Lightning channel video array observation method and system based on electric field trigger identification

Abstract

The invention discloses a lightning channel video array observation method and system based on electric field trigger identification, and relates to the technical field of lightning channel video array observation, and the method comprises the following steps: S1, carrying out the uninterrupted observation of cloud-to-ground lightning activities in a visual space range through a video camera array, and after an electric field trigger signal is received, carrying out the video camera array observation; recording and storing video original data in a set time interval before and after the triggering moment; according to the lightning channel video array observation method and system based on electric field trigger identification, an omnibearing video shooting observation sensor array is composed of a plurality of shooting probes, the number of the probes and a field angle meet a specific relation so as to realize 360-degree omnibearing coverage, and corresponding optical detection distances are configured according to different geographical environments, so that the observation accuracy of the lightning channel is improved. Therefore, no-dead-angle and high-reliability optical observation of lightning activities in a visible space range is realized, and the integrity and the globality of observation data are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lightning channel video array observation, in particular to a lightning channel video array observation method and system based on electric field trigger identification. BACKGROUND

[0002] The physical effects such as large current, strong electromagnetic radiation, high temperature and shock wave accompanying the lightning discharge process pose a great safety threat to human activities. Monitoring the indirect signals such as sound, light and electromagnetic signals accompanying the lightning process and using them for lightning positioning and lightning discharge energy inversion are of great significance for the regional lightning activity statistical analysis and lightning fault tracing of power transmission line systems, wind power and photovoltaic systems.

[0003] The optical signals generated by lightning activity can best reflect the development and distribution characteristics of the discharge channel. Online observation of local areas by high-speed cameras, high-speed cameras, ordinary cameras and other optical shooting means is also an important means to determine the lightning attachment point, analyze the lightning occurrence mechanism and lightning probability. The existing lightning optical observation technology still has the following defects in the optical observation of lightning activities on target objects such as wind turbines, power transmission lines and lightning towers: due to the randomness and dispersion of lightning activities, the observation of high-speed cameras in small target observation areas cannot be separated from personnel on duty. Due to the limitation of shooting hardware resources, the observation field of view is narrow, so the observation efficiency is extremely low, and the human, equipment resources and cost are huge; the lightning observation technology based on low-cost medium-speed cameras, still cameras or ordinary cameras has realized unattended to a certain extent, but the existing technical solutions still have the problems of limited observation field of view, huge storage resource occupation of observation raw data, low effective signal feature recognition and extraction efficiency, etc., so it needs to be improved. SUMMARY

[0004] The purpose of the present application is to provide a lightning channel video array observation method and system based on electric field trigger identification to solve the problems of limited observation field of view, low observation efficiency, high human and equipment cost, low effective signal recognition and extraction efficiency and huge data storage resource occupation in the prior art.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a lightning channel video array observation method based on electric field trigger identification, comprising the following steps:

[0006] S1, continuously observing the cloud-to-ground lightning activities in the visible space range by a video camera array, and recording and storing the video raw data in a set time interval before and after the trigger time after receiving the electric field trigger signal;

[0007] S2, sensing the electric field radiation pulse signal in a wide range through the electric field sensor, and outputting a trigger level signal to the video camera array when the electric field pulse amplitude exceeds a preset trigger threshold;

[0008] S3, based on the key feature recognition algorithm of the fast electric field pulse of lightning channel discharge, screening the locally stored electric field pulse original signal, and identifying the fast electric field pulse of cloud-to-ground lightning event and its occurrence time;

[0009] S4, according to the occurrence time of the identified fast electric field pulse, matching and intercepting the corresponding video segment from the locally stored video data, and deleting the video data outside the video segment;

[0010] S5, transmitting the identified fast electric field signal and the intercepted video segment to the background server, and based on the lightning channel frame recognition algorithm, processing the video segment in frames, and extracting single frame photos containing lightning channel optical images.

[0011] Further, in step S1, the video camera array is composed of n probes, and the field of view angle of a single probe is θ, and θ·n≥360° is satisfied.

[0012] Further, the optical detection distance of the video camera array is set according to the geographical environment of the observation point, and is not less than 50km in high-altitude grassland area, and is not less than 15km in mountainous area and high building density city.

[0013] Further, in step S1, the set time interval is 5 seconds before the trigger time to 1 minute after the trigger.

[0014] Further, in step S2, the detection range of the electric field sensor is not less than 2 times the maximum optical observation distance of the video camera array.

[0015] Further, the lightning channel frame recognition algorithm includes the following sub-steps:

[0016] Frame processing is performed on the video segment to obtain continuous single frame images;

[0017] Each frame image is subjected to noise reduction processing, and the gray value of each pixel point is extracted to form a gray array;

[0018] The gray arrays corresponding to the continuous frames are subjected to difference calculation, and when the difference value exceeds a set threshold, the frame image is determined as valid lightning channel optical image and is stored.

[0019] The lightning channel video array observation system based on electric field trigger recognition comprises:

[0020] The omnidirectional video camera observation sensor array is used for video acquisition of lightning activities in the visible space range.

[0021] an electric field sensing module for sensing the electric field radiation pulse signal and outputting a trigger level signal when the electric field pulse amplitude exceeds a trigger threshold value;

[0022] a local industrial computer connected with the sensor array and the electric field sensing module, the industrial computer comprising:

[0023] a video camera acquisition and monitoring module for controlling video acquisition parameters;

[0024] an electric field signal high-speed acquisition module for acquiring and processing electric field signals;

[0025] a lightning image recognition module for performing fast electric field signal recognition and video slice extraction according to the trigger level signal;

[0026] a local storage module for storing raw data and processing results;

[0027] a remote transmission module and a background server control center for receiving and processing fast electric field signals and video segments sent by the remote transmission module.

[0028] Further, the remote transmission module comprises a remote transmission software and a wireless network module, and the background server control center comprises a server and a monitoring software for frame extraction, viewing and analysis of the received data.

[0029] Further, the video camera array comprises at least 6 optical probes installed on a single bracket, and the field of view angle of a single probe is not less than 60°.

[0030] Further, the sampling rate of the electric field signal high-speed acquisition module is not less than 100 MS / s.

[0031] Compared with the prior art, the lightning channel video array observation method and system based on electric field trigger recognition provided by the present application realize 360° omnidirectional coverage by using a full-range video camera observation sensor array composed of multiple camera probes, and the number of probes and the field of view angle satisfy a specific relationship, and the corresponding optical detection distance is configured according to different geographical environments, so that optical observation with no dead angle and high reliability in the visual space range of lightning activity is realized, and the integrity and generality of observation data are ensured.

[0032] By setting the electric field sensing module with a detection range not less than 2 times the maximum observation distance of the optical video array, and outputting a trigger level signal to the video camera array when a field radiation pulse exceeding the threshold value is sensed, effective cooperation and precise synchronization of fast electric field sensing measurement and optical video camera observation in a wide range are realized, the interference of irrelevant lightning signals at a long distance is excluded, and the redundancy of data recording is reduced.

[0033] By setting video acquisition monitoring, electric field signal high-speed acquisition, lightning image recognition and local storage function modules in the local industrial computer, and based on fast electric field pulse feature recognition algorithm and video slice extraction strategy, the identification of target signals, the cutting of video clips and the deletion of irrelevant original data are completed locally, thereby realizing the localization and intelligent processing of observation data at the acquisition end, and significantly releasing the local storage resources.

[0034] By setting a remote transmission module composed of remote transmission software, a wireless network module and a background server control center, and wirelessly transmitting the target fast electric field signal and the video slice signal after local identification processing, instead of all original data, to the background, the bandwidth pressure of the wireless transmission channel is greatly reduced, and the data transmission efficiency is improved.

[0035] By setting a lightning channel frame recognition algorithm in the background server control center, the uploaded video slices are automatically framed, denoised, gray value extracted and difference calculated to extract effective lightning channel optical image single frame photos, thereby providing a high-efficiency and convenient data analysis tool for background researchers, and reducing the operation difficulty and labor cost of manual screening of massive original video data.

[0036] By integrating the video camera array, the electric field sensing module, the local industrial computer and the remote transmission module into a complete observation system, and optimizing their collaborative work process, the omnidirectional, automated and unattended observation of lightning activity discharge optical channel and fast electric field pulse signal, and the efficient extraction of key feature information are realized, and the efficiency and automation level of lightning observation are improved as a whole. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0038] Figure 1 The lightning video array monitoring system structure schematic diagram provided for the embodiments of the present application;

[0039] Figure 2 The video camera array arrangement plan view provided for the embodiments of the present application;

[0040] Figure 3 The lightning video array monitoring method flow chart based on electric field trigger recognition provided for the embodiments of the present application. DETAILED DESCRIPTION

[0041] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings.

[0042] As shown in the accompanying Figure 1 to the accompanying Figure 3 :

[0043] Example I:

[0044] The present application provides a lightning channel video array observation system based on electric field trigger recognition, comprising:

[0045] All-directional video camera observation sensor array: 6 camera probes are installed on a single support at the site, the field angle of a single camera probe is greater than 60°, and the total field angle satisfies 360° all-directional coverage. The optical detection distance is set according to the geographical environment of the observation point: when located in a high-altitude vast prairie area, the farthest detection distance is 50km; when located in a mountainous area or a high building density city, the farthest detection distance is 15km. The array is used for continuously shooting the natural cloud-to-ground lightning activity in the visible space range.

[0046] Electric field sensing module: an electromagnetic sensor is used for sensing the electric field radiation pulse signals generated by lightning activity in a wide range. The detection range is not less than 2 times the maximum observation distance of the optical video array, so as to ensure effective sensing and smooth response to the fast electric field waveform generated by lightning activity in the optical visible range.

[0047] Local industrial computer: carrying a video camera acquisition and monitoring module, an electric field signal high-speed acquisition module and a local storage module.

[0048] The video camera acquisition and monitoring module is realized through a video monitoring software, and is used for adjusting the video resolution, video quality, acquisition frame number and shooting time length parameters before and after triggering acquisition.

[0049] The electric field signal high-speed acquisition module comprises a high-speed acquisition card with a maximum acquisition speed of 100MS / s and an electric field monitoring software, and is used for realizing electric field pulse trigger threshold adjustment, sampling rate setting and recording and storing electric field pulse waveforms.

[0050] The local storage module is used for storing original video signals, electric field signals and processing results. The industrial computer also runs a lightning image recognition software, which is used for executing image recognition and extraction after receiving a triggering command.

[0051] Remote transmission module and background server control center: the remote transmission module is composed of a remote transmission software with breakpoint resume function and a 4G wireless network module. The background server control center comprises a remote server and a server monitoring software, which is used for receiving remotely transmitted data, and providing data storage, query, parameter setting and data analysis functions.

[0052] The steps of the method include:

[0053] S1: continuously observing the visual space range through the video camera array, and temporarily storing the video data in the local storage module; at the same time, sensing the environmental electric field intensity through the electric field sensing module.

[0054] S2: when the electric field monitoring software monitors that the electric field intensity E(t) exceeds the preset triggering threshold E t , it is determined that there is lightning activity, the moment is recorded as the triggering moment T s , and an image recognition triggering command is output.

[0055] S3: the electric field monitoring software starts recording and storing the electric field waveform file; the lightning image recognition software receives the triggering moment T s .

[0056] S4: the lightning image recognition software takes the array observation video data in the time interval [T s -T cut , T s +T cut ] (T cut is set to 10 seconds) centered on T s , forms n video clips; then the video clips are processed frame by frame to obtain a single-frame image group; the noise of each frame image is processed, and the gray value of each pixel point in the photo is extracted to form a gray value array corresponding to the single-frame photo pixel A×B; the gray value arrays of consecutive single-frame photos are differentially calculated, and when the difference reaches a set threshold, it is determined that the frame is an effective lightning channel photo and is stored; finally, the original data of the intercepted video clips is deleted.

[0057] S5: the remote transmission module wirelessly transmits the stored electric field waveform file and the recognized lightning channel photo to the background server control center for viewing and analysis by the background control center.

[0058] Embodiment Two:

[0059] This embodiment is basically the same as the previous embodiment, except that the lightning channel frame recognition algorithm is further limited.

[0060] Based on the lightning channel frame recognition algorithm running in the lightning image recognition software in the local industrial computer or in the background server control center, the running principle includes the following successive steps:

[0061] Frame processing is performed on the truncated and extracted array observation video data.

[0062] Noise reduction processing is performed on each frame image, and the gray value of each pixel point in the photo is extracted to form an A-row-by-B-column gray value array G AXB; wherein each element G(x i ,y i ) of the gray value array is represented by a value between 0 and 255, and the greater the value, the higher the brightness of the pixel.

[0063] The gray value arrays corresponding to at least two consecutive single-frame photos of the same probe are subjected to difference calculation; when the difference between the gray value arrays of the two consecutive frames reaches an initial set threshold value, it is determined that the latter frame photo corresponding to the array is an effective photo of a lightning channel; by adjusting the difference threshold value, the sensitivity of the single-frame criterion can be improved.

[0064] Example Three

[0065] This example is basically the same as the previous example, except that the key parameter configuration of the video array and the electric field sensor is further limited.

[0066] The video camera array observation has a number of probes n and a probe field of view angle θ satisfying the formula: θ·n≥360°, to ensure full coverage in the azimuth. In one specific implementation of the present embodiment, six probes with a field of view angle of 70° are used, and the total field of view coverage is 420°, achieving full-azimuth redundant coverage.

[0067] When receiving the electric field trigger signal, the video camera array records and separately stores the array video data 5 seconds before and 1 minute after the trigger signal. The video data in this specific time interval is the object to be intercepted and processed subsequently.

[0068] The technical parameters of the electric field sensing module ensure that its detection range is not less than twice the maximum observation distance of the optical video array. For example, when the optical array has a maximum observation distance of 50 km in a grassland area, the electric field sensor should have a detection range of not less than 100 km; when the optical array has a maximum observation distance of 15 km in a city area, the electric field sensor should have a detection range of not less than 30 km. In this way, lightning activities within the optical visual range can be effectively triggered and recorded.

[0069] Comparative Example

[0070] Description of Prior Art Solution

[0071] System Composition

[0072] Electric field detection: a low-frequency lightning electric field detection array (LFEDA) composed of nine fast electric field change measuring instruments is used to detect all-flash activities based on low-frequency (LF) and very low-frequency (VLF) bands.

[0073] Optical observation: a single high-speed camera is used for optical observation, which has a fixed field of view angle and a limited observation range.

[0074] Workflow

[0075] The electric field detection array and the high-speed camera are arranged separately in space, and are correlated by post-data comparison.

[0076] The electric field array continuously records the low-frequency electric field signals generated by the lightning discharge process, has full lightning three-dimensional positioning capability, and the average value of the backstroke plane positioning error is 102 meters.

[0077] The high-speed camera continuously shoots or triggers recording on a specific area based on a preset program or manual judgment.

[0078] Data processing:

[0079] The electric field data and the optical video data are independently stored and transmitted, and are matched and fused by time stamp in the later stage.

[0080] The optical video data is usually a complete recording video, and the transmission and storage pressure is large, and manual browsing or general video processing algorithm is needed to extract effective frames, so the efficiency is low.

[0081] Comparison analysis table:

[0082]

[0083] Through the comparative example, it can be concluded that the depth fusion of the electric field trigger and the video array, the localized intelligent recognition and data screening solve the inherent defects of the prior art in the observation range, data synchronization, processing efficiency and resource consumption.

[0084] The above only describes certain exemplary embodiments of the present application by way of illustration, and it is not doubtful that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present application. Therefore, the above figures and description are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the present application.

Claims

1. A method for observing lightning channels using video arrays based on electric field triggering identification, characterized in that, Includes the following steps: S1. Continuously observe cloud-to-ground lightning activity within the visible space using a video camera array, and record and store the raw video data within a set time interval before and after the triggering time upon receiving an electric field triggering signal. S2. The electric field radiation pulse signal is sensed over a wide area by an electric field sensor. When the amplitude of the electric field pulse exceeds a preset trigger threshold, a trigger level signal is output to the video camera array. S3. A key feature recognition algorithm based on fast electric field pulses of lightning channel discharge is used to filter the original electric field pulse signals stored locally and identify the fast electric field pulses of cloud-to-ground lightning events and their occurrence times. S4. Based on the identified occurrence time of the fast electric field pulse, match and extract the corresponding video segment from the locally stored video data, and delete the video data other than the video segment; S5. Transmit the identified fast electric field signal and the captured video segment to the backend server, perform frame segmentation processing on the video segment based on the lightning channel frame recognition algorithm, and extract single-frame photos containing lightning channel optical images.

2. The lightning channel video array observation method based on electric field triggering identification according to claim 1, characterized in that, In step S1, the video camera array consists of n probes, and the field of view of a single probe is θ, which satisfies θ·n≥360°.

3. The lightning channel video array observation method based on electric field triggering identification according to claim 2, characterized in that, The optical detection range of the video camera array is set according to the geographical environment of the observation point, not less than 50km in high-altitude grassland areas and not less than 15km in mountainous areas and cities with high building density.

4. The lightning channel video array observation method based on electric field triggering identification according to claim 1, characterized in that, In step S1, the set time interval is from 5 seconds before the trigger time to 1 minute after the trigger time.

5. The lightning channel video array observation method based on electric field triggering identification according to claim 1, characterized in that, In step S2, the detection range of the electric field sensor is not less than twice the maximum optical observation distance of the video camera array.

6. The lightning channel video array observation method based on electric field triggering identification according to claim 1, characterized in that, The lightning channel frame-segmentation identification algorithm includes the following sub-steps: The video clip is divided into frames to obtain continuous single-frame images; Denoising is performed on each frame of the image, and the grayscale values ​​of each pixel are extracted to form a grayscale array; Differential calculations are performed on the grayscale arrays corresponding to consecutive frames. When the difference exceeds a set threshold, the frame image is determined to be a valid lightning channel optical image and stored.

7. A lightning channel video array observation system based on electric field triggering identification, applicable to the lightning channel video array observation method based on electric field triggering identification as described in any one of claims 1 to 6, characterized in that, include: An all-around video camera observation sensor array is used to collect video of lightning activity within the visible space. The electric field sensing module is used to sense electric field radiation pulse signals and output a trigger level signal when the amplitude of the electric field pulse exceeds the trigger threshold. A local industrial control computer, connected to a sensor array and an electric field sensing module, includes: The video capture and monitoring module is used to control video capture parameters; High-speed electric field signal acquisition module, used to acquire and process electric field signals; The lightning strike image recognition module is used to perform fast electric field signal recognition and video slice extraction based on the trigger level signal; The local storage module is used to store raw data and processing results; The remote transmission module and back-end server control center are used to receive and process fast electric field signals and video clips sent by the remote transmission module.

8. The lightning channel video array observation system based on electric field triggering identification according to claim 7, characterized in that, The remote transmission module includes remote transmission software and a wireless network module, and the back-end server control center includes a server and monitoring software, which are used to extract, view and analyze the received data in frames.

9. The lightning channel video array observation system based on electric field triggering identification according to claim 7, characterized in that, The video camera array includes at least 6 optical probes mounted on a single bracket, with each probe having a field of view of not less than 60°.

10. The lightning channel video array observation system based on electric field triggering identification according to claim 7, characterized in that, The sampling rate of the high-speed electric field signal acquisition module is no less than 100MS / s.

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