Lightning monitoring system for overhead transmission line

Abstract

The utility model discloses a lightning monitoring system for an overhead transmission line, and relates to the field of lightning monitoring, and the system comprises a current transformer, an ADC module, and a main control module. The current transformer is used for collecting lightning current signals of the overhead transmission line and converting the collected lightning current signals into voltage signals; the ADC module is connected with the current transformer and is used for carrying out analog-to-digital conversion on the voltage signal; and the main control module is connected with the ADC module and is used for carrying out lightning monitoring on the overhead transmission line according to the voltage signal after analog-to-digital conversion. According to the invention, the lightning stroke condition of the overhead transmission line can be rapidly monitored and identified, and safe and stable operation of the overhead transmission line is guaranteed.

Description

Technical Field

[0001] This application relates to the field of lightning monitoring, and in particular to a lightning monitoring system for overhead transmission lines. Background Technology

[0002] Overhead transmission lines are the main channels for transmitting electrical energy and an important component of the power grid. They are characterized by their wide distribution and long transmission distances, making them highly susceptible to lightning strikes due to the influence of terrain, geology, and meteorological conditions. Lightning strikes and backflashovers can cause insulator damage, wire breaks, and other faults, leading to line tripping and power outages. Furthermore, if lightning overvoltages travel along the line into substations, they can subject equipment to excessively high voltages, causing insulation damage and severely impacting system safety and stability. For 110kV and below systems, 40% to 60% of accidents are caused by lightning strikes on overhead transmission lines, and the probability of lightning-induced faults is even higher in mountainous areas, areas with frequent lightning strikes, and areas with high soil resistivity.

[0003] As the transmission voltage of power transmission systems gradually increases, the surge voltage in elevated towers becomes increasingly higher, leading to more frequent lightning strikes on elevated transmission lines. Consequently, the lightning protection problem for elevated transmission lines becomes more serious, and the contradiction between lightning hazards and safe operation of the lines increases with the increase in voltage levels. Utility Model Content

[0004] The purpose of this application is to provide a lightning monitoring system for overhead transmission lines, which can quickly monitor and identify lightning strikes on overhead transmission lines, thereby ensuring the safe and stable operation of overhead transmission lines.

[0005] To achieve the above objectives, this application provides a lightning monitoring system for overhead transmission lines, comprising: a current transformer for acquiring lightning current signals of overhead transmission lines and converting the acquired lightning current signals into voltage signals; an ADC module connected to the current transformer for performing analog-to-digital conversion on the voltage signals; and a main control module connected to the ADC module for performing lightning monitoring on the overhead transmission lines based on the analog-to-digital converted voltage signals.

[0006] Optionally, the current transformer is a Rogowski coil.

[0007] Optionally, the ADC module is a dual-channel ADC module.

[0008] Optionally, the main control module uses an FPGA chip.

[0009] Optionally, the overhead transmission line lightning monitoring system further includes an SDRAM module, which is connected to the ADC module and the main control module respectively, for storing the voltage signal after analog-to-digital conversion.

[0010] Optionally, the overhead transmission line lightning monitoring system further includes a 4G module connected to the main control module, used to send the lightning monitoring results of the overhead transmission line by the main control module to the cloud server.

[0011] Optionally, the overhead transmission line lightning monitoring system further includes a LoRa communication module connected to the main control module; the main station and sub-stations in the overhead transmission line lightning monitoring system communicate through the LoRa communication module.

[0012] Optionally, the overhead transmission line lightning monitoring system further includes a power supply module for supplying power to the ADC module, the main control module, the SDRAM module, the 4G module, and the LoRa communication module.

[0013] Optionally, the overhead transmission line lightning monitoring system further includes: buttons for initializing each module of the overhead transmission line lightning monitoring system; and LED indicator lights for displaying the initialization completion status of the overhead transmission line lightning monitoring system and the waiting transmission status during the data transmission process of the sub-sites.

[0014] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides an overhead transmission line lightning monitoring system, which collects the lightning current signal of the overhead transmission line through a current transformer and performs lightning monitoring on the overhead transmission line through a main control module, thereby enabling rapid monitoring and identification of the lightning strike situation of the overhead transmission line and ensuring the safe and stable operation of the overhead transmission line. Attached Figure Description

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

[0016] Figure 1 A schematic diagram of the functional modules of an overhead transmission line lightning monitoring system provided in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of a Rogowski coil with a rectangular cross-section.

[0018] Figure 3 This is the logic block diagram of the power supply module. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] In one exemplary embodiment, such as Figure 1 As shown, an overhead transmission line lightning monitoring system is provided, including: a current transformer 2, an ADC module 3, and a main control module 4.

[0022] (1) Current transformer 2 is used to collect the lightning current signal of overhead transmission line 1 and convert the collected lightning current signal into a voltage signal.

[0023] In this embodiment, the current transformer 2 uses a Rogowski coil. The theoretical basis for measuring current with a Rogowski coil is Faraday's law of electromagnetic induction and Ampere's circuital law. A Rogowski coil consists of a conductor uniformly wound around a frame of a non-magnetic material with a uniform cross-section. A current-carrying conductor passes perpendicularly through the center of the coil. By sensing the change in magnetic flux generated by the current-carrying conductor, a voltage signal proportional to the magnitude of the measured current can be induced.

[0024] Figure 2 The image shows a Rogowski coil with a rectangular cross-section. Figure 2 In this circuit, the current being measured passes through the center of the coil, denoted as . ; The inner radius of the skeleton; The outer radius of the skeleton; This refers to the thickness of the skeleton. To induce electromotive force; This refers to the number of coil turns. It represents the magnetic flux density; The vacuum permeability; The magnetic flux of the coil; t is the average radius of the coil; t is the measurement time. Let be the area. Assuming the current-carrying conductor is infinitely long, then according to the Biot-Savart theorem:

[0025] (1)

[0026] When the conductor being measured is far from the coil, the magnetic flux passing through the coil is approximately:

[0027] (2)

[0028] According to the law of electromagnetic induction, we can obtain:

[0029] (3)

[0030] Let the mutual inductance of the coils be Then we have:

[0031] (4)

[0032] Equation (3) can be simplified to:

[0033] (5)

[0034] As shown in equation (5), the induced electromotive force output by the Rogowski coil is proportional to the differential signal of the measured current, and the proportionality coefficient is the mutual inductance coefficient. Therefore, by adding an integrator to integrate the output signal of the Rogowski coil, the waveform of the measured current can be obtained. This is the measurement principle of the Rogowski coil.

[0035] (2) The ADC module 3 is connected to the current transformer 2 and is used to perform analog-to-digital conversion on the voltage signal.

[0036] In this embodiment, ADC module 3 uses a dual-channel AD module. Since four Rogowski coils are used for data acquisition, two dual-channel AD modules are employed. These two modules convert the analog data from the four Rogowski coils into digital values, then average the data from these four channels and store the result in SDRAM (Synchronous Dynamic Random Access Memory) module 5. Because lightning current data is bipolar (positive and negative), the trigger circuit design must ensure reliable triggering for both positive and negative polarities.

[0037] In this embodiment, the AD module uses the AD9248, a high-performance analog-to-digital converter (ADC) featuring dual cores, 3V, 14-bit operation, and a maximum speed of 65 MSPS. The AD9248 integrates two high-performance sample-and-hold amplifiers and a reference voltage source, employing a multi-stage differential pipeline architecture and built-in output error correction logic to ensure 14-bit accuracy at a maximum data rate of 65 MSPS, with no missing codes across the entire operating temperature range. The AD9248 supports wide-bandwidth differential sample-and-hold amplifiers, allowing users to select various input ranges and offsets, including single-ended applications. This device is suitable for a variety of applications, including communications, imaging, and medical ultrasound.

[0038] The formula for the correspondence between the collected digital quantities and the lightning current data is as follows:

[0039] (6)

[0040] Where I represents the measured current, This represents the measured 14-bit data. This indicates the conversion ratio of the Rogowski coil. In this embodiment, a conversion ratio of ±100kA to ±10V is selected. .

[0041] During transmission, data is transmitted in 16-bit binary format, while the data collected by the AD module is in 14-bit binary format. The format of the AD data received by the main station from each sub-station is 00XX_XXXX_XXXX_XXXXB, meaning the first two bits are padded with zeros, and the last 14 bits are the data bits. To distinguish data from different sub-stations, a 16-bit sub-station sequence number with the first two bits set to 1 is sent before each data segment for identification. For example, C001H represents data from sub-station 1, and C00AH represents data from sub-station 10. In this lightning monitoring system, each sub-station collects lightning current signals through current transformer 2. The main station collects data from multiple sub-stations and transmits it to the cloud server.

[0042] (3) The main control module 4 is connected to the ADC module 3 and is used to monitor the overhead transmission line 1 for lightning strikes based on the voltage signal after analog-to-digital conversion. The main control module 4 determines the lightning strike situation of the overhead transmission line 1 by comparing the voltage signal after analog-to-digital conversion with a set safety value.

[0043] In this embodiment, the main control module 4 uses an FPGA chip, specifically the EP4CE10F17C8 chip, which is based on Altera's Cyclone IV series FPGA chip. It has the following main features: abundant logic resources, capable of implementing various complex digital logic functions; built-in 504 Kbit memory for storing data and configuration information; support for multiple clock inputs and outputs to achieve complex timing control; and provides multiple communication interfaces such as UART, SPI, and I2C for convenient data interaction with external devices. It employs low-power design technology to reduce power consumption while meeting performance requirements.

[0044] In this embodiment, the program is programmed into the FPGA chip via a JTAG module. The JTAG module has four signal lines: TMS, TCK, TDI, and TDO, which are the mode selection, clock, data input, and data output lines, respectively. It supports online debugging, allowing users to view the internal status and signals while the FPGA chip is running. The power supply pin of the JTAG module is connected to a 2.5V power supply, and the GND pin is grounded.

[0045] The circuit board structures for the master station and sub-stations are identical. During use, the communication channel and the type of master station or sub-station can be selected using two 0-ohm resistors: `route` and `site`. These two signals control the FPGA program. For example, if `site` is 0, the FPGA program is a sub-station program; conversely, if `site` is 1, the program is a master station program. This simplifies hardware circuit design and enables "one board for multiple uses."

[0046] (4) The above-mentioned overhead transmission line lightning monitoring system also includes an SDRAM module 5, which is connected to the ADC module 3 and the main control module 4 respectively, and is used to store the voltage signal after analog-to-digital conversion.

[0047] In this embodiment, the memory uses SDRAM module 5, model W9825G6KH-6. This memory has 4 banks, each bank has 4M storage cells, and each storage cell is 16 bits. Therefore, the memory size is 4M × 4 × 16 = 32MB. The memory occupied by a single lightning current waveform is... .in, The amount of data for a single lightning current waveform collected. The sampling frequency of the AD module. For sampling duration, The number of bytes occupied by each data point. The sum of the main discharge time and subsequent discharge time is estimated to be 10ms. Therefore, the sampling time for a lightning current signal is... . Take 2 bytes. Taking 50MHz as an example, the memory occupied by one lightning current is... Therefore, this SDRAM module 5 can store a maximum of 32 lightning current data at a time.

[0048] (5) The above-mentioned overhead transmission line lightning monitoring system also includes a 4G module 6, which is connected to the main control module 4 and is used to send the lightning monitoring results of the overhead transmission line by the main control module 4 to the cloud server.

[0049] In this embodiment, the 4G module 6 uses the ATK-M750C module from ALIENTEK. The ATK-IDM750C / IDM751C is a high-performance 4GCat1 DTU product developed by the ALIENTEK team, supporting China Mobile 4G, China Unicom 4G, and China Telecom 4G SIM cards. Its core functions are high speed, low latency, and wireless data transmission, enabling rapid solutions for wireless data transmission in various application scenarios.

[0050] It supports TCP / UDP / HTTP / MQTT / DNS / RNDIS / NTP protocols, supports connection to various cloud servers (such as: Atomic Cloud, Alibaba Cloud, Baidu Cloud and OneNET), supports TCP / UDP / HTTP / MQTT data pass-through, supports USB wireless network cards, supports automatic timed data collection tasks, supports base station positioning, supports custom heartbeat packets and registration packets, supports configuration parameters for host computer / AT commands / SMS / pass-through commands, and supports both RS232 and RS485 serial interfaces. It can be widely used in wireless data transmission, power industry, industrial control, water conservancy industry, environmental protection industry, agricultural applications, data collection systems, and smart homes, among many other fields.

[0051] The pin connections for 4G module 6 are as follows: VCC pin connects to a 12V power supply, GND pin is grounded, RX pin connects to the USART2_TX pin of the FPGA chip, and TX pin connects to the USART2_RX pin of the FPGA chip. A SIM card must be inserted into the corresponding slot during use. If the signal is weak, an external antenna can be connected to improve it.

[0052] (6) The above-mentioned overhead transmission line lightning monitoring system also includes a LoRa communication module 7 connected to the main control module 4. The main station and sub-stations in this lightning monitoring system communicate through the LoRa communication module 7.

[0053] The LoRa communication module 7 uses the ATK-LORA-01 module from ALIENTEK. This model is a small, low-power, high-performance, long-range LoRa wireless serial port module launched by ALIENTEK. The module design uses the high-efficiency ISM band RF SX1278 spread spectrum chip. The module operates at a frequency of 410MHz~441MHz, with 32 channels in 1MHz increments. Various parameters such as serial port rate, transmit power, air speed, and operating mode can be modified online via AT commands, and firmware upgrades are also supported.

[0054] The LoRa communication module 7 has 6 pins, connected as follows: VCC pin is connected to a 3.3V power supply, GND pin is grounded, RX pin is connected to the USART_TX pin of the FPGA chip, TX pin is connected to the USART_RX pin of the FPGA chip, and MD0 and AUX pins are connected to two pins of the FPGA chip. The operating mode of the LoRa communication module 7 is controlled by the output levels of these two pins of the FPGA chip (i.e., the levels of the MD0 and AUX pins). The operating modes of the LoRa communication module 7 are shown in Table 1.

[0055] Table 1

[0056]

[0057] In configuration mode (MD0=1, AUX=0), the FPGA chip sends setting commands (setting serial port mode, baud rate, transmission rate, communication channel, transmission mode, transmit power, etc.) to the LoRa communication module 7 via UART3. In communication mode (MD0=0, AUX=0), data transmission between the sub-site and the master site can be achieved through the LoRa communication module 7.

[0058] In this embodiment, the default baud rate of the overhead transmission line lightning monitoring system is 115200.

[0059] In this embodiment, the LoRa communication module 7 adopts a transparent transmission mode. To prevent other LoRa communication modules from receiving unwanted data, the sub-site needs to send a request signal to the master site before transmitting data. After the master site responds, the sub-site begins to send data to the master site. If the sub-site and the master site do not establish a connection, any other received data is considered invalid. This ensures targeted transmission to the master site in transparent transmission mode.

[0060] The overhead transmission line lightning monitoring system provided in this application realizes data transmission between the system and the cloud server via 4G, and data transmission between the sensor data and the gateway data exchange via the LoRa communication protocol, thereby achieving reliable transmission of lightning current data from the sub-site to the main site and from the main site to the cloud server.

[0061] (7) The above-mentioned overhead transmission line lightning monitoring system also includes a power supply module ( Figure 1 (Not shown in the image), the power module is used to supply power to the ADC module 3, the main control module 4, the SDRAM module 5, the 4G module 6 and the LoRa communication module 7.

[0062] In this embodiment, as Figure 3 As shown, the power module uses 12~36V DC power. After power is connected to the power interface, the voltage is stepped down to 12V by an HT7463A DC / DC power chip to provide 12V power to the 4G module 6. The 12V voltage is then converted to 5V by a TPS5430 DC / DC power chip to provide 5V power to the LoRa communication module 7 and ADC module 3. An LDO step-down circuit using an AMS1117 chip converts the 5V voltage to 3.3V, 2.5V, and 1.2V to power the main control module 4, SDRAM module 5, and FLASH chip.

[0063] When supplying power to the sub-sites of the overhead transmission line lightning monitoring system, the power interface is required to use DC power supply. The minimum voltage value must not be lower than 12V and the maximum voltage value must not exceed 36V. In this embodiment, a solar cell with a 12V DC output is used to supply power to the circuit board. The solar cell is equipped with a lithium battery.

[0064] (8) The above-mentioned overhead transmission line lightning monitoring system also includes: buttons and LED indicator lights ( Figure 1 (Not shown in the image). The buttons are used to initialize each module of the overhead transmission line lightning monitoring system; the LED indicators are used to display the initialization completion status of the overhead transmission line lightning monitoring system and the waiting transmission status during the data transmission process of the sub-sites.

[0065] This embodiment includes two buttons, KEY1 and KEY2, for initializing each module. It also includes two LED indicators, LED1 and LED2, to display the system initialization completion and the waiting status during sub-site transmission. Specific operations are shown in Table 2.

[0066] Table 2

[0067]

[0068] After the substation of the overhead transmission line lightning monitoring system is powered on, the key KEY2 button needs to be pressed to initialize the LoRa communication module 7. At this time, AUX is low and MD0 is high. Wait for the indicator LED1 on the development board to light up for 1 second and then turn off, which indicates that the system initialization is complete. MD0 will automatically jump to low level, i.e., communication mode.

[0069] After the development board is powered on, the 4G module 6, like the LoRa communication module 7, needs to have its button KEY2 pressed to initialize it. After all modules are initialized, the indicator LED1 will light up for 1 second and then turn off, after which it will enter the data transmission state.

[0070] (9) The above-mentioned overhead transmission line lightning monitoring system also includes: a GPS module 7 and an SD card 8, both connected to the main control module 4, which are used to locate the lightning monitoring system and to store the data processed by the main control module 4, respectively.

[0071] The overhead transmission line lightning monitoring system provided in this application has the following advantages.

[0072] (1) The sampling rate in current lightning current acquisition systems is around 10MHz. For a 1.2 / 50us lightning current waveform, only 12 data points can be acquired from the wavefront. With the delay of the lightning current identification trigger circuit, the actual number of acquired wavefront data points is less than 12. In this embodiment, a sampling rate of 50MHz is used to acquire lightning current. A maximum of 60 data points can be acquired for the above waveform, which can accurately reconstruct the lightning current waveform.

[0073] (2) The LoRa self-organizing network and 4G wireless transmission are combined. The LoRa communication module has strong anti-interference capability and the 4G module has long distance wireless transmission. This solves the problem that the system cannot transmit data due to electromagnetic interference near the power transmission tower, and also ensures long-distance data transmission.

[0074] (3) The main station and the sub-station share a set of circuit boards. A 0-ohm resistor is used to select the program, thereby determining the sub-station and the main station.

[0075] (4) The device is small in size and light in weight, easy to install and simple to operate.

[0076] It should be noted that the data involved in this application (including but not limited to data used for analysis, data stored, data displayed, etc.) are all information and data that have been fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A lightning monitoring system for overhead transmission lines, characterized in that, include: Current transformers are used to collect lightning current signals from overhead transmission lines and convert the collected lightning current signals into voltage signals. An ADC module, connected to the current transformer, is used to perform analog-to-digital conversion on the voltage signal; The main control module, connected to the ADC module, is used to monitor the overhead transmission line for lightning strikes based on the voltage signal after analog-to-digital conversion.

2. The overhead transmission line lightning monitoring system according to claim 1, characterized in that, The current transformer uses a Rogowski coil.

3. The overhead transmission line lightning monitoring system according to claim 1, characterized in that, The ADC module is a dual-channel AD module.

4. The overhead transmission line lightning monitoring system according to claim 1, characterized in that, The main control module uses an FPGA chip.

5. The overhead transmission line lightning monitoring system according to claim 1, characterized in that, The overhead transmission line lightning monitoring system also includes: The SDRAM module is connected to both the ADC module and the main control module, and is used to store the voltage signal after analog-to-digital conversion.

6. The overhead transmission line lightning monitoring system according to claim 5, characterized in that, The overhead transmission line lightning monitoring system also includes: The 4G module, connected to the main control module, is used to send the lightning monitoring results of the overhead transmission line by the main control module to the cloud server.

7. The overhead transmission line lightning monitoring system according to claim 6, characterized in that, The overhead transmission line lightning monitoring system also includes a LoRa communication module connected to the main control module; the main station and sub-stations in the overhead transmission line lightning monitoring system communicate through the LoRa communication module.

8. The overhead transmission line lightning monitoring system according to claim 7, characterized in that, The overhead transmission line lightning monitoring system also includes: The power supply module is used to supply power to the ADC module, the main control module, the SDRAM module, the 4G module and the LoRa communication module.

9. The overhead transmission line lightning monitoring system according to claim 8, characterized in that, The overhead transmission line lightning monitoring system also includes: The buttons are used to initialize the various modules in the overhead transmission line lightning monitoring system. LED indicator lights are used to display the initialization completion status of the overhead transmission line lightning monitoring system and the waiting transmission status during the data transmission process of the sub-sites.

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