Method for improving the accuracy of electrostatic potential measurement

Abstract

The application discloses a method for improving the precision of electrostatic potential measurement, comprising the following steps: S1, constructing an RC series circuit, and obtaining a current I0 according to the Kirchhoff's voltage law; S2, calculating a bias current I0(t) according to the current I0; S3, correcting the bias current I0(t) to obtain an actual induced current I(t) C The electrostatic potential measurement sensor in the prior art usually has the technical problems of low measurement precision, poor linearity, great influence of environmental temperature and humidity, and incapability of measurement in a high-humidity environment.

Description

Technical Field

[0001] This application relates to the technical field of potential measurement, and more particularly to a method for improving the accuracy of electrostatic potential measurement. Background Technology

[0002] After the output hard switch of the substation protection panel is closed, a voltage, or electrostatic potential, will exist on the signal line. Therefore, to ensure that maintenance personnel can promptly understand whether the output hard switch is in the correct open / closed state, it is necessary to measure the electrostatic potential of the signal line. The electrostatic potential of the signal line is mainly achieved through an electrostatic potential measurement sensor. That is, the magnitude of the induced current is calculated from the measured electrostatic potential, and the magnitude of the induced current reflects the measurement accuracy of the electrostatic potential measurement sensor. However, existing electrostatic potential measurement sensors are affected by the instantaneous bias current when calculating the induced current of the electrostatic potential of the signal line. As a result, there is a certain error between the measured induced current and the actual induced current. That is, the electrostatic potential measured by the existing electrostatic potential measurement sensor has an error with the actual electrostatic potential. Therefore, it has technical problems such as low measurement accuracy, poor linearity, great influence from ambient temperature and humidity, and inability to measure in high humidity environment.

[0003] Therefore, it is necessary to improve the existing electrostatic potential measurement sensors to enhance the accuracy of electrostatic potential measurement. Summary of the Invention

[0004] This application provides a method for improving the accuracy of electrostatic potential measurement to solve the above-mentioned technical problems.

[0005] In view of this, this application provides a method for improving the accuracy of electrostatic potential measurement, characterized by comprising the following steps: S1. Construct an RC series circuit and obtain the current according to Kirchhoff's voltage law. ; S2, then based on the current The bias current is calculated. ; S3, Regarding the bias current Make corrections to obtain the actual induced current. .

[0006] Optionally, in step S1, the specific process of constructing the RC series circuit includes: An electric field shaping plate is added to an electrostatic potential measurement sensor to obtain the measurement part of the sensor. This measurement part consists of a measured wire core, insulating sheath, electric field shaping plate, support column, shielding sheet, and induction sheet. The measured wire core, insulating sheath, and electric field shaping plate form a capacitor. The electric field shaping plate and the shielding sheet constitute a capacitor. The electric field shaping plate and the induction sheet constitute a variable capacitor. The electric field shaping plate is then connected to the support column, which is grounded, thus creating a resistor between the electric field shaping plate and the ground using FR4 material. Then, based on the capacitance and resistance Construct an RC series circuit.

[0007] Optionally, in step S1, an RC series circuit is constructed, and the current is obtained according to Kirchhoff's voltage law. The specific process includes: Based on the constructed RC series circuit, the expression for Kirchhoff's voltage law is obtained as follows: ; in, This indicates the grounding resistance of the electric field shaping plate. This represents the voltage across the capacitor formed by the signal line and the electric field shaping plate. This represents the capacitance formed by the signal line and the electric field shaping plate. Based on the above ; Obtain the current: .

[0008] Optionally, in step S2, the current is then... The bias current is calculated. The specific process includes: According to the current The charging process is a first-order linear differential equation: ; Then, for the equation Solving for the problem, we get: ; Then regarding the above Perform differentiation, and based on the current... The bias current is obtained as follows: .

[0009] Optionally, in step S3, the actual induced current The expression is: ; Among them, the e It is a constant.

[0010] Optionally, the electric field shaping plate is installed above the electrostatic potential measuring sensor, and support columns are provided at the four corners of the lower end of the electric field shaping plate. The bottom end of the support column is in contact with the upper surface of the sensing sheet.

[0011] Optionally, the support column is a polyimide support column.

[0012] Optionally, the upper surface of the electric field shaping plate is provided with an arc-shaped groove.

[0013] Optionally, the electric field shaping plate is made of a metal conductor, with the upper surface of the electric field shaping plate being an electric field capturing surface and the lower surface being an electric field shaping surface.

[0014] As can be seen from the above technical solutions, the embodiments of this application have the following advantages: This application provides a method for improving the accuracy of electrostatic potential measurement. Through step S1, an RC series circuit is constructed, and the current is obtained according to Kirchhoff's voltage law. S2, then based on the current... The bias current is calculated. S3, the bias current Make corrections to obtain the actual induced current. The specific process of constructing the RC series circuit includes: adding an electric field shaping plate to the electrostatic potential measurement sensor to obtain the measurement part of the electrostatic potential measurement sensor, wherein the measurement part consists of the measured wire core, the insulating wire sheath, the electric field shaping plate, the support column, the shielding sheet, and the sensing sheet; and forming a capacitor by connecting the measured wire core, the insulating wire sheath, and the electric field shaping plate. The electric field shaping plate and the shielding sheet constitute a capacitor. The electric field shaping plate and the induction sheet constitute a variable capacitor. The electric field shaping plate is then connected to the support column, which is grounded, thus creating a resistor between the electric field shaping plate and the ground using FR4 material. Then, based on the capacitance and resistance An RC series circuit is constructed to eliminate the influence of bias current on the measured electrostatic potential through a bias current elimination algorithm, thereby obtaining the actual induced current and improving the measurement accuracy of the electrostatic potential sensor. This, in turn, improves the measurement accuracy of the electrostatic potential on the signal line, ensuring that maintenance personnel can promptly understand whether the outlet hard plate is in the correct open / closed state. Simultaneously, a larger grounding resistance is provided to further reduce the bias current, preventing weak electrostatic potentials from being weakened during measurement. This further improves the measurement accuracy of the electrostatic potential sensor and prevents the phenomenon of unmeasurable electrostatic potentials when they are weak, thus further enhancing the measurement sensitivity. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating the steps of a method for improving the accuracy of electrostatic potential measurement provided in an embodiment of this application. Figure 2 This is a schematic diagram of the structure of an electrostatic potential measurement sensor without an added electric field shaping plate, which is a method for improving the accuracy of electrostatic potential measurement provided in this application embodiment. Figure 3 This is a schematic diagram of the measurement principle of an electrostatic potential measurement sensor without an added electric field shaping plate, which is a method for improving the accuracy of electrostatic potential measurement provided in this application embodiment. Figure 4 This is a schematic diagram of the electric field capturing surface of an electric field shaping plate, which is used in an embodiment of this application to improve the accuracy of electrostatic potential measurement. Figure 5 This is a schematic diagram of the electric field shaping surface of an electric field shaping plate, which is used in an embodiment of this application to improve the accuracy of electrostatic potential measurement. Figure 6 This is a schematic diagram of the structure of an electrostatic potential measurement sensor with an added electric field shaping plate, which is provided in the embodiments of this application to improve the accuracy of electrostatic potential measurement. Figure 7 This is a front view schematic diagram of an electrostatic potential measurement sensor with an added electric field shaping plate, which is provided in the embodiments of this application to improve the accuracy of electrostatic potential measurement. Figure 8 This is a schematic diagram of the induced electric field of the induction sheet without the addition of an electric field shaping plate, which is a method for improving the accuracy of electrostatic potential measurement provided in this application embodiment. Figure 9 This is a schematic diagram of an induction plate with an added electric field induction element, which is part of a method for improving the accuracy of electrostatic potential measurement provided in this application embodiment. Figure 10 The equivalent circuit diagram of an electrostatic potential measurement sensor with an added electric field shaping plate is provided in the embodiments of this application to improve the accuracy of electrostatic potential measurement. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0018] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the layers related to the present invention and are not drawn according to the actual number, shape and size ratio of the layers in the actual implementation. In the actual implementation, the form and number of each layer can be arbitrarily changed, and the layer layout may also be more complex.

[0019] Numerous details are explored in the following description to provide a more thorough explanation of embodiments of the invention; however, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details.

[0020] Figure 10 The equivalent circuit diagram for improving the accuracy of electrostatic potential measurement in this application is shown below. Figure 10 As shown, 110V is the signal line core voltage, R2 is the resistor used for induced current, AMP is the signal amplification circuit, and the resistor R1 formed between the electric field shaping board and ground through FR4 is typically around 10V. 9 Although the resistance is very large (Ω·cm), under an induced voltage of 110V, at time t=0, there exists... With a bias current of 110nA, when the electric field of the electrostatic potential is weak, the actual induced current is measured. When the amplitude is small, only about 10nA, the measured electrostatic potential signal will be too small or even disappear. Therefore, it is necessary to improve the method to eliminate the influence of the bias current on the measured electrostatic potential.

[0021] like Figure 1 The diagram shown is a flowchart of a method for improving the accuracy of electrostatic potential measurement according to an embodiment of this application. The method for improving the accuracy of electrostatic potential measurement according to this embodiment includes the following steps: S1. Construct an RC series circuit and obtain the current according to Kirchhoff's voltage law. ; S2, then based on the current The bias current is calculated. ; S3, Regarding the bias current Make corrections to obtain the actual induced current. .

[0022] Furthermore, in step S1, the specific process of constructing the RC series circuit includes: An electric field shaping plate is added to an electrostatic potential measurement sensor to obtain the measurement part of the sensor. This measurement part consists of a measured wire core, insulating sheath, electric field shaping plate, support column, shielding sheet, and induction sheet. The measured wire core, insulating sheath, and electric field shaping plate form a capacitor. The electric field shaping plate and the shielding sheet constitute a capacitor. The electric field shaping plate and the induction sheet constitute a variable capacitor. The electric field shaping plate is then connected to the support column, which is grounded, thus creating a resistor between the electric field shaping plate and the ground using FR4 material. Then, based on the capacitance and resistance Construct an RC series circuit.

[0023] Specifically, the electrostatic potential measurement sensor without the addition of an electric field shaping plate consists of a shielding plate, an induction plate, a motor rotor, and a signal processing circuit board. The motor rotor drives the shielding plate to rotate, achieving periodic blocking of the electric field, which causes the induction plate to generate a periodic current. After conversion, amplification, and processing by the signal processing circuit board, the electrostatic potential of the measured signal line is calculated.

[0024] Specifically, the measurement principle of the electrostatic potential measurement sensor without the added electric field shaping plate is as follows: The electrostatic potential measurement sensor without an electric field shaping plate consists of two metal plates coaxially mounted on the motor output shaft: a shielding plate and a sensing plate. The shielding plate is positioned above the sensing plate and rotates stably with the motor output shaft, blocking electric field lines through grounding. The sensing plate is fixed below the shielding plate and insulated from the motor output shaft. When the grounded shielding plate rotates uniformly with the motor output shaft, the sensing plate, placed in the electric field, is partially blocked by the shielding plate. The blocked area changes periodically. Let S1 be the area of ​​the sensing plate exposed to the electric field, and S2 be the area blocked by the shielding plate. If the field strength of the DC electric field generated by the electrostatic potential of the measured signal line is... Then the dielectric constant of air is Without considering the effect of edge effects on the electric field, the amount of charge induced on the inductor plate is... It can be represented as: ; according to ,right By taking the derivative, the induced current in the electric field can be obtained. for: ; As the shielding plate rotates, the formula... It undergoes periodic changes, therefore It also undergoes periodic changes, the magnitude of which is proportional to the electric field strength. This allows for the measurement of electrostatic potential.

[0025] Furthermore, in step S1, an RC series circuit is constructed, and the current is obtained according to Kirchhoff's voltage law. The specific process includes: Based on the constructed RC series circuit, the expression for Kirchhoff's voltage law is obtained as follows: ; in, This indicates the grounding resistance of the electric field shaping plate. This represents the voltage across the capacitor formed by the signal line and the electric field shaping plate. This represents the capacitance formed by the signal line and the electric field shaping plate. Based on the above , obtain the current: .

[0026] Furthermore, in step S2, based on the current... The bias current is calculated. The specific process includes: According to the current The charging process is a first-order linear differential equation: ; Then, for the equation Solving for the problem, we get: ; Then regarding the above Perform differentiation, and based on the current The bias current is obtained: ; Based on the above Calculations yielded the following: ; Based on the above The bias current is obtained through calculation: .

[0027] Furthermore, the upper surface of the electric field shaping plate is provided with an arc-shaped groove. The electric field shaping plate is made of a metal conductor. The upper surface of the electric field shaping plate is the electric field capturing surface, and the lower surface is the electric field shaping surface. Specifically, the electric field shaping plate is made of aluminum alloy, and its upper surface is designed with a 3mm arc-shaped groove as the electric field capturing surface, wrapping a 1.5 square millimeter RV multi-strand soft core signal line to prevent the signal line from shifting, while capturing the electric field of the surface signal line. The lower surface of the electric field shaping plate is a complete plane, serving as the electric field shaping surface, providing a shaped electric field for the electric field sensing element below. The electric field shaping plate is installed above the electrostatic potential measurement sensor. After shaping the electric field of the signal line being measured, it is transmitted to the electrostatic potential measurement sensor for potential measurement.

[0028] Furthermore, the process of comparing the electrostatic potential measurement sensor without the added electric field shaping plate with the electrostatic potential measurement sensor with the added electric field shaping plate is as follows: First, let's analyze the induced current in the signal line measured by the electrostatic potential measurement sensor without adding an electric field shaping plate: To simplify the calculation without affecting the solution, let the charge of the signal line core be... Ignore its diameter; the dielectric strength of the signal line insulation is , radius is ; at the distance from the outer insulation of the signal line The location is the sensing element of the electrostatic potential measurement sensor, such as... Figure 2 and Figure 8 As shown: According to Gauss's law in an electric field and the boundary conditions at the junction of two media, we know that: ; Inside the insulating dielectric layer: ; Outside the insulating dielectric layer: ; Due to the presence of the dielectric layer, the equivalent charge The result is corrected by the dielectric constant as follows: ; Will Substitute We can obtain: ; Based on the above It can be deduced that, without the addition of an electric field shaping plate, the induced current in the electric field is: .

[0029] Secondly, the analysis and calculation show that, with the addition of the electric field shaping plate, the induced current in the signal line measured by the electrostatic field sensor is as follows: To maintain the same parameters as in the analysis without the electric field shaping plate, let the charge on the signal line core be... Ignore its diameter; the dielectric strength of the signal line insulation is , radius is ; at the distance from the outer insulation of the signal line The location is the sensing plate of the electrostatic potential measurement sensor, such as... Figure 6 and Figure 9 As shown: Let the surface potential of the signal line insulation be... for: ; Because of the addition of an electric field shaping plate made of a metal conductor, the free electrons inside can move freely. When an external electric field acts on the metal, the free electrons inside the conductor will redistribute until the electric field inside the conductor is completely canceled out. Therefore, the electric field shaping plate is an equipotential body. When electrostatic equilibrium is reached, the potential of the electric field shaping plate is equal everywhere. Therefore, the potentials of the electric field capturing surface and the electric field shaping surface of the electric field plate are the same. Since the electric field shaping surface on the bottom of the electric field shaping plate is a conductor and an equipotential surface, the electric field is distributed along its normal direction, forming a uniform electric field between it and the electric field measuring induction plate. Its electric field strength can be expressed as: ; in, The distance between the electric field shaping plate and the electric field measuring induction plate, combined with the above. and the Solving the equation, the electric field induced current of the electrostatic potential measuring sensor can be obtained as follows: ; Finally, the magnitudes of the electric field induced current with and without the electric field shaping plate are compared: By comparing the induced currents in the two electric fields and then quotienting them, we can obtain the following: ; In practical engineering applications, due to limitations in processing technology, generally ,and Meanwhile, the dielectric constant of air is also considered. ,get: ; Therefore, it can be seen that the ratio of the induced current after adding the electric field shaping plate to the induced current without adding the electric field shaping plate is much greater than 1. Thus, the induced current measured after adding the electric field shaping plate is significantly increased, which reflects that the measurement accuracy of the electrostatic potential measurement sensor is improved.

[0030] Furthermore, the electric field shaping plate is installed above the electrostatic potential measuring sensor, and support columns are provided at the four corners of the lower end of the electric field shaping plate. The bottom end of the support column is in contact with the upper end surface of the sensing sheet, and the support column is a polyimide support column.

[0031] Specifically, to further improve the measurement accuracy of the electrostatic potential sensor, it is necessary to reduce the bias current. Therefore, polyimide support columns with better insulation properties are selected for the four support columns of the electric field shaping plate. The polyimide support columns typically have an insulation resistance of 10 ohms. 12 Ω·cm, thereby reducing the current. For induced current Due to the influence of the polyimide support pillars located at the bottom of the electric field shaping plate, such as Figure 5 and Figure 6 As shown.

[0032] By setting a polyimide support between the electric field shaping plate and the sensing plate of the electrostatic potential measurement sensor, the bias current can be eliminated.

[0033] Specifically, firstly, a circuit model is established to represent the bias current generated during electrostatic potential measurement.

[0034] After adding the electric field shaping plate, the measuring part of the electrostatic potential measurement sensor consists of the core of the signal line being measured, the insulating sheath, the electric field shaping plate, the support column, the shielding sheet, and the sensing sheet. The signal line core, insulation sheath, and electric field shaping plate constitute capacitor C1; the electric field shaping plate and shielding sheet constitute capacitor C2; the electric field shaping plate and induction sheet constitute variable capacitor C3; and since the electric field shaping plate is connected to the support column, and the support column is grounded, a resistor R1 is formed between the electric field shaping plate and ground through FR4 material. Its equivalent circuit diagram is shown below. Figure 10 As shown; In the equivalent circuit diagram, 110V is the signal line core voltage; R2 is the resistor used for induced current; AMP is the signal amplification circuit; the resistor R1 formed between the electric field shaping board and ground through FR4 is typically 10V. 9 Although the resistance is very large (Ω·cm), under an induced voltage of 110V, at time t=0, there exists... With a bias current of 110nA, when the electric field of the electrostatic potential is weak, the induced current is measured. I ( t When the amplitude is small, only about 10nA, the measured electrostatic potential signal will be too small or even disappear.

[0035] Secondly, an algorithm for eliminating bias current is established. According to the equivalent circuit, Kirchhoff's voltage law is satisfied in the RC series circuit composed of C1 and R1: ; in, This indicates the grounding resistance of the electric field shaping plate. This represents the voltage across the capacitor formed by the signal line and the electric field shaping plate. This represents the capacitance formed by the signal line and the electric field shaping plate. According to the above Therefore, the current is: ; According to the current The charging process is a first-order linear differential equation: ; Then, for the equation Solving for the problem, we get: ; Then regarding the above Perform differentiation, and based on the current ,get: ; Based on the above Calculations yielded the following: ; Based on the above The bias current is obtained through calculation: ; Then through the After making corrections, the corrected induced current is obtained. for:

[0036] Right now ; Among them, the e It is a constant; Where V = 110V, R1 and C1 can be measured experimentally, that is, generally R1 = 10V. 9 Ω, C1=10pF, through the aforementioned Calculations show that eliminating the influence of bias current on the measured induced current improves the measurement accuracy of the electrostatic potential sensor.

[0037] Finally, further reducing the impact of bias current in hardware is as follows: Through formula It can be seen that increasing R1 can significantly reduce the bias current. When using polyimide pillars, its R1=10 12 Ω, much higher than the resistance formed through FR4, in which case the bias current Much smaller than the electric field-induced current, and using the formula Calculations can completely eliminate the influence of bias current on electrostatic potential measurement.

[0038] Therefore, this method improves the measurement accuracy of the electrostatic potential sensor, thereby enhancing the measurement accuracy of the electrostatic potential on the signal line and ensuring that maintenance personnel can promptly understand whether the outlet hard plate is in the correct open / closed state. Simultaneously, it provides a larger grounding resistance to further reduce the bias current and prevent weak electrostatic potential signals from being weakened during measurement. This further improves the measurement accuracy of the electrostatic potential sensor and prevents measurement failures when the electrostatic potential signal is weak, thus further enhancing measurement sensitivity.

[0039] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for improving the accuracy of electrostatic potential measurement, characterized in that, Includes the following steps: S1. Construct an RC series circuit and obtain the current according to Kirchhoff's voltage law. ; S2, then based on the current The bias current is calculated. ; S3, Regarding the bias current Make corrections to obtain the actual induced current. ; The specific process of constructing the RC series circuit includes: An electric field shaping plate is added to an electrostatic potential measurement sensor to obtain the measurement part of the sensor. This measurement part consists of a measured wire core, insulating sheath, electric field shaping plate, support column, shielding sheet, and induction sheet. The measured wire core, insulating sheath, and electric field shaping plate form a capacitor. The electric field shaping plate and the shielding sheet constitute a capacitor. The electric field shaping plate and the induction sheet constitute a variable capacitor. The electric field shaping plate is then connected to the support column, which is grounded, thus creating a resistor between the electric field shaping plate and the ground using FR4 material. Then, based on the capacitance and resistance Construct an RC series circuit.

2. The method for improving the accuracy of electrostatic potential measurement according to claim 1, characterized in that, In step S1, an RC series circuit is constructed, and the current is obtained according to Kirchhoff's voltage law. The specific process includes: Based on the constructed RC series circuit, the expression for Kirchhoff's voltage law is obtained as follows: ； in, This indicates the grounding resistance of the electric field shaping plate. This represents the voltage across the capacitor formed by the signal line and the electric field shaping plate. This represents the capacitance formed by the signal line and the electric field shaping plate. Based on the above ; Obtain the current: 。 3. The method for improving the accuracy of electrostatic potential measurement according to claim 2, characterized in that, In step S2, the current is then... The bias current is calculated. The specific process includes: According to the current The charging process is a first-order linear differential equation: ； Then, for the equation Solving for the problem, we get: ； Then regarding the above Perform differentiation, and based on the current... The bias current is obtained as follows: 。 4. The method for improving the accuracy of electrostatic potential measurement according to claim 3, characterized in that, In step S3, the actual induced current The expression is: Among them, the e It is a constant.

5. The method for improving the accuracy of electrostatic potential measurement according to claim 1, characterized in that, The electric field shaping plate is installed above the electrostatic potential measuring sensor. Support columns are provided at the four corners of the lower end of the electric field shaping plate, and the bottom end of the support columns is in contact with the upper surface of the sensing sheet.

6. The method for improving the accuracy of electrostatic potential measurement according to claim 1, characterized in that, The upper surface of the electric field shaping plate is provided with an arc-shaped groove.

7. The method for improving the accuracy of electrostatic potential measurement according to claim 6, characterized in that, The electric field shaping plate is made of a metal conductor, with its upper surface being an electric field capturing surface and its lower surface being an electric field shaping surface.

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