Offshore electric field detection equipment based on corona current measurement

Abstract

The invention discloses an offshore electric field detection device based on corona current measurement. The offshore electric field detection device comprises a floating platform, a corona probe, a balance weight, a multi-parameter detection unit, a data processing unit, a Beidou communication module and a composite power supply system. The floating platform is made of corrosion-resistant composite materials, and a sealed cabin is arranged in the floating platform. A corona probe is mounted at the top and adopts a multi-stage gradient structure and a hydrophobic coating, so that the salt spray corrosion resistance is remarkably improved. The electric field detection equipment integrates corona current, salt mist concentration, wind speed, attitude and other sensors, collects environment and platform motion data in real time, calculates electric field intensity through a dynamic coupling correction algorithm of corona current, salt mist, wind speed and platform attitude, and inhibits environment and platform motion interference by combining adaptive filtering and data compression technologies. And high-precision measurement of sea surface electric field intensity is realized. And data compression and Beidou encryption transmission technologies are adopted, so that ultra-long-distance data return is realized.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric physics and ocean electric field technology, and in particular to an offshore electric field detection device based on corona current measurement, which is used for real-time monitoring of sea surface electric field intensity and improving electric field measurement accuracy and equipment reliability through dynamic correction of multiple environmental parameters. Background Art

[0002] Lightning activity is a direct product of dramatic changes in the atmospheric electric field. Land lightning detection technology has been relatively mature after decades of development. Fixed electric field instrument networks and ground-based radar systems can realize real-time monitoring and early warning of lightning activity, and predict the charge distribution of thunderstorm clouds by measuring the gradient changes in the ground electric field intensity. However, the development of lightning detection technology in marine environments is seriously lagging behind. According to statistics, global marine lightning activities are frequent and the intensity is significantly higher than that on land. At present, the prediction of marine thunderstorms mainly relies on the monitoring of changes in the electric field intensity of the sea surface. The existing technology has significant defects in the field of real-time detection of the sea surface electric field. The existing technology mostly relies on monitoring ships carrying mobile electric field detection equipment to conduct intermittent sampling in local sea areas, and indirectly infer the charge distribution of thunderstorm clouds by measuring the electric field intensity of the sea surface. This method consumes a lot of manpower and material resources, has high detection costs, and is limited by speed and maneuverability, making it difficult to achieve large-scale, long-term continuous monitoring. What's more serious is that ships need to return to port to avoid the wind in bad weather, resulting in interruption of data collection, and this period is exactly the high incidence stage of lightning activity. Drones equipped with micro electric field sensors can quickly reach the target sea area, but their flight time is usually less than 2 hours, and their wind resistance is limited to less than level 5. In severe convective weather, drones are prone to falling into the sea due to rain and turbulence. The actual application scenarios are extremely limited. Although traditional buoy-type monitoring devices can be deployed at fixed points, they focus more on conventional parameters such as wind speed and water temperature, and there is no detection equipment specifically for electric field strength. A few studies use anchored buoys to integrate electric field sensors, but their designs have fundamental defects. Traditional spherical electric field probes are easily covered by salt spray, resulting in decreased corona discharge stability and large drift errors in measured data. The attitude changes caused by the buoy's fluctuations with the waves will significantly change the distance between the probe and the sea surface, generating false electric field signals. The buoy lacks the ability to synchronize multi-parameter corrections, and cannot remove environmental interference such as wind speed and salt spray concentration, resulting in low data credibility. Data is transmitted wirelessly, and due to the limitations of wireless communication equipment, the transmission distance is limited, and only offshore electric field detection can be performed. The above technical defects seriously restrict the application of key scenarios such as marine thunderstorm warning and lightning path prediction. It is necessary to develop a high-precision offshore electric field detection equipment that is resistant to environmental interference, can be self-powered for a long time, and supports dynamic correction to fill the technical gap in the field of marine lightning monitoring. It is very necessary to detect offshore electric fields in the distant seas and study the changes in electric field intensity gradients to predict thunderstorm weather through Beidou short message remote data transmission. Summary of the invention

[0003] The object of the present invention is to provide an offshore electric field detection device based on corona current measurement, which includes a floating platform, a corona probe, a balance weight, a multi-parameter detection unit, a data processing unit, a Beidou satellite communication module, and a power supply unit. The floating platform is made of corrosion-resistant composite materials and has a sealed cabin inside. The corona probe is installed on the top. The corona probe adopts a multi-stage gradient structure and a hydrophobic coating, significantly improving the anti-salt fog corrosion ability. The electric field detection device integrates sensors such as corona current, salt fog concentration, wind speed, and attitude, and collects environmental and platform motion data in real time. The electric field intensity is calculated through a dynamic coupling correction algorithm of corona current with salt fog, wind speed, and platform attitude. Combining adaptive filtering and data compression technology, it suppresses environmental and platform motion interference and realizes high-precision measurement of the sea surface electric field intensity. By using data compression and Beidou encrypted transmission technology, it realizes ultra-long-distance data transmission. The device adopts a composite power supply system of photovoltaic cells and wave generators in cooperation with a storage battery for power supply to achieve long-term endurance. The present invention is applicable to the fields of marine electromagnetic environment monitoring and meteorological warning, and has the advantages of flexible deployment, high reliability, and low cost.

[0004] The present invention is realized through the following technical solutions: The offshore electric field detection device based on corona current measurement includes: a floating platform 1, a corona probe 2, a balance weight 3, a detection unit 4, a data processing unit 5, a Beidou satellite communication module 6, and a power supply unit 7. The floating platform 1 is made of corrosion-resistant composite materials, with a sealed cabin inside and a corona probe 2 mounting seat on the top. The corona probe 2 is vertically installed on the top of the floating platform 1, and the height is ≥ 1 meter. The balance weight 3 is suspended below the floating platform 1, and is symmetrically arranged to ensure the balance of the floating platform 1. The detection unit 4 includes a corona current detection module 41, a salt fog detection module 42, a seawater conductivity detection module 43, a temperature detection module 44, a wind speed detection module 45, an acceleration detection module 46, and a three-axis attitude detection module 47. The data processing unit 5 is integrated in the sealed cabin. By measuring the corona discharge current of the corona probe 2 and resolving it through the corona current detection module 41, the sea surface electric field intensity is obtained. The salt fog detection module 42 is used to correct the influence of the air salt fog concentration above the sea surface on the electric field intensity. The wind speed detection module 45 is used to correct the influence of the wind speed on the electric field intensity. The acceleration detection module 46 is used to detect the height of the floating platform 1 rising and falling. The three-axis attitude detection module 47 is used to detect the inclination angle of the floating platform 1 swinging, and corrects the influence of the attitude of the floating platform 1 rising and falling height and swinging inclination angle on the electric field intensity. The seawater conductivity detection module 43 and the temperature detection module 44 are used to judge the relationship with the air salt fog concentration.

[0005] The data processing unit 5 performs signal filtering, compression, and outlier marking algorithms on the detection data of the detection unit 4, and resolves the electric field intensity on the sea surface EThe Beidou satellite communication module 6 obtains the coordinate position, marks the timestamp, transmits the electric field strength data, air salt spray concentration and platform coordinates through short messages, and the monitoring center generates a thermal map based on the returned electric field strength and air salt spray concentration and Beidou coordinate superposition data fusion.

[0006] The electric field strength E , calculated using the following formula: , in, α The correction coefficient is 0.5~0.8, n is the number of free electrons per unit volume (unit: m −3 ), q is the charge of a single electron (1.602×10 −19 coulomb), μ is the electron mobility (the mobility of electrons in air is about 1.3×10 −4 m 2 / V⋅s), A is the effective area of ​​the probe (unit: m 2 ); Effects of air salt spray concentration, wind speed, and floating platform 1 posture on the electric field strength. Corrected electric field strength E co The following formula is used for calculation: , in: The height difference Δ between the corona probe 2 and the sea surface caused by the ups and downs of the floating platform 1 h ( t ), h 0 is the characteristic scale of corona discharge; To correct the swing angle, θ ( t ) is the platform inclination angle; Wind speed correction, v ( t ) is the wind speed, β The empirical coefficient is 0.1. v 0 Take 1m / s as the reference wind speed; Corrected for salt spray, c ( t ) is the salt spray concentration, coefficient γ Take 0.2, the base concentration c 0 =1mg / m 3 The acceleration detection module 46 obtains the acceleration a , calculate Δ by the following formula h ( t ), , the three-axis attitude detection module 47 obtains the platform tilt angle θ ( t ), the wind speed detection module 45 obtains the wind speed v ( t ), the salt spray detection module 42 obtains the salt spray concentration c ( t ). h 0 、 β 、 γ Determined by fitting laboratory simulation or on-sea measured data, substitute the correction factor into the formula, and dynamically calculate the corrected electric field strength E co , and perform Kalman filtering to suppress high-frequency noise.

[0007] The top surface of the floating platform 1 is provided with a bracket 11. The bracket 11 is made of carbon fiber material and coated with a DSAN coating with a hydrophobic angle > 150° on the outer layer. An anchor ring 12 is provided at the bottom of the floating platform 1, and is connected to the anchor 14 by a cable 13 made of Kevlar.

[0008] The tip of the corona probe 2 is a tungsten alloy needle-like structure with a diameter ≤ 0.1 mm, and is installed at the top of the bracket 11. The tip of the corona probe 2 adopts a multi-stage gradient structure, and the diameter gradually shrinks from 2 mm to 0.1 mm from the root to the tip. The tungsten alloy tip is polished by electron beam, and the surface roughness Ra ≤ 0.05 μ m, and is coated with a salt spray-resistant tungsten alloy film layer. The corona probe 2 is connected to the corona current detection module 41 by a cable with a Teflon insulating tape shielding layer and connected to the data processing unit 5.

[0009] The salt spray detection module 42 measures the salt spray concentration by the laser scattering method. By measuring the scattering signal of salt particles in the flowing air to the laser, the content and particle size distribution of salt particles are obtained, and the level of the salt spray content in the air is obtained in real time. The salt spray particle concentration measurement range of the salt spray detection module 42 is 0~10 mg / m³, and the particle size distribution measurement range is 0.5~10 μ m.

[0010] The built-in data processing unit 5 coordinates energy supply and has a low-power sleep mode. It can automatically activate all detection modes according to the set startup threshold, and enter the sleep mode automatically when the threshold is lower, only performing corona current detection. The data processing unit 5 acquires raw data from the detection unit 4, uses moving average and Kalman filtering algorithms to remove noise, improves data accuracy, adopts bit splicing method for data compression, reduces the data volume, reduces the workload of the communication module, and improves the transmission efficiency. The data processing unit 5 is equipped with an adaptive filtering module, which uses a band-stop filter based on the ocean wave spectrum, with the center frequency locked at 0.1 - 0.3 Hz, to eliminate the low-frequency interference signals caused by ocean wave motion and effectively suppress the electric field measurement error caused by platform swaying. The data processing unit 5 identifies and marks abnormal data through the moving window median or isolation forest algorithm, ensures the accuracy and reliability of the data, packs the processed data into a complete data packet, compresses it into a binary packet, and sends it through the short message of the Beidou satellite communication module 6.

[0011] The power supply unit 7 includes a photovoltaic panel 71, a wave-swing generator 72, and a storage battery 73. The photovoltaic panel 71 uses monocrystalline silicon cells, and the wave-swing generator 72 uses a pendulum-type small generator. The photovoltaic panel 71 and the wave-swing generator 72 are connected to the storage battery 73 inside the platform through a BMS battery management system, and the storage battery 73 uses a lithium battery pack.

[0012] The Beidou satellite communication module 6 is encrypted with AES-256 and transmitted through the Beidou RDSS channel. The single-message capacity is 1200 bytes, and a data packet is sent through the short message every 5 minutes.

[0013] The beneficial effects of the present invention are as follows: The electric field intensity is dynamically corrected through the salt spray concentration, wind speed, platform height, and inclination, and the error is greatly reduced. The anti-salt spray design of the corona probe adopts a gradient structure, a hydrophobic coating, and a tungsten alloy coating to effectively prevent the probe from being eroded by seawater. The adaptive filtering band-stop filter based on the ocean wave spectrum eliminates the 0.1 - 0.3 Hz low-frequency interference. Through the dynamic correction formula and Kalman filtering, the error of electric field intensity calculation is ≤5%; the composite power supply system can still work continuously under the condition of no light. The Beidou encrypted short message transmission is adopted, and the data backhaul is not restricted by distance, realizing ultra-long-distance data backhaul. The equipment cost is low, and it can be batch deployed in the open sea area. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an elevation view of the present invention; Figure 2 It is a plan view of the present invention; Figure 3 It is a block diagram of the electric field intensity detection principle of the present invention.

[0015] In the figure: 1 - floating platform, 2 - corona probe, 3 - counterweight, 4 - detection unit, 5 - data processing unit, 6 - Beidou satellite communication module, 7 - power supply unit, 11 - support, 12 - anchor ring, 13 - cable, 14 - anchor, 31 - counterweight support rod, 32 - cross brace, 41 - corona current detection module, 42 - salt spray detection module, 43 - seawater conductivity detection module, 44 - temperature detection module, 45 - wind speed detection module, 46 - acceleration detection module, 47 - three-axis attitude detection module, 71 - photovoltaic panel, 72 - wave generator, 73 - storage battery. Detailed implementation manners

[0016] For better understanding of the present invention by those skilled in the art, in combination with Figures 1 to 3 the present application is further described. In the description of this specification, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or parts referred to must have a specific orientation, be constructed and operated in a specific orientation. The content mentioned in the implementation manners is not a limitation to the present invention.

[0017] The offshore electric field detection device based on corona current measurement of the present invention includes: a floating platform 1, a corona probe 2, a counterweight 3, a detection unit 4, a data processing unit 5, a Beidou satellite communication module 6, and a power supply unit 7. The elevation view of the present invention is shown in Figure 1 and the plan view of the present invention is shown in Figure 2 The principle block diagram of the electric field strength detection of the present invention is shown in Figure 3。The floating platform 1 is made of corrosion-resistant composite materials. Specifically, the floating platform 1 uses a glass fiber-reinforced epoxy composite material to make the shell, and the inside is filled with polyurethane foam material. The floating platform 1 is provided with a sealed cabin inside, and the waterproof grade of the sealed cabin is IP68, which is used to place the data processing unit 5 and the Beidou satellite communication module 6. The top of the floating platform 1 is provided with a mounting seat for the corona probe 2, and the corona probe 2 is vertically installed on the top of the floating platform 1, with a height ≥ 1 meter. The top surface of the floating platform 1 is provided with a bracket 11, and the bracket 11 is made of carbon fiber material, and the outer layer is coated with a DSAN coating with a hydrophobic angle > 150°. The balance weights 3 are suspended below the floating platform 1, arranged symmetrically, and made of lead counterweight blocks to ensure that the platform inclination angle ≤ 5°, ensuring the balance of the floating platform 1. The balance weights 3 are cantilevered outward by the balance weight struts 31 to increase the anti-overturning ability of the floating platform 1, and the balance weight struts 31 are connected and fixed by a cross brace 32 to increase the strength of the balance weight struts 31. The balance weight struts 31 and the cross brace 32 use steel pipes as support members, and are wound with carbon fiber materials on the outside to prevent seawater erosion. The bottom of the floating platform 1 is provided with an anchor ring 12, which is connected to the anchor 14 by a cable 13 made of Kevlar. The length of the cable 13 should be determined according to the depth of the detection sea area, and a margin of 10% - 20% should be reserved compared to the seawater depth, so that the floating platform 1 can float and move freely without being carried away by the waves. If the purpose of the detection is to study the free floating trajectory of the floating platform 1 with ocean waves and ocean currents and randomly detect the electric field intensity of the ocean, the cable 13 and the anchor 14 can be not set.

[0018] The tip of the corona probe 2 is a tungsten alloy needle-like structure with a diameter ≤ 0.1 mm, installed at the top of the bracket 11. The tip of the corona probe 2 adopts a multi-stage gradient structure, and the diameter gradually shrinks from 2 mm to 0.1 mm from the root to the tip. The tungsten alloy tip is processed by electron beam polishing, and the surface roughness Ra ≤ 0.05 μ m, and is coated with a salt spray-resistant tungsten alloy film layer on the surface. The corona probe 2 and the corona current detection module 41 are connected to the data processing unit 5 by a cable with a Teflon insulation tape shielding layer.

[0019] The detection unit 4 includes a corona current detection module 41, a salt spray detection module 42, a seawater conductivity detection module 43, a temperature detection module 44, a wind speed detection module 45, an acceleration detection module 46, and a three-axis attitude detection module 47. The salt spray detection module 42 is used to correct the influence of the salt spray concentration in the air above the sea surface on the electric field intensity. The salt spray detection module 42 uses the laser scattering method to measure the salt spray concentration. By measuring the scattering signal of the laser by the salt particles in the flowing air, the content and particle size distribution of the salt particles are obtained, and the level of the salt spray content in the air is obtained in real time. The salt spray concentration meter of model MHY-YW6 is used, and the measurement range of the salt spray particle concentration is 0 - 10 mg / m³, and the measurement range of the particle size distribution is 0.5 - 10 μm. The wind speed detection module 45 is used to correct the influence of wind speed on the electric field strength. The wind speed detection module 45 adopts a mechanical anemometer with a range of 0~50m / s. The acceleration detection module 46 is used to detect the height of the floating platform 1 up and down. The model VSA001 is adopted. The detection range is ±25g and the accuracy is ±0.2%; the three-axis attitude detection module 47 is used to detect the inclination of the floating platform 1. The model YIS106 is adopted. The detection angle: roll, pitch ±60°, heading ±180°, accuracy: roll, pitch 0.1°, heading 0.5°. The data processing unit 5 corrects the influence of the salt spray concentration, wind speed and the attitude of the floating platform 1 up and down height and the swing inclination angle on the electric field strength. The seawater conductivity detection module 43 and the temperature detection module 44 are used to judge the relationship with the air salt spray concentration.

[0020] The power supply unit 7 includes a photovoltaic panel 71, a wave swing generator 72, and a battery 73. The photovoltaic panel 71 uses a monocrystalline silicon cell, and the wave swing generator 72 uses a pendulum-type small generator. The photovoltaic panel 71 and the wave swing generator 72 are connected to the battery 73 inside the platform through the BMS battery management system. The battery 73 uses a lithium battery pack. The photovoltaic cell 71 has a power of 50W, the wave generator 72 has an output power of 30W, and the battery 73 has a capacity of 500Wh. The power management adopts a strategy of photovoltaic priority and wave power generation supplement. When the light intensity is greater than 200W / m², photovoltaic power supply is used first. When the platform swing frequency is greater than 0.2Hz, the wave generator is started, and when the battery switch has a remaining power of less than 20%, the non-core module is turned off.

[0021] The corona current detection module 41 measures the corona discharge current of the corona probe 2 and calculates the sea surface electric field strength through the corona current detection module 41. E . Corona discharge occurs near the tip electrode. When the electric field strength is high enough, the gas molecules are ionized, generating a large number of positive ions and secondary electrons, forming a self-sustaining discharge. The corona discharge current is nonlinearly positively correlated with the electric field strength. By measuring the corona discharge current, the magnitude of the electric field strength can be inferred. The data processing unit 5 performs signal filtering, compression and outlier marking algorithms on the detection data of the detection unit 4 to calculate the electric field strength on the sea surface. E . Calculate the electric field strength from the corona current E , calculated using the following formula: , in, α The correction coefficient is 0.5~0.8, n is the number of free electrons per unit volume (unit: m −3 ), at standard atmospheric pressure, the number of free electrons in air is n About 10 9 m −3 ,q is the elementary charge (1.602×10 −19 Coulomb), μ is the electron mobility (the electron mobility in air is approximately 1.3×10 −4 m 2 / V⋅s), A is the effective area of the probe (unit: m 2 ).

[0022] The swaying of the floating platform 1 will accelerate the air flow, and the wind speed v affects the electric field through two mechanisms, changing the electron mobility μ which is positively correlated with the wind speed, accelerating the diffusion of salt aerosol, and affecting the free electron density n . Therefore, it is necessary to correct the electric field strength E . The influence of the air salt fog concentration, wind speed, and the attitude of the floating platform 1 on the electric field strength is corrected using the following formula: , where: is the change in height Δ h ( t ) between the corona probe 2 and the sea surface caused by the up and down fluctuations of the floating platform 1, h 0 is the characteristic scale of corona discharge, h 0 is the characteristic decay scale describing the change of the electric field strength with height, and its physical essence is related to the vertical distribution characteristics of the atmospheric electric field. h 0 determines the influence degree of the platform height fluctuation Δ h ( t ) on the electric field measurement. The larger h 0 , the slower the attenuation of the electric field with height (the environmental electric field distribution is more uniform); h 0 The smaller, the more significant the attenuation of the electric field with height (the electric field is concentrated in the near-sea area). The h 0 in the marine environment is usually 10 - 50 meters, and is closely related to the following factors: atmospheric conductivity (salt fog and humidity increase conductivity, which may increase h 0 ); space charge distribution (the thickness of the charge layer under thunderstorm clouds affects the vertical gradient of the electric field); turbulent mixing (turbulent diffusion in the marine boundary layer leads to the homogenization of the electric field distribution). is the correction for the swaying angle, θ ( t ) is the tilt angle of the platform; is the correction for the wind speed, v ( t ​) is the wind speed, β is the empirical coefficient, taking 0.1, v 0 is the reference wind speed, taking 1 m / s; is the salt spray correction, c ( t ) is the salt spray concentration, and the coefficient γ takes 0.2, and the reference concentration c 0 = 1 mg / m 3 .

[0023] In the above correction, the acceleration detection module 46 obtains the height change Δ of the corona probe 2 h ( t ) The core principle of the sensor of the acceleration detection module 46 to measure the up and down undulating height is to deduce the displacement change through the integral operation of acceleration and eliminate the error by combining the dynamic compensation algorithm. According to Newton's second law F = ma , Newton's second law and acceleration integral, the acceleration detection module 46 obtains the instantaneous acceleration by measuring the inertial force received by the mass a , and the displacement change Δ can be obtained through two integral operations h , which is calculated by the following formula: represents the displacement Δ h is the acceleration a with respect to time t of the second integral result. The three-axis attitude detection module 47 obtains the platform tilt angle θ ( t ). The wind speed detection module 45 obtains the wind speed v ( t ). The salt spray detection module 42 obtains the salt spray concentration c ( t ). h 0 , β , γ are determined by fitting laboratory simulation or on-sea measured data. Substitute the correction factor into the formula to dynamically calculate the corrected electric field strength E co , and use Kalman filtering to suppress high-frequency noise.

[0024] The data processing unit 5 adopts the STM32H7 processor, integrating the filtering, algorithm, compression and abnormal value marking of electric field strength, salt spray concentration, seawater conductivity, temperature, wind speed, acceleration, and triaxial attitude. All components of the data processing unit 5 are integrated on a PCB board and placed in a sealed cabin using a melt-sealed package. The data processing unit 5 obtains the original data from the detection unit 4, removes noise using the sliding average and Kalman filter algorithms to improve data accuracy, and uses the bit splicing method to compress data, reduce the amount of data, reduce the workload of the communication module, and improve transmission efficiency. The data processing unit 5 is equipped with an adaptive filtering module, which adopts a band-stop filter based on the wave spectrum, and the center frequency is locked at 0.1~0.3Hz to eliminate the low-frequency interference signal caused by the wave movement, and effectively suppress the electric field measurement error caused by the platform shaking. The data processing unit 5 identifies and marks abnormal data through the sliding window median or the isolation forest algorithm to ensure the accuracy and reliability of the data. The Beidou satellite communication module 6 obtains the coordinate position, marks the timestamp, and transmits it to the data processing unit 5. The data processing unit 5 packages the processed data with the coordinate position and time information into a complete data packet, compresses it into a binary packet, and sends it through the Beidou satellite communication module 6 short message.

[0025] The data processing unit 5 has built-in coordinated power supply and low-power sleep mode, which can automatically start all detection modes according to the set start threshold, and automatically enter the sleep mode when it is lower than the start threshold, only perform corona current detection, and shut down other non-core modules. The start threshold is based on 1.5 to 2 times the average current detected by the corona current detection module 41 in sunny weather. The data processing unit 5 has a built-in self-diagnosis protocol. If the battery is abnormal or the sensor fails, the fault code is actively reported through a short message.

[0026] It is encrypted with AES-256 and transmitted through the Beidou RDSS channel. The capacity of a single message is 1200 bytes. A short message is sent every 5 minutes. The electric field strength data, air salt spray concentration and platform coordinates are transmitted through short messages. The monitoring center generates a thermal map based on the returned electric field strength and air salt spray concentration and the Beidou coordinate superposition data.

[0027] Example 1: The floating platform 1 has a diameter of 2 meters, the upper bracket 11 is 1 meter higher than the top surface of the platform, the corona probe 2 is a cylinder with a lower diameter of 5 mm, and a cone with a 2 mm bottom, a 0.1 mm top, and a height of 50 mm. After assembly, the probe has a surface area of ​​0.0033066 m 2 , the floating platform 1 weighs 50 kg (excluding the weight of the counterweight 3), and the center of gravity height H 平台 =0.25m, 4 counterweights 3 are arranged symmetrically, horizontal distance from platform center r =2m (extended outwards through the balance hammer support rod 31), single hammer weight m锤 =8kg, bottom distance of suspended floating platform 1 h =−2m. Total center of gravity height H 总 calculate: , the total center of gravity is located 0.628 meters below the bottom of the platform, which enhances the anti-overturning ability of the floating platform 1 and improves stability; Restoring torque calculation: , calculate the wind speed that can be resisted as v ≈20.73m / s wind, wind speed and wind level comparison table, 20.73 m / s wind speed corresponds to approximately level 8 wind; Buoyancy calculation: The bottom of floating platform 1 is hemispherical. Based on its deadweight of 50 kg and 4 counterweights weighing 32 kg, the platform displacement is 1.57m 3 , buoyancy (density of water ρ =1000kg / m 3 ): F 浮 =1000×1.57×9.8≈15386N, total weight (platform + counterweight): W 总 =(50+32)×9.8=803.6N, <15386N, sufficient buoyancy, safe design.

[0028] Example 2: Corona probe 2 is the same as Example 1, with a surface area of ​​0.0033066 m 2 , is the correction factor α Take 0.65, n For 10 9 m −3 , q 1.602×10 −19 coulomb, μ 1.3×10 −4 m 2 / V⋅s. The corona current detected by the corona current detection module 41 is I= 2.937×10 −8 A, that is, I = 29.37nA, is calculated according to the following formula: , , ; Considering the ups and downs and tilt of the floating platform caused by waves, the influence of the salt spray concentration and temperature of the air on the electric field strength, the electric field strength of the detection E To make corrections: , The platform rises and falls, causing the height of the probe to change with the sea surface Δh ( t ) After the acceleration calculation, it is 2m, and the characteristic scale h 0 According to experience, it is taken as 25m, and the height fluctuation correction . The tilt angle detected by the platform's three-axis attitude detection is 30°, and the swing angle correction , and the wind speed detection module 45 measures the wind speed as v = 15m / s, and the empirical coefficient β ≈ 0.1, and the reference wind speed v 0 = 1m / s, and the wind speed correction . The salt spray detection module 42 detects the salt spray concentration c = 1.4mg / m 3 , and the coefficient γ is taken as 0.2, and the salt spray correction . The calculated result of the correction factor is 1.5995. Substituting E = 25.62 kV / m, the corrected electric field strength E co = 40.98 kV / m.

[0029] The above embodiments are only examples for illustrating the present invention. The relationship between the corona current and the electric field strength needs to be determined through experiments, collecting data for regression to determine their correlation. The characteristic scale h 0 , the empirical coefficient β , and the salt spray coefficient γ are determined by fitting through laboratory simulation or on-site measurement data at sea.

[0030] The present invention is a one-way communication detection device, that is, the electric field strength result detected by the offshore electric field detection device is transmitted back through the Beidou short message. The monitoring center receives and demodulates the transmitted data through the Beidou navigation system, and the monitoring center cannot send instructions to the offshore electric field detection device. Using the present invention, the detection device can be placed in a preset sea area by a ship, and multiple devices can form a detection network. The data is transmitted back through the short message of the Beidou navigation system, and data can be transmitted back as long as the area covered by the Beidou navigation system is applicable to the detection of the electric field strength in the open sea.

[0031] The description and drawings of this application are only a specific embodiment, not restrictive. Those skilled in the art, under the inspiration of this application, without departing from the purpose of this application and the scope protected by the claims, can also make many forms, all within the protection scope of this application.

Claims

1. An offshore electric field detection device based on corona current measurement, characterized in that: include: A floating platform (1), a corona probe (2), a counterweight (3), a detection unit (4), a data processing unit (5), a Beidou satellite communication module (6), and a power supply unit (7); the floating platform (1) is made of corrosion-resistant composite materials, has a sealed cabin inside, and has a corona probe (2) mounting seat on the top; the corona probe (2) is vertically mounted on the top of the floating platform (1) at a height of ≥1 meter; the counterweight (3) is suspended below the floating platform (1) and symmetrically arranged to ensure that the floating platform (1) is balanced; the detection unit (4) comprises a corona current detection module (41), a salt spray detection module (42), a seawater conductivity detection module (43), a temperature detection module (44), a wind speed detection module (45), an acceleration detection module (46), and a three-axis attitude detection module (47); The data processing unit (5) is integrated in the sealed cabin, and measures the corona discharge current of the corona probe (2) and obtains the sea surface electric field strength through the corona current detection module (41). The salt spray detection module (42) is used to correct the influence of the air salt spray concentration above the sea surface on the electric field strength. The wind speed detection module (45) is used to correct the influence of the wind speed on the electric field strength. The acceleration detection module (46) is used to detect the up and down height of the floating platform (1). The three-axis attitude detection module (47) is used to detect the inclination angle of the floating platform (1) and correct the influence of the attitude of the floating platform (1) on the electric field strength by the up and down height and the inclination angle of the swing. The seawater conductivity detection module (43) and the temperature detection module (44) are used to judge the relationship with the air salt spray concentration. The data processing unit (5) performs signal filtering, compression and abnormal value marking algorithms on the detection data of the detection unit (4) to calculate the electric field strength on the sea surface. E The Beidou satellite communication module (6) obtains the coordinate position, marks the timestamp, and transmits the electric field strength data, air salt spray concentration and platform coordinates through short messages. The monitoring center generates a thermal map based on the returned electric field strength and air salt spray concentration and the Beidou coordinate superposition data.

2. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The electric field strength E , calculated using the following formula: ， in, α is the correction coefficient (take 0.5~0.8), n is the number of free electrons per unit volume (unit: m −3 ), q is the charge of a single electron (1.602×10 −19 coulomb), μ is the electron mobility (the mobility of electrons in air is about 1.3×10 −4 m 2 / V⋅s), A is the effective area of ​​the probe (unit: m²); Effects of air salt spray concentration, wind speed, and floating platform (1) posture on the electric field strength, and the corrected electric field strength E co The following formula is used for calculation: ， in: The height difference between the corona probe (2) and the sea surface caused by the ups and downs of the floating platform (1) is Δ h ( t ), h 0 is the characteristic scale of corona discharge; To correct the swing angle, θ ( t ) is the platform inclination angle; is the wind speed correction, v ( t ) is the wind speed, β The empirical coefficient is 0.

1. v 0 is the reference wind speed, which is 1m / s; Corrected for salt spray, c ( t ) is the salt spray concentration, coefficient γ Take 0.2, the base concentration c 0 = 1 mg / m 3 ; The acceleration detection module (46) obtains the acceleration a , calculate Δ by the following formula h ( t ), , the three-axis attitude detection module (47) obtains the platform tilt angle θ ( t ), the wind speed detection module (45) obtains the wind speed v ( t ), the salt spray detection module (42) obtains the salt spray concentration c ( t ); h 0. β , γ Determined by laboratory simulation or fitting of offshore measured data, the correction factor is substituted into the formula to dynamically calculate the corrected electric field strength. E co , and Kalman filtering suppresses high frequency noise.

3. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The top surface of the floating platform (1) is provided with a bracket (11), the bracket (11) is made of carbon fiber material, and the outer layer is coated with a DSAN coating with a hydrophobic angle greater than 150°; the bottom of the floating platform (1) is provided with an anchor ring (12), which is connected to the anchor (14) by a cable (13) made of Kevlar.

4. The marine electric field detection device based on corona current measurement according to claim 1 or 2, characterized in that: The tip of the corona probe (2) is a tungsten alloy needle structure with a diameter of ≤0.1 mm, which is installed at the top of the bracket (11). The tip of the corona probe (2) adopts a multi-level gradient structure, and the diameter gradually decreases from 2 mm to 0.1 mm from the root to the tip. The tungsten alloy tip is processed by electron beam polishing, and the surface roughness Ra is ≤0.05 μ m, the surface of which is coated with a salt spray resistant tungsten alloy film layer, and the corona probe (2) is connected to the corona current detection module (41) and is connected to the data processing unit (5) using a cable with a Teflon insulation tape shielding layer.

5. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The salt fog detection module (42) uses a laser scattering method to determine the salt fog concentration. By measuring the scattering signal of the laser by the salt particles in the flowing air, the content and particle size distribution of the salt particles are obtained, and the level of the salt fog content in the air is obtained in real time. The salt fog detection module (42) has a salt fog particle concentration measurement range of 0~10mg / m³ and a particle size distribution measurement range of 0.5~10 μ m.

6. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The data processing unit (5) has a built-in coordinated power supply and low-power sleep mode, and can automatically start all detection modes according to a set start threshold, and automatically enter the sleep mode when the start threshold is lower than the start threshold, and only perform corona current detection; the data processing unit (5) obtains raw data from the detection unit (4), removes noise using a sliding average and Kalman filter algorithm to improve data accuracy, and uses a bit splicing method to compress data to reduce the amount of data, reduce the workload of the communication module, and improve transmission efficiency; the data processing unit (5) is provided with an adaptive filtering module, which uses a band-stop filter based on the wave spectrum, and the center frequency is locked at 0.1-0.3 Hz to eliminate low-frequency interference signals caused by wave movement and effectively suppress electric field measurement errors caused by platform shaking; the data processing unit (5) identifies and marks abnormal data through a sliding window median or an isolation forest algorithm to ensure data accuracy and reliability, and packages the processed data into a complete data packet, compresses it into a binary packet, and sends it as a short message through the Beidou satellite communication module (6).

7. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The power supply unit (7) comprises a photovoltaic panel (71), a wave generator (72), and a storage battery (73); the photovoltaic panel (71) is a single crystal silicon cell; the wave generator (72) is a pendulum-type small generator; the photovoltaic panel (71) and the wave swing generator (72) are connected to the storage battery (73) inside the platform via a BMS battery management system; the storage battery (73) is a lithium battery pack.

8. The marine electric field detection device based on corona current measurement according to claim 1, characterized in that: The Beidou satellite communication module (6) has a built-in encryption chip, which is encrypted using AES-256 and then transmitted through the Beidou RDSS channel. The capacity of a single message is 1200 bytes, and a short message is sent once every 5 minutes.

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