Electric field measuring device

Abstract

The invention particularly relates to an electric field measuring device, and belongs to the technical field of electric power measurement. Comprising a voltage sensor, a conditioning circuit and an electric field calculator. The electric field sensor sequentially comprises four layers of metal polar plates from top to bottom, namely a first metal polar plate, a second metal polar plate, a third metal polar plate and a fourth metal polar plate; the conditioning circuit comprises a first differential amplifier circuit, a second differential amplifier circuit and a third differential amplifier circuit; the electric field calculator can calculate electric field intensity data according to the voltage data obtained by the conditioning circuit. According to the invention, the voltage data acquired by the voltage sensor with the multi-layer polar plate structure is conditioned through the three-stage differential conditioning circuit, so that common-mode interference on two adjacent polar plates and environmental electromagnetic interference in the transformer substation are eliminated, and the voltage measurement precision of the voltage sensor in the transformer substation is improved; therefore, the calculated electric field intensity is more accurate.

Description

Technical Field

[0001] The invention specifically relates to an electric field measuring device, belonging to the technical field of electric power measurement. Background Art

[0002] At present, there is no one on duty in power substations of 220kV and below, and there is a trend of less people on duty in power substations above 500kV. These put forward higher requirements for the operation and maintenance of coil equipment in substations. In order to ensure the healthy state of coil equipment, regular maintenance or status maintenance is required. When carrying out maintenance work, the area near the frequent power outage is the energized area. In order to ensure the personal safety of maintenance personnel, it is also necessary to measure the electric field strength to determine whether the working area is energized. Most of the existing methods for detecting electric field strength use electric field sensors based on single capacitor plates to detect the electric field strength in the substation. Due to the complex electromagnetic environment at the substation site, the electric field sensor based on a single capacitor plate will receive strong electromagnetic interference, resulting in inaccurate measurement of the electric field strength. At the same time, the electric field sensor with a single capacitor plate cannot crosslink more electric field vectors due to the small equivalent area of ​​a single plate, which makes it difficult for the sensor to perceive high-frequency and fast electric fields. Summary of the invention

[0003] The technical problem to be solved by the present invention is how to improve the measurement accuracy of the electric field strength in a high-voltage substation.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is: an electric field measuring device, including a voltage sensor, a conditioning circuit and an electric field calculator; the electric field sensor includes four layers of metal plates from top to bottom, namely a first metal plate, a second metal plate, a third metal plate and a fourth metal plate; the diameters of the first metal plate and the fourth metal plate are the same; the diameters of the second metal plate and the third metal plate are the same; the diameters of the first metal plate and the fourth metal plate are greater than the diameters of the second metal plate and the third metal plate; the first metal plate to the fourth metal plate are wrapped with epoxy resin; the conditioning circuit includes three differential amplifier circuits, namely a first differential amplifier circuit, a second differential amplifier circuit and a third differential amplifier circuit; the non-inverting input terminal of the first differential amplifier circuit is connected to the first metal plate, and the inverting input terminal of the first differential amplifier circuit is connected to the second metal plate; the non-inverting input terminal of the second differential amplifier circuit is connected to the third metal plate, and the inverting input terminal of the second differential amplifier circuit is connected to the fourth metal plate; the non-inverting input terminal of the third differential amplifier circuit is connected to the output terminal of the first differential amplifier circuit, the inverting input terminal of the third differential amplifier circuit is connected to the output terminal of the second differential amplifier circuit, and the output terminal of the third differential amplifier circuit is connected to an electric field calculator; the electric field calculator can calculate the electric field strength data according to the voltage data obtained by the conditioning circuit.

[0005] Furthermore, the first differential amplifier circuit includes a first operational amplifier, two first base resistors and two first gain resistors. ; Connect two first basic resistors to the inverting input terminal and the non-inverting input terminal of the first operational amplifier respectively; connect a first gain resistor One end of the resistor is connected to the non-inverting input terminal of the first operational amplifier, and the other end is grounded; another first gain resistor One end of is connected to the output terminal of the first operational amplifier, and the other end of is connected to the inverting input terminal of the first operational amplifier.

[0006] Furthermore, the second differential amplifier circuit includes a second operational amplifier, two second base resistors and two second gain resistors. ; Connect two second basic resistors to the inverting input terminal and the non-inverting input terminal of the second operational amplifier respectively; connect a second gain resistor One end is connected to the non-inverting input terminal of the second operational amplifier, and the other end is grounded; another second gain resistor One end of is connected to the output terminal of the second operational amplifier, and the other end of is connected to the inverting input terminal of the second operational amplifier.

[0007] Further, the third differential amplifier circuit includes a third operational amplifier, two third base resistors and two third gain resistors. ; Connect two third basic resistors to the inverting input terminal and the non-inverting input terminal of the third operational amplifier respectively; connect a third gain resistor One end is connected to the non-inverting input terminal of the third operational amplifier, and the other end is grounded; another third gain resistor One end of is connected to the output terminal of the third operational amplifier, and the other end of is connected to the inverting input terminal of the third operational amplifier.

[0008] Furthermore, the electric field calculator calculates the electric field strength according to the voltage data obtained by the conditioning circuit as shown in the following formula (1):

[0009] (1)

[0010] In formula (1), is the electric field strength data calculated by the electric field calculator based on the voltage data at time t obtained by the conditioning circuit; is the voltage data at time t obtained by the conditioning circuit; are the first, second and third conditioning coefficients, all of which are empirical values; is the dielectric constant of air; are the metal effective areas of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate respectively; R m1 is the sampling resistance value between the first metal plate and the second metal plate; R m2 is the sampling resistance value between the third metal plate and the fourth metal plate; They are respectively the voltage data measured at time t of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate.

[0011] The beneficial effects of the present invention are as follows: 1. The present invention adopts a voltage sensor with a multi-layer plate structure, which overcomes the problem that the electric field sensor with a single capacitor plate cannot interlink more electric field vectors due to the small equivalent area of ​​a single plate, making it difficult for the sensor to sense high-frequency and fast electric fields. 2: The present invention conditions the voltage data collected by the voltage sensor with a multi-layer plate structure through a three-level differential conditioning circuit, eliminates the common-mode interference on the two adjacent plates and the environmental electromagnetic interference in the substation, and increases the voltage measurement accuracy of the voltage sensor in the substation, thereby making the calculated electric field strength more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The utility model relates to a voltage sensor in an electric field measuring device of the present invention.

[0013] Figure 2 The invention relates to a conditioning circuit in an electric field measuring device. DETAILED DESCRIPTION

[0014] The electric field measuring device of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0015] Example

[0016] The electric field measuring device in this embodiment includes a voltage sensor, a conditioning circuit and an electric field calculator. Figure 1 As shown, the electric field sensor includes four layers of metal plates from top to bottom, namely the first metal plate, the second metal plate, the third metal plate and the fourth metal plate; the diameters of the first metal plate and the fourth metal plate are the same; the diameters of the second metal plate and the third metal plate are the same; the diameters of the first metal plate and the fourth metal plate are greater than the diameters of the second metal plate and the third metal plate; the first metal plate to the fourth metal plate are wrapped with epoxy resin.

[0017] like Figure 2 As shown, the conditioning circuit includes three differential amplifier circuits, namely a first differential amplifier circuit, a second differential amplifier circuit and a third differential amplifier circuit. The first differential amplifier circuit includes a first operational amplifier, two first basic resistors and two first gain resistors. ; Connect two first basic resistors to the inverting input terminal and the non-inverting input terminal of the first operational amplifier respectively; connect a first gain resistor One end is connected to the non-inverting input terminal of the first operational amplifier, and the other end is grounded; another first gain resistor One end is connected to the output end of the first operational amplifier, and the other end is connected to the inverting input end of the first operational amplifier. The non-inverting input end of the first differential amplifier circuit is connected to the first metal plate, and the inverting input end of the first differential amplifier circuit is connected to the second metal plate.

[0018] The second differential amplifier circuit includes a second operational amplifier, two second base resistors and two second gain resistors. ; Connect two second basic resistors to the inverting input terminal and the non-inverting input terminal of the second operational amplifier respectively; Connect a second gain resistor One end is connected to the non-inverting input of the second operational amplifier and the other end is grounded; another second gain resistor One end is connected to the output end of the second operational amplifier, and the other end is connected to the inverting input end of the second operational amplifier. The non-inverting input end of the second differential amplifier circuit is connected to the third metal plate, and the inverting input end of the second differential amplifier circuit is connected to the fourth metal plate.

[0019] The third differential amplifier circuit includes a third operational amplifier, two third base resistors and two third gain resistors. ; Connect two third basic resistors to the inverting input terminal and the non-inverting input terminal of the third operational amplifier respectively; Connect a third gain resistor One end of the resistor is connected to the non-inverting input of the third operational amplifier, and the other end is grounded; another third gain resistor One end of is connected to the output end of the third operational amplifier, and the other end is connected to the inverting input end of the third operational amplifier. The non-inverting input end of the third differential amplifier circuit is connected to the output end of the first differential amplifier circuit, the inverting input end of the third differential amplifier circuit is connected to the output end of the second differential amplifier circuit, and the output end of the third differential amplifier circuit is connected to the electric field calculator.

[0020] The electric field calculator can calculate the electric field strength data based on the voltage data obtained by the conditioning circuit. The specific calculation formula is shown in the following formula (1):

[0021] (1)

[0022] In formula (1), It is the electric field strength data calculated by the electric field calculator based on the voltage data at time t obtained by the conditioning circuit; is the voltage data at time t obtained by the conditioning circuit; are the first, second and third conditioning coefficients, all of which are empirical values; is the dielectric constant of air; are the metal effective areas of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate; R m1 is the sampling resistance value between the first metal plate and the second metal plate; R m2 is the sampling resistance value between the third metal plate and the fourth metal plate; They are respectively the voltage data measured at time t of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate.

Claims

1. An electric field measuring device, characterized in that: The invention comprises a voltage sensor, a conditioning circuit and an electric field calculator; the electric field sensor comprises four layers of metal plates from top to bottom, namely a first metal plate, a second metal plate, a third metal plate and a fourth metal plate; the first metal plate and the fourth metal plate have the same diameter; the second metal plate and the third metal plate have the same diameter; the diameters of the first metal plate and the fourth metal plate are larger than the diameters of the second metal plate and the third metal plate; the first metal plate to the fourth metal plate are wrapped with epoxy resin; the conditioning circuit comprises three differential amplifier circuits, namely a first differential amplifier circuit, a second differential amplifier circuit and a third differential amplifier circuit; the first differential The non-inverting input terminal of the amplifier circuit is connected to the first metal plate, and the inverting input terminal of the first differential amplifier circuit is connected to the second metal plate; the non-inverting input terminal of the second differential amplifier circuit is connected to the third metal plate, and the inverting input terminal of the second differential amplifier circuit is connected to the fourth metal plate; the non-inverting input terminal of the third differential amplifier circuit is connected to the output terminal of the first differential amplifier circuit, the inverting input terminal of the third differential amplifier circuit is connected to the output terminal of the second differential amplifier circuit, and the output terminal of the third differential amplifier circuit is connected to an electric field calculator; the electric field calculator can calculate the electric field strength data according to the voltage data obtained by the conditioning circuit.

2. The electric field measuring device according to claim 1, characterized in that: The first differential amplifier circuit includes a first operational amplifier, two first base resistors and two first gain resistors. ; Connect two first basic resistors to the inverting input terminal and the non-inverting input terminal of the first operational amplifier respectively; connect a first gain resistor One end of the resistor is connected to the non-inverting input terminal of the first operational amplifier, and the other end is grounded; another first gain resistor One end of is connected to the output terminal of the first operational amplifier, and the other end of is connected to the inverting input terminal of the first operational amplifier.

3. The electric field measuring device according to claim 1, characterized in that The second differential amplifier circuit includes a second operational amplifier, two second basic resistors and two second gain resistors. ; Connect two second basic resistors to the inverting input terminal and the non-inverting input terminal of the second operational amplifier respectively; connect a second gain resistor One end is connected to the non-inverting input terminal of the second operational amplifier, and the other end is grounded; another second gain resistor One end of is connected to the output terminal of the second operational amplifier, and the other end of is connected to the inverting input terminal of the second operational amplifier.

4. The electric field measuring device according to claim 1, characterized in that: The third differential amplifier circuit includes a third operational amplifier, two third base resistors and two third gain resistors. ; Connect two third basic resistors to the inverting input terminal and the non-inverting input terminal of the third operational amplifier respectively; connect a third gain resistor One end is connected to the non-inverting input terminal of the third operational amplifier, and the other end is grounded; another third gain resistor One end of is connected to the output terminal of the third operational amplifier, and the other end of is connected to the inverting input terminal of the third operational amplifier.

5. The electric field measuring device according to claim 1, characterized in that: The electric field calculator calculates the electric field strength according to the voltage data obtained by the conditioning circuit as shown in the following formula (1): （1） In formula (1), is the electric field strength data calculated by the electric field calculator based on the voltage data at time t obtained by the conditioning circuit; is the voltage data at time t obtained by the conditioning circuit; are the first, second and third conditioning coefficients, all of which are empirical values; is the dielectric constant of air; are the metal effective areas of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate respectively; R m1 is the sampling resistance value between the first metal plate and the second metal plate; R m2 is the sampling resistance value between the third metal plate and the fourth metal plate; They are respectively the voltage data measured at time t of the first metal plate, the second metal plate, the third metal plate and the fourth metal plate.

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