Multi-dimensional space electric field measuring device and power transmission line fault positioning method and system

Abstract

The invention discloses a multi-dimensional space electric field measuring device and a power transmission line fault positioning method and system, and the device comprises a three-dimensional electric field sensor, an electro-optical conversion module, a photoelectric receiving module, a conditioning circuit, and an FPGA high-speed digital collection module. The power transmission line fault positioning method comprises the following steps: acquiring second voltage signals in X, Y and Z directions at the positions where at least two three-dimensional sensors are arranged in an overhead transmission line by using a multi-dimensional space electric field measuring device; when the second voltage signal in any direction fluctuates, determining the moment of voltage fluctuation; and fault positioning is carried out based on the position information of the layout positions of any two three-dimensional electric field sensors and the voltage fluctuation moment, and the fault position is determined. The multi-dimensional space electric field measuring device has the characteristics of miniaturization, adjustable sensitivity, high bandwidth and high dynamic range, multiple paths of signals can be accessed at the same time, multi-point layout is facilitated, and the multi-dimensional space electric field measuring device can be effectively applied to the field of transmission line fault positioning.

Description

Technical Field

[0001] The present invention relates to the technical field of spatial electric fields of overhead high-voltage transmission lines in power systems, and more specifically, to a multi-dimensional spatial electric field measurement device, a transmission line fault location method, and a system. Background Art

[0002] Due to various reasons such as operation modes, natural environments, weather conditions, and biological activities, high-voltage transmission lines in power systems are extremely prone to faults such as short circuits or groundings. After a fault occurs, quickly and accurately locating the fault location is of great significance for the operation and maintenance of the system and the restoration of power supply. Currently, most of the traveling wave measurement sensors for fault voltages and currents are contact type, with Rogowski coils and voltage dividers as typical technical routes. However, the above measurement means require power outage installation and maintenance of the line, with a large construction difficulty, and it is difficult to perform distributed deployment and signal acquisition at multiple points. Therefore, the non-contact fault transient voltage measurement technology based on spatial induced electric fields can effectively overcome the above problems and be used for the wavefront detection and location of fault traveling waves.

[0003] Currently, commonly used electric field sensors are mostly one-dimensional structures, which have problems such as polarization direction limitations, incomplete spatial information, and difficulty in synchronizing scattered antenna layouts. One-dimensional antennas face bottleneck problems such as narrow bandwidth, slow response speed, and small dynamic range when measuring the transient electromagnetic fields of fault transient traveling wave signals, and it is difficult to meet the high-bandwidth, high-dynamic, and full-vector synchronous measurement requirements in transient strong electric field environments.

[0004] Therefore, it is necessary to develop a three-dimensional electric field measurement device applicable to the electromagnetic environment around high-voltage equipment and its overhead transmission lines in power systems, as well as a positioning method for transmission lines. Summary of the Invention

[0005] The present invention proposes a multi-dimensional spatial electric field measurement device, a transmission line fault location method, and a system to solve the problem of how to locate transmission line faults.

[0006] To solve the above problems, according to one aspect of the present invention, a multi-dimensional spatial electric field measurement device is provided. The device includes: a three-dimensional electric field sensor, an electro-optic conversion module, an optical-electric receiving module, a conditioning circuit, and an FPGA high-speed digital acquisition module; wherein,

[0007] The three-dimensional electric field sensor includes: three electric field antennas, and the three electric field antennas are used to measure first electric field signals in three mutually perpendicular X, Y, and Z directions in space respectively;

[0008] The electro-optic conversion module is connected to the three-dimensional electric field sensor and is used to perform electro-optic conversion on the first electric field signal and convert the first electric field signal into an optical signal;

[0009] The photoelectric receiver is connected to the electro-optical conversion module and is used for performing photoelectric conversion on the optical signal to convert the optical signal into a current signal;

[0010] The conditioning circuit is connected to the photoelectric receiving module and is used for converting the current signal into a voltage signal and amplifying it to the required signal amplitude to obtain second voltage signals in the X, Y, and Z directions;

[0011] The FPGA high-speed digital acquisition module is connected to the conditioning circuit and is used for acquiring the second voltage signals.

[0012] Preferably, the three-dimensional electric field sensor further includes: a sensor shielding structure disposed outside the three electric field antennas and used for shielding external signals; wherein, the three electric field antennas are placed at the geometric center of the metal shielding surface.

[0013] Preferably, the sensor shielding structure is a shielding body with a square structure.

[0014] Preferably, the electric field antenna is an ultra-wideband monopole antenna.

[0015] According to another aspect of the present invention, there is provided a transmission line fault location method based on the multi-dimensional space electric field measurement device as described above, and the method includes:

[0016] Using the multi-dimensional space electric field measurement device to obtain second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in the overhead transmission line;

[0017] When there is a fluctuation in the second voltage signal in any direction, determine the moment of the voltage fluctuation;

[0018] Based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of the voltage fluctuation, perform fault location to determine the fault location.

[0019] Preferably, the performing fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of the voltage fluctuation to determine the fault location includes:

[0020]

[0021] wherein, x is the distance between two adjacent two-dimensional magnetic field measurement transmission line fault location devices, x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

[0022] Preferably, the method further includes:

[0023] Determine the thickness coefficient η of the electric field antenna in the following manner, including:

[0024]

[0025] Determine the effective height h of the electric field antenna in the following manner e , including:

[0026]

[0027] Determine the lower cut-off frequency f of the electric field antenna in the following manner L , including:

[0028]

[0029] where h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried.

[0030] According to another aspect of the present invention, there is provided a transmission line fault location system based on the multi-dimensional space electric field measurement device as described above. The system includes:

[0031] A voltage signal measurement unit for obtaining second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor installation locations arranged in the overhead transmission line by using the multi-dimensional space electric field measurement device;

[0032] A fluctuation time determination unit for determining the time of voltage fluctuation when there is a fluctuation in the second voltage signal in any direction;

[0033] A location unit for performing fault location based on the position information of any two three-dimensional electric field sensor installation locations and the time of voltage fluctuation to determine the fault location.

[0034] Preferably, the location unit performs fault location based on the position information of any two three-dimensional electric field sensor installation locations and the time of voltage fluctuation to determine the fault location, including:

[0035]

[0036] where x is the distance between two adjacent two-dimensional magnetic field measurement transmission line fault location devices, x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

[0037] Preferably, the system further includes: a parameter determination unit for:

[0038] The thickness coefficient η of the electric field antenna is determined in the following manner, including:

[0039]

[0040] The effective height h of the electric field antenna is determined in the following manner e , including:

[0041]

[0042] The lower cut-off frequency f of the electric field antenna is determined in the following manner L , including:

[0043]

[0044] where h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried by it.

[0045] The present invention provides a multi-dimensional space electric field measurement device, including: a three-dimensional electric field sensor, an electro-optic conversion module, a photoelectric receiving module, a conditioning circuit, and an FPGA high-speed digital acquisition module. A transmission line fault location method and system based on the multi-dimensional space electric field measurement device as described above are also provided, including: obtaining second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in an overhead transmission line by using the multi-dimensional space electric field measurement device; when there is a fluctuation in the second voltage signal in any direction, determining the moment of voltage fluctuation; and performing fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of voltage fluctuation to determine the fault location. The multi-dimensional space electric field measurement device of the present invention has the characteristics of miniaturization, adjustable sensitivity, high bandwidth, and high dynamic range. The response consistency of the single-axis sensor is better than 0.1 ns. Multiple signals can be simultaneously accessed, and the synchronous timing reaches 300 ps. It is convenient for multi-point deployment and is suitable for three-dimensional measurement and polarization direction analysis of the space induction electric field caused by fault overvoltage of high-voltage overhead transmission lines. The transmission line fault location method of the present invention can be effectively applied to fields such as non-contact measurement of transmission line overvoltage, fault location, and lightning location, and has significant practical value and engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] By referring to the following drawings, the exemplary embodiments of the present invention can be more fully understood:

[0047] Figure 1 is a schematic structural diagram of a multi-dimensional space electric field measurement device 100 according to an embodiment of the present invention;

[0048] Figure 2 The frequency-domain response curve of the BUF802 chip according to an embodiment of the present invention in the CL mode;

[0049] Figure 3 The schematic diagram of the conditioning circuit according to an embodiment of the present invention;

[0050] Figure 4 The amplitude-frequency response curve of the electric field sensor according to an embodiment of the present invention;

[0051] Figure 5 The schematic diagram of the normalized electric field at the antenna for different shield shapes according to an embodiment of the present invention;

[0052] Figure 6 The schematic diagram of the normalized scattered field at the antenna for different shield shapes according to an embodiment of the present invention;

[0053] Figure 7 The schematic diagram of the simulation model of the electric field sensor according to an embodiment of the present invention;

[0054] Figure 8 The time-domain waveform diagram of the induced voltage in each axial direction under square-wave excitation according to an embodiment of the present invention;

[0055] Figure 9 The flowchart of the transmission line fault location method 900 based on the multi-dimensional space electric field measurement device according to an embodiment of the present invention;

[0056] Figure 10 The schematic diagram of the mirror image analysis method of the near-field electric field of the overhead transmission line according to an embodiment of the present invention;

[0057] Figure 11 The structural schematic diagram of the transmission line fault location system 1100 based on the multi-dimensional space electric field measurement device according to an embodiment of the present invention. Detailed implementation manners

[0058] Now, exemplary embodiments of the present invention will be introduced with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not limitations on the present invention. In the drawings, the same units / components are denoted by the same reference numerals.

[0059] Unless otherwise specified, the terms used herein (including technical terms) have the ordinary meaning understood by those skilled in the relevant technical field. Additionally, it can be understood that terms defined in commonly used dictionaries should be construed to have a meaning consistent with their context in the relevant field, and should not be construed as having an idealized or overly formal meaning.

[0060] The present invention provides a multi-dimensional space electric field measurement device, which is based on a monopole rod antenna structure, a conditioning circuit, a field programmable gate array (FPGA) high-speed digital acquisition module, etc., and can realize synchronous measurement of the full waveforms of time-domain signals in three spatial dimensions of the electric field in a transient electromagnetic environment. Through a triaxial orthogonal layout of monopole electrically small antenna arrays, the present invention can sense electric field signals in different polarization directions in real time. After high-bandwidth differential amplification and signal limiting conditioning inside the sensor, the field programmable gate array completes local digital acquisition of analog signals through high-speed digital acquisition, and transmits digital signals to the backend signal processing and display unit over a long distance through optical fibers. The analog bandwidth of the present invention can cover the frequency spectrum ranges of direct current, power frequency, corona to partial discharge signals in overhead transmission lines; it overcomes the problems of unstable coefficients, insufficient bandwidth, and insufficient accuracy during the transmission of analog signals by optical fibers. By adopting front-end digital sampling based on FPGA technology and transmitting digital signals through optical fibers, it can be effectively applied to the measurement of electric field signals around overhead high-voltage transmission and distribution lines. At the same time, the sensor of the present invention has the characteristics of miniaturization, adjustable sensitivity, high bandwidth, and high dynamic range. The response consistency of the single-axis sensor is better than 0.1 ns, multiple signals can be accessed simultaneously, the synchronous timing reaches 300 ps, which is convenient for multi-point layout, and is suitable for three-dimensional measurement and polarization direction analysis of the space induced electric field caused by fault overvoltage in high-voltage overhead transmission lines. It can be effectively applied to fields such as non-contact measurement of transmission line overvoltage, fault location, and lightning location, and has significant practical value and engineering application prospects.

[0061] Figure 1 FIG. is a schematic structural diagram of a multi-dimensional space electric field measurement device 100 according to an embodiment of the present invention. As Figure 1 shown, the multi-dimensional space electric field measurement device provided by the embodiment of the present invention has the characteristics of miniaturization, adjustable sensitivity, high bandwidth, and high dynamic range. The response consistency of the single-axis sensor is better than 0.1 ns, multiple signals can be accessed simultaneously, the synchronous timing reaches 300 ps, which is convenient for multi-point layout, and is suitable for three-dimensional measurement and polarization direction analysis of the space induced electric field caused by fault overvoltage in high-voltage overhead transmission lines. The multi-dimensional space electric field measurement device 100 provided by the embodiment of the present invention includes: a three-dimensional electric field sensor 101, an electro-optical conversion module 102, an optical-electric receiving module 103, a conditioning circuit 104, and an FPGA high-speed digital acquisition module 105.

[0062] Preferably, the three-dimensional electric field sensor 101 includes: three electric field antennas for respectively measuring first electric field signals in three mutually perpendicular X, Y, and Z directions in space.

[0063] Preferably, the electro-optic conversion module 102 is connected to the three-dimensional electric field sensor and is configured to perform electro-optic conversion on the first electric field signal to convert the first electric field signal into an optical signal.

[0064] Preferably, the optical receiver 103 is connected to the electro-optic conversion module and is configured to perform opto-electric conversion on the optical signal to convert the optical signal into a current signal.

[0065] Preferably, the conditioning circuit 104 is connected to the optical receiver module and is configured to convert the current signal into a voltage signal and amplify it to a required signal amplitude to obtain second voltage signals in the X, Y, and Z directions.

[0066] Preferably, the FPGA high-speed digital acquisition module 105 is connected to the conditioning circuit and is configured to acquire the second voltage signal.

[0067] Preferably, the three-dimensional electric field sensor 101 further includes: a sensor shielding structure disposed outside the three electric field antennas for shielding external signals; wherein the three electric field antennas are placed at the geometric center of a metal shielding surface.

[0068] Preferably, the sensor shielding structure is a shielding body with a square structure.

[0069] Preferably, the electric field antenna is an ultra-wideband monopole antenna.

[0070] In the present invention, the three-dimensional measurement device can be functionally divided into a three-dimensional electric field sensor, an electro-optic conversion module, an optical receiver module, a conditioning circuit, and an FPGA high-speed digital acquisition module. The working process of the entire measurement device is as follows: Electric field signals are induced by three mutually perpendicular electric field antennas in the three-dimensional electric field sensor, and the output electrical signals drive the electro-optic conversion module to achieve the conversion of electro-optic signals after passing through a coupling circuit, obtaining optical signals. The optical signals are transmitted through optical fibers to a high-speed PIN-type optical detection module for reception to achieve opto-electric signal conversion. The output current signal is converted into a voltage signal by the conditioning circuit and amplified to the required signal amplitude, and finally, the three-dimensional second voltage signals are input into a waveform receiving device. The three-dimensional electric field measurement device of the present invention measures the field signals in three mutually perpendicular directions X, Y, and Z in space through three measurement channels.

[0071] In the present invention, the electric field antenna in the electric field sensor is a ultra-wideband monopole rod antenna. For an antenna with a length equal to h and a radius of a, when the antenna length is much smaller than the electric field wavelength, the antenna can be called an electrically small antenna. The radiation energy of an electrically small antenna is very small and can be regarded as a measurement at a certain point in space. It has the advantages of small geometric size, wide frequency band width, large measurement range, adjustable indicators, etc., and is commonly used for the measurement of transient electric field signals. The monopole rod electrically small antenna is an antenna with a rod structure and a monopole form, and is usually placed on a large metal surface or the ground during use. When performing electric field measurement, the metal shell serves as an image ground, and the monopole rod electrically small antenna forms an electric dipole to sense the space electric field. Subsequently, it is used in cooperation with a conditioning circuit to form an electric field measurement probe.

[0072] When the geometric size of the antenna is determined, the thickness coefficient of the antenna can be calculated by the following formula:

[0073]

[0074] The electrically small antenna can be regarded as a metal cylinder. The definition of its effective height is the ratio of the antenna output voltage to the incident electric field strength. When the antenna size is much smaller than the measured electric field wavelength, the effective height can be calculated by the following formula:

[0075]

[0076] The sensitivity of the monopole electrically small antenna is determined by the effective length of the antenna. During actual measurement, the sensitivity of the antenna during measurement can be changed by changing the geometric height of the antenna, so as to adapt to the measurement of electric fields with different field strengths.

[0077] When 2πh / λ << 1 is satisfied, the antenna impedance can be ignored and regarded as a capacitive load with an equivalent capacitance of C a :

[0078]

[0079] where ε0 is the vacuum permittivity. When the monopole rod electrically small antenna operates with a load, the Thevenin equivalent law can be used for research, and the load is equivalent to a parallel circuit of C l , R l . The Thevenin equivalent circuit of the antenna and the conditioning circuit is as Figure 1 shown. Among them, U l represents the load voltage; E represents the input field strength; R l represents the resistance of the load; C a , C lThey represent the equivalent capacitance of the electrically small antenna and the capacitance of the load it carries respectively. The equivalent voltage is related to the input field strength. When analyzing the equivalent circuit, the Laplace transform method is used to solve the transfer function in the equivalent circuit. When the input field strength is expressed as E, the equivalent voltage can be expressed as:

[0080] U a (s) = E(s)·h e (4)

[0081] The transfer function between the output voltage and the input field strength can be expressed as:

[0082]

[0083] When the geometric size of the antenna is fixed, both the effective height and the equivalent capacitance are constant values. It can be seen from the formula that when the load resistance is small, the output voltage is the differential of the input field strength. When the load resistance is large, the transfer function can be approximated as:

[0084]

[0085] It can be considered that when the antenna size is fixed and the load resistance of the conditioning circuit is a high impedance, the transfer function of the electrically small antenna is independent of frequency, the output voltage is linearly related to the input field strength, and it meets the requirements for full waveform testing of high frequency electric field signals. In this case, the lower cut-off frequency of the antenna can be calculated:

[0086]

[0087] It is shown by the lower cut-off frequency of the rod-shaped electrically small antenna that the lower cut-off frequency of the rod-shaped electrically small antenna is mainly affected by the equivalent capacitance of the antenna circuit, the load capacitance and the load resistance. Usually, in order to make the lower cut-off frequency of the rod-shaped electrically small antenna lower, a high impedance matching scheme is often adopted, that is, a larger load resistance is selected.

[0088] Since the output impedance of the antenna is high impedance while the impedance of the signal line on the circuit board is 50Ω, a conditioning circuit is required to complete the impedance conversion from high impedance to 50Ω, and it is necessary to ensure that within a relatively wide frequency band range, the frequency response curve of the circuit is relatively flat. Therefore, in the present invention, the impedance conversion device of the conditioning circuit is selected as the BUF802 chip produced by Texas Instruments (TI). The BUF802 has two operating modes, BF and CL, which are respectively applicable to different situations. In order to achieve the purpose of wideband measurement in the present invention, the BUF802 is made to operate in the CL operating mode. In the CL operating mode, the BUF802 has a main path and an auxiliary path. The input signal is frequency-divided by a capacitor to form a high-frequency signal and a low-frequency signal. The high-frequency signal passes through the main path, and the low-frequency signal passes through the auxiliary path. The two are re-integrated at the output end to form an output signal. The existence of the two transmission paths causes the frequency response of the BUF802 to be divided into the following three parts: the low-frequency band, the high-frequency band, and the transition section. In the transition section, the main path and the auxiliary path work simultaneously to generate an output signal, as Figure 2 shown. Wideband measurement requires the electric field measurement probe to have consistent performance in the low-frequency band and the high-frequency band, that is, the gain in the low-frequency band and the gain in the high-frequency band need to be kept consistent. If there is a difference in gain, the measurement result will show an amplitude distortion phenomenon. During the experiment, continuous adjustment can be made to smooth the gain curve, and the conditioning circuit design is as Figure 3 shown.

[0089] In the present invention, a network analyzer is used to measure the bandwidth of the conditioning circuit. A network analyzer is an electronic instrument used to measure the network parameters of an electronic network, especially for measuring and analyzing the performance of radio frequency (RF) and microwave signal systems. It can be used to evaluate antenna characteristics, including gain, loss, reflection, phase, and impedance, etc. The sweep frequency curve of the sensor is as Figure 4 shown. According to the frequency response diagram, the analog bandwidth range of the measurement probe is 0 - 1.5 GHz, which can cover the induced electric field signals caused by steady-state power frequency voltage, transient overvoltage, lightning overvoltage, switching operation overvoltage, very fast transient overvoltage (VFTO), etc. generated during the operation of the transmission line in the power system.

[0090] For the measurement of electromagnetic pulse signals for broadband transients, due to the requirement of anti-electromagnetic interference, existing solutions use fiber optic transmission of analog signals, which have problems such as insufficient analog bandwidth, poor conversion coefficient accuracy and stability. Therefore, in the present invention, at the measurement front end, the analog signal output by the sensor is digitally sampled, and the digital signal is transmitted through the fiber optic signal, which can not only achieve high-fidelity measurement of the analog signal, but also complete the anti-interference function of the signal through fiber optic communication. The system composition of the high-speed digital collector mainly includes a field-programmable gate array (FPGA) control unit, a digital sampling unit of a high-speed analog-to-digital converter (ADC), and other main parts.

[0091] The FPGA chip is mainly responsible for configuring and controlling the clock chip and the ADC to make them work properly. The ADC converts the analog signal into a digital signal and gives it to the FPGA chip. The FPGA chip caches and controls the flow of the data, stores the data in the DDR, reads out the data in the DDR, and gives it to the QSFP. The QSFP gives the data to the host computer software through the fiber optic cable. The host computer software visually displays the data and analyzes and processes the data to perform FFT transformation. By using the clock chip LMK04832 to provide synchronous clocks to multiple ADC chips at the same time, the timing synchronization between multiple sampling channels can be completed, and the minimum synchronous clock can reach 300 ps.

[0092] In the present invention, a shielding structure is provided outside the electric field antenna. Based on the theory of electromagnetic wave propagation and scattering, the disturbance mechanism of the metal shielding structure on the transient electric field measurement system is modeled and simulated. The research shows that when an external electric field acts on the metal shell of the sensor, an equivalent surface magnetic current source will be induced on its surface. This equivalent surface source will excite an additional scattered electric field, which will be superimposed with the original incident electric field at the receiving antenna, resulting in distortion of the electric field waveform, especially significant in the high-frequency components. According to the equivalent field source theory, the metal surface in the shielding shell parallel to the polarization direction of the incident electric field is the main scattering source. The scattered electric field in the far-field region (such as at the antenna) can be expressed as a weighted integral of the equivalent surface magnetic current source, and its expression is:

[0093]

[0094] Among them, represents the equivalent surface magnetic current source, r and r′ are both spatial vectors, representing the receiving position and the excitation source position respectively. The frequency-domain normalized scattering function is defined as:

[0095]

[0096] Research shows that the width, thickness, and structural shape of the metal shell all have a significant impact on the intensity of the scattering field. Among them, reducing the shell width and thickness, adopting a square or circular symmetric structure, and placing the receiving antenna at the geometric center of the metal surface can effectively reduce the interference of the scattering field and improve the linear consistency and system bandwidth of electric field measurement. Based on the three-dimensional electromagnetic full-wave electromagnetic simulation software CST Studio Suite, the electric field and scattering field at the antenna of the shielding body with square (120mm×120mm×15mm), circular (radius r = 60mm, height h = 15mm), and rectangular (120mm×30mm×15mm) structures were simulated and analyzed, and the results are as Figure 5 , Figure 6 shown. The frequency-domain electric field response of the cuboid structure is the flattest, with a variation range within ±0.15 dB in the range of 0 - 2 GHz. The amplitude fluctuation ranges of the square and circular shapes are ±0.4 dB and ±0.5 dB respectively; while from the spectrogram of the normalized scattering field, it can be seen that the scattered electric field of the rectangle is higher than that of the square and circular shapes. Considering the above simulation conclusions and taking into account the processing cost and structural symmetry, the square structure shielding body is selected in this invention.

[0097] In addition, according to the principle of the monopole antenna, the shielding metal surface is equivalent to the mirror plane of the antenna. To ensure the geometric symmetry between the antenna and the mirror metal ground, avoid non-uniform reflection and distortion caused by the antenna deviating from the edge, and improve the stability and consistency of the antenna equivalent impedance, the rod-shaped monopole antenna is placed at the geometric center of the metal shielding surface.

[0098] In this invention, the CST microwave studio was used to simulate and model the monopole rod antenna, and the simulation model is as Figure 7 shown. The electrically small monopole antenna can only sense the electric field parallel to the antenna direction. Therefore, three mutually perpendicular antennas can respectively output the induced voltages in three axial directions. According to the induced voltages U x , U y , U z and the transfer functions A x , A y , A z of each path, the axial components E x , E y , E z of the spatial electric field can be calculated. Then the magnitude of the spatial electromagnetic pulse electric field intensity is:

[0099]

[0100] The main polarization direction (angles with the x, y, and z axes) of the spatial electric field is:

[0101]

[0102] The purpose of the three-dimensional electric field sensor is to measure the electric field intensity of the electromagnetic pulse with the polarization direction at a certain position in space, and it can reflect the variation laws of its field intensity and polarization direction with time simultaneously. Therefore, it is necessary to verify the electric field polarization calculation method through simulation. Modeling and simulation are carried out in the CST software. The three-way antenna structure and load impedance of the three-dimensional sensor are exactly the same. The antenna length is 10 mm, the load capacitance is 1 pF, and the load resistance is 1 MΩ. The simulation uses a plane wave excitation to select a square wave with a leading edge and a trailing edge of 1 ns each and a pulse width of 20 ns. The upper limit frequency of the corresponding excitation signal is about The propagation direction of the plane wave is (1, 1, 1), the electric field intensity is (-1000, -2000, 3000) V / m, and the synthetic electric field intensity is 3741.66 V / m.

[0103] From Figure 8 It can be seen that the maximum induced voltages of the X-axis, Y-axis, and Z-axis measurement antennas are -1.322 V, -2.644 V, and 3.952 V respectively, and the synthetic voltage is 4.932 V. The induced voltages of the antennas in each axial direction can reproduce the spatial electric field waveform, and the working frequency band covers the nanosecond electromagnetic pulse frequency band. The voltage waveform under the square wave excitation is as Figure 8 shown. The figure shows the induced voltage waveforms in the X, Y, and Z axial directions. The synthetic voltage is the root mean square of the three directions. Table 1 statistically shows the polarization direction calculated according to formula (9) under the plane wave excitation. The results show that the angles between the spatial electric field and each axis are basically consistent with the calculated directions of the induced voltages, and the error is less than 0.1%, meeting the acceptable range of engineering errors. Therefore, the three-dimensional space electric field measurement device of the present invention can achieve accurate measurement.

[0104] Figure 9 FIG. 900 is a flowchart of a transmission line fault location method based on a multi-dimensional space electric field measurement device according to an embodiment of the present invention. As Figure 9 shown, the transmission line fault location method based on the multi-dimensional space electric field measurement device provided by the embodiment of the present invention can be effectively applied to fields such as non-contact measurement of transmission line overvoltage, fault location, and lightning location, and has significant practical value and engineering application prospects. The transmission line fault location method 900 based on the multi-dimensional space electric field measurement device as described above provided by the embodiment of the present invention starts from step 901. In step 901, the multi-dimensional space electric field measurement device is used to obtain the second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in the overhead transmission line.

[0105] In step 102, when there is a fluctuation in the second voltage signal in any direction, the moment of the voltage fluctuation is determined.

[0106] In step 103, based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of the voltage fluctuation, fault location is performed to determine the fault location.

[0107] Preferably, the fault location is determined based on the position information of any two three-dimensional electric field sensor deployment locations and the time of voltage fluctuation, and the fault location determination includes:

[0108]

[0109] where x is the distance between two adjacent two-dimensional magnetic field measurement transmission line fault location devices, and x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

[0110] Preferably, the method further includes:

[0111] Determining the thickness coefficient η of the electric field antenna by the following method, including:

[0112]

[0113] Determining the effective height h of the electric field antenna e , including:

[0114]

[0115] Determining the lower cut-off frequency f of the electric field antenna L , including:

[0116]

[0117] where h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried.

[0118] In the present invention, considering the overhead high-voltage transmission line scenario, the soil is regarded as an ideal conductor, and the electric field lines are perpendicular to the ground surface. The near-field electric field of the transmission line can be calculated by the mirror method. As Figure 10 shown, considering a conductor with a height of H i and carrying a positive charge +Q i , the conductor is located above the mirror plane of the earth. The earth can be equivalent to the mirror plane, and the conductor that is the mirror relative to the earth is located below the mirror platform. The distance between the conductor and its mirror conductor is 2H i , and it carries a negative charge -Q i . In a multi-conductor overhead transmission line, the relationship between the phase voltage and the conductor charge is expressed as:

[0119] V phase = PQ(12)​​​​​​​​​​​

[0120] Among them, V phase is the phase voltage vector matrix, Q is the wire surface charge vector matrix, and P is the potential coefficient matrix, which is determined by the spatial layout between conductors. The analytical formula for specific parameters is as follows:

[0121]

[0122] After determining the charge quantity, the spatial electric field component E P (x, y, z) = (E x , E y , E z ), and the polarization components of each x, y, and z axis are respectively:

[0123]

[0124] Among them, L i is the radial distance from the wire to the measurement point, and L′ i is the radial distance from the mirror wire to the measurement point. According to formula (14), the analytical relationship between the spatial electric field and the conductor surface charge E p = P E Q can be obtained.

[0125] In an actual measurement scenario, the three-dimensional electric field sensor is set at a certain height from the wire, and the instantaneous electric field full waveforms in the x, y, and z directions are measured and recorded. According to the linear relationship between the electric field and the charge, the wire charge can be inversely solved, and then according to the charge-voltage linear relationship, the line phase voltage can be inversely deduced.

[0126]

[0127] Through formula (15), the mapping relationship between the spatial electric field of the overhead transmission line and the phase voltage can be established, and the phase voltage can be inversely solved through the measured electric field signal.

[0128] Therefore, in the overhead transmission line, multiple electric field sensors are distributed, and based on the voltage data measured by two sensors, the fault location can be measured and located by the time difference method.

[0129] Specifically, use the multi-dimensional spatial electric field measurement device to obtain the second voltage signals in the X, Y, and Z directions at the locations of at least two three-dimensional sensors arranged in the overhead transmission line; when there is a fluctuation in the second voltage signal in any direction, determine the moment of the voltage fluctuation; based on the position information of any two three-dimensional electric field sensor arrangements and the moment of the voltage fluctuation, perform fault location to determine the fault location. Among them, assume at position x gA ground fault occurred at a certain location. Sensors A and B are located at x1 and x2 respectively, and the traveling wave velocity is v (a typical value in overhead transmission lines is 2.9×10 8 m / s). In the measurement system, positioning is carried out in the following manner, including:

[0130]

[0131] where x is the distance between two adjacent two-dimensional magnetic field measurement transmission line fault location devices, x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

[0132] Figure 11 is a schematic structural diagram of a transmission line fault location system 1100 based on a multi-dimensional space electric field measurement device according to an embodiment of the present invention. As Figure 11 shown, the transmission line fault location system 1100 based on the multi-dimensional space electric field measurement device provided by the embodiment of the present invention includes: a voltage signal measurement unit 1101, a fluctuation time determination unit 1102, and a location unit 1103.

[0133] Preferably, the voltage signal measurement unit 1101 is configured to obtain second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in the overhead transmission line by using the multi-dimensional space electric field measurement device.

[0134] Preferably, the fluctuation time determination unit 1102 is configured to determine the time of voltage fluctuation when there is a fluctuation in the second voltage signal in any direction.

[0135] Preferably, the location unit 1103 is configured to perform fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the time of voltage fluctuation to determine the fault location.

[0136] Preferably, the location unit 1103 performs fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the time of voltage fluctuation to determine the fault location, including:

[0137]

[0138] where x is the distance between two adjacent two-dimensional magnetic field measurement transmission line fault location devices, x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

[0139] Preferably, the system further includes: a parameter determination unit, configured to:

[0140] The thickness coefficient η of the electric field antenna is determined in the following manner, including:

[0141]

[0142] The effective height h of the electric field antenna is determined in the following manner e , including:

[0143]

[0144] The lower cut-off frequency f of the electric field antenna is determined in the following manner L , including:

[0145]

[0146] where h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried by it.

[0147] The power transmission line fault location system 1100 based on the multi-dimensional space electric field measurement device in the embodiment of the present invention corresponds to the power transmission line fault location method 100 based on the multi-dimensional space electric field measurement device in another embodiment of the present invention, which will not be elaborated here.

[0148] The present invention has been described by referring to a few embodiments. However, as is well known to those skilled in the art, other embodiments equivalent to those disclosed above in the present invention equally fall within the scope of the present invention.

[0149] Generally, all terms used in the present invention are interpreted according to their ordinary meanings in the technical field, unless otherwise clearly defined therein. All references to "a / the [device, component, etc.]" are to be interpreted openly as at least one instance of the device, component, etc., unless otherwise clearly stated. The steps of any method disclosed herein do not necessarily have to be run in the exact order disclosed, unless clearly stated.

[0150] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0151] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0152] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0153] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operating steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the present invention.

Claims

1. A multi-dimensional space electric field measurement device, characterized in that, The device includes: a three-dimensional electric field sensor, an electro-optic conversion module, an optoelectronic receiving module, a conditioning circuit, and an FPGA high-speed digital acquisition module; wherein, The three-dimensional electric field sensor includes: three electric field antennas, which are used to measure the first electric field signals in the three mutually perpendicular X, Y, and Z directions in space respectively; The electro-optic conversion module is connected to the three-dimensional electric field sensor and is used to perform electro-optic conversion on the first electric field signal and convert the first electric field signal into an optical signal; The optoelectronic receiver is connected to the electro-optic conversion module and is used to perform optoelectronic conversion on the optical signal and convert the optical signal into a current signal; The conditioning circuit is connected to the optoelectronic receiving module and is used to convert the current signal into a voltage signal and amplify it to the required signal amplitude to obtain the second voltage signals in the X, Y, and Z directions; The FPGA high-speed digital acquisition module is connected to the conditioning circuit and is used to acquire the second voltage signals.

2. The device according to claim 1, characterized in that The three-dimensional electric field sensor further includes: a sensor shielding structure, which is placed outside the three electric field antennas and is used to shield external signals; wherein, the three electric field antennas are placed at the geometric center of the metal shielding surface.

3. The device according to claim 2, characterized in that, The sensor shielding structure is a shielding body with a square structure.

4. The device according to claim 1, characterized in that, The electric field antenna is an ultra-wideband monopole antenna.

5. A transmission line fault location method based on the multi-dimensional space electric field measurement device according to any one of claims 1-4, characterized in that, The method includes: Using a multi-dimensional space electric field measurement device to obtain the second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in an overhead transmission line; When there is a fluctuation in the second voltage signal in any direction, determining the moment of voltage fluctuation; Based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of voltage fluctuation, performing fault location to determine the fault location.

6. The method according to claim 5, wherein The performing fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of voltage fluctuation to determine the fault location includes: Where x is the distance between two adjacent two-dimensional magnetic field measurement power transmission line fault location devices, and x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

7. The method according to claim 5, wherein The method further includes: Using the following method to determine the thickness coefficient η of the electric field antenna, including: Determine the effective height h of the electric field antenna in the following manner e , including: Determine the lower cut-off frequency f of the electric field antenna in the following manner L , including: Among them, h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried by the antenna.

8. A power transmission line fault location system based on the multi-dimensional space electric field measurement device according to any one of claims 1-4, characterized in that, The system includes: A voltage signal measurement unit, which is used to use a multi-dimensional space electric field measurement device to obtain the second voltage signals in the X, Y, and Z directions at at least two three-dimensional sensor deployment locations arranged in an overhead transmission line; A fluctuation moment determination unit, which is used to determine the moment of voltage fluctuation when there is a fluctuation in the second voltage signal in any direction; A positioning unit, which is used to perform fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of voltage fluctuation to determine the fault location.

9. The system according to claim 8, characterized in that The positioning unit, performing fault location based on the position information of any two three-dimensional electric field sensor deployment locations and the moment of voltage fluctuation to determine the fault location, includes: Wherein, x is the distance between two adjacent two-dimensional magnetic field measurement power transmission line fault location devices, and x g is the distance between the fault location device that first receives the fault waveform and the fault point, v is the wave velocity, and Δt is the time difference between adjacent wave peaks.

10. The system according to claim 8, wherein The system further includes: a parameter determination unit, which is used to: Using the following method to determine the thickness coefficient η of the electric field antenna, including: Determine the effective height h of the electric field antenna in the following manner e , including: Determine the lower cut-off frequency f of the electric field antenna in the following manner L , including: where h is the length of the antenna; a is the radius of the antenna; R l represents the resistance of the load carried by the antenna; C a and C l respectively represent the equivalent capacitance of the antenna and the capacitance of the load carried by the antenna.

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