the second transmission line are both normally energized and operated, the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the fourth transmission line is both normally energized and operated.

[0064] The seventh connection mode is that the first transmission line, the second transmission line and the third transmission line are all energized and operate normally, the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded.

[0065] The eighth connection mode is that the first transmission line, the second transmission line and the third transmission line are all energized and operate normally, the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open.

[0066] Specifically, the zero-sequence electrical parameters at the head end and the zero-sequence electrical parameters at the end of each transmission line can be used to reflect the operating status of the four non-full-line parallel transmission lines. Among them, the zero-sequence electrical parameters at the head end may include the zero-sequence voltage at the head end and the zero-sequence current at the head end, and the zero-sequence electrical parameters at the end end may include the zero-sequence voltage at the end and the zero-sequence current at the end. That is, the present application can measure the zero-sequence voltage at the head end, the zero-sequence current at the head end, the zero-degree voltage at the end, and the zero-degree current at the end of each transmission line under different connection modes.

[0067] In this step, each transmission line can be connected according to the above-mentioned eight connection methods, so that the four non-full-line parallel transmission lines are in a partially energized normal operation state, and the head-end zero-sequence electrical parameters and terminal zero-sequence electrical parameters of the first transmission line, the second transmission line, the third transmission line and the fourth transmission line under the eight connection methods are measured respectively, so as to obtain the head-end zero-degree electrical parameters of each transmission line under different connection methods.

[0068] It should be noted that, for the first transmission line and the second transmission line, their terminal zero-sequence electrical parameters may be the zero-sequence electrical parameters at the line length l1. For the third transmission line and the fourth transmission line, their terminal zero-sequence electrical parameters may be the zero-sequence electrical parameters at the line length l1+l2.

[0069] In some examples, the present application can use a synchronous measurement device to synchronously measure the zero-sequence electrical parameters of the head end of each transmission line and the zero-sequence electrical parameters of the end of each transmission line. For example, the synchronous measurement device can be connected to the line head end of the first transmission line, the line head end of the second transmission line, the line head end of the third transmission line, the line head end of the fourth transmission line, the line end of the first transmission line, the line end of the second transmission line, the line end of the third transmission line, and the line end of the fourth transmission line, and synchronously measure the zero-sequence voltage and zero-sequence current at the head and end of the first transmission line, the zero-sequence voltage and zero-sequence current at the head and end of the second transmission line, the zero-sequence voltage and zero-sequence current at the head and end of the third transmission line, and the zero-sequence voltage and zero-sequence current at the head and end of the fourth transmission line.

[0070] S104: Calculate the four-loop relationship matrix m1 and the double-loop relationship matrix m2 respectively according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode.

[0071] Among them, the four-loop relationship matrix m1 is used to reflect the relationship between the electrical parameters at the beginning and end of the four-loop section, including the first intermediate matrix A. It can be understood that the beginning of the four-loop section can be the beginning of the line, and the end can be the position of the transmission line at the line length l1. For the first transmission line and the second transmission line, the beginning and end of the four-loop section are the beginning and end of the transmission line; for the third transmission line and the fourth transmission line, the beginning of the four-loop section is the beginning of the transmission line, and the end of the four-loop section is the position of the transmission line at a distance of l1 from the beginning of the line. The four-loop relationship matrix m1 can reflect the mathematical relationship between the zero-sequence electrical parameters of each transmission line at the beginning of the four-loop section and the zero-sequence electrical parameters of each transmission line at the end of the four-loop section.

[0072] The dual-circuit relationship matrix m2 is used to reflect the relationship between the electrical parameters at the beginning and end of the dual-circuit part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2. It can be understood that the beginning of the dual-circuit part can be the position of the transmission line at the line length l1, and the end of the dual-circuit part can be the position of the transmission line at the line length l1+l2. The dual-circuit relationship matrix m2 can reflect the mathematical relationship between the zero-sequence electrical parameters of the third transmission line and the fourth transmission line in the dual-circuit part and the zero-sequence electrical parameters of the third transmission line and the fourth transmission line in the dual-circuit part.

[0073] In this step, the four-loop relationship matrix m1 and the double-loop relationship matrix m2 can be determined according to the zero-sequence electrical parameters of the first end of the first transmission line in eight connection modes, the zero-sequence electrical parameters of the terminal of the first transmission line in eight connection modes, the zero-sequence electrical parameters of the second transmission line in eight connection modes, the zero-sequence electrical parameters of the terminal of the second transmission line in eight connection modes, the zero-sequence electrical parameters of the first end of the third transmission line in eight connection modes, the zero-sequence electrical parameters of the terminal of the third transmission line in eight connection modes, the zero-sequence electrical parameters of the first end of the fourth transmission line in eight connection modes, and the zero-sequence electrical parameters of the terminal of the fourth transmission line in eight connection modes.

[0074] In some optional implementations, S104 may include step A1 and step A2, wherein:

[0075] Step A1: Determine the head-end electrical parameter relationship matrix M of the four non-full-line parallel transmission lines according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode.

[0076] Among them, the head-end electrical parameter relationship matrix M is used to reflect the mathematical relationship between the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the four non-full-line parallel transmission lines. It should be noted that in the four non-full-line parallel transmission lines, the end of the first transmission line and the end of the second transmission line are both at the position of the line length l1, and the end of the third transmission line and the end of the fourth transmission line are both at the position of the line length l1+l2.

[0077] In this step, the head-end electrical parameter relationship matrix M of the four non-full-line parallel transmission lines can be determined based on the head-end zero-sequence electrical parameters of each transmission line under the eight connection modes. In some optional embodiments, the head-end electrical parameter relationship matrix M can be obtained by using the following expression:

[0078]

[0079] In the formula, the superscript of each vector indicates the connection mode, the number in the subscript is the transmission line identifier, the "s" in the subscript indicates the zero-sequence electrical parameter at the head end, the "p" in the subscript indicates the zero-sequence electrical parameter at the end, U indicates the zero-sequence voltage, and I indicates the zero-sequence current.

[0080] by , , , For example, represents the terminal zero-sequence voltage of the first transmission line in the first connection mode, represents the zero-sequence voltage at the first end of the fourth transmission line in the third connection mode, represents the zero-sequence current at the first end of the second transmission line in the seventh connection mode, Represents the terminal zero-sequence current of the third transmission line in the fifth connection mode.

[0081] Step A2: Based on the head-end electrical parameter relationship matrix M and the preset constraints, the function Solve and obtain the four-loop relationship matrix m1 and the two-loop relationship matrix m2.

[0082] Among them, the four-loop relationship matrix m1 is , B is the second intermediate matrix, C is the third intermediate matrix, and D is the fourth intermediate matrix. The double-loop relationship matrix m2 is .

[0083] In some optional embodiments, due to the existence of the first intermediate matrix A and the fourth intermediate matrix D , that is, the first intermediate matrix A is the transposed matrix of the fourth intermediate matrix D, so the preset constraint relationship can be:

[0084]

[0085]

[0086] In the formula, is the element in the third row and third column of the first intermediate matrix A, is the element in the third row and third column of the fourth intermediate matrix D, is the element in the third row and fourth column of the first intermediate matrix A, is the element in the fourth row and third column of the fourth intermediate matrix D, is the element in the second row and third column of the first intermediate matrix A, is the element in the third row and second column of the fourth intermediate matrix D, is the element in the second row and fourth column of the first intermediate matrix A, is the element in the fourth row and second column of the fourth intermediate matrix D.

[0087] In this step, when the head-end electrical parameter relationship matrix M is determined, the function Solve to obtain the four-loop relationship matrix m1 and the two-loop relationship matrix m2.

[0088] S106: Based on the first intermediate matrix A, determine a first impedance parameter and a first admittance parameter of the four-loop part.

[0089] The first impedance parameter refers to the impedance parameter of the four-loop portion, which is used to indicate the impedance characteristics of the four-loop portion, which can be represented in the form of a matrix. The first admittance parameter is the admittance parameter of the four-loop portion, which is used to indicate the admittance characteristics of the four-loop portion, which can be represented in the form of a matrix.

[0090] In this step, considering that the zero-sequence parameters of the four-circuit part and the double-circuit part of the non-all-parallel four-circuit transmission line are different due to the difference in electromagnetic coupling, the two sections have different zero-sequence parameters. Therefore, the zero-sequence distribution parameters can be defined for the two different sections.

[0091] For the impedance parameters of the four-loop section, the distributed zero-sequence self-impedance per unit length of each transmission line can be determined according to the first intermediate matrix A. For example, the distributed zero-sequence self-impedance per unit length of the first transmission line in the four-loop section is calculated respectively: , the zero-sequence self-impedance per unit length of the second transmission line in the four-loop section is , the zero-sequence self-impedance per unit length of the third transmission line in the four-loop section is , the zero-sequence self-impedance per unit length of the fourth transmission line in the four-loop section is .

[0092] For the impedance parameters of the four-loop section, the unit length distributed zero-sequence mutual impedance between each transmission line and the remaining transmission lines in the four-loop section can also be determined according to the first intermediate matrix A. For example, the unit length distributed zero-sequence mutual impedance of the first transmission line and the second transmission line can be determined respectively , the distributed zero-sequence mutual impedance per unit length of the first transmission line and the third transmission line , the distributed zero-sequence mutual impedance per unit length of the first transmission line and the fourth transmission line , the distributed zero-sequence mutual impedance per unit length of the second transmission line and the third transmission line , the distributed zero-sequence mutual impedance per unit length of the second transmission line and the fourth transmission line , the distributed zero-sequence mutual impedance per unit length of the third transmission line and the fourth transmission line .

[0093] This step can generate a line impedance parameter matrix (i.e., first impedance parameter) of the four-loop section of the four-loop non-full-line parallel transmission line according to the unit length distributed zero-sequence self-impedance of each transmission line and the unit length distributed zero-sequence mutual impedance between each transmission line and the remaining transmission lines in the four-loop section of the four-loop non-full-line parallel transmission line. Exemplarily, the line impedance parameter matrix of the four-loop section can be:

[0094]

[0095] For the admittance parameters of the four-loop part, the distributed zero-sequence self-admittance per unit length of each transmission line can be determined according to the first intermediate matrix A. For example, the distributed zero-sequence self-admittance per unit length of the first transmission line can be determined respectively , the distributed zero-sequence self-admittance per unit length of the second transmission line , the third transmission line unit length distributed zero sequence self-admittance , the distributed zero-sequence self-admittance per unit length of the fourth transmission line .

[0096] For the admittance parameters of the four-loop section, the distributed zero-sequence mutual admittance per unit length between each transmission line and the remaining transmission lines in the four-loop section of the four-loop non-full-line parallel transmission line can also be determined according to the first intermediate matrix A. For example, the distributed zero-sequence mutual admittance per unit length of the first transmission line and the second transmission line can be determined respectively: , the distributed zero-sequence mutual admittance per unit length of the first transmission line and the third transmission line , the distributed zero-sequence mutual admittance per unit length of the first transmission line and the fourth transmission line , the distributed zero-sequence mutual admittance per unit length of the second transmission line and the third transmission line , the distributed zero-sequence mutual admittance per unit length of the second transmission line and the fourth transmission line , the distributed zero-sequence mutual admittance per unit length of the third transmission line and the fourth transmission line .

[0097] In this step, the admittance parameter matrix (i.e., the first admittance parameter) of the four-loop part of the four-loop non-full-line parallel transmission line can be generated according to the zero-sequence self-admittance per unit length of each transmission line and the distributed zero-sequence mutual admittance per unit length between each transmission line and the remaining transmission lines in the four-loop part of the four-loop non-full-line parallel transmission line. Exemplarily, the line admittance parameter matrix of the four-loop part of the four-loop non-full-line parallel transmission line can be:

[0098]

[0099] In some optional implementations, S106 may include step B1, step B2, and step B3, wherein:

[0100] Step B1: According to the first eigenvalue of the first intermediate matrix A , the second eigenvalue , the third eigenvalue and the fourth eigenvalue , calculate the fourth eigenvalue of matrix T , the fifth eigenvalue , the sixth eigenvalue and the seventh eigenvalue ;in, , Z is the first impedance parameter, and Y is the first admittance parameter.

[0101] In some optional embodiments, the eigenvalues ​​of the matrix T may be calculated using the following expression:

[0102]

[0103] Where arch is the inverse hyperbolic cosine function.

[0104] Step B2: According to the fourth eigenvalue , the fifth eigenvalue , the sixth eigenvalue and the seventh eigenvalue , the first impedance parameter Z is calculated using the following expression:

[0105]

[0106] Where B is the second intermediate matrix; P is the matrix composed of the eigenvectors of matrix T, is the inverse matrix of P, sh is the hyperbolic sine function; x is the distance from the position to be solved of the transmission line to the end of the four-loop part, and the value range of x is [0, l1].

[0107] Step B3: Based on the first impedance parameter Z, use the expression The first admittance parameter Y is calculated; where, is the inverse matrix of Z.

[0108] S108: Calculate the first double-return characteristic root r based on the first intermediate variable A1 and the second intermediate variable A2 a and the second double characteristic root r b .

[0109] Among them, the first double characteristic root r a and the second double characteristic root r b For the matrix The two characteristic roots of the matrix ,in, is the second impedance parameter, is the second admittance parameter, is the first transformation parameter, is the second transformation parameter.

[0110] In some optional implementations, this step can use the following expressions to calculate the first double-return characteristic root r a and the second double characteristic root r b :

[0111]

[0112] Where cosh is the hyperbolic cosine function.

[0113] S110: According to the first double-return characteristic root r a , the second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, determine the second impedance parameter and the second admittance parameter of the double-loop part.

[0114] In the figure, the second impedance parameter refers to the impedance parameter of the dual-loop part, which is used to indicate the impedance characteristics of the dual-loop part, which can be represented in the form of a matrix. The second admittance parameter is the admittance parameter of the dual-loop part, which is used to indicate the admittance characteristics of the dual-loop part, which can be represented in the form of a matrix.

[0115] In this step, the line impedance parameters of the double-circuit part can be calculated based on the first double-circuit characteristic root r a , the second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, respectively determine the unit length distributed zero-sequence self-impedance of the double-circuit portion of the third transmission line and the fourth transmission line, and the unit length distributed zero-sequence mutual impedance of the double-circuit portion of the third transmission line and the fourth transmission line. For example, the unit length distributed zero-sequence self-impedance of the double-circuit portion of the third transmission line and the fourth transmission line can be determined , and the distributed zero-sequence mutual impedance per unit length of the double-circuit section of the third transmission line and the fourth transmission line .

[0116] In addition, this step can generate a line impedance parameter matrix (i.e., a second impedance parameter) of the double-circuit portion according to the unit length distributed zero-sequence self-impedance of the double-circuit portion of the third transmission line and the fourth transmission line and the unit length distributed zero-sequence mutual impedance of the double-circuit portion of the third transmission line and the fourth transmission line. For example, the line impedance parameter matrix of the double-circuit portion of the four-circuit non-full-line parallel transmission line is Can be:

[0117]

[0118] For the line admittance parameters of the double-circuit part, the first double-circuit characteristic root r a , the second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, respectively determine the unit length distributed zero-sequence self-admittance of the double-circuit part of the third transmission line and the fourth transmission line , and the distributed zero-sequence mutual admittance per unit length of the double-circuit section of the third transmission line and the fourth transmission line .

[0119] The present application can generate a line admittance parameter matrix of the double-circuit portion according to the unit length distributed zero-sequence self-admittance of the double-circuit portion of the third transmission line and the fourth transmission line and the unit length distributed zero-sequence mutual admittance of the double-circuit portion of the third transmission line and the fourth transmission line. For example, the line admittance parameter matrix of the double-circuit portion is Can be:

[0120]

[0121] In some optional embodiments, S110 includes step C1, step C2 and step C3, wherein:

[0122] Step C1: According to the first double-return characteristic root r a and the second double characteristic root r b , the first transformation parameters are determined by the following expressions: and the second transformation parameter :

[0123]

[0124] Step C2: According to the first double characteristic root r a , the second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, the second impedance parameter is determined by the following expression :

[0125]

[0126]

[0127] In the formula, is the distributed zero-sequence self-impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section; is the distributed zero-sequence mutual impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit section; sinh is a hyperbolic sine function;

[0128] Step C3: According to the first transformation parameter , the second transformation parameter and the second impedance parameter , the second admittance parameter is determined using the following expression :

[0129]

[0130]

[0131] In the formula, is the distributed zero-sequence self-admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit section; It is the distributed zero-sequence mutual admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit section.

[0132] S112: Determine zero-sequence distributed parameters of four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distributed parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance.

[0133] In this step, Kirchhoff's principle can be used to analyze the line impedance parameter matrix and the admittance parameter matrix to determine the zero-sequence parameters of the four non-full-line parallel transmission lines.

[0134] In some optional embodiments, this step may use the following expression to determine the zero-sequence distribution parameters of four non-full-line parallel transmission lines:

[0135]

[0136] In the formula, is the distributed zero-sequence impedance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence resistance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence inductance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence admittance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence capacitance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence self-impedance per unit length of the third and fourth transmission lines in the double-circuit section, is the distributed zero-sequence mutual impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence self-admittance per unit length of the third and fourth transmission lines in the double-circuit section, is the distributed zero-sequence mutual admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence self-resistance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence mutual resistance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence self-inductance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence mutual inductance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence self-capacitance per unit length of the third transmission line and the fourth transmission line in the double-circuit section, is the distributed zero-sequence mutual capacitance per unit length of the third transmission line and the fourth transmission line in the double-circuit section.

[0137] For example, the following expressions can be used to calculate the zero-sequence resistance, zero-sequence inductance and zero-sequence capacitance of four non-full-line parallel transmission lines:

[0138]

[0139] In the formula, is the distributed zero-sequence self-resistance per unit length of the first transmission line, is the distributed zero-sequence self-resistance per unit length of the second transmission line, is the distributed zero-sequence self-resistance per unit length of the third transmission line, is the distributed zero-sequence self-resistance per unit length of the fourth transmission line, is the distributed zero-sequence self-resistance per unit length of the double-circuit line of the third transmission line and the fourth transmission line, is the zero-sequence mutual resistance per unit length between the first transmission line and the second transmission line, is the zero-sequence mutual resistance per unit length of the first transmission line and the third transmission line, is the zero-sequence mutual resistance per unit length of the first transmission line and the fourth transmission line, is the zero-sequence mutual resistance per unit length between the second transmission line and the third transmission line, is the zero-sequence mutual resistance per unit length of the second transmission line and the fourth transmission line, is the distributed zero-sequence mutual resistance per unit length of the third transmission line and the fourth transmission line, It is the zero-sequence mutual resistance per unit length of the double-circuit part of the third transmission line and the fourth transmission line.

[0140] is the distributed zero-sequence self-inductance per unit length of the first transmission line, is the distributed zero-sequence self-inductance per unit length of the second transmission line, is the distributed zero-sequence self-inductance per unit length of the third transmission line, is the distributed zero-sequence self-inductance per unit length of the fourth transmission line, is the distributed zero-sequence self-inductance per unit length of the double-circuit line of the third transmission line and the fourth transmission line, is the distributed zero-sequence mutual inductance per unit length between the first transmission line and the second transmission line, is the distributed zero-sequence mutual inductance per unit length of the first transmission line and the third transmission line, is the distributed zero-sequence mutual inductance per unit length of the first transmission line and the fourth transmission line, is the distributed zero-sequence mutual inductance per unit length between the second transmission line and the third transmission line, is the distributed zero-sequence mutual inductance per unit length of the second transmission line and the fourth transmission line, is the distributed zero-sequence mutual inductance per unit length of the third transmission line and the fourth transmission line, It is the distributed zero-sequence mutual inductance per unit length of the double-circuit part of the third transmission line and the fourth transmission line.

[0141] is the distributed zero-sequence self-capacitance per unit length of the first transmission line, is the distributed zero-sequence self-capacitance per unit length of the second transmission line, is the distributed zero-sequence self-capacitance per unit length of the third transmission line, is the distributed zero-sequence self-capacitance per unit length of the fourth transmission line, is the distributed zero-sequence self-capacitance per unit length of the double-circuit portion of the third transmission line and the fourth transmission line, is the distributed zero-sequence mutual capacitance per unit length between the first transmission line and the second transmission line, is the zero-sequence mutual capacitance per unit length between the first transmission line and the third transmission line, is the distributed zero-sequence mutual capacitance per unit length between the first transmission line and the fourth transmission line, is the distributed zero-sequence mutual capacitance per unit length between the second transmission line and the third transmission line, is the distributed zero-sequence mutual capacitance per unit length between the second transmission line and the fourth transmission line, is the distributed zero-sequence mutual capacitance per unit length between the third transmission line and the fourth transmission line, It is the distributed zero-sequence mutual capacitance per unit length of the double-circuit portion of the third transmission line and the fourth transmission line.

[0142] In the above embodiment, the four-loop non-full-line parallel transmission line can be divided into a four-loop part and a double-loop part. In the process of measuring the zero-sequence distributed parameters, the zero-sequence electrical parameters of the head end and the terminal zero-sequence electrical parameters of each transmission line under eight connection modes can be measured respectively, and the relationship between the electrical parameters of the head and terminal of the four-loop part (i.e., the four-loop relationship matrix) and the relationship between the electrical parameters of the head and terminal of the double-loop part (i.e., the double-loop relationship matrix) can be determined accordingly. Then, the present application can determine the impedance parameters and admittance parameters of the four-loop part according to the first intermediate matrix in the four-loop relationship matrix, and obtain the impedance parameters and admittance parameters of the double-loop part according to the first intermediate variable, the second intermediate variable, the third intermediate variable and the fourth intermediate variable in the double-loop relationship matrix. Finally, the present application can measure the zero-sequence parameters of the four-loop non-full-line parallel transmission lines based on the impedance parameters and admittance parameters of the four-loop part and the impedance parameters and admittance parameters of the double-loop part. In this way, the technical effect of effectively solving the zero-sequence parameters of four non-full-line parallel transmission lines can be achieved, thereby solving the technical problem of being unable to effectively solve the line parameters of multiple non-full-line parallel transmission lines under an asymmetric simplified model, and then obtaining more accurate zero-sequence distribution parameters of four non-full-line parallel transmission lines.

[0143] The method of the above embodiment is further introduced below.

[0144] For example, for the four-circuit part of the four-circuit non-full-line parallel transmission line, the line impedance parameter matrix and the admittance parameter matrix are analyzed, and the line transmission line equation can be determined as follows:

[0145]

[0146]

[0147] In the formula, , is the terminal voltage on the four-circuit partial infinitesimal element dx of the four-circuit parallel transmission line. Among them, , , , They are the terminal voltages of the first transmission line, the second transmission line, the third transmission line and the fourth transmission line on the four-loop line part infinitesimal element dx respectively. , is the current on the microelement dx of the four-circuit partial parallel transmission line, , , , are the currents on the four-loop line elements dx of the first transmission line, the second transmission line, the third transmission line and the fourth transmission line respectively. It is the voltage drop on the microelement dx of the four-circuit partial parallel transmission line.

[0148] Optionally, the third formula and the fourth formula can be obtained by taking the derivative of both sides of the line transmission line equation and simplifying them according to the second formula;

[0149] The second formula is:

[0150]

[0151] The third formula is:

[0152] The fourth formula is:

[0153] The third formula and the fourth formula are solved in the same way. In this embodiment, the solution of the third formula is taken as an example for explanation.

[0154] Take Laplace transform on both sides of the third formula, and substitute the zero-sequence voltage and zero-sequence current at the end of the four-circuit part of the four-circuit non-full-line parallel transmission line to obtain the fifth formula;

[0155] The fifth formula is:

[0156] Where: is the voltage at the end of the first transmission line, is the voltage at the end of the second transmission line, is the voltage at the end of the four-circuit section of the third transmission line, is the voltage at the end of the four-circuit section of the fourth transmission line, is the current at the end of the first transmission line, is the current at the end of the second transmission line, is the current at the end of the four-circuit section of the third transmission line, is the current at the end of the four-circuit section of the fourth transmission line, is the fourth-order unit matrix. In the fifth formula The modulus can be expressed as the sixth formula;

[0157] The sixth formula is:

[0158] in, is the eigenvalue of the matrix T, The physical meaning of is the propagation coefficient of the four-circuit part of the four-circuit non-full-line parallel transmission line in the embodiment.

[0159] According to the matrix P composed of the eigenvectors corresponding to the matrix in the second formula, the seventh formula is obtained:

[0160]

[0161] Perform an inverse Laplace transform on both sides of the equal sign of the fifth formula, and Substituting in, we can get the eighth formula:

[0162]

[0163] In the formula, is the voltage at the end of the first transmission line, is the voltage at the end of the second transmission line, is the voltage at the end of the third transmission line, is the voltage at the end of the fourth transmission line, is the current at the end of the first transmission line, is the current at the end of the second transmission line, is the current at the end of the third transmission line, is the current at the end of the fourth transmission line.

[0164] The matrix A in the eighth formula can be expressed by the ninth formula:

[0165]

[0166] From the ninth formula, we can get that matrix A and matrix T have the same eigenvector, and the eigenvalues ​​of the matrices are: .

[0167] The matrix B in the eighth formula can be expressed by the tenth formula, which is:

[0168]

[0169] The fourth formula is inverse Laplace transformed and Substituting in, we can get the eleventh formula, which is:

[0170]

[0171] The matrix C and matrix D in the eleventh formula are solved in the same way as the matrix A and matrix B, and the matrix C and matrix D have the following relationship: .

[0172] Thus, the mathematical model of the relationship between the zero-sequence distribution parameters of the four-circuit non-full-line parallel transmission line and the voltage and current at the beginning and end of the line can be obtained, which is expressed as the twelfth formula. The twelfth formula is:

[0173]

[0174] For the double-circuit part of the four-circuit non-full-line parallel transmission line, the line impedance parameter matrix and the admittance parameter matrix are analyzed, and the line transmission line equation can be determined as follows:

[0175]

[0176] In the formula, and They are respectively the terminal voltages of the third transmission line and the fourth transmission line on the double-circuit line section infinitesimal element dx. and They are the currents of the third transmission line and the fourth transmission line on the double-circuit line part infinitesimal element dx respectively. and It is the voltage drop of the third transmission line and the fourth transmission line on the microelement dx of the double-circuit line section.

[0177] Optionally, by taking the derivative of both sides of the transmission line equation of the double-circuit line, the thirteenth and fourteenth formulas can be obtained. The thirteenth formula is:

[0178] In the formula, .

[0179] The fourteenth formula is:

[0180] In the formula, .

[0181] The solution method of the thirteenth formula is the same as that of the fourteenth formula. In this embodiment, the solution of the thirteenth formula is taken as an example for explanation.

[0182] Taking Laplace transform on both sides of the thirteenth formula, and substituting into the zero-sequence voltage and zero-sequence current at the end of the double-circuit part of the four non-full-line parallel transmission lines, the fifteenth formula is obtained, which is:

[0183]

[0184] In the fifteenth formula: E is the second-order identity matrix, The modulus can be expressed as the sixteenth formula, which is:

[0185]

[0186] In the formula, and It can be defined by the seventeenth formula; , For the matrix The two characteristic roots of , and the eighteenth formula can be derived to get , , and The quantitative relationship between them.

[0187] The seventeenth formula is:

[0188] The eighteenth formula is:

[0189] Perform an inverse Laplace transform on both sides of the equal sign of the fifteenth formula, and Substituting in, we can get the nineteenth formula, which is:

[0190]

[0191] Similarly, solving the fourteenth formula can give the twentieth formula, which is:

[0192]

[0193] It should be noted that the , , and They are all intermediate variables, only used for formula derivation, and are not measured data.

[0194] Thus, the mathematical model of the relationship between the zero-sequence distribution parameters of the double-circuit part of the four-circuit non-full-line parallel transmission line and the voltage and current at the beginning and end of the line can be obtained, which is expressed as the twenty-first formula. The twenty-first formula is:

[0195]

[0196] In the formula, , , , , , is an intermediate variable and can be expressed as Formula 22, Formula 23 and Formula 24.

[0197] The 22nd formula is:

[0198]

[0199] The twenty-third formula is:

[0200]

[0201] The twenty-fourth formula is:

[0202]

[0203] Optionally, since the transmission equation of the four-circuit part of the four-circuit non-full-line parallel transmission line is an eighth-order matrix, it is rewritten as an eighth-order matrix according to the transmission equation of the double-circuit part of the four-circuit non-full-line parallel transmission line, and expressed as the twenty-fifth formula, the twenty-fifth formula is:

[0204]

[0205] Optionally, according to the twelfth formula and the twenty-fifth formula, a mathematical model of the relationship between the zero-sequence distribution parameters of four non-full-line parallel transmission lines and the voltage and current at the beginning and end of the line can be obtained, which is expressed as the twenty-sixth formula. The twenty-sixth formula is:

[0206]

[0207] Optionally, the head-end zero-sequence voltage and head-end zero-sequence current of each transmission line obtained under the eight connection modes, and the terminal zero-sequence voltage and terminal zero-sequence current of each transmission line obtained under the eight connection modes in this embodiment are substituted into the twenty-seventh formula to obtain the matrix M.

[0208] The twenty-seventh formula is:

[0209]

[0210] In the formula, the meaning of the relevant parameters can be found in the above text and will not be repeated in this article.

[0211] Optionally, the twenty-eighth formula can be used to obtain , the twenty-eighth formula is:

[0212]

[0213] Optionally, since the first intermediate matrix A and the fourth intermediate matrix D exist In this embodiment, the simultaneous equations yield the twenty-ninth formula, which is:

[0214]

[0215] Optionally, the relationship between the intermediate variables A1, A2, B1, B2, C1 and C2 can be expressed as a 30th formula, which is:

[0216]

[0217] Optionally, six intermediate variables A1, A2, B1, B2, C1 and C2 can be obtained by solving any six equations in the twenty-ninth formula and the thirtieth formula.

[0218] Optionally, by substituting the intermediate variables A1, A2, B1, B2, C1 and C2 into the twenty-eighth formula, the matrix .

[0219] Optionally, the eigenvalues ​​of the matrix A are Substitute into the 31st formula to calculate the eigenvalue of matrix T .

[0220] The thirty-first formula is:

[0221]

[0222] Optionally, the matrix T is calculated according to the thirty-second formula, and the thirty-second formula is:

[0223]

[0224] Optionally, the matrix Z is calculated according to the thirty-third formula, and the thirty-third formula is:

[0225]

[0226] Optionally, the matrix Y is calculated according to the thirty-fourth formula, which is: .

[0227] Optionally, two characteristic roots of the matrix T0 can be calculated according to the 22nd formula: , , expressed as the thirty-fifth formula:

[0228]

[0229] The two eigenvalues ​​of matrix T0 , Substituting into the 36th formula, we can get the transformation parameters and , where the thirty-sixth formula is:

[0230]

[0231] Optionally, according to the twenty-third formula, it can be calculated that and , expressed as the thirty-seventh formula:

[0232]

[0233] Optionally, according to the seventeenth formula, it can be calculated that and , expressed as the thirty-eighth formula:

[0234]

[0235] Optionally, the calculation of the zero-sequence resistance, zero-sequence inductance and zero-sequence capacitance of the four non-full-line parallel transmission lines may refer to the description of the above embodiment, and the present application will not go into details here.

[0236] Embodiment 2:

[0237] The technical solution of the embodiment of the present invention is illustrated below in conjunction with preferred implementation modes.

[0238] The embodiment of the present invention proposes a method for measuring zero-sequence distributed parameters of four-circuit non-full-line parallel transmission lines, by measuring the zero-sequence voltage and zero-sequence current at the beginning and end of each transmission line in the four-circuit non-full-line parallel transmission lines, and then constructing a line impedance parameter matrix and an admittance parameter matrix according to the zero-sequence voltage and zero-sequence current at the beginning and end of each transmission line, and then mathematically deriving and solving the line impedance parameter matrix and the admittance parameter matrix to obtain the zero-sequence parameters of the four-circuit non-full-line parallel transmission lines, which can achieve the technical effect of effectively solving the zero-sequence parameters of the four-circuit non-full-line parallel transmission lines, and then solve the technical problem that the line parameters of multiple non-full-line parallel transmission lines under an asymmetric simplified model cannot be effectively solved.

[0239] Figure 2 The illustrated embodiment is based on an engineering application scenario, and proposes a method for measuring the zero-sequence distributed parameters of four non-full-line parallel transmission lines, further improving the method for measuring the distributed parameters of four non-full-line parallel transmission lines, overcoming the drawback of large measurement errors caused by measuring long lines using the traditional method based on a centralized parameter model, and can measure multiple zero-sequence parameters such as zero-sequence resistance, zero-sequence inductance, and zero-sequence capacitance at one time, with a measurement accuracy much higher than that of traditional measurement methods, meeting the actual design needs of the project.

[0240] Figure 2 The present invention is a flowchart of a method for accurately measuring zero-sequence distributed parameters of four non-full-line parallel transmission lines according to an embodiment of the present invention, and the process includes the following steps:

[0241] Step 201, defining a transmission line.

[0242] Optionally, Figure 3 is a schematic diagram of a tower structure of four non-full-line parallel transmission lines according to an embodiment of the present invention, wherein the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line are as follows Figure 3 shown.

[0243] Step 202, defining the connection mode.

[0244] The connection modes include a first connection mode, a second connection mode, a third connection mode, a fourth connection mode, a fifth connection mode, a sixth connection mode, a seventh connection mode, and an eighth connection mode.

[0245] Optionally, the first connection mode is: the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, the second transmission line is energized normally, the third transmission line is energized normally, and the fourth transmission line is energized normally.

[0246] Optionally, the second connection mode is: the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, the second transmission line operates normally with power, the third transmission line operates normally with power, and the fourth transmission line operates normally with power.

[0247] Optionally, the third connection mode is: the first transmission line is energized normally, the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, the third transmission line is energized normally, and the fourth transmission line is energized normally.

[0248] Optionally, the fourth connection mode is: the first transmission line is energized and operates normally, the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, the third transmission line is energized and operates normally, and the fourth transmission line is energized and operates normally.

[0249] Optionally, the fifth connection mode is: the first transmission line is energized and operates normally, the second transmission line is energized and operates normally, the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the fourth transmission line is energized and operates normally.

[0250] Optionally, the sixth connection mode is: the first transmission line is energized and operates normally, the second transmission line is energized and operates normally, the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the fourth transmission line is energized and operates normally.

[0251] Optionally, the seventh connection mode is: the first transmission line is energized normally, the second transmission line is energized normally, the third transmission line is energized normally, the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded.

[0252] Optionally, the eighth connection mode is: the first transmission line is energized normally, the second transmission line is energized normally, the third transmission line is energized normally, the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open.

[0253] Step 203, calculating the zero-sequence component under different zero-sequence connection modes.

[0254] In this embodiment, the zero-sequence components under different zero-sequence connection modes include: the zero-sequence voltage and zero-sequence current at the head end of the first transmission line under different zero-sequence connection modes, and the zero-sequence voltage and zero-sequence current at the end of the first transmission line under different zero-sequence connection modes; the zero-sequence voltage and zero-sequence current at the head end of the second transmission line under different zero-sequence connection modes, and the zero-sequence voltage and zero-sequence current at the end of the second transmission line under different zero-sequence connection modes; the zero-sequence voltage and zero-sequence current at the head end of the third transmission line under different zero-sequence connection modes, and the zero-sequence voltage and zero-sequence current at the end of the third transmission line under different zero-sequence connection modes; the zero-sequence voltage and zero-sequence current at the head end of the fourth transmission line under different zero-sequence connection modes, and the zero-sequence voltage and zero-sequence current at the end of the fourth transmission line under different zero-sequence connection modes.

[0255] Optionally, Figure 5 It is a schematic diagram of a partial distributed parameter model of four-circuit parallel transmission lines according to an embodiment of the present invention.

[0256] Under different connection modes, the zero-sequence voltage at the head end of the first transmission line is: ; The zero-sequence current at the head end of the first transmission line under different connection modes is: ; The zero-sequence voltage at the head end of the second transmission line under different connection modes is: ; The zero-sequence current at the head end of the second transmission line under different connection modes is: ; The zero-sequence voltage at the head end of the third transmission line under different connection modes is: ; The zero-sequence current at the head end of the third transmission line under different connection modes is: ; The zero-sequence voltage at the head end of the fourth transmission line under different connection modes is: ; The zero-sequence current at the head end of the fourth transmission line under different connection modes is: .

[0257] Under different connection modes, the zero-sequence voltage at the end of the first transmission line is: ; The zero-sequence voltage at the end of the second transmission line under different connection modes is: ; The zero-sequence voltage at the end of the third transmission line under different connection modes is: ; The zero-sequence voltage at the end of the fourth transmission line under different connection modes is: .

[0258] Optionally, Figure 6 It is a schematic diagram of a partial distributed parameter model of a double-circuit line of four non-full-line parallel transmission lines according to an embodiment of the present invention.

[0259] Optionally, the zero-sequence voltage at the head end of the third transmission line under different connection modes is: ; The zero-sequence current at the head end of the third transmission line under different connection modes is: ; The zero-sequence voltage at the head end of the fourth transmission line under different connection modes is: ; The zero-sequence current at the head end of the fourth transmission line under different connection modes is: .

[0260] The zero-sequence voltage at the end of the third transmission line under different connection modes is: ; The zero-sequence current at the end of the third transmission line under different connection modes is: ; The zero-sequence voltage at the end of the fourth transmission line under different connection modes is: ; The zero-sequence current at the end of the fourth transmission line under different connection modes is: .

[0261] Step 204, calculating an intermediate matrix according to the zero-sequence component.

[0262] In this embodiment, the intermediate variables A1, A2, B1, B2, C1 and C2, as well as the intermediate matrix are calculated according to the measured line head end voltage value, terminal end voltage value, head end current value and terminal end current value. .

[0263] Optionally, the intermediate variables A1, A2, B1, B2, C1 and C2 and the intermediate matrix The calculation of can refer to the aforementioned Formulas 27 to 30, which will not be repeated here.

[0264] Step 205, calculating the eigenvalues ​​of the intermediate matrix.

[0265] In this embodiment, the eigenvalues ​​of the matrix are calculated ; Calculate the eigenvalues ​​of matrix T based on the eigenvalues ​​of matrix A ; while calculating the matrix The two characteristic roots of , .

[0266] Optionally, the calculation of the eigenvalues ​​of the calculation matrix T can refer to the aforementioned formula 31. The calculation of the characteristic roots of can refer to the aforementioned formula 35, which will not be repeated here.

[0267] Step 206, calculating the transformation matrix and transformation parameters.

[0268] In this embodiment, the transformation matrix T is calculated based on the matrix P formed by the eigenvalues ​​of the matrix A; The characteristic root calculation transformation parameters and .

[0269] Optionally, the calculation of the transformation matrix T can refer to the aforementioned formula 32, and the transformation parameters and The calculation of can refer to the aforementioned Formula 36, ​​which will not be repeated here.

[0270] Step 207, calculating line impedance parameters and line admittance parameters of four non-full-line parallel transmission lines.

[0271] In this embodiment, the impedance parameters of the four-circuit partial line of the four-circuit parallel transmission line are calculated according to the matrix Z; the admittance parameters of the four-circuit partial line of the four-circuit parallel transmission line are calculated according to the matrix Y; and Calculate the impedance parameters of the double-circuit part of the four-circuit parallel transmission line; and Calculate the line admittance parameters of the double-circuit portion of four non-full-line parallel transmission lines.

[0272] Optionally, the calculation of the line impedance parameters and line admittance parameters of the four-circuit portion of the four-circuit non-full-line parallel transmission lines can refer to the aforementioned Formula 33 and Formula 34, and the calculation of the line impedance parameters and line admittance parameters of the double-circuit portion of the four-circuit non-full-line parallel transmission lines can refer to the aforementioned Formula 37 and Formula 38, which will not be repeated here.

[0273] Step 208, calculating the zero-sequence resistance, zero-sequence inductance and zero-sequence capacitance of the four non-full-line parallel transmission lines according to the line impedance parameters and the line admittance parameters.

[0274] Optionally, the calculation of the zero-sequence resistance, zero-sequence inductance and zero-sequence capacitance of the four non-full-line parallel transmission lines may refer to the introduction of the aforementioned step S112, which will not be repeated here.

[0275] In this embodiment, according to Figure 1 The tower structure diagram of the four non-full-line parallel transmission lines shown in the figure is used to establish a simulation model in PSCAD. Figure 7 1 is a schematic diagram of a PSCAD simulation model of a four-circuit non-full-line parallel transmission line according to an embodiment of the present invention. Table 1 is an example table of theoretical values ​​of unit length of a transmission line, reflecting the theoretical values ​​of unit length of a transmission line.

[0276] Table 1 Example of theoretical values ​​of zero-sequence distribution parameters for four non-full-line parallel transmission lines

[0277]

[0278] Optionally, the simulation sets the length l2 of the double-circuit part of the four-circuit non-full-line parallel transmission line to be unchanged at 100 km, and changes the length l1 of the four-circuit part of the four-circuit non-full-line parallel transmission line from 200 km to 500 km. The measurement results obtained by measuring using the method of the present invention are shown in Table 2, Table 3, and Table 4. Table 2 is an example table of zero-sequence resistance simulation measurement results, Table 3 is an example table of zero-sequence inductance simulation measurement results, and Table 4 is an example table of zero-sequence capacitance simulation measurement results.

[0279] Table 2 Example table of zero-sequence resistance simulation measurement results

[0280]

[0281] Table 3 Example table of zero-sequence inductance simulation measurement results

[0282]

[0283] Table 4 Example table of zero-sequence capacitance simulation measurement results

[0284]

[0285] Optionally, under the same simulation settings, the measurement results obtained by the traditional measurement method are shown in Tables 5, 6, and 7. Table 5 is an example table of the zero-sequence resistance simulation measurement results of the traditional method, Table 6 is an example table of the zero-sequence inductance simulation measurement results of the traditional method, and Table 7 is an example table of the zero-sequence capacitance simulation measurement results of the traditional method.

[0286] Table 5 Example of zero-sequence resistance simulation measurement results using traditional methods

[0287]

[0288] Table 6 Example of traditional method zero-sequence inductance simulation measurement results

[0289]

[0290] Table 7 Example of zero-sequence capacitance simulation measurement results using traditional methods

[0291]

[0292] Figure 8 is a schematic diagram comparing the measurement error of a transmission line length change according to an embodiment of the present invention with that of an improved traditional method, such as Figure 8 As shown in Table 2-7, the measurement errors of the method of the present invention and the traditional method are compared when the transmission line length is 200-500 km, where R, L, and C are the maximum values ​​of the relative errors of the line zero-sequence resistance, zero-sequence inductance, and zero-sequence capacitance. Figure 8The following conclusions can be drawn:

[0293] The measurement accuracy of the present application is not affected by the distance of the transmission line, because the embodiment of the present invention is based on the parameter derivation under the distribution model, taking into account the distribution effect of the line, and is therefore applicable to four-circuit non-full-line parallel transmission lines of any length. The traditional method can perform relatively accurate zero-sequence parameter measurements on short-distance lines (not exceeding 200 kilometers) through a lumped parameter model. However, as the line length increases, the measurement error gradually increases due to the distribution effect of the line. This shows that the applicability of traditional methods for zero-sequence distributed parameter measurements of long-distance lines is limited. Furthermore, the zero-sequence parameters of the four-circuit part of the four-circuit non-full-line parallel transmission line and the two-circuit first part of the four-circuit non-full-line parallel transmission line are treated identically, which is not suitable for the measurement of four-circuit non-full-line parallel transmission lines in principle, highlighting the limitations of traditional methods.

[0294] The measurement accuracy of the method of the embodiment of the present invention is not affected by the degree of deviation of the theoretical value of the line parameter, because the embodiment of the present invention does not impose any restrictions on the theoretical value of the zero-sequence parameter during theoretical derivation, so the embodiment of the present invention is applicable to four-circuit non-full-line parallel transmission lines of any voltage level.

[0295] In this embodiment, by measuring the zero-sequence voltage and zero-sequence current at the beginning and end of each transmission line in the four non-full-line parallel transmission lines, and then constructing a line impedance parameter matrix and an admittance parameter matrix according to the zero-sequence voltage and zero-sequence current at the beginning and end of each transmission line, and then mathematically deriving and solving the line impedance parameter matrix and the admittance parameter matrix, the zero-sequence parameters of the four non-full-line parallel transmission lines are obtained, which can achieve the technical effect of effectively solving the zero-sequence parameters of the four non-full-line parallel transmission lines, and then solve the technical problem that the line parameters of multiple non-full-line parallel transmission lines under the asymmetric simplified model cannot be effectively solved.

[0296] The following describes an energized measurement device for zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model provided in an embodiment of the present application. The device described below and the method described above can be referenced to each other.

[0297] In some embodiments, the present application provides a live measurement device for zero-sequence distribution parameters of four-circuit non-full-line parallel transmission lines under an asymmetric simplified model. The four-circuit non-full-line parallel transmission line includes a four-circuit line part and a double-circuit line part. The four-circuit line part consists of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line, and the length of the four-circuit line part is l1; the double-circuit line part consists of a third transmission line and a fourth transmission line, and the length of the double-circuit line part is l2. The device includes:

[0298] A zero-sequence electrical parameter measurement module is used to measure the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode, respectively;

[0299] A relationship matrix calculation module is used to calculate the four-circuit relationship matrix m1 and the double-circuit relationship matrix m2 according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode; wherein the four-circuit relationship matrix m1 is used to reflect the relationship between the head-end electrical parameters of the four-circuit part, including the first intermediate matrix A; the double-circuit relationship matrix m2 is used to reflect the relationship between the head-end electrical parameters of the double-circuit part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2;

[0300] A first impedance-admittance parameter determination module, used to determine a first impedance parameter and a first admittance parameter of a four-loop part based on a first intermediate matrix A;

[0301] A double-pass characteristic root determination module is used to calculate the first double-pass characteristic root r based on the first intermediate variable A1 and the second intermediate variable A2. a and the second double characteristic root r b ;

[0302] The second impedance and admittance parameter determination module is used to determine the impedance and admittance parameters according to the first double-loop characteristic root r a , the second double characteristic root r b , a third intermediate variable B1 and a fourth intermediate variable B2, to determine a second impedance parameter and a second admittance parameter of the double loop portion;

[0303] A zero-sequence distribution parameter determination module is used to determine the zero-sequence distribution parameters of the four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distribution parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance;

[0304] Wherein: the first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0305] The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0306] The third connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally;

[0307] The fourth connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the first transmission line, the third transmission line and the fourth transmission line are all normally energized and operated;

[0308] The fifth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0309] The sixth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally;

[0310] The seventh connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally;

[0311] The eighth connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally.

[0312] In some embodiments, the relationship matrix calculation module includes:

[0313] A head-end electrical parameter relationship matrix determination unit is used to determine the head-end electrical parameter relationship matrix M of four non-full-line parallel transmission lines according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode;

[0314] The solving unit is used to solve the function based on the head-end electrical parameter relationship matrix M and the preset constraints. Solve and obtain the four-loop relationship matrix m1 and the two-loop relationship matrix m2;

[0315] Among them, the four-loop relationship matrix m1 is , B is the second intermediate matrix, C is the third intermediate matrix, and D is the fourth intermediate matrix; the double-loop relationship matrix m2 is .

[0316] In one embodiment, the present application also provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the energized measurement method of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model in any embodiment.

[0317] In one embodiment, the present application also provides a computer device, which stores computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the energized measurement method of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model in any embodiment.

[0318] Indicatively, Fig. 9 The internal structure diagram of a computer device provided in an embodiment of the present application is shown in FIG. 1 . In one example, the computer device may be a server. Fig. 9 The computer device 900 includes a processing component 902, which further includes one or more processors, and a memory resource represented by a memory 901, for storing instructions executable by the processing component 902, such as an application. The application stored in the memory 901 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 902 is configured to execute instructions to perform the steps of the live measurement method of zero-sequence distribution parameters of four non-full-line parallel transmission lines under the asymmetric simplified model described in any of the above embodiments.

[0319] The computer device 900 may further include a power supply component 903 configured to perform power management of the computer device 900, a wired or wireless network interface 904 configured to connect the computer device 900 to a network, and an input / output (I / O) interface 905. The computer device 900 may operate based on an operating system stored in the memory 901, such as Windows Server TM, Mac OS X TM, Unix TM, Linux TM, Free BSD TM, or the like.

[0320] Those skilled in the art will understand that the internal structure of the computer device shown in the present application is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0321] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. Herein, "one", "one", "said", "the" and "it" may also include plural forms, unless the context clearly indicates another way. A plurality refers to at least two cases, such as 2, 3, 5 or 8, etc. "And / or" includes any and all combinations of the relevant listed items.

[0322] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

[0323] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model, characterized in that: The four-circuit non-full-line parallel transmission line includes a four-circuit line part and a double-circuit line part, the four-circuit line part is composed of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line, and the length of the four-circuit line part is l1; The double-circuit line portion is composed of the third transmission line and the fourth transmission line, and the length of the double-circuit line portion is l2; the method comprises: Respectively measure the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in a first connection mode, a second connection mode, a third connection mode, a fourth connection mode, a fifth connection mode, a sixth connection mode, a seventh connection mode, and an eighth connection mode; According to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode, respectively calculate the four-loop relationship matrix m1 and the double-loop relationship matrix m2; wherein the four-loop relationship matrix m1 is used to reflect the relationship between the head-end electrical parameters of the four-loop part, including the first intermediate matrix A; the double-loop relationship matrix m2 is used to reflect the relationship between the head-end electrical parameters of the double-loop part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2; Determine a first impedance parameter and a first admittance parameter of the four-loop portion based on the first intermediate matrix A; Based on the first intermediate variable A1 and the second intermediate variable A2, the first double-return characteristic root r is calculated. a and the second double characteristic root r b ; According to the first double-return characteristic root r a The second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, determining the second impedance parameter and the second admittance parameter of the double loop part; Determine the zero-sequence distributed parameters of the four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distributed parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance; in: The first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The third connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The fourth connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The fifth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally; The sixth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the first transmission line, the second transmission line and the fourth transmission line are all energized and run normally; The seventh connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally; The eighth connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open, and the first transmission line, the second transmission line and the third transmission line are all operated normally with power.

2. The method according to claim 1, characterized in that The method of calculating the four-loop relationship matrix m1 and the two-loop relationship matrix m2 respectively according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode includes: Determine the head-end electrical parameter relationship matrix M of the four non-full-line parallel transmission lines according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode; Based on the head-end electrical parameter relationship matrix M and the preset constraints, the function Solving and obtaining the four-loop relationship matrix m1 and the two-loop relationship matrix m2; Among them, the four-loop relationship matrix m1 is , B is the second intermediate matrix, C is the third intermediate matrix, and D is the fourth intermediate matrix; the double-loop relationship matrix m2 is .

3. The method according to claim 2, characterized in that The determining the first impedance parameter and the first admittance parameter of the four-loop part based on the first intermediate matrix A comprises: According to the first eigenvalue of the first intermediate matrix , the second eigenvalue , the third eigenvalue and the fourth eigenvalue , calculate the fourth eigenvalue of matrix T , the fifth eigenvalue , the sixth eigenvalue and the seventh eigenvalue ;in, , Z is the first impedance parameter, and Y is the first admittance parameter; According to the fourth eigenvalue , the fifth eigenvalue , the sixth eigenvalue and the seventh eigenvalue , the first impedance parameter Z is calculated using the following expression: Wherein, B is the second intermediate matrix; P is a matrix composed of eigenvectors of matrix T, is the inverse matrix of P, sh is the hyperbolic sine function; x is the distance from the position to be solved of the transmission line to the end of the four-loop part, and the value range of x is [0, l1]; According to the first impedance parameter Z, the expression The first admittance parameter Y is obtained by calculation; wherein, is the inverse matrix of Z.

4. The method according to claim 2, characterized in that: The first double-return characteristic root r is calculated based on the first intermediate variable A1 and the second intermediate variable A2. a and the second double characteristic root r b ,include: The first double-return characteristic root r is calculated using the following expressions: a and the second double characteristic root r b : Where cosh is the hyperbolic cosine function.

5. The method according to claim 1, characterized in that According to the first double-circular characteristic root r a The second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, determining the second impedance parameter and the second admittance parameter of the double loop part, including: According to the first double-return characteristic root r a and the second double characteristic root r b , the first transformation parameters are determined by the following expressions: and the second transformation parameter : According to the first double-return characteristic root r a The second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, the second impedance parameter is determined by the following expression : In the formula, Distributing zero-sequence self-impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section; is the distributed zero-sequence mutual impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section; sinh is a hyperbolic sine function, According to the first transformation parameter , the second transformation parameter and the second impedance parameter , the second admittance parameter is determined using the following expression : In the formula, Distributing zero-sequence self-admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section; The zero-sequence mutual admittance is distributed per unit length of the third transmission line and the fourth transmission line in the double-circuit line section.

6. The method according to any one of claims 1 to 5, characterized in that: Determining the zero-sequence distributed parameters of the four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter includes: According to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter, the zero-sequence distributed parameter of the four non-full-line parallel transmission lines is determined by using the following expression: In the formula, is the distributed zero-sequence impedance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence resistance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence inductance per unit length of the i-th transmission line and the j-th transmission line in the four-loop portion, is the distributed zero-sequence admittance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, is the distributed zero-sequence capacitance per unit length of the i-th transmission line and the j-th transmission line in the four-loop section, The distributed zero-sequence self-impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section is: The zero-sequence mutual impedance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section is distributed, is the distributed zero-sequence self-admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, is the distributed zero-sequence mutual admittance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, is the distributed zero-sequence self-resistance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, The distributed zero-sequence mutual resistance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section is: is the distributed zero-sequence self-inductance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, is the distributed zero-sequence mutual inductance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, is the distributed zero-sequence self-capacitance per unit length of the third transmission line and the fourth transmission line in the double-circuit line section, A zero-sequence mutual capacitance is distributed per unit length of the third transmission line and the fourth transmission line in the double-circuit line section.

7. An energized measurement device for zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model, characterized in that: The four-circuit non-full-line parallel transmission line includes a four-circuit line part and a double-circuit line part, the four-circuit line part is composed of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line, and the length of the four-circuit line part is l1; The double-circuit line section is composed of the third transmission line and the fourth transmission line, and the length of the double-circuit line section is l2; the device comprises: A zero-sequence electrical parameter measurement module is used to measure the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode, respectively; A relationship matrix calculation module, used to calculate the four-loop relationship matrix m1 and the double-loop relationship matrix m2 respectively according to the head-end zero-sequence electrical parameters and the terminal zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode; wherein the four-loop relationship matrix m1 is used to reflect the relationship between the head-end electrical parameters of the four-loop part, including the first intermediate matrix A; the double-loop relationship matrix m2 is used to reflect the relationship between the head-end electrical parameters of the double-loop part, including the first intermediate variable A1, the second intermediate variable A2, the third intermediate variable B1, the fourth intermediate variable B2, the fifth intermediate variable C1 and the sixth intermediate variable C2; A first impedance-admittance parameter determination module, used to determine a first impedance parameter and a first admittance parameter of the four-loop part based on the first intermediate matrix A; A double-pass characteristic root determination module is used to calculate the first double-pass characteristic root r based on the first intermediate variable A1 and the second intermediate variable A2. a and the second double characteristic root r b ; The second impedance and admittance parameter determination module is used to determine the impedance and admittance parameters according to the first double-loop characteristic root r a The second double characteristic root r b , the third intermediate variable B1 and the fourth intermediate variable B2, determining the second impedance parameter and the second admittance parameter of the double loop part; A zero-sequence distributed parameter determination module, used to determine the zero-sequence distributed parameters of the four non-full-line parallel transmission lines according to the first impedance parameter, the first admittance parameter, the second impedance parameter and the second admittance parameter; the zero-sequence distributed parameters include zero-sequence capacitance, zero-sequence resistance and zero-sequence inductance; in: The first connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is grounded, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The second connection mode is that the first end of the first transmission line is connected to a single-phase power supply and the end of the first transmission line is open, and the second transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The third connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is grounded, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The fourth connection mode is that the first end of the second transmission line is connected to a single-phase power supply and the end of the second transmission line is open, and the first transmission line, the third transmission line and the fourth transmission line are all energized and operated normally; The fifth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is grounded, and the first transmission line, the second transmission line and the fourth transmission line are all energized and operated normally; The sixth connection mode is that the first end of the third transmission line is connected to a single-phase power supply and the end of the third transmission line is open, and the first transmission line, the second transmission line and the fourth transmission line are all energized and run normally; The seventh connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is grounded, and the first transmission line, the second transmission line and the third transmission line are all energized and operated normally; The eighth connection mode is that the first end of the fourth transmission line is connected to a single-phase power supply and the end of the fourth transmission line is open, and the first transmission line, the second transmission line and the third transmission line are all operated normally with power.

8. The device according to claim 7, characterized in that The relationship matrix calculation module includes: A head-end electrical parameter relationship matrix determining unit, used to determine the head-end electrical parameter relationship matrix M of the four non-full-line parallel transmission lines according to the head-end zero-sequence electrical parameters and the end zero-sequence electrical parameters of each transmission line in the first connection mode, the second connection mode, the third connection mode, the fourth connection mode, the fifth connection mode, the sixth connection mode, the seventh connection mode, and the eighth connection mode; A solving unit is used to solve the function based on the head-end electrical parameter relationship matrix M and preset constraints. Solving and obtaining the four-loop relationship matrix m1 and the two-loop relationship matrix m2; Among them, the four-loop relationship matrix m1 is , B is the second intermediate matrix, C is the third intermediate matrix, and D is the fourth intermediate matrix; the double-loop relationship matrix m2 is .

9. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the method for energized measurement of zero-sequence distribution parameters of four non-full-line parallel transmission lines under an asymmetric simplified model as described in any one of claims 1 to 6.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, which, when executed by the one or more processors, perform the steps of the method for energized measurement of zero-sequence distribution parameters of four non-full-line parallel transmission lines under the asymmetric simplified model as described in any one of claims 1 to 6.

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