Wind power plant current collection line lightning arrester on-line monitoring device

Abstract

The utility model relates to an on-line monitoring device for a current collection line lightning arrester of a wind power plant, which comprises a three-phase bus voltage reference acquisition device, an A-phase lightning arrester current acquisition device, a B-phase lightning arrester current acquisition device and a C-phase lightning arrester current acquisition device, and the A-phase lightning arrester current acquisition device, the B-phase lightning arrester current acquisition device and the C-phase lightning arrester current acquisition device are arranged on the current collection line lightning arrester. The three-phase bus voltage reference acquisition device communicates with the A, B and C three-phase lightning arrester current acquisition devices through a Lora spread spectrum module based on SPI synchronous communication. Compared with 2.4 G or 5.8 G communication schemes such as zigbee, Wi-Fi and the like, the Lora module with the 433M frequency of the SPI bus is adopted, although the communication rate is low, the frequency of the Lora module is lower, the diffraction through-wall capacity is higher, and the Lora module is particularly suitable for occasions where shielding walls penetrate through the interior and the exterior of a transformer substation in a crossed mode.

Description

Technical Field

[0001] The utility model belongs to the field of arrester monitoring, in particular to an on-line monitoring device for arresters of a wind farm collector line. Background Technique

[0002] Zinc oxide (MOA) arresters, as an important protection device, are widely used in overvoltage protection of power systems. The arrester not only serves as a lightning current impact device, but also has good limiting ability for internal overvoltages that occur in the power system. When the protected equipment is subjected to lightning or internal overvoltage impacts, the zinc oxide arrester conducts the overvoltage that appears in the electrical equipment to the ground, so that the electrical equipment is protected from the influence of lightning overvoltage. Currently, the main monitoring methods for arresters are as follows:

[0003] (1) Total current method: mainly monitor the leakage current of the MOA.

[0004] (2) Fundamental wave method: obtain the total current, system voltage amplitude and phase through the fast Fourier transform method, and then calculate the resistive component in the total current through the phase difference between the two.

[0005] (3) Third harmonic method: The third harmonic of the resistive current is one of the characteristic quantities for diagnosing the fault state of the arrester. This method is to take the sum of the total currents of three-phase arresters, that is, take the zero-sequence current.

[0006] (4) Capacitive current compensation method: The basic principle is that the external compensation circuit provides reverse capacitive current. By continuously adjusting the magnitude of the compensation current, the capacitive current component is offset, so as to obtain the resistive current component.

[0007] (5) Harmonic analysis method: The basic method and principle of the harmonic method combine the main advantages of the fundamental wave method and the third harmonic method. Sample the voltage signal and the total current signal, and then through Fourier transform, obtain the fundamental wave and the signals of each harmonic of the two signals. Its characteristic quantities include the total leakage current and the resistive component therein, including its fundamental wave and each harmonic component.

[0008] Currently, the arrester monitors commonly used in engineering practice generally adopt the total current method, that is, they are connected in series to the grounding circuit of the arrester to collect the total leakage current and the number of lightning strikes. This sensor can only be seen by the staff during inspection and does not have the function of network transmission. In the currently disclosed patents, most adopt the above several methods or a combined application. The core innovation points generally include the following aspects:

[0009] A passive power supply scheme is proposed to develop and improve the power supply method. For example, Patent CN220671548U proposes a wireless monitoring system for lightning arresters and a lightning arrester using solar composite power supply, which comprehensively uses solar energy and CT power supply to monitor the leakage current. Patent document CN 117907716A also gives a passive CT power supply scheme, and at the same time adds the internal temperature monitoring of the lightning arrester on the basis of current monitoring. Patent CN219225045U proposes a passive zinc oxide lightning arrester leakage current on-line monitoring device, which uses CT power supply, only measures the total current, and has a low-power design.

[0010] Research on the optimization of the mechanical structure design of lightning arrester monitoring devices to enhance waterproof and easy maintenance performance. Patent CN116047356A proposes a pillar-type zinc oxide lightning arrester low-voltage end on-line monitoring device, which mainly measures the leakage current and proposes a portable toolbox structure design to improve the easy maintenance performance. Patent CN117936207A proposes a lightning arrester with live monitoring and sealing functions, focusing on structural improvement and having a camera for monitoring at the same time. Patent CN219245588U proposes an on-line monitoring device for metal oxide lightning arresters, which is an improvement on the structure of traditional lightning arrester monitoring devices.

[0011] Increase the types of data monitored by lightning arresters to achieve a more accurate lightning arrester status. The lightning arrester on-line monitoring device of CN114264896B modifies the traditional lightning arrester monitor and adds 1 zinc oxide sampling resistor, so as to obtain the transient fault current. Patent CN117110688B is installed on the traditional lightning arrester base. In addition to monitoring the total leakage current and counting, it adds temperature monitoring.

[0012] Adopt a wireless synchronous sampling method to obtain the leakage current and phase reference voltage. CN202126472U proposes a zinc oxide lightning arrester leakage current on-line monitoring device based on wireless synchronization technology, which measures the total current and resistive current and uses the Zigbee network for synchronous sampling. Patent CN205038271U is a distributed wireless synchronous zinc oxide lightning arrester on-line monitoring device. It uses the Beidou timing clock for synchronization outdoors and switches to the radio frequency timing clock for synchronization indoors, so as to achieve wireless voltage and current synchronous sampling.

[0013] Abandon the traditional voltage and current sampling sensors and adopt more advanced sensors. For example, CN220455422U proposes a cloud-edge interaction lightning arrester leakage current high-precision monitoring system, which uses a TMR current sensor based on the quantum tunneling effect to collect current. Patent CN219392161U proposes an improvement scheme for the current sensor of an on-line monitoring device for zinc oxide lightning arresters. By setting a compensation coil and a compensation resistor in parallel to form a compensation component, the linearity of current acquisition is improved, and at the same time, the phase angle fluctuation range of the bus voltage signal and the zinc oxide lightning arrester current signal is small.

[0014] Based on the hardware of conventional monitoring devices, more advanced and complex analysis methods are adopted, with an emphasis on innovation in analysis methods. For example, Patent CN110794252A proposes an on-line monitoring device and method for zinc oxide arresters, which comprehensively analyzes resistive current, capacitive current, and total current. Patent CN210835138U conducts real-time on-line monitoring of the total current, resistive current, capacitive current, lightning strike times, and lightning strike moments of arresters. This solution uses the common phase of the 220V mains power supply in the substation as a reference to measure the signals of capacitive and voltage transformers for analysis.

[0015] The currently published monitoring schemes for zinc oxide arresters generally have the following deficiencies:

[0016] The commonly used arrester monitors in traditional engineering applications can only measure the total leakage current and lightning strike times, and have no networking function, requiring personnel to conduct inspections to discover problems.

[0017] In the existing schemes, although the CT power supply method achieves low power consumption, due to the too small leakage current, the performance of monitoring data is sacrificed, that is, only single data can be monitored and uploaded, making it difficult to achieve complex monitoring and analysis.

[0018] In the proposed improved monitoring schemes for arresters, basically the total current method and harmonic analysis method are adopted, that is, an ADC sampling chip is used to collect voltage and current signals, and Fourier (FFT) transformation is performed for analysis. However, due to cost constraints, ADC conversion chips generally use 16-bit or less ADC conversion chips, with low precision. And, considering cost and operation stability, embedded single-chip microcomputer processors are mostly used, whose processing precision and speed are limited, making it difficult to achieve high-precision measurement.

[0019] The synchronization accuracy of the existing wireless synchronization schemes needs to be improved. For example, zigbee wireless synchronization uses 2.4G radio frequency, which has weak wall penetration ability and only has an effective communication distance of 50 meters in open areas. Moreover, the synchronization mechanism depends on the zigbee cellular network, with certain uncertainties and poor practicability. The GPS Beidou time synchronization method has a large deviation in time synchronization accuracy in indoor environments and cloudy days due to poor satellite signals. Utility Model Content

[0020] The purpose of this utility model is to overcome the deficiencies of the prior art and provide an on-line monitoring device for arresters in a wind farm collector line that combines low-speed and high-speed signal transmission, is easy to install, and has high transmission stability.

[0021] The technical solution adopted by this utility model is:

[0022] An on-line monitoring device for lightning arresters of a wind farm collector line, comprising a three-phase bus voltage reference acquisition device, an A-phase lightning arrester current acquisition device, a B-phase lightning arrester current acquisition device, and a C-phase lightning arrester current acquisition device. The A, B, and C-phase lightning arrester current acquisition devices are installed on the collector line lightning arresters, and the three-phase bus voltage reference acquisition device communicates with the A, B, and C-phase lightning arrester current acquisition devices through a Lora spread spectrum module based on SPI synchronous communication.

[0023] Moreover, the three-phase bus voltage reference acquisition device is installed at the outdoor or indoor bus PT terminal.

[0024] Moreover, the A, B, and C-phase lightning arrester current acquisition devices all adopt the power supply method of solar panels plus lead-acid batteries.

[0025] Moreover, the A, B, and C-phase lightning arrester current acquisition devices all use the electric energy metering chip ADE7880 to collect the leakage current of the zinc oxide lightning arrester under normal conditions through high-precision A, B, and C-phase through-hole zero-flux current transformers.

[0026] Moreover, the signal output ports of the through-hole zero-flux current transformers of each phase of the zinc oxide lightning arrester are sequentially connected to an IV conversion circuit, a signal amplitude amplification circuit, and a low-pass filter circuit, and then connected to the analog input port of the ADE7880 electric energy chip.

[0027] Moreover, the A, B, and C-phase lightning arrester current acquisition devices all control the output of the DAC module through the STM32F407 single-chip microcomputer and connect it to the voltage signal input port of the electric energy metering chip ADE7880. The STM32F407 single-chip microcomputer controls the DAC module to output a 50Hz sine wave to provide a sine wave signal for the electric energy metering chip ADE7880.

[0028] Moreover, the STM32F407 single-chip microcomputer accesses the registers of the electric energy metering chip ADE7880 through the IIC bus, and at the same time accesses the original waveform register of ADE7880 through the HSDC port for obtaining original data.

[0029] Moreover, the zinc oxide lightning arrester resamples the transient waveform of the zinc oxide lightning arrester struck by lightning through a high-frequency current transformer, and generates a pulse signal through a lightning strike counting circuit to the STM32F407 single-chip microcomputer for the single-chip microcomputer to count.

[0030] Moreover, the STM32F407 single-chip microcomputer accesses the integrated environmental temperature and humidity sensor SHT10 through the IIC bus for measuring the environmental temperature and humidity.

[0031] Moreover, the three-phase bus voltage reference acquisition device is mainly used to acquire the zero-crossing signals of the three-phase bus voltage, and send zero-crossing broadcast signals through the 433M module. At the same time, the three-phase bus voltage reference acquisition device reads the total current and resistive component of the leakage current of the zinc oxide arrester, the total current and resistive component of the fundamental wave and harmonic waves, the ambient temperature and humidity, and the parameters of the lightning strike times calculated by the A, B, and C phase arrester current sampling devices through the 433M module, and uploads them to the server through the 4G module. Among them, the three-phase bus voltage reference acquisition device uses the STM32F407 single-chip microcomputer to acquire the zero-crossing signals of the three-phase bus voltage through the zero-crossing detection circuit, and acquires the A, B, and C phase voltage parameters of the bus voltage transformer through the bipolar-to-unipolar circuit.

[0032] The advantages and positive effects of the present utility model are as follows:

[0033] The present utility model adopts the Lora module with a 433M frequency of the SPI bus. Compared with the 2.4G or 5.8G communication solutions such as zigbee and Wi-Fi, although its communication rate is low, its frequency is lower and its diffraction and wall penetration ability is stronger, which is especially suitable for the occasions of indoor and outdoor cross-penetration of shielding walls in substations.

[0034] In order to adapt to the overall networking idea, the present utility model uses the power metering chip ADE7880 as the core of harmonic calculation. Compared with the traditional general solution of independent ADC + single-chip microcomputer or DSP processor solution, its algorithm is more advanced, the sampling rate is higher, and the ADC bit number is better. ADE7880 is specially designed for high-precision power metering, with a high-precision 24-bit ADC inside, a sampling rate of 1.024MHz, and at the same time, a high-performance digital signal processor and processing algorithm are built in, which can accurately calculate the effective values of voltage and current, calculate the power factor, measure and calculate the total (fundamental wave and harmonic waves) active / apparent power, and measure the fundamental wave active / reactive power, etc. Description of the Drawings

[0035] Figure 1 is the block diagram of the on-line monitoring device for the arrester of the wind farm collector line involved in the present utility model;

[0036] Figure 2 is the block diagram of the A, B, and C phase arrester current sampling devices (the three arrester current sampling devices are the same, and are uniformly referred to as the arrester current sampling device in the figure);

[0037] Figure 3 is the block diagram of the three-phase bus voltage reference acquisition device. Detailed Embodiment

[0038] The present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present utility model cannot be limited thereby.

[0039] See Figure 1 , an on-line monitoring device for arresters of a wind farm collector line, which includes a three-phase bus voltage reference acquisition device, an A-phase arrester current acquisition device, a B-phase arrester current acquisition device, and a C-phase arrester current acquisition device. The A, B, and C three-phase arrester current acquisition devices are installed on the collector line arresters. The three-phase bus voltage reference acquisition device and the A, B, and C three-phase arrester current acquisition devices communicate with each other by using a Lora spread spectrum module based on SPI synchronous communication. The three-phase bus voltage reference acquisition device is installed at the outdoor or indoor bus PT terminal.

[0040] See Figure 2 , the A, B, and C three-phase arrester current acquisition devices all adopt the power supply mode of a solar panel plus a lead-acid battery. The A, B, and C three-phase arrester current acquisition devices all use the electric energy metering chip ADE7880 to sample the total current leakage current: the leakage current of the zinc oxide arrester under normal conditions is collected through a high-precision through-hole zero-flux current transformer. The signal output ports of the through-hole zero-flux current transformers of each phase of the zinc oxide arrester are sequentially connected to an IV conversion circuit, a signal amplitude amplification circuit, and a low-pass filter circuit, and then connected to the analog input port of the ADE7880 electric energy chip. Since the leakage current signal is often only at the level of 10 μA to 10 mA, the signal needs to go through steps such as IV conversion, signal amplitude amplification, and low-pass filtering through the signal amplification circuit module, and then enter the analog input port of the ADE7880 electric energy chip.

[0041] The A, B, and C three-phase arrester current acquisition devices control the DAC module output of the STM32F407 single-chip microcomputer to be connected to the voltage signal input port of the electric energy metering chip ADE7880. The STM32F407 single-chip microcomputer controls the DAC module to output a 50 Hz sine wave to provide a sine wave signal for the electric energy metering chip ADE7880. Thus, the ADE7880 can realize the calculation of the effective values of voltage and current, the calculation of power factor, the measurement and calculation of total (fundamental wave and harmonic) active / apparent power, and the measurement of fundamental wave active / reactive power, etc. Since the ADE7880 electric energy chip is mainly used for smart meters and is not a dedicated ADC chip, a voltage signal needs to be provided to it to perform various voltage and current, active and reactive power calculations. The present utility model controls the DAC module of the STM32F407 single-chip microcomputer to output a 50 Hz sine wave to provide a sine wave signal for the ADE7880.

[0042] The STM32F407 microcontroller can access the ADE7880 registers through the I2C bus. At the same time, it can access the original waveform register of ADE7880 through the HSDC port to obtain the original data for further analysis.

[0043] The zinc oxide arrester resamples the transient waveform of the zinc oxide arrester struck by lightning through a high-frequency current transformer, and generates a pulse signal through the lightning strike counting circuit to the STM32F407 microcontroller for the microcontroller to count.

[0044] The STM32F407 microcontroller accesses the integrated environmental temperature and humidity sensor SHT10 through the I2C bus to measure the environmental temperature and humidity for compensating the leakage current.

[0045] See Figure 3 The three-phase bus voltage reference acquisition device is mainly used to acquire the zero-crossing signals of the three-phase bus voltage, and send out zero-crossing broadcast signals through the 433M module. At the same time, the three-phase bus voltage reference acquisition device reads the total current and resistive component of the zinc oxide arrester leakage current, the total current and resistive component of the fundamental wave and harmonic waves, the environmental temperature and humidity, the number of lightning strikes and other parameters obtained by calculation from the A, B, and C phase arrester current sampling devices through the 433M module, and uploads them to the server through the 4G module. The three-phase bus voltage reference acquisition device uses the STM32F407 microcontroller to acquire the zero-crossing signals of the three-phase bus voltage through the zero-crossing detection circuit, and acquires the A, B, and C phase voltage signals of the bus voltage transformer through the bipolar-to-unipolar circuit. The relevant signals are used for monitoring and comparison.

[0046] The networking idea of the above circuit is as follows: Based on the 433M module of the SPI bus, the synchronization of the wireless sine voltage signal is realized. The phase of the sine signal generated by the DAC module is not randomly given. Instead, when the three-phase bus voltage reference acquisition device acquires the zero-crossing of the bus A-phase PT, it will send out a broadcast synchronization message through the Lora spread spectrum module of the 433M frequency. The STM32F407 microcontroller in the A-phase arrester current sampling device receives this synchronization message through the 433M module, and then controls the DAC module to output a standard 50Hz sine signal with an initial phase of 0°. The synchronization accuracy is within 5us. Using the 433M module based on the SPI bus has better real-time synchronization performance and higher synchronization accuracy compared with asynchronous methods such as the TTL serial port.

[0047] To achieve the above technical effects, the present utility model uses the electrical energy metering chip ADE7880 for voltage and current calculation, rather than using an independent ADC chip + microcontroller processor for calculation. ADE7880 is a high-precision metering chip designed by ADI for three-phase power systems. It has a high-performance 24-bit ADC and a DSP processor inside, with built-in hardware and software filters. The internal program can calculate parameters such as the effective value of voltage, the effective value of current, active power, reactive power, apparent power, frequency, and harmonic distortion of AC signals. At the same time, it can provide functions such as phase sequence alarm, amplitude alarm, signal loss, and frequency abnormality. It uses a 24-bit ADC, and its performance is far higher than the solution of independently using an ADC chip for sampling and programming the microcontroller for calculation. Lightning strike counting function: mainly resamples the transient waveform of the zinc oxide arrester struck by lightning through a high-frequency current transformer, and generates a pulse signal to the STM32F407 microcontroller through the lightning strike counting circuit for the microcontroller to count.

[0048] Thus, an on-line monitoring of the arrester for the wind farm collector line with a lower frequency, stronger diffraction and wall penetration ability, and being particularly suitable for the occasions of crossing and penetrating the shielding wall inside and outside the substation is realized.

[0049] Although the embodiments and drawings of the present utility model are disclosed for illustrative purposes, those skilled in the art can understand that: without departing from the spirit and scope of the present utility model and the appended claims, various substitutions, changes, and modifications are possible. Therefore, the scope of the present utility model is not limited to the content disclosed in the embodiments and drawings.

Claims

1. An online monitoring device for lightning arrester of wind farm collector line, characterized by: It includes a three-phase bus voltage reference acquisition device, an A-phase lightning arrester current acquisition device, a B-phase lightning arrester current acquisition device, and a C-phase lightning arrester current acquisition device. The A, B, and C three-phase lightning arrester current acquisition devices are installed on the collector line arrester. The three-phase bus voltage reference acquisition device and the A, B, and C three-phase lightning arrester current acquisition devices use a Lora spread spectrum module based on SPI synchronous communication to achieve communication.

2. The wind farm collector line arrester online monitoring device according to claim 1, characterized in that: The three-phase bus voltage reference acquisition device is installed at the outdoor or indoor bus PT terminal.

3. The wind farm collector line arrester online monitoring device according to claim 1, characterized in that: The A, B, C three-phase lightning arrester current collection devices are all powered by solar panels plus lead-acid batteries.

4. The wind farm collector line arrester online monitoring device according to claim 1, characterized in that: The A, B, C three-phase arrester current collection devices all use the electric energy metering chip ADE7880 to collect the leakage current of the zinc oxide arrester when it is normal through the high-precision A, B, C three-phase through-type zero-flux current transformer.

5. The wind farm collector line arrester online monitoring device according to claim 4 is characterized in that: The signal output port of the through-core zero-flux current transformer of each phase of the zinc oxide lightning arrester is sequentially connected to an IV conversion circuit, a signal amplitude amplification circuit, a low-pass filter circuit, and then connected to an analog input port of an ADE7880 power chip.

6. The wind farm collector line arrester online monitoring device according to claim 4, characterized in that: The A, B, and C three-phase lightning arrester current acquisition devices are all connected to the voltage signal input port of the electric energy metering chip ADE7880 through the STM32F407 single-chip microcomputer to control the DAC module output. The STM32F407 single-chip microcomputer controls the DAC module to output a 50Hz sine wave to provide a sine wave signal for the electric energy metering chip ADE7880.

7. The wind farm collector line arrester online monitoring device according to claim 6, characterized in that: The STM32F407 microcontroller accesses the register of the energy metering chip ADE7880 through the IIC bus, and accesses the original waveform register of the ADE7880 through the HSDC port to obtain the original data.

8. The wind farm collector line arrester online monitoring device according to claim 6, characterized in that: The zinc oxide lightning arrester resamples the transient waveform of the zinc oxide lightning arrester being struck by lightning through a high-frequency current transformer, and generates a pulse signal to the STM32F407 single-chip microcomputer through a lightning strike counting circuit for single-chip microcomputer counting.

9. The wind farm collector line arrester online monitoring device according to claim 6, characterized in that: The STM32F407 single chip microcomputer accesses the integrated environment temperature and humidity sensor SHT10 through the IIC bus to measure the temperature and humidity of the environment.

10. The wind farm collector line arrester online monitoring device according to claim 6, characterized in that: The three-phase bus voltage reference acquisition device is mainly used to collect the zero-crossing signal of the bus three-phase voltage, and send a zero-crossing broadcast signal through the 433M module. At the same time, the three-phase bus voltage reference acquisition device reads the zinc oxide lightning arrester leakage current parameters obtained by the A, B, and C three-phase lightning arrester current sampling device through the 433M module, and uploads them to the server through the 4G module. Among them, the three-phase bus voltage reference acquisition device uses the STM32F407 single-chip microcomputer to collect the zero-crossing signal of the bus three-phase voltage through the zero-crossing detection circuit, and collects the A, B, and C three-phase voltage parameters of the bus voltage transformer through the bipolar to unipolar circuit.

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