CN-115494294-B - Non-contact high-voltage measuring device with self-checking capability and measuring method thereof

CN115494294BCN 115494294 BCN115494294 BCN 115494294BCN-115494294-B

Abstract

The invention discloses a non-contact high-voltage measuring device with self-checking capability and a measuring method thereof, wherein the device comprises an electric field sensing device, a signal conditioning circuit and a signal receiving and processing device, the core of the electric field sensing device is two measuring electrode plates and a shielding electrode plate, the two measuring electrode plates are placed inside the shielding electrode plate and symmetrically distributed relative to a wire to be tested, electric insulation is realized among the electrode plates through insulating elastic materials, the signal conditioning circuit is used for sampling voltage signals on the two measuring electrode plates capable of representing electric field intensity and amplifying and filtering the voltage signals, and the signal receiving and processing device is used for processing and outputting the sampled voltage signals and judging the correctness of measured data. The electric field induction device provided by the invention adopts two measuring electrode plates and one shielding electrode plate, so that the accuracy of the measuring device can be effectively improved, the measuring device has self-checking capability, and the measuring reliability is improved.

Inventors

PEI LIQIANG
WANG HONGBIN
HUANG QINGDAN
WANG YONG
HUANG HUIHONG
LI XIAO
SONG HAOYONG
WANG HAO
LI XIN

Assignees

广东电网有限责任公司广州供电局

Dates

Publication Date: 20260508
Application Date: 20221018

Claims (9)

1. The non-contact high-voltage measuring device with the self-checking capability is characterized by comprising an electric field sensing device, a signal conditioning circuit and a received signal processing device; The electric field induction device comprises two measuring electrode plates and a shielding electrode plate, wherein the two measuring electrode plates are placed in the shielding electrode plate and are symmetrically distributed relative to a wire to be tested, and the two measuring electrode plates and the shielding electrode plate respectively form two paths of input signals of a signal conditioning circuit; The signal conditioning circuit is used for conditioning analog voltage signals acquired from two measuring electrode plates respectively, and each signal conditioning circuit comprises a first-stage amplifying circuit, a voltage follower, a second-stage amplifying circuit and a filter circuit, wherein the input of the first-stage amplifying circuit is the analog voltage signal on the measuring electrode plate, and the output of the first-stage amplifying circuit is connected with the input of the voltage follower; The receiving signal processing device comprises a double-input signal acquisition circuit, a double-channel analog-to-digital conversion circuit and a digital signal processing circuit, wherein the double-input signal acquisition circuit is connected with the outputs of two filter circuits in the signal conditioning circuit, the output of the double-input signal acquisition circuit is connected with the input of the double-channel analog-to-digital conversion circuit, and the output of the double-channel analog-to-digital conversion circuit is connected with the input of the digital signal processing circuit; The radius of the measuring electrode plates is determined by the voltage level to be measured, when the high-voltage measuring device works normally, the shielding electrode plates are grounded, a wire to be measured can generate an electric field inside the shielding electrode plates, the two measuring electrode plates generate voltage change under the action of the electric field, when the voltage level is large, the two measuring electrode plates are close to the shielding electrode plates on the premise that the electric field strength is smaller than the breakdown strength of the insulating elastic filler so as to achieve the purpose of indirectly reducing the voltage, when the voltage level is small, the two measuring electrode plates are close to the wire to be measured on the premise that the electric field strength is smaller than the breakdown strength of the insulating elastic filler so as to achieve the purpose of improving the voltage ratio, and the insulating elastic filler is used for electric insulation and fixation and is arranged between the electrode plates.
2. The non-contact high voltage measurement device with self-test capability according to claim 1, wherein the electric field sensing device further comprises an insulating elastic filler between the respective electrode plates for electrical insulation and fixation and a material constituting the electrode plates, the material comprising a base material and a copper foil; the shape of the shielding electrode plate is a first side surface thin wall formed by a common hollow cylinder, and the copper foil is plated on the inner side wall or the outer side wall of the first side surface thin wall, wherein the thickness of the first side surface thin wall is more than 0.1mm; The two measuring electrode plates are the same in shape and are second side surface thin walls formed by common hollow arc-shaped cylinders, the copper foil is plated on the inner wall side or the outer wall side of the second side surface thin walls, the angle of the second side surface thin walls is 10-30 degrees, the thickness of the second side surface thin walls is consistent with that of the shielding electrode plates, the measuring electrode plates and the shielding electrode plates are coaxial in space positions, the two measuring electrode plates are placed in the shielding electrode plates, the length of the shielding electrode plates in the axial direction is three times or more than that of the measuring electrode plates, and a middle through hole diameter is reserved at the central shaft of each electrode plate for placing a wire to be measured.
3. The non-contact high-voltage measuring device with the self-checking capability according to claim 1 is characterized in that the signal conditioning circuit is two paths of mutually independent conditioning circuits, the first-stage amplifying circuit is a variable capacitor connected in parallel with a coupling capacitor between the measuring electrode plate and the shielding electrode plate, the variable capacitor is used as a sampling circuit and a first-stage amplifying circuit, the amplification factor of the first-stage amplifying circuit is smaller than 1, the amplification factor of the second-stage amplifying circuit is adjusted according to the range of voltage to be detected, and the filtering circuit is used for filtering the voltage amplified by the second-stage amplifying circuit to filter high-frequency harmonic waves and improve the signal quality of the sampled voltage.
4. The non-contact high-voltage measurement device with self-checking capability according to claim 1, wherein the dual-input signal acquisition circuit samples two paths of analog voltage signals after passing through the signal conditioning circuit, the two paths of analog voltage signals are converted into two paths of digital voltage signals through the dual-channel analog-to-digital conversion circuit, and finally the two paths of digital voltage signals are processed by the digital signal processing circuit, and the core of the digital signal processing circuit is a microprocessor.
5. A measuring method of a non-contact high voltage measuring device with self-test capability according to any one of claims 1-4, characterized by the steps of: When the non-contact high-voltage measuring device with self-checking capability works normally, the coupling capacitance value between a wire to be tested and two measuring electrode plates and the coupling capacitance value between the two measuring electrode plates and the shielding electrode plates are calculated, and two paths of analog voltage signals on the two measuring electrode plates are calculated; the two paths of analog voltage signals on the two measuring electrodes are amplified and filtered by a signal conditioning circuit to obtain amplified two paths of analog voltage signals; and finally, the digital signal processing circuit performs inversion calculation on the two paths of digital voltage signals to obtain a voltage value to be measured, and meanwhile, the two paths of digital voltage signals are compared to ensure the reliability of data.
6. The method according to claim 5, wherein the calculating the coupling capacitance value between the wire to be measured and the two measuring electrode plates and the coupling capacitance value between the two measuring electrode plates and the shielding electrode plates is specifically: assuming that the two measuring electrode plates are strictly and symmetrically distributed relative to the lead to be measured, the calculation formula of the coupling capacitance value between the lead to be measured and the two measuring electrode plates is as follows: ; Wherein C is the coupling capacitance value between the wire to be measured and the measuring polar plate, epsilon is the dielectric constant of the insulating elastic filler, L is the axial length of the measuring polar plate, theta is the angle of the measuring polar plate, R 1 is the radius of the cylinder where the measuring polar plate is positioned, and R is the radius of the wire to be measured; the calculation formula of the coupling capacitance value between the two measuring electrode plates and the shielding electrode plate is as follows: ; Wherein C 0 is the coupling capacitance value between the measuring polar plate and the shielding polar plate, epsilon is the dielectric constant of the insulating elastic filler, L is the axial length of the measuring polar plate, theta is the angle of the measuring polar plate, R 2 is the radius of the shielding polar plate, and R 1 is the radius of the cylinder where the measuring polar plate is positioned; The formula for calculating the two paths of analog voltage signals U 0 on the two measuring electrode plates is as follows: ; Wherein U is the voltage value on the wire to be tested.
7. The measurement method according to claim 5, further comprising: When the lead to be measured moves slightly to cause that the two measuring electrode plates are distributed in a non-strict symmetry way relative to the lead to be measured, the coupling capacitance value between the two measuring electrode plates and the shielding electrode plates is still C 0 , but the capacitance between the lead to be measured and the two measuring electrode plates is slightly changed due to the change of the distance, and the calculation formula of the coupling capacitance value between the lead to be measured and the two measuring electrode plates is as follows: ; Wherein, C 01 and C 02 respectively represent the coupling capacitance value between the measuring electrode plate and the wire to be measured when the two measuring electrode plates are distributed non-strictly symmetrically relative to the wire to be measured, ε is the dielectric constant of the insulating elastic filler, L is the axial length of the measuring electrode plate, θ is the angle of the measuring electrode plate, r 1 and r 2 are the average distance between the wire to be measured and the two measuring electrode plates respectively, d is the diameter of the round position where the measuring electrode plate is located and is a fixed value, and r is the radius of the wire to be measured.
8. The measurement method according to claim 7, wherein the calculation formula of the amplified two analog voltage signals U 1 is: ; Wherein k is the amplification factor of the signal conditioning circuit, U 0 is two paths of analog voltage signals on two measuring electrode plates, C 0 is the coupling capacitance value between the measuring electrode plates and the shielding electrode plates, and U is the voltage value on a wire to be measured.
9. The method according to claim 5, wherein the specific step of comparing two digital voltage signals to ensure the reliability of data is: When the electrode plate works normally, the micro-movement of the lead wire to be measured can cause the two measured voltage values to be not identical, at the moment, after the digital signal processing circuit receives the two paths of digital voltage signals, the two paths of digital voltage signals are compared, namely, a threshold value is set for the difference value of the two paths of digital voltage signals, the magnitude of the threshold value depends on the grade of the voltage to be measured, if the difference value of the two paths of digital voltage signals is smaller than the set threshold value, the measured voltage value is still reliable, otherwise, if the difference value of the two paths of digital voltage signals is larger than the set threshold value, the measured data is abnormal.

Description

Non-contact high-voltage measuring device with self-checking capability and measuring method thereof Technical Field The invention belongs to the fields of electrical engineering, measurement and control technology and instruments, and particularly relates to a non-contact high-voltage measurement device with self-checking capability and a measurement method thereof. Background Along with the continuous development and perfection of the electric power system, the voltage level is continuously improved, the difficulty of voltage measurement is continuously increased, the traditional voltage measurement mode is usually contact measurement, direct electrical connection is needed between the voltage measurement instrument and the conductor to be measured, the surface insulating layer of the conductor to be measured needs to be destroyed before the voltage measurement is carried out, however, the higher the voltage level is, the easier the conductor insulating layer is destroyed, the power system faults such as short circuit are caused, and the damage to the electric power system is larger, so that the non-contact voltage measurement research becomes the main research direction. The current non-contact voltage measurement principle is mature, the common non-contact voltage measurement sensor is a non-contact differential voltage sensor, common mode interference can be restrained to a certain extent, but the voltage sensor cannot judge the accuracy of measurement data by itself, and the differential voltage sensor cannot meet the requirement of measurement accuracy in the case of high voltage measurement accuracy, so that the non-contact high-voltage measurement device is based on the purpose development research with high measurement accuracy while realizing the self-checking function. Disclosure of Invention The invention aims to overcome the defects and shortcomings of the prior art, and provides a non-contact high-voltage measuring device with self-checking capability and a measuring method thereof, the electric field induction device is of a concentric cylinder structure formed by the two measuring electrode plates and the shielding electrode plate, so that the device has self-checking capability and ensures accuracy of measuring data. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention provides a non-contact high-voltage measuring device with self-checking capability, which comprises an electric field sensing device, a signal conditioning circuit and a received signal processing device; The electric field induction device comprises two measuring electrode plates and a shielding electrode plate, wherein the two measuring electrode plates are arranged in the shielding electrode plate and symmetrically distributed relative to a wire to be tested, and the two measuring electrode plates and the shielding electrode plate respectively form two paths of input signals of the signal conditioning circuit; The signal conditioning circuit is used for conditioning analog voltage signals acquired from two measuring electrode plates respectively, and each signal conditioning circuit comprises a first-stage amplifying circuit, a voltage follower, a second-stage amplifying circuit and a filter circuit, wherein the input of the first-stage amplifying circuit is the analog voltage signal on the measuring electrode plate, and the output of the first-stage amplifying circuit is connected with the input of the voltage follower; The receiving signal processing device comprises a double-input signal acquisition circuit, a double-channel analog-to-digital conversion circuit and a digital signal processing circuit, wherein the double-input signal acquisition circuit is connected with the outputs of two filter circuits in the signal conditioning circuit, the output of the double-input signal acquisition circuit is connected with the input of the double-channel analog-to-digital conversion circuit, and the output of the double-channel analog-to-digital conversion circuit is connected with the input of the digital signal processing circuit. Preferably, the electric field sensing device further comprises an insulating elastic filler for electrically insulating and fixing between the respective electrode plates and a material constituting the electrode plates, the material comprising a base material and a copper foil; the shape of the shielding electrode plate is a first side surface thin wall formed by a common hollow cylinder, and the copper foil is plated on the inner side wall or the outer side wall of the first side surface thin wall, wherein the thickness of the first side surface thin wall is more than 0.1mm; The two measuring electrode plates are the same in shape and are second side surface thin walls formed by common hollow arc-shaped cylinders, the copper foil is plated on the inner wall side or the outer wall side of the second side surface thin walls, the angle of