Non-contact voltage measurement method for overhead lines

Abstract

The present invention discloses a non-contact voltage measurement method suitable for overhead lines, comprising: modeling and analyzing the electric field of the overhead line; deploying a sensor array on the ground; utilizing each deployed sensor to measure the electric field strength; combining the electric field strengths measured by all sensors with the modeling analysis results to construct a sensor measurement equation system to obtain the electric field strength measured by each sensor; solving the measurement equation system to obtain estimated values ​​of the overhead line height, instantaneous voltage, and relative position parameters; constructing a proportional coefficient matrix using the estimated values ​​of the overhead line height, instantaneous voltage, and relative position parameters; and in a subsequent measurement phase, utilizing the field strengths measured by the sensors in combination with the proportional coefficient matrix to obtain the voltage of each overhead line. This measurement scheme does not require contact with the overhead line and is safe and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage measurement, and in particular to a non-contact voltage measurement method suitable for overhead lines. Background Art

[0002] Voltage is a crucial parameter in power systems, and voltage measurement is crucial. Traditionally, high-voltage measurements have relied on a voltage transformer, directly connected to the conductor under test. The voltage is calculated by multiplying the low-voltage signal on the transformer's secondary side by its transformation ratio. Voltage transformers are bulky, expensive to produce, transport, and install, and insulation difficulty increases with increasing voltage levels.

[0003] With the development of sensing technology, the performance of electric field sensors has been continuously improved, making it possible to measure the voltage of a conductor by using the electric field distribution in the space around the conductor. However, there is currently no faster and more effective measurement solution. Summary of the Invention

[0004] The present invention aims to provide a non-contact voltage measurement method applicable to overhead lines, which does not require contact with the overhead lines and has the advantages of being safe and convenient.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A non-contact voltage measurement method applicable to overhead lines, comprising:

[0007] Modeling and analysis of the electric field of overhead lines;

[0008] deploying sensor arrays on the ground;

[0009] The electric field strength measured by the sensor array is combined with the modeling and analysis results of the overhead line electric field to construct the electric field measurement equations.

[0010] Solve the electric field measurement equations to obtain the estimated values ​​of the height of each overhead line, the voltage of each overhead line, and the relative position parameters of each overhead line and the sensor;

[0011] The obtained heights of the overhead lines and the estimated values ​​of the relative position parameters between the overhead lines and the sensors are used to construct a proportional coefficient matrix. In the subsequent measurement stage, the voltages of the overhead lines are obtained by combining the electric field strength measured by the sensors with the proportional coefficient matrix.

[0012] It can be seen from the technical solution provided by the present invention that by measuring the ground electric field below the overhead line, the overhead line voltage and position can be indirectly calculated. As long as there is no relative displacement between the overhead line and the sensor, the overhead line voltage can be directly calculated using the sensor output, which reduces the calculation burden. Moreover, there is no need to contact the overhead line, which has the advantages of safety and convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 A flowchart of a non-contact voltage measurement method applicable to overhead lines provided in an embodiment of the present invention;

[0015] Figure 2 A schematic diagram of an overhead line cross-section analysis provided by an embodiment of the present invention;

[0016] Figure 3 An analysis diagram of the ground electric field below the overhead line provided by an embodiment of the present invention;

[0017] Figure 4 A schematic diagram of multi-overhead line voltage measurement provided by an embodiment of the present invention;

[0018] Figure 5 A graph showing electric field measurement values ​​within 20 milliseconds for nine electric field sensors provided in an embodiment of the present invention;

[0019] Figure 6 A graph showing voltage values ​​of three overhead lines calculated using a proportional coefficient matrix according to an embodiment of the present invention;

[0020] Figure 7 This is a graph showing the error between the calculated and true values ​​of the voltages of three overhead lines provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] First, the following terms may be used in this article:

[0023] The terms "include," "comprises," "contains," "has," or other similar expressions should be interpreted as non-exclusive. For example, "including certain technical features (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products, or manufactured articles, etc.) should be interpreted as including not only the technical features explicitly listed, but also other technical features known in the art that are not explicitly listed.

[0024] The following describes in detail a non-contact voltage measurement method for overhead lines, provided by the present invention. Any information not described in detail in the embodiments of the present invention represents prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of the present invention, the measurement is performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer. Instruments used in the embodiments of the present invention, where the manufacturer is not specified, are commercially available conventional products.

[0025] like Figure 1 As shown, a non-contact voltage measurement method applicable to overhead lines mainly includes the following steps:

[0026] Step 1: Model and analyze the electric field of overhead lines.

[0027] like Figure 2 As shown in the figure, a schematic diagram of the electric field modeling of overhead lines is shown, and the actual lines are simplified as follows:

[0028] 1) The overhead line is simplified as an infinitely long straight cylinder. The charge is evenly distributed along the length of the overhead line. The overhead line is parallel to the ground and the sag of the overhead line is not considered.

[0029] 2) The ground is simplified to an infinite plane with a potential of 0.

[0030] 3) Ignore the influence of towers and nearby objects.

[0031] In the embodiment of the present invention, a simulated charge method is used to model and analyze the electric field in the cross section of the overhead line.

[0032] like Figure 3 As shown, the overhead line radius is r0, the height is h, the voltage is u, and the electric field strength at point P on the ground is:

[0033]

[0034] Where E is the electric field intensity at point P, and d is the lateral distance from point P to the bottom of the overhead line.

[0035] Step 2: Deploy the sensor array on the ground.

[0036] like Figure 4As shown, let the number of overhead lines be N, and the voltage of the i-th overhead line be u i , height h i , the lateral distance from the first sensor is d i The number of sensors is n = 3N. A linear array is constructed and placed on the ground, perpendicular to the overhead line. The distance between the jth sensor and the first sensor is m. j , obviously, m1=0.

[0037] Step 3: Use the electric field strength measured by the sensor array and the ground electric field expression in step 1 to construct the electric field measurement equations as follows:

[0038]

[0039] Among them, E j (j=1,2,…,n) is the electric field strength measured by the jth sensor (known), N is the number of overhead lines (known), u i (i=1,2,…,N) is the voltage of the i-th overhead line (to be determined), r0 represents the radius of the overhead line (known), h i (i=1,2,…,N) is the height of the i-th overhead line (unknown), m j (j=1,2,…,n) represents the distance between the jth sensor and the first sensor (known and m1=0), d i (i=2,3,…,N) represents the lateral distance (unknown) between the i-th overhead line and the first sensor.

[0040] Step 4: Solve the measurement equations (3N equations) to obtain the overhead line height h i , overhead line voltage u i (instantaneous voltage) and relative position parameter d i Estimated value of (3N unknowns).

[0041] In the embodiment of the present invention, the measurement equations are solved using a solution method for multivariate nonlinear equations.

[0042] It should be noted that solving the measurement equations is an essential step of the present invention, but the present invention is not limited to a specific solution method. Numerous methods exist for solving such multivariate nonlinear equations, including gradient methods, Newton's method, quasi-Newton's method, penalty function methods, ant colony algorithms, and particle swarm algorithms. These mathematical algorithms themselves are not innovative elements of the present invention. The appropriate solution method can be selected based on a balance of various factors, such as the specific equation size, convergence speed requirements, and hardware computing power requirements.

[0043] The overhead line voltage u obtained at this time i It can be understood as the electric field strength E measured by the sensor at the current moment jThe voltage of the i-th overhead line at the current moment is calculated. In order to facilitate the calculation of the overhead line voltage at subsequent moments, the measurement process is simplified by constructing a proportional coefficient matrix. For details, see the solution provided in the subsequent step 5.

[0044] Step 5: Use the estimated values ​​of the overhead line height and relative position parameters to construct a proportional coefficient matrix. In the subsequent measurement stage, the field strength measured by the sensor is combined with the proportional coefficient matrix to obtain the voltage of each overhead line.

[0045] In the embodiment of the present invention, the constructed proportional coefficient matrix is ​​expressed as: K = [k ji ] n×N ; K represents the relative position relationship between the overhead line and the electric field sensor, where

[0046]

[0047] In the above formula, k ji It represents the transformation relationship between the i-th overhead line and the j-th sensor calculated using the estimated values ​​of the overhead line height and relative position parameters.

[0048] Overhead line voltage vector U=[u1,u2,…,u N ] T And the sensor output electric field E=[E1,E2,…,E n ] T The following relationship exists:

[0049] E=KU

[0050] Among them, u i represents the voltage of the i-th overhead line, i=1,2,…,N, N is the number of overhead lines, E j represents the output electric field strength of the jth sensor, j = 1, 2, ..., n, n = 3N is the number of sensors, and T represents the vector transpose sign.

[0051] As long as there is no relative displacement between the overhead line and the sensor, the proportional coefficient matrix K will not change. Therefore, only one round of iteration is required to obtain the matrix proportional coefficient matrix K. In the subsequent measurement phase, the electric field strength vector E' measured by the sensor and the proportional coefficient matrix are used to obtain the overhead line voltage vector U' at each moment in the subsequent measurement phase, which can be expressed as:

[0052] U'=K + E'

[0053] Among them, K + is the generalized inverse matrix of the proportional coefficient matrix K, U'=[u1',u2',…,u N '] T ,u i' represents the voltage of the i-th overhead line at each moment in the subsequent measurement phase, and the sensor outputs the electric field vector E'=[E1',E2',…,E n '] T , E j ' represents the electric field strength output by the jth sensor at each moment in the subsequent measurement phase.

[0054] Through the above solution provided by the embodiment of the invention, in the subsequent measurement phase, the electric field vector E' output by the sensor at the corresponding moment can be used to quickly calculate the overhead line voltage vector U' at the corresponding moment.

[0055] The above-mentioned solution of the embodiment of the present invention indirectly calculates the voltage and position of the overhead line by measuring the ground electric field below the overhead line. As long as there is no relative displacement between the overhead line and the sensor, the overhead line voltage can be directly calculated using the sensor output, which reduces the calculation burden. Moreover, there is no need to contact the overhead line, which has the advantages of safety and convenience.

[0056] For ease of understanding, a simulation test of the above solution of the present invention is performed below in conjunction with a scenario example.

[0057] The simulation test selected a 110kV three-phase overhead line scenario, and the relevant parameters are as follows:

[0058] The number of overhead lines N = 3, overhead line parameters: r0 = 0.0108, h1 = 8.8, h2 = 11.7, h3 = 8.9, d1 = -1.9, d2 = 4.1, d3 = 10.2, unit: meter.

[0059] Instantaneous voltage values: u1 = 155563.49, u2 = -77781.75, u3 = -77781.75 Unit: Volt.

[0060] The number of electric field sensors n=9, the sensor array and its relative position parameters are: m1=0, m2=1, m3=2, m4=3, m5=4, m6=5, m7=6, m8=7, m9=8, unit: meter.

[0061] Sensor output electric field strength: E1 = 2005.66, E2 = 1553.76, E3 = 1042.22, E4 = 506.81, E5 = -21.76, E6 = -519.72, E7 = -969.45, E8 = -1357.26, E9 = -1671.82, unit: volt / meter.

[0062] At this point, the measurement equations are as follows:

[0063]

[0064] In this example, Newton's method is used to solve the problem, and the estimated values ​​of the nine unknowns are as follows:

[0065] Overhead line parameters: h1=8.800000006, h2=11.699999996, h3=8.899999998, d1=-1.899999,97, d2=4.100000001, d3=10.200000003, unit: meter.

[0066] Instantaneous voltage values: u1 = 155659.24, u2 = -77817.73, u3 = -77829.08 Unit: Volt.

[0067] The scale factor matrix is ​​as follows:

[0068]

[0069] Its generalized inverse matrix is ​​as follows:

[0070]

[0071] The 9 sensors then output the following 20 milliseconds: Figure 5 As shown, using the matrix K + The voltages of the three overhead lines can be obtained, such as Figure 6 As shown, the error of the voltage measurement value relative to the true value is as follows Figure 7 As shown, it can be seen that the absolute error of voltage measurement is less than 20 volts.

[0072] Through the description of the above embodiments, those skilled in the art will clearly understand that the above embodiments can be implemented through software or by using software plus a necessary general-purpose hardware platform. Based on this understanding, the technical solutions of the above embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, a USB flash drive, a mobile hard disk, etc.) and includes a number of instructions for causing a computer device (such as a personal computer, a server, or a network device) to execute the methods described in the various embodiments of the present invention.

[0073] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A non-contact voltage measurement method suitable for overhead lines, characterized in that: include: Modeling and analysis of the electric field of overhead lines; deploying sensor arrays on the ground; The electric field strength measured by the sensor array is combined with the modeling and analysis results of the overhead line electric field to construct the electric field measurement equations. Solve the electric field measurement equations to obtain the estimated values ​​of the height of each overhead line, the voltage of each overhead line, and the relative position parameters of each overhead line and the sensor; The obtained heights of the overhead lines and the estimated values ​​of the relative position parameters between the overhead lines and the sensors are used to construct a proportional coefficient matrix. In the subsequent measurement phase, the electric field strength measured by the sensors is combined with the proportional coefficient matrix to obtain the voltage of each overhead line. Among them, the constructed proportional coefficient matrix is ​​expressed as: K = [k ji ] n×N ; K represents the relative position relationship between the overhead line and the electric field sensor, where Among them, k ji represents the transformation relationship between the i-th overhead line and the j-th sensor calculated using the estimated values ​​of the overhead line height and relative position parameters; m j represents the distance between the jth sensor and the first sensor, j = 1, 2, ..., n, n represents the number of sensors; r0 represents the radius of the overhead line; h i represents the height of the i-th overhead line, d i represents the lateral distance between the i-th overhead line and the first sensor, i = 1, 2, …, N, where N represents the number of overhead lines.

2. The non-contact voltage measurement method for overhead lines according to claim 1, characterized in that: The modeling analysis of the overhead line electric field includes: The electric field of overhead line cross section is modeled and analyzed using the simulated charge method; Assume that the radius of the overhead line is r0, the height is h, and the voltage is u. Then the electric field strength at point P on the ground is: Where E is the electric field intensity at point P, and d is the lateral distance from point P to the bottom of the overhead line.

3. The non-contact voltage measurement method for overhead lines according to claim 1, characterized in that: The sensor array arranged on the ground includes: Assume the number of overhead lines is N, and the voltage of the i-th overhead line is u i , height h i , the lateral distance from the first sensor is d i The number of sensors is n = 3N. A linear array is constructed and placed on the ground, perpendicular to the overhead line. The distance between the jth sensor and the first sensor is m. j .

4. A non-contact voltage measurement method applicable to overhead lines according to claim 1, 2 or 3, characterized in that: The constructed electric field measurement equations are expressed as: Among them, E j represents the electric field strength measured by the jth sensor, m j represents the distance between the jth sensor and the first sensor, j = 1, 2, ..., n, n represents the number of sensors; r0 represents the radius of the overhead line, u i represents the voltage of the i-th overhead line, i=1,2,…,N, N represents the number of overhead lines; h i represents the height of the i-th overhead line, d i represents the lateral distance between the i-th overhead line and the first sensor.

5. The non-contact voltage measurement method applicable to overhead lines according to claim 1, characterized in that: The method for solving the measurement equations includes: solving the measurement equations using a solution method for multivariate nonlinear equations.

6. The non-contact voltage measurement method for overhead lines according to claim 1, characterized in that: Overhead line voltage vector U=[u1,u2,…,u N ] T And the sensor output electric field E=[E1,E2,…,E n ] T The following relationship exists: E=KU Among them, u i Represents the voltage of the i-th overhead line, i=1,2,…,N,E j represents the electric field strength measured by the jth sensor, j = 1, 2, ..., n, n is the number of sensors, and T represents the vector transpose sign.

7. A non-contact voltage measurement method applicable to overhead lines according to claim 1 or 6, characterized in that: In the subsequent measurement phase, the sensor output electric field E' is combined with the proportional coefficient matrix to obtain the overhead line voltage vector U' at each moment in the subsequent measurement phase, which is expressed as: U'=K + E' Among them, K + is the generalized inverse matrix of the proportional coefficient matrix K, U'=[u1',u2',…,u N '] T ,u i ' represents the voltage of the i-th overhead line at each moment in the subsequent measurement phase, i=1,2,…,N, N is the number of overhead lines, E'=[E1',E2',…,E n '] T , E j ' represents the electric field strength measured by the jth sensor at each moment in the subsequent measurement phase, j = 1, 2, ..., n, n is the number of sensors, and T represents the vector transpose sign.

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