Isotropic broadband voltage measuring method and sensing system

Abstract

The invention discloses an isotropic broadband voltage measurement method and a sensing system. Distributed capacitance between a spherical electric field coupling voltage sensor and a measured conductor, stray capacitance to the ground and grounding measurement resistance are modulated to meet a first constraint condition; a differential input circuit is connected between each pair of electrodes in the spherical electric field coupling voltage sensor, and the distance between the spherical electric field coupling voltage sensor and a measured conductor and the distance between each pair of electrodes in the spherical electric field coupling voltage sensor are adjusted at the same time. The mutual capacitance between each pair of electrodes and the measured conductor simultaneously meets a second constraint condition and a third constraint condition; the modulated spherical electric field is coupled with a voltage sensor to obtain a space electric field differential signal of the line, and voltage distribution on the line is calculated; according to the method, an NSGA-III-JADE method of adaptive differential evolution is adopted, inversion voltage on the line is determined from voltage distribution on the line, and broadband measurement of the voltage of the line with the bandwidth ranging from 50 Hz to 10 MHz is achieved.

Description

Technical Field

[0001] The present invention relates to the field of broadband voltage measurement, and in particular to an isotropic broadband voltage measurement method and a sensing system based on an NSGA-III-JADE algorithm. Background Art

[0002] The high-frequency harmonics and transient overvoltage components in the line seriously affect the line power quality and power system safety, so broadband measurement of line voltage is of great significance.

[0003] In the prior art, broadband voltage standard measurement is based on the requirements for the frequency characteristics of the broadband standard measuring device itself, and the lower and upper frequency waveforms are selected for tracing, which greatly reduces the difficulty of tracing. The broadband voltage standard measuring device includes: a broadband voltage divider and a secondary measuring device. The voltage signal is first converted through the broadband voltage divider and then sequentially enters the measuring device for secondary conversion and acquisition of the voltage. The two processes are relatively independent. The voltage scale factor of the measuring device is the product of the voltage scale factor of the voltage divider and the secondary measuring device. The voltage scale factor is traced separately from the voltage divider and the secondary measuring device, which makes the tracing method more operational. Since the impulse waveform is a non-repetitive frequency waveform and its frequency component is very complex, the amplitude-frequency characteristic is more suitable for tracing the alternating current with a repetitive frequency, and it is more reasonable to evaluate the dynamic characteristics of the impulse voltage. The broadband transient voltage divider measuring device includes a high-voltage arm unit, which is used to divide the high voltage of the measured line to obtain a divided low voltage, and send the divided low voltage to the low-voltage arm unit; a low-voltage arm unit, which is used to send the divided low voltage to a broadband transient measurement unit; a broadband transient measurement unit, which is used to measure the divided low voltage sent by the low-voltage arm unit, and determine the high voltage of the measured line according to the divided low voltage and the voltage divider ratio; the device uses low-inductance ceramic capacitors and non-inductive resistors for multi-stage series connection, and can be directly connected to the transmission line to measure the high voltage of the measured circuit in real time; the device can measure the voltage with high amplitude, wide bandwidth and little influence from the external environment; the real waveform of the overvoltage can be determined, which is of great significance to the safe and stable operation of the transmission line. However, the prior art still uses PT for voltage measurement, and the electromagnetic transformer is easily affected by ferromagnetic resonance; the transient characteristics of the capacitive transformer are poor, and high-frequency resonance may be generated under high-frequency overvoltage. The electric field sensor has a wide frequency response range and can effectively capture high-frequency harmonics and transient overvoltage components, providing more comprehensive voltage signal information, but it has strict requirements on the installation position and angle. Therefore, it is necessary to propose a method that can measure isotropic broadband voltage. Summary of the invention

[0004] In order to solve the shortcomings in the prior art, the present invention provides an isotropic broadband voltage measurement method and system based on NSGA-III-JADE algorithm, realizes spatial electric field measurement based on electric field sensing probes with three pairs of electrodes symmetrically distributed, inverts and solves the voltage according to the distance between the electric field and the probe-line by using a non dominated sorting genetic algorithm-III-adaptive differential evolution fusion method (NSGA-III-JADE, Non dominated Sorting Genetic Algorithm-III-AdaptiveDifferentialEvolution withOptionalExternalArchive), and determines the final voltage output by combining a superior and inferior solution distance method (TOPSIS, Technique for Order Preference by Similarityto IdealSolution), thereby forming an isotropic broadband voltage measurement system, and realizing broadband measurement of line voltage with a bandwidth of 50Hz-10MHz.

[0005] The present invention adopts the following technical solution.

[0006] The present invention proposes an isotropic broadband voltage measurement method, which uses a spherical electric field coupling voltage sensor for measurement. The spherical electric field coupling voltage sensor includes P pairs of isotropic electric field sensing probes, each pair of probes includes a pair of symmetrically distributed electrodes, including:

[0007] Step 1: Obtain the distributed capacitance C between the spherical electric field coupling voltage sensor and the conductor being measured t , the stray capacitance C of the spherical electric field coupled voltage sensor to the ground d , and the grounded measuring resistance R connected to the spherical electric field coupling voltage sensor m ; When the three modulation parameters meet the first constraint condition, go to step 2;

[0008] Step 2: A differential input circuit is connected between each pair of electrodes in the spherical electric field coupled voltage sensor, and the mutual capacitance C between each pair of electrodes after the differential input circuit is connected is obtained. m0 , the mutual capacitance C between each pair of electrodes and the conductor being measured m ; At the same time, adjust the distance between the spherical electric field coupling voltage sensor and the conductor to be measured and the distance between each pair of electrodes in the spherical electric field coupling voltage sensor. When the mutual capacitance C between each pair of electrodes and the conductor to be measured m0 When the second constraint condition and the third constraint condition are satisfied at the same time, proceed to step 3;

[0009] Step 3: Use the modulated spherical electric field coupled voltage sensor to obtain the spatial electric field differential signal of the line; calculate the voltage distribution on the line based on the spatial electric field differential signal of the line; and use the NSGA-III-JADE method of adaptive differential evolution to determine the inversion voltage on the line from the voltage distribution on the line as the voltage measurement result.

[0010] Preferably, the first constraint is: t +C d )R m is greater than a first set threshold, and the first set threshold is not less than 10.

[0011] Preferably, the second constraint is: C m0 / C m is greater than a second set threshold, and the second set threshold is not less than 10.

[0012] Preferably, the third constraint is: C m0 / C d is greater than a third set threshold, and the third set threshold is not less than 10.

[0013] Preferably, when the first constraint condition is met, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship:

[0014]

[0015] In the formula, H s (s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition is satisfied, is the frequency domain signal of the equivalent potential of the conductor under test, V s (s) is the frequency domain signal of the output voltage of the spherical electric field coupled voltage sensor.

[0016] Preferably, when the first constraint condition, the second constraint condition, and the third constraint condition are satisfied, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship:

[0017]

[0018] In the formula, H s ′(s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition, the second constraint condition and the third constraint condition are satisfied. is the frequency domain signal of the equivalent potential of the conductor under test, V s (s) is the frequency domain signal of the output voltage of the spherical electric field coupled voltage sensor.

[0019] Preferably, step 3 comprises:

[0020] Step 3.1, using a differential input circuit to obtain a spatial electric field differential signal of the line; and calculating the voltage distribution on the line according to the spatial electric field differential signal of the line;

[0021] In step 3.2, the electric field calculation value is obtained according to the voltage distribution on the line. The NSGA-III-JADE method of adaptive differential evolution is used, with the minimum mean square error between the actual measured value of the electric field and the calculated value of the electric field as the optimization goal, and the inversion voltage of the line is obtained from the voltage distribution as the voltage measurement result.

[0022] Preferably, step 3.2 comprises:

[0023] 1) Set the initial population; each measurement point on the line corresponds to a voltage distribution value, and each individual in the initial population represents a voltage distribution value, which is a candidate solution for the inversion voltage;

[0024] 2) Assume that there are N voltage distribution values ​​V1, V2, ..., V in the population. N , each voltage distribution value corresponds to an electric field calculation value; the optimization goal is to minimize the mean square error between the actual measured value of the electric field and the calculated value of the electric field, satisfying the following relationship:

[0025]

[0026] In the formula, f i (x) is the optimization target value at the i-th measurement point under the decision variable x; is the actual measured value of the j-th dimension electric field at the ith measurement point; is the calculated value of the j-th dimension electric field obtained by calculating the voltage distribution value at the i-th measurement point under the decision variable x; M is the electric field dimension;

[0027] 3) In the population, the voltage distribution values ​​are non-dominated sorted according to the optimization target to obtain a new population;

[0028] 4) Merge the initial population and the new population into a temporary population, and repeat steps 2) to 4) based on the temporary population for iterative solution; when the number of iterations is reached, use the TOPSIS method to determine the inversion voltage of the line in the temporary population obtained in the last iteration.

[0029] Preferably, in the population, the voltage distribution values ​​are non-dominatedly sorted according to the optimization target to obtain a new population, including:

[0030] 3.1) Under the decision variables p and q, the optimization target value at the i-th measurement point satisfies f i (p)≤f i (q) and there is at least one measurement point where the optimization objective value satisfies f j (p)<fj (q), it represents that individual p dominates individual q; the population is divided into multiple fronts, the first front contains all non-dominated solutions, the second front contains solutions dominated by the first front but not dominated by the second front, and so on;

[0031] 3.2) Randomly select three different individuals x from different frontiers r1 、x r2 、x r3 , based on the decision variable x at the i-th measurement point i , generate a new individual v with the following relationship i :

[0032] v i =x r1 +F·(x r2 -x r3 )+CR·(x r1 -x i )

[0033] In the formula, x r1 、x r2 、x r3 is the random selection of three different individuals in different frontiers; F is the mutation scaling factor; CR is the crossover probability.

[0034] Preferably, adaptive differential evolution is performed on the variation scaling factor and the crossover probability according to the voltage level and transient voltage frequency of the conductor to be measured.

[0035] The present invention also proposes an isotropic broadband voltage measurement sensor system, comprising: a spherical electric field coupling voltage sensor and an electric field measurement device;

[0036] The spherical electric field coupling voltage sensor includes P pairs of isotropic electric field sensing probes, each pair of probes includes a pair of symmetrically distributed electrodes, and P is an integer not less than 3; the isotropic electric field sensing probe with three pairs of symmetrically distributed electrodes includes a spherical probe;

[0037] The electric field measuring device includes: a signal conditioning module, an analog-to-digital conversion module, an MCU, a distance measurement module, a distance display module and a signal acquisition controller;

[0038] The spherical probe transmits the spatial electric field differential signal of the line to the signal conditioning module; the signal conditioning module is used to implement filtering, level raising and buffer following of the spatial electric field differential signal of the line; the analog-to-digital conversion module is used to convert the spatial electric field differential signal output by the signal conditioning module into a digital signal and transmit it to the MCU; the MCU is used to transmit the processed signal to the signal acquisition controller, and the signal acquisition controller transmits the signal to the distance display module; the ranging module is used to measure the distance H between the ranging module and the line, and the ranging module includes: an ultrasonic ranging module.

[0039] Preferably, the spherical probe includes an AA' plate, a BB' plate and a CC' plate; the AA' plate, the BB' plate and the CC' plate are used to measure the spatial electric field differential signal of the circuit, and the structural parameters of each plate satisfy the following relationship:

[0040]

[0041] Where θ is the azimuth angle of the probe, is the pitch angle of the probe.

[0042] Preferably, the spherical probe is mounted on the upper surface of the signal acquisition controller through a retractable sensor bracket, and the distance measurement module is also mounted on the upper surface of the signal acquisition controller, so that the distance D from the spherical probe to the line satisfies the following relationship:

[0043] D=Hhr

[0044] Where h is the length of the telescopic sensor bracket and r is the radius of the spherical probe.

[0045] Preferably, the electric field measuring device further comprises: a power supply module, a communication module, a near-field alarm module and a host computer;

[0046] The near-field alarm module is used to issue an alarm when the distance between the electric field sensor probe and the transmission line is less than the set threshold; the communication module is used to transmit data to the host computer after selecting the wireless transmission mode or the wired transmission mode according to actual needs; the power module is used to supply power to the signal conditioning module, the analog-to-digital conversion module, the MCU, the ranging module, the near-field alarm module, the distance display module and the signal acquisition controller.

[0047] The beneficial effects of the present invention are that, compared with the prior art, at least the method and system proposed by the present invention use an electric field sensing probe with three pairs of spherical electrodes symmetrically distributed to measure the electric field. The electric field distortion in the electrode area is small and is basically not affected by the sensor measurement angle, and has the characteristics of homogeneous measurement. The voltage is inverted based on the NSGA-III-JADE algorithm to achieve the measurement of broadband voltage signals of different levels. In addition, the system also integrates ranging function and near-field alarm function. The ranging module provides precise positioning, optimizes the layout, and improves the reliability of the measurement data; the near-field alarm module can ensure personnel safety, prevent equipment damage, and enhance system stability. The method and system proposed by the present invention have relatively consistent response characteristics when the probe is in different assembly directions, and the directional error is small, which can achieve accurate measurement of broadband voltage signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of the isotropic broadband voltage measurement method proposed by the present invention;

[0049] Figure 2 is a single electrode measurement equivalent circuit diagram of a spherical electric field coupled voltage sensor in an embodiment of the present invention;

[0050] Figure 3 It is a measurement equivalent circuit of a pair of symmetrically distributed electrodes in the spherical electric field coupled voltage sensor in the embodiment of the present invention;

[0051] Figure 4 It is a structural block diagram of the isotropic broadband voltage measurement sensor system proposed by the present invention;

[0052] Figure 5 is a schematic diagram of measuring the distance D from the probe to the line in an embodiment of the present invention;

[0053] Figure 6 is a steady-state test result of the system in an embodiment of the present invention;

[0054] Figure 7 It is the test result of 1.2 / 50μs transient overvoltage impulse response of the system in the embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0056] The electric field strength value around the conductor to be measured has a certain proportional relationship with the voltage of the conductor itself, and the electric field strength value will decrease as the distance between the measurement point and the conductor increases. Within the frequency and size range corresponding to the conductor to be measured, the time taken for the electromagnetic wave to propagate can be ignored, so the conductor voltage and the electric field strength around the conductor change synchronously in time, and the indirect measurement of the conductor potential is achieved by measuring the electric field strength value around the conductor.

[0057] Traditional transformers need to maintain electrical connection with the conductor being measured to achieve voltage measurement. For traditional voltage transformers, whether it is an electromagnetic voltage transformer based on the transformer principle or a capacitive voltage transformer with an intermediate transformer, its essence is to use the magnetic field energy in the iron core as a medium to transfer electric field energy between the primary and secondary sides, and rely on the turns ratio of the primary and secondary windings to achieve the transformation of voltage levels. This process is always accompanied by energy transfer and loss. Due to ferromagnetic resonance, traditional voltage transformers may experience high-frequency oscillations, and capacitive voltage transformers also have the problem that the secondary input cannot follow the primary voltage changes.

[0058] The present invention proposes to measure voltage by electric field coupling, directly obtain electric field strength signal, and thus achieve the purpose of indirectly measuring conductor voltage. In this process, basically no current is generated, and there is no exchange of functional energy between the power system and the electric field measurement sensor.

[0059] The present invention proposes an isotropic broadband voltage measurement method, which uses a spherical electric field coupling voltage sensor for measurement. The spherical electric field coupling voltage sensor includes P pairs of isotropic electric field sensing probes, each pair of probes includes a pair of symmetrically distributed electrodes, such as Figure 1 As shown, including:

[0060] Step 1: Obtain the distributed capacitance C between the spherical electric field coupling voltage sensor and the conductor being measured t , the stray capacitance C of the spherical electric field coupled voltage sensor to the ground d , and the grounded measuring resistance R connected to the spherical electric field coupling voltage sensor m ; When the three modulation parameters meet the first constraint, go to step 2.

[0061] Specifically, the single electrode measurement equivalent circuit diagram of the spherical electric field coupled voltage sensor used in the present invention is as follows: Figure 2 shown. Figure 2 middle, is the equivalent potential of the conductor being measured and is the input voltage of the spherical electric field coupled voltage sensor, V s (t) is the output voltage of the spherical electric field coupling voltage sensor, V0(t) is the output voltage of the integration circuit connected to the spherical electric field coupling voltage sensor; wherein the equivalent circuit of the spherical electric field coupling voltage sensor includes: the distributed capacitance C between the sensor and the conductor being measured t , the stray capacitance C of the sensor to ground d , the ground measuring resistance R of the sensor connection m The equivalent circuit of the integration circuit connected to the spherical electric field coupled voltage sensor includes: a first resistor R1 and a first capacitor C1.

[0062] The equivalent circuit of the spherical electric field coupled voltage sensor is a first-order RC circuit model, and the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship:

[0063]

[0064] In the formula, H s (s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition is satisfied, is the frequency domain signal of the equivalent potential of the conductor under test, V s(s) is the frequency domain signal of the output voltage of the spherical electric field coupled voltage sensor, and s is the integration operator.

[0065] When (C t +C d )R m When <<1, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship:

[0066]

[0067] At this time, the spherical electric field coupled voltage sensor works in the differential mode, V0(t) and The differential component is proportional to the input voltage of the spherical electric field coupled voltage sensor. It is linearly related to the voltage V0(t) output after passing through the integration circuit.

[0068] When (C t +C d )R m >>1, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship:

[0069]

[0070] At this time, the first constraint is: (C t +C d )R m is greater than the first set threshold; the first set threshold is not less than 10; when the first constraint condition is met through modulation, the spherical electric field coupled voltage sensor works in the self-integration mode, V s (t) The spherical electric field coupled voltage sensor does not need an external integrating circuit, and can also realize the input voltage of the spherical electric field coupled voltage sensor. With the output voltage V s (t) is in a linear relationship.

[0071] Most voltage frequencies in power systems are within the 50Hz fundamental frequency range, but transient voltage frequencies may reach the MHz level. t and stray capacitance C d To pF level, adjust the grounding measurement resistance R m When reaching GΩ level, (C t +C d )R m >>1, making the spherical electric field coupled voltage sensor work in the self-integration mode, ensuring the input voltage of the spherical electric field coupled voltage sensor With the output voltage V s (t) is linearly related, and broadband measurement is also achieved.

[0072] Therefore, the present invention proposes to modulate the distributed capacitance C between the spherical electric field coupling voltage sensor and the conductor to be measured. t , the stray capacitance C of the spherical electric field coupled voltage sensor to the ground d , and the grounded measuring resistance R connected to the spherical electric field coupling voltage sensor m , to satisfy the first constraint (C t +C d )R m >>1, go to step 2.

[0073] Step 2: A differential input circuit is connected between each pair of electrodes in the spherical electric field coupled voltage sensor, and the mutual capacitance C between each pair of electrodes after the differential input circuit is connected is obtained. m0 , the mutual capacitance C between each pair of electrodes and the conductor being measured m ; At the same time, adjust the distance between the spherical electric field coupling voltage sensor and the conductor to be measured and the distance between each pair of electrodes in the spherical electric field coupling voltage sensor. When the mutual capacitance C between each pair of electrodes and the conductor to be measured m0 When the second constraint and the third constraint are satisfied at the same time, proceed to step 3.

[0074] In the spherical electric field coupled voltage sensor used in the present invention, a pair of symmetrically distributed electrodes is used to measure the equivalent circuit as shown in FIG. Figure 3 As shown, C m is the mutual capacitance between a pair of electrodes and the conductor being measured, and the mutual capacitance C m It is related to the distance between the electrode and the conductor being measured. Since the distance between the electrode and the conductor being measured is large, the mutual capacitance C m Smaller; a differential input circuit is connected between a pair of electrodes, C m0 The mutual capacitance between a pair of electrodes after the differential input circuit is connected. Since the distance between a pair of electrodes is adjustable, the mutual capacitance C between a pair of electrodes can be adjusted by adjusting the distance between the pair of electrodes. m0 Much larger than the mutual capacitance C between a pair of electrodes and the conductor being measured m , and the mutual capacitance C between a pair of electrodes m0 It is also much larger than the stray capacitance C of the sensor to the ground. d , therefore, in satisfying (C t +C d )R m >>1, the differential input circuit will not change the transfer function of the spherical electric field coupled voltage sensor working in the self-integration mode, and the transfer function satisfies the following relationship:

[0075]

[0076] In the formula, H s′(s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition, the second constraint condition and the third constraint condition are satisfied.

[0077] Specifically, the present invention adopts the method of simultaneously adjusting the distance between the spherical electric field coupling voltage sensor and the conductor to be measured and the distance between a pair of electrodes to modulate the mutual capacitance C m0 Satisfy the second constraint, the second constraint is: C m0 / C m is greater than the second set threshold, the third constraint is: C m0 / C d is greater than the third set threshold, wherein the second set threshold and the third value set threshold are not less than 10. m0 >>C m , and C m0 >>C d , the same modulation method is used for each pair of electrodes in the spherical electric field coupled voltage sensor.

[0078] Step 3: Use the modulated spherical electric field coupled voltage sensor to obtain the spatial electric field differential signal of the line; calculate the voltage distribution on the line based on the spatial electric field differential signal of the line; and use the NSGA-III-JADE method of adaptive differential evolution to determine the inversion voltage on the line from the voltage distribution on the line as the voltage measurement result.

[0079] Specifically, step 3 includes:

[0080] Step 3.1, using a differential input circuit to obtain a spatial electric field differential signal of the line; and calculating the voltage distribution on the line according to the spatial electric field differential signal of the line;

[0081] Specifically, the present invention connects a differential input circuit between each pair of electrodes, and uses the differential input circuit to obtain the spatial electric field differential signal of the line. The differential input circuit has the characteristics of resisting common-mode interference from the environment and only amplifying the differential signal, thereby significantly improving the anti-interference ability of the system and reducing the influence of stray capacitance. Therefore, the present invention connects a differential input circuit between three pairs of electrodes.

[0082] At each measuring point on the line, a modulated spherical electric field coupled voltage sensor is used to obtain the spatial electric field differential signal of the line. According to the spatial electric field differential signal at each measuring point, the voltage distribution value at each measuring point on the line is calculated.

[0083] In step 3.2, the electric field calculation value is obtained according to the voltage distribution on the line. The NSGA-III-JADE method of adaptive differential evolution is used, with the minimum mean square error between the actual measured value of the electric field and the calculated value of the electric field as the optimization goal, and the inversion voltage of the line is obtained from the voltage distribution as the voltage measurement result.

[0084] Specifically, step 3.2 includes:

[0085] 1) Set the initial population;

[0086] Each measuring point on the line corresponds to a voltage distribution value. Each individual in the initial population represents a voltage distribution value, and the voltage distribution value is a candidate solution for the inversion voltage.

[0087] 2) Assume that there are N voltage distribution values ​​V1, V2, ..., V in the population. N , each voltage distribution value corresponds to an electric field calculation value; the optimization goal is to minimize the mean square error between the actual measured value of the electric field and the calculated value of the electric field, satisfying the following relationship:

[0088]

[0089] In the formula, f i (x) is the optimization target value at the i-th measurement point under the decision variable x; is the actual measured value of the j-th dimension electric field at the ith measurement point; is the calculated value of the j-th dimensional electric field obtained by calculating the voltage distribution value at the ith measurement point under the decision variable x; M is the electric field dimension.

[0090] In the present invention, the reverse voltage of the line is used as the decision variable x, which is a non-restrictive and preferred choice. When the reverse voltage of the line is used as the decision variable, a more accurate voltage measurement result can be obtained by optimization. The distance between the spherical electric field coupling voltage sensor and the conductor to be measured can also be used as the decision variable, and a more suitable measurement point can be obtained by optimization; the distance between each pair of electrodes in the spherical electric field coupling voltage sensor can also be used as the decision variable, and a suitable spherical electric field coupling voltage sensor structure can be obtained by optimization.

[0091] 3) In the population, the voltage distribution values ​​are non-dominatedly sorted according to the optimization target to obtain a new population; including:

[0092] 3.1) Under the decision variables p and q, the optimization target value at the i-th measurement point satisfies f i (p)≤f i (q) and there is at least one measurement point where the optimization objective value satisfies f j (p)<f j(q), it represents that individual p dominates individual q; the population is divided into multiple frontiers, the first front contains all non-dominated solutions, the second front contains solutions dominated by the first front but not dominated by the second front, and so on.

[0093] 3.2) Randomly select three different individuals x from different frontiers r1 、x r2 、x r3 , based on the decision variable x at the i-th measurement point i , generate a new individual v with the following relationship i :

[0094] v i =x r1 +F·(x r2 -x r3 )+CR·(x r1 -x i )

[0095] In the formula, x r1 、x r2 、x r3 is the random selection of three different individuals in different frontiers; F is the mutation scaling factor; CR is the crossover probability.

[0096] Among them, adaptive differential evolution is performed on the mutation scaling factor and crossover probability according to the voltage level and transient voltage frequency of the conductor to be tested; the NSGA-III-JADE method using adaptive differential evolution is a non-restrictive and better choice. Based on adaptive differential evolution, the NSGA-III-JADE method can not only dynamically adjust the mutation parameters, but also retain the advantages of the NSGA-III-JADE method in diversity distribution.

[0097] The new individual v i Add to new populations;

[0098] 4) Merge the initial population and the new population into a temporary population, and repeat steps 2) to 4) based on the temporary population for iterative solution; when the number of iterations is reached, use the TOPSIS method to determine the inversion voltage of the line in the temporary population obtained in the last iteration.

[0099] The present invention proposes an isotropic broadband voltage measurement method based on NSGA-III-JADE algorithm, which has a wide frequency response range and realizes accurate measurement of space vector electric field. The NSGA-III-JADE algorithm is introduced to perform voltage measurement inversion calculation, and the TOPSIS algorithm is combined to realize high-precision and reliable measurement of broadband voltage signals.

[0100] The present invention also proposes an isotropic broadband voltage measurement sensor system, such as Figure 4As shown, it includes: a spherical electric field coupling voltage sensor and an electric field measuring device; wherein the spherical electric field coupling voltage sensor includes P pairs of isotropic electric field sensing probes, each pair of probes includes a pair of symmetrically distributed electrodes, and P is an integer not less than 3.

[0101] The present invention proposes to use an isotropic electric field sensing probe with three pairs of electrodes symmetrically distributed to obtain the spatial electric field differential signal of the line. Then, an electric field measuring device is used to obtain the spatial electric field of the line according to the spatial electric field differential signal, and the electric field measuring device is used to obtain the distance from the electric field sensing probe to the line. This is a non-restrictive and preferred choice. Those skilled in the art can use different probes and electric field measuring devices to obtain the spatial electric field of the line and the distance from the electric field sensing probe to the line according to actual conditions.

[0102] In a non-limiting preferred embodiment, the isotropic electric field sensing probe with three pairs of electrodes symmetrically distributed includes but is not limited to a spherical probe, such as Figure 2 As shown, the spherical probe includes AA' plate, BB' plate and CC' plate; the AA' plate, BB' plate and CC' plate are used to measure the spatial electric field differential signal of the line, and the structural parameters of each plate satisfy the following relationship:

[0103]

[0104] Where θ is the azimuth angle of the probe, is the pitch angle of the probe.

[0105] Using an isotropic electric field sensing probe with three pairs of electrodes symmetrically distributed, the isotropic voltage of the line space electric field is measured.

[0106] In a non-limiting preferred embodiment, Figure 4 and Figure 5 As shown, the electric field measurement device includes but is not limited to: a signal conditioning module, an analog-to-digital conversion module, a power module, an MCU, a communication module, a distance measurement module, a near-field alarm module, a distance display module, a signal acquisition controller, and a host computer.

[0107] The spherical probe transmits the spatial electric field differential signal of the line to the signal conditioning module; the signal conditioning module is used to implement filtering, level raising and buffering and following of the spatial electric field differential signal of the line; the analog-to-digital conversion module is used to convert the spatial electric field differential signal output by the signal conditioning module into a digital signal and transmit it to the MCU; the ranging module is used to measure the distance H between the ranging module and the line, and the ranging module includes but is not limited to: an ultrasonic ranging module;

[0108] like Figure 5As shown, the spherical probe is installed on the upper surface of the signal acquisition controller through a retractable sensor bracket, and the distance measurement module is also installed on the upper surface of the signal acquisition controller. Therefore, the distance D from the spherical probe to the line satisfies the following relationship:

[0109] D=Hhr

[0110] Where h is the length of the telescopic sensor bracket and r is the radius of the spherical probe.

[0111] The near-field alarm module is used to issue an alarm when the distance between the electric field sensor probe and the transmission line is less than the set threshold, thereby ensuring that the working environment is within a safe range; the communication module is used to transmit data to the host computer after selecting the wireless transmission mode or the wired transmission mode according to actual needs; the power module is used to supply power to the signal conditioning module, the analog-to-digital conversion module, the MCU, the ranging module, the near-field alarm module, the distance display module, and the signal acquisition controller.

[0112] Finally, the electric field measuring device outputs the spatial electric field signal of the line and the distance from the electric field sensing probe to the line.

[0113] Before the system is officially used, a calibration test must be carried out. The system must be placed under a circuit with known voltage waveforms of different levels, the probe must be adjusted to different heights, the system output must be calibrated with the known voltage waveform, and the system performance must be verified.

[0114] The working process of the isotropic broadband voltage measurement sensor system proposed by the present invention includes:

[0115] 1) Arrange the probes. When the probes are too close to the line, an alarm will be sounded and the sensor height will be readjusted until the measurement requirements are met.

[0116] 2) After the probe signal is filtered, amplified and conditioned, the processed signal is transmitted to the signal acquisition controller;

[0117] 3) The signal acquisition controller transmits the signal to the display terminal, completes the voltage inversion calculation, and draws the waveform.

[0118] The electric field measuring device and the display terminal can be selected by wired / wireless means according to the needs and usage scenarios. The display terminal performs voltage inversion calculation based on the electric field and probe-line distance D data provided by the electric field measuring device, and reconstructs the voltage waveform of each phase according to the calculation result structure.

[0119] The steady-state, transient, and anti-angle deviation test results of the present invention are as follows:

[0120] Figure 6 The steady-state test results of the system designed by the present invention are shown in Figure 2. The transient test results of the system designed by the present invention are shown in Figure 2. Figure 7The three-phase output of the arc-surface six-electrode electric field sensor has good followability. Within this excitation range, the phase difference of each signal is less than 1.8°, and the delay of the three-dimensional electric field component signal compared with the standard source signal is less than 0.56μs.

[0121] Rotate 45°, 90°, 135° and their combined angles along the x, y, z axis and their combined xyz axis, such as (45°, 0°, 0°) represents a 45° central angle deflection along the x axis, and (45°, 45°, 45°) represents a 45° angle deflection in the xyz direction. A total of 13 groups of different deviation angle combination tests were conducted, and each group was repeated 5 times to obtain the amplitude error and standard deviation of the test results, where the standard deviation is characterized by the amplitude error of multiple measurements as a parameter. The overall test results are shown in Table 1.

[0122] Table 1 Response characteristics of the sensor at different bias angles

[0123]

[0124] When the sensor is at the positive position (0°, 0°, 0°), the electric field amplitude measurement error is less than 2%, and the standard deviation and uncertainty are very small, proving that the sensor measures the electric field amplitude through the three-dimensional electric field component vector synthesis method, with good accuracy and stability. Therefore, the isotropic broadband voltage measurement method and system designed by the present invention has the advantages of small size, simple structure design, wide response bandwidth, high steady-state measurement accuracy, and fast transient response, and is suitable for broadband measurement scenarios for power frequency, harmonics and transient voltages.

[0125] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0126] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0127] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0128] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An isotropic broadband voltage measurement method, using a spherical electric field coupling voltage sensor for measurement, the spherical electric field coupling voltage sensor comprising P pairs of isotropic electric field sensing probes, each pair of probes comprising a pair of symmetrically distributed electrodes, characterized in that: include: Step 1: Obtain the distributed capacitance C between the spherical electric field coupling voltage sensor and the conductor being measured t , the stray capacitance C of the spherical electric field coupled voltage sensor to the ground d , and the grounded measuring resistance R connected to the spherical electric field coupling voltage sensor m ; When the three modulation parameters meet the first constraint condition, go to step 2; Step 2: A differential input circuit is connected between each pair of electrodes in the spherical electric field coupled voltage sensor, and the mutual capacitance C between each pair of electrodes after the differential input circuit is connected is obtained. m0 , the mutual capacitance C between each pair of electrodes and the conductor being measured m ; At the same time, adjust the distance between the spherical electric field coupling voltage sensor and the conductor to be measured and the distance between each pair of electrodes in the spherical electric field coupling voltage sensor. When the mutual capacitance C between each pair of electrodes and the conductor to be measured m0 When the second constraint condition and the third constraint condition are satisfied at the same time, proceed to step 3; Step 3: Use the modulated spherical electric field coupled voltage sensor to obtain the spatial electric field differential signal of the line; calculate the voltage distribution on the line based on the spatial electric field differential signal of the line; and use the NSGA-III-JADE method of adaptive differential evolution to determine the inversion voltage on the line from the voltage distribution on the line as the voltage measurement result.

2. The isotropic broadband voltage measurement method according to claim 1, characterized in that: The first constraint is: t +C d )R m is greater than a first set threshold, and the first set threshold is not less than 10.

3. The isotropic broadband voltage measurement method according to claim 2, characterized in that: The second constraint is: C m0 / C m is greater than a second set threshold, and the second set threshold is not less than 10.

4. The isotropic broadband voltage measurement method according to claim 3, characterized in that: The third constraint is: C m0 / C d is greater than a third set threshold, and the third set threshold is not less than 10.

5. The isotropic broadband voltage measurement method according to claim 2, characterized in that: When the first constraint is met, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship: In the formula, H s (s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition is satisfied, is the frequency domain signal of the equivalent potential of the conductor under test, V s (s) is the frequency domain signal of the output voltage of the spherical electric field coupled voltage sensor.

6. The isotropic broadband voltage measurement method according to claim 4, characterized in that: When the first constraint condition, the second constraint condition, and the third constraint condition are met, the transfer function of the spherical electric field coupled voltage sensor satisfies the following relationship: In the formula, H s ′(s) is the transfer function of the spherical electric field coupled voltage sensor when the first constraint condition, the second constraint condition and the third constraint condition are satisfied. is the frequency domain signal of the equivalent potential of the conductor under test, V s (s) is the frequency domain signal of the output voltage of the spherical electric field coupled voltage sensor.

7. The isotropic broadband voltage measurement method according to claim 1, characterized in that: Step 3 includes: Step 3.1, using a differential input circuit to obtain a spatial electric field differential signal of the line; and calculating the voltage distribution on the line according to the spatial electric field differential signal of the line; In step 3.2, the electric field calculation value is obtained according to the voltage distribution on the line. The NSGA-III-JADE method of adaptive differential evolution is used, with the minimum mean square error between the actual measured value of the electric field and the calculated value of the electric field as the optimization goal, and the inversion voltage of the line is obtained from the voltage distribution as the voltage measurement result.

8. The isotropic broadband voltage measurement method according to claim 7, characterized in that: Step 3.2 includes: 1) Set the initial population; each measurement point on the line corresponds to a voltage distribution value, and each individual in the initial population represents a voltage distribution value, which is a candidate solution for the inversion voltage; 2) Assume that there are N voltage distribution values ​​V1, V2, ..., V in the population. N , each voltage distribution value corresponds to an electric field calculation value; the optimization goal is to minimize the mean square error between the actual measured value of the electric field and the calculated value of the electric field, satisfying the following relationship: In the formula, f i (x) is the optimization target value at the i-th measurement point under the decision variable x; is the actual measured value of the j-th dimension electric field at the ith measurement point; is the calculated value of the j-th dimension electric field obtained by calculating the voltage distribution value at the i-th measurement point under the decision variable x; M is the electric field dimension; 3) In the population, the voltage distribution values ​​are non-dominated sorted according to the optimization target to obtain a new population; 4) Merge the initial population and the new population into a temporary population, and repeat steps 2) to 4) based on the temporary population for iterative solution; when the number of iterations is reached, use the TOPSIS method to determine the inversion voltage of the line in the temporary population obtained in the last iteration.

9. The isotropic broadband voltage measurement method according to claim 8, characterized in that: In the population, the voltage distribution values ​​are non-dominated and sorted according to the optimization goal to obtain a new population, including: 3.1) Under the decision variables p and q, the optimization target value at the i-th measurement point satisfies f i (p)≤f i (q) and there is at least one measurement point where the optimization objective value satisfies f j (p)<f j (q), it represents that individual p dominates individual q; the population is divided into multiple frontiers, the first front contains all non-dominated solutions, the second front contains solutions dominated by the first front but not dominated by the second front, and so on; 3.2) Randomly select three different individuals x from different frontiers r1 、x r2 、x r3 , based on the decision variable x at the i-th measurement point i , generate a new individual v with the following relationship i : v i =x r1 +F·(x r2 -x r3 )+CR·(x r1 -x i ) In the formula, x r1 、x r2 、x r3 is the random selection of three different individuals in different frontiers; F is the mutation scaling factor; CR is the crossover probability.

10. The isotropic broadband voltage measurement method according to claim 9, characterized in that: Adaptive differential evolution is performed on the mutation scaling factor and crossover probability according to the voltage level and transient voltage frequency of the conductor to be tested.

11. An isotropic broadband voltage measurement sensor system, characterized in that: include: Spherical electric field coupled voltage sensor and electric field measuring device; The spherical electric field coupling voltage sensor includes P pairs of isotropic electric field sensing probes, each pair of probes includes a pair of symmetrically distributed electrodes, and P is an integer not less than 3; the isotropic electric field sensing probe with three pairs of symmetrically distributed electrodes includes a spherical probe; The electric field measuring device includes: a signal conditioning module, an analog-to-digital conversion module, an MCU, a distance measurement module, a distance display module and a signal acquisition controller; The spherical probe transmits the spatial electric field differential signal of the line to the signal conditioning module; the signal conditioning module is used to implement filtering, level raising and buffer following of the spatial electric field differential signal of the line; the analog-to-digital conversion module is used to convert the spatial electric field differential signal output by the signal conditioning module into a digital signal and transmit it to the MCU; the MCU is used to transmit the processed signal to the signal acquisition controller, and the signal acquisition controller transmits the signal to the distance display module; the ranging module is used to measure the distance H between the ranging module and the line, and the ranging module includes: an ultrasonic ranging module.

12. The isotropic broadband voltage measurement sensor system according to claim 11, characterized in that: The spherical probe includes AA' plate, BB' plate and CC' plate. The AA' plate, BB' plate and CC' plate are used to measure the spatial electric field differential signal of the line. The structural parameters of each plate satisfy the following relationship: Where θ is the azimuth angle of the probe, is the pitch angle of the probe.

13. The isotropic broadband voltage measurement sensor system according to claim 11, characterized in that: The spherical probe is installed on the upper surface of the signal acquisition controller through a retractable sensor bracket, and the distance measurement module is also installed on the upper surface of the signal acquisition controller. Therefore, the distance D from the spherical probe to the line satisfies the following relationship: D=Hhr Where h is the length of the telescopic sensor bracket and r is the radius of the spherical probe.

14. The isotropic broadband voltage measurement sensor system according to claim 11, characterized in that: The electric field measuring device also includes: a power supply module, a communication module, a near-field alarm module and a host computer; The near-field alarm module is used to issue an alarm when the distance between the electric field sensor probe and the transmission line is less than the set threshold; the communication module is used to transmit data to the host computer after selecting the wireless transmission mode or the wired transmission mode according to actual needs; the power module is used to supply power to the signal conditioning module, the analog-to-digital conversion module, the MCU, the ranging module, the near-field alarm module, the distance display module and the signal acquisition controller.

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