A kind of ion flow resistant direct current electric field detection device and method

Abstract

The present invention provides an anti-ion flow DC electric field detection device and method, which belongs to the field of electric field detection. For the detection of the nominal electric field under the condition of ion flow interference, two electric field sensors are set to perform electrostatic field detection, and a reference cover plate and a differential cover plate with different conditions are set above the two electric field sensors. The reference cover plate and the differential cover plate have different ion attachment and dissipation characteristics to the external ion flow field because of different materials or different surface roughness. That is, under the same ion flow field interference condition, the number of ions attached to the reference cover plate and the differential cover plate is different, and the electric field values ​​detected by the corresponding electric field sensors are different, so that the nominal field excluding the influence of the ion flow field can be extracted by differential means. The present invention can realize accurate and effective detection of the target electric field.

Description

Technical Field

[0001] The invention belongs to the field of electric field detection, and in particular relates to an anti-ion flow direct current electric field detection device and method. Background Art

[0002] The electric field environment near the high-voltage DC transmission line in the power system has always been the focus of attention and an important application field of electric field sensors. The measurement of this electric field environment is of great significance for optimizing the construction of power projects and reducing the harm of the electromagnetic environment near the transmission line. However, in the DC ion flow field environment formed by the DC high-voltage transmission line, the presence of ion flow and space charge interferes with the output of the electric field sensor, affecting the measurement accuracy of the DC ion flow field synthetic electric field.

[0003] When a DC high-voltage transmission line is in operation, the charges on the transmission line will generate an electric field. When the surface electric field strength exceeds the air breakdown strength, the transmission line will experience corona discharge, generating a large amount of space charge. Driven by the electric field force, these space charges migrate in a directional manner to form an ion flow. The electric field generated by the space charge is superimposed on the nominal electric field generated by the charges on the transmission line to form a synthetic electric field. The synthetic electric field consists of two parts: one is the electrostatic field formed by the charges carried by the transmission line, also known as the nominal electric field; the other is the electric field generated by the space charge. The synthetic electric field is the superposition of the nominal electric field and the space charge electric field, and its size mainly depends on the transmission line voltage and the severity of the transmission line corona discharge. In some cases, the ground synthetic electric field may reach 2 to 3.5 times the ground nominal electric field.

[0004] In order to accurately measure the nominal electric field strength, it is necessary to consider the influence of ion flow and space charge on the output characteristics of the electric field sensor, that is, to test and calibrate the electric field sensor in a DC ion flow field environment. Compared with field grinding and vibration electric field sensors, the new electric field sensor based on MEMS technology has the advantages of small electric field distortion and small influence on ion flow and space charge distribution, which is conducive to improving the measurement accuracy in a DC ion flow field environment. However, for the output characteristics of MEMS electric field sensors in a DC ion flow field and test calibration methods, further technical means and test methods are still needed.

[0005] In the prior art, there is a composite detection device with two electric field sensor probes. By designing the probe cover plates at different heights, it is considered that the electric field generated by the external ion flow field is only related to the cover plate height. Therefore, the interference of the external ion flow field can be reduced by differential operation of the two probes. However, the inconsistency of the structure of different probe heights will affect the local distribution of the electric field at the probe, resulting in inaccurate electric field measurement.

[0006] In the prior art, a detection device for an ion flow field is designed to synchronously detect the spatial ion flow field. Different calibration coefficients are used according to different ion flow fields to obtain the nominal electric field value. However, since an ion flow detection device is added, the complexity of the system structure is increased. In addition, it is necessary to establish an ion flow field calibration environment and calibrate different ion flow fields multiple times in advance, and the operation steps are complicated. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides an anti-ion flow DC electric field detection device and method, which overcomes the interference of the electric field generated by the ion flow in a detection environment where the ion flow exists, and accurately and effectively detects the target electric field.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] A DC electric field detection device resistant to ion flow interference comprises an electric field sensor, a shell, an internal electronic unit, a reference cover, a differential cover and a supporting wall; the electric field sensor is fixed to the shell by a connector and connected to the internal electronic unit by a wire; there are two electric field sensors; the shell is used to accommodate the internal electronic unit, support the electric field sensor, and fix and protect the internal electronic unit; the reference cover is used to encapsulate and protect one electric field sensor; the reference cover is supported by the supporting wall; the differential cover is used to encapsulate and protect another electric field sensor; the differential cover and the reference cover are made of different materials, or when the two are made of the same material and are not metal, the two have different surface roughness; the differential cover is supported by the supporting wall; the supporting wall is supported by the shell.

[0010] Furthermore, the internal electronic unit includes an electronic circuit, which is connected to the electric field sensor through a wire and is used to perform voltage conversion, signal conditioning, analog-to-digital conversion, signal processing and transmission on the current signal output by the electric field sensor, and at the same time provide an excitation drive signal for the electric field sensor.

[0011] Furthermore, the external electric field and ion flow act on the two electric field sensors through the reference cover and the differential cover respectively.

[0012] Furthermore, the electric field sensor is a sensor device that converts an external electric field into a current signal using MEMS technology.

[0013] Furthermore, the shell is made of aluminum, iron or copper.

[0014] Furthermore, the material of the reference cover plate is metal, polytetrafluoroethylene or polyvinyl chloride; the material of the differential cover plate is metal, polytetrafluoroethylene or polyvinyl chloride.

[0015] Furthermore, the support wall is a thin-walled structure, and the material is ceramic or plastic.

[0016] The present invention also provides a method for detecting a DC electric field that is resistant to ion flow interference, comprising: detecting a nominal electric field under ion flow interference conditions, setting two electric field sensors for electrostatic field detection, setting a reference cover plate and a differential cover plate with different conditions above the two electric field sensors, detecting two different electric field values ​​by the two electric field sensors respectively encapsulated and protected by the reference cover plate and the differential cover plate, performing differential calculation on the two electric field values ​​to extract the nominal electric field that excludes the influence of the ion flow field; the different conditions are that the materials of the reference cover plate and the differential cover plate are different, or the surface roughness is different when the materials of the reference cover plate and the differential cover plate are the same.

[0017] Furthermore, the different conditions are: the reference cover plate is made of metal, and the differential cover plate is made of polytetrafluoroethylene or polyvinyl chloride; or the reference cover plate is made of polytetrafluoroethylene or polyvinyl chloride with a surface roughness Ra=0.1, and the differential cover plate is made of the same material as the reference cover plate with a surface roughness Ra=0.4.

[0018] Furthermore, in the nominal electric field under the condition of ion flow interference, the output value of the electric field sensor is obtained and calculated:

[0019]

[0020] in, is the electric field value detected by the electric field sensor under the reference cover, is the nominal electric field value to be detected in the outside world; is the electric field value detected by the electric field sensor under the differential cover; It represents the ratio of the ion flow field sensing capability of the differential cover plate to the reference cover plate, which is a fixed coefficient;

[0021] Obtain the ion flow field sensing capability ratio of the differential cover plate to the reference cover plate Finally, when actually measuring the electrostatic field, the following formula is used to calculate the external nominal electric field value to be detected:

[0022] .

[0023] Beneficial effects:

[0024] 1. The present invention can accurately obtain the target electric field signal from the target electric field and the ion flow electric field in an ion flow environment;

[0025] 2. The symmetrical design of the present invention can ensure uniform distribution of the target electric field and the ion flow electric field at the probe, avoiding local electric field distortion and shielding of the electric field.

[0026] 3. The present invention does not require multiple calibration operations of the ion flow field environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a DC electric field detection device that resists ion flow interference according to the present invention;

[0028] Figure 2 A schematic diagram of the internal electronic unit.

[0029] Among them, 1-electric field sensor, 2-housing, 3-internal electronic unit, 4-reference cover, 5-differential cover, 6-support wall, 301-temperature sensor, 302-current-voltage conversion circuit, 303-differential amplifier circuit, 304-analog-digital conversion unit, 305-boost module, 306-digital signal synthesis unit, 307-power management unit, 308-controller processing unit 308, 309-communication unit. DETAILED DESCRIPTION

[0030] like Figure 1 As shown, a DC electric field detection device resistant to ion flow interference of the present invention includes an electric field sensor 1, a housing 2, an internal electronic unit 3, a reference cover plate 4, a differential cover plate 5 and a support wall 6.

[0031] The electric field sensor 1 is a sensor device that uses MEMS technology to convert external electric fields into current signals. The electric field sensor 1 is fixed to the housing 2 with a connector and connected to the internal electronic unit 3 through a wire. The electric field sensor 1 includes two.

[0032] The housing 2 is used to accommodate the internal electronic unit 3 , and its material can be metal aluminum, iron, copper, etc., and is used to support the electric field sensor 1 and fix and protect the internal electronic unit 3 .

[0033] The reference cover plate 4 is used to encapsulate and protect the electric field sensor 1 to prevent the influence of environmental factors such as airflow, dust, light, etc. on the sensor chip of the electric field sensor 1. The reference cover plate 4 is made of metal or polytetrafluoroethylene, polyvinyl chloride, etc. The reference cover plate 4 is supported by the support wall 6, and the two are glued or mechanically fastened.

[0034] The differential cover plate 5 is used to encapsulate and protect the electric field sensor 1 to prevent the influence of environmental factors such as external airflow, dust, light, etc. on the sensor chip of the electric field sensor 1. The material of the differential cover plate 5 is metal or polytetrafluoroethylene, polyvinyl chloride, etc. The differential cover plate 5 needs to be made of a different material from the reference cover plate 4; when the two are made of the same material and are not metal, the surface roughness of the two needs to be different. The differential cover plate 5 is supported by a support wall 6, and the two are glued or mechanically fastened.

[0035] The support wall 6 is a thin-walled structure made of ceramic or plastic, etc., and is used to support the reference cover plate 4 and the differential cover plate 5. The support wall 6 is supported by the housing 2, and the two are glued or mechanically fastened.

[0036] like Figure 2 As shown, the internal electronic unit 3 drives the electric field sensor 1 and stimulates the electric field sensor 1 to work normally; it includes an electronic circuit, which is connected to the electric field sensor 1 through a wire, and is used to convert the current signal output by the electric field sensor 1 into voltage, perform signal conditioning, analog-to-digital conversion, signal processing and transmission, etc., and at the same time provide an excitation driving signal for the electric field sensor 1.

[0037] The internal electronic unit 3 includes a temperature sensor 301 , a current-voltage conversion circuit 302 , a differential amplifier circuit 303 , an analog-digital conversion unit 304 , a boost module 305 , a digital signal synthesis unit 306 , a power management unit 307 , a controller processing unit 308 , and a communication unit 309 .

[0038] The internal electronic unit completes the current-to-voltage conversion of the output signal of the electric field sensor 1 through the current-to-voltage conversion circuit 302, and converts the output signal of the electric field sensor 1 into a voltage signal that is easy to process; the voltage signal is amplified and filtered through the differential amplifier circuit 303, and the signal conditioning after the current-voltage change is completed, and the size and frequency of the signal are adjusted to within the range of the back-end processing unit; the voltage signal is analog-to-digital converted by the analog-to-digital conversion unit 304, so that the signal is easy to digitally process; the digital signal is demodulated and processed to extract the signal quantity representing the detected electric field value; the signal is processed by the controller processing unit 308 to convert and adjust the format of the signal detection result for signal communication and transmission; the formatted detection result is transmitted through serial communication for subsequent processing.

[0039] The temperature sensor 301 and the controller processing unit 308 are connected via the communication port IIC, using a digital direct output mode to monitor the temperature changes of the internal electronic unit;

[0040] The current-voltage conversion circuit 302 is electrically connected to the differential amplifier circuit 303 of the subsequent stage, and is used to convert the output current signal of the electric field sensor 1 into a voltage signal, so as to facilitate the processing by the internal electronic unit 3;

[0041] The differential amplifier circuit 303 receives the voltage signal output by the current-voltage conversion circuit 302 of the previous stage, is electrically connected to the analog-digital conversion unit 304 of the subsequent stage, amplifies and filters the signal, and adjusts the signal range to the working range of the internal electronic unit 3;

[0042] The analog-to-digital conversion unit 304 is electrically connected to the differential amplifier circuit 303 of the previous stage and to the controller processing unit 308 of the subsequent stage to perform digital conversion on the analog signal;

[0043] The boost module 305 is electrically connected to the power management unit 307, responsible for increasing the voltage to 20V, and is electrically connected to the electric field sensor 1 as a DC driving signal for the electric field sensor 1;

[0044] The digital signal synthesis unit 306 is electrically connected to the controller processing unit 308 through the SPI communication interface, and is electrically connected to the electric field sensor 1; under the timing control of the controller processing unit 308, an AC signal with a characteristic frequency and amplitude is generated as an AC driving signal of the electric field sensor 1;

[0045] The power management unit 307 is electrically connected to the temperature sensor 301, the current-voltage conversion circuit 302, the differential amplifier circuit 303, the analog-digital conversion unit 304, the boost module 305, the digital signal synthesis unit 306, the controller processing unit 308, and the communication unit 309 to provide a working voltage;

[0046] The controller processing unit 308 is electrically connected to the analog-to-digital conversion unit 304, the digital signal synthesis unit 306, and the communication unit 309 to achieve timing control, signal digital demodulation, and signal communication format adjustment;

[0047] The communication unit 309 is electrically connected to the controller processing unit 308, receives digital signals from the controller processing unit 308, and sends data in the form of serial wireless communication; preferably, the communication unit 309 adopts a wireless Bluetooth hardware mode.

[0048] The external electric field and ion flow act on the two electric field sensors 1 through the reference cover 4 and the differential cover 5 respectively. Since the amount of charges attached to the reference cover 4 and the differential cover 5 is different, the electric field values ​​felt on the two electric field sensors 1 are also different, which respectively include the external electric field and the electric field generated by the charges attached to the ion flow.

[0049] The present invention also provides a method for detecting a DC electric field with resistance to ion flow interference, comprising the following steps:

[0050] Step 1: Set two structural design modes. Both structural design modes can achieve the purpose of the present invention, and one of them can be selected for application:

[0051] a. The design reference cover plate 4 is made of metal, and the design differential cover plate 5 is made of polytetrafluoroethylene or polyvinyl chloride with a surface roughness of Ra=0.1;

[0052] b. The design reference cover plate 4 is made of polytetrafluoroethylene or polyvinyl chloride with a surface roughness of Ra=0.1, and the design differential cover plate 5 is made of the same material with a surface roughness of Ra=0.4.

[0053] Step 2: In a standard ion flow field generation and calibration environment, obtain the output value of the electric field sensor 1 and calculate:

[0054]

[0055] in, is the electric field value detected by the electric field sensor under the reference cover, is the nominal electric field value to be detected in the outside world; is the electric field value detected by the electric field sensor under the differential cover; It represents the ratio of the ion flow field sensing capability of the differential cover plate 5 to the reference cover plate 4, which is a fixed coefficient;

[0056] Step 3: Obtain the ion flow field sensing capability ratio of the differential cover plate 5 to the reference cover plate 4 After that, when actually measuring the electrostatic field, the following formula can be used to calculate the external nominal electric field value to be detected:

[0057]

[0058] The present invention aims at detecting the nominal electric field under the condition of ion flow interference, arranges two electric field sensors 1 to perform electrostatic field detection, and arranges a reference cover plate 4 and a differential cover plate 5 with different conditions above the two electric field sensors 1. The reference cover plate 4 and the differential cover plate 5 have different ion attachment and dissipation characteristics to the external ion flow field due to different materials or different surface roughnesses, that is, under the same ion flow field interference condition, the number of ions attached to the reference cover plate 4 and the differential cover plate 5 is different, and the corresponding electric field values ​​detected by the electric field sensor 1 are different, so that the nominal field excluding the influence of the ion flow field can be extracted by differential means.

[0059] The principle of the present invention is:

[0060] 1. The detection electric field of the electric field sensor 1 under the reference cover plate 4 includes the influence of the nominal electric field and the ion flow field, that is:

[0061]

[0062] in, is the electric field value detected by the electric field sensor 1 under the reference cover 4, is the nominal electric field value to be detected from the outside world, The ion flow interference field is generated by the electric charges attached to the reference cover plate 4 by the ion flow.

[0063] 2. The detection electric field of the electric field sensor 1 under the differential cover plate 5 includes the influence of the nominal electric field and the ion flow field, that is:

[0064]

[0065] in, is the electric field value detected by the electric field sensor 1 under the differential cover plate 5, is the external nominal electric field to be detected. As mentioned above, when the reference cover plate 4 and the differential cover plate 5 are made of different materials or have different surface roughness, the number of ions attached to the reference cover plate 4 and the differential cover plate 5 will be different. It represents the ratio of the ion flow field sensing capability of the differential cover plate 5 to the reference cover plate 4. It is a fixed coefficient and has nothing to do with the external electric field. It is only related to the cover plate material and surface roughness. It can be obtained by ion flow environment and standard electric field calibration experiments. The general value range is 2-4.

[0066] 3. The external nominal electric field value to be detected can be calculated from the measured values ​​of the two electric field sensors 1:

[0067] .

Claims

1. A DC electric field detection device that resists ion flow interference, characterized in that: It comprises an electric field sensor, a shell, an internal electronic unit, a reference cover, a differential cover and a supporting wall; the electric field sensor is fixed to the shell by a connector and connected to the internal electronic unit by a wire; there are two electric field sensors; the shell is used to accommodate the internal electronic unit, support the electric field sensor, and fix and protect the internal electronic unit; the reference cover is used to encapsulate and protect one electric field sensor; the reference cover is supported by the supporting wall; the differential cover is used to encapsulate and protect another electric field sensor; the differential cover and the reference cover are made of different materials, or when the two are made of the same material and are not metal, the two have different surface roughness; the differential cover is supported by the supporting wall; the supporting wall is supported by the shell; Two electric field sensors respectively protected by the reference cover plate and the differential cover plate detect two different electric field values, and perform differential calculation on the two electric field values ​​to extract the nominal electric field excluding the influence of the ion flow field; In the detection environment where ion flow exists, the interference of the electric field generated by the ion flow is overcome and the target electric field is accurately and effectively detected.

2. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The internal electronic unit includes an electronic circuit, which is connected to the electric field sensor through a wire and is used to perform voltage conversion, signal conditioning, analog-to-digital conversion, signal processing and transmission on the current signal output by the electric field sensor, and at the same time provide an excitation drive signal for the electric field sensor.

3. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The external electric field and ion flow act on the two electric field sensors through the reference cover and the differential cover respectively.

4. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The electric field sensor is a sensor device that uses MEMS technology to convert external electric fields into current signals.

5. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The shell is made of aluminum, iron or copper.

6. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The material of the reference cover plate is metal, polytetrafluoroethylene or polyvinyl chloride; the material of the differential cover plate is metal, polytetrafluoroethylene or polyvinyl chloride.

7. The device for detecting a DC electric field against ion flow interference according to claim 1, characterized in that: The supporting wall is a thin-walled structure, and the material is ceramic or plastic.

8. A method for detecting a DC electric field with resistance to ion flow interference, characterized in that: include: The nominal electric field under the condition of ion flow interference is detected, two electric field sensors are set to perform electrostatic field detection, a reference cover plate and a differential cover plate with different conditions are set above the two electric field sensors, two different electric field values ​​are detected by the two electric field sensors respectively encapsulated and protected by the reference cover plate and the differential cover plate, and the two electric field values ​​are differentially calculated and extracted to obtain the nominal electric field that excludes the influence of the ion flow field; the different conditions are that the reference cover plate and the differential cover plate are made of different materials, or the reference cover plate and the differential cover plate have different surface roughness when the materials are the same; the different conditions are: the reference cover plate is made of metal, and the differential cover plate is made of polytetrafluoroethylene or polyvinyl chloride; or the reference cover plate is made of polytetrafluoroethylene or polyvinyl chloride with a surface roughness of Ra=0.1, and the differential cover plate is made of the same material as the reference cover plate with a surface roughness of Ra=0.

4.

9. The detection method according to claim 8, characterized in that: include: In the nominal electric field under the condition of ion flow interference, the output value of the electric field sensor is obtained and calculated: ； in, is the electric field value detected by the electric field sensor under the reference cover, is the nominal electric field value to be detected in the external environment; is the electric field value detected by the electric field sensor under the differential cover; It represents the ratio of the ion flow field sensing capability of the differential cover plate to the reference cover plate, which is a fixed coefficient; Obtain the ion flow field sensing capability ratio of the differential cover plate to the reference cover plate Finally, when actually measuring the electrostatic field, the following formula is used to calculate the external nominal electric field value to be detected: 。

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