A system and method for real-time monitoring of SPDs

Abstract

The application discloses a kind of SPD real-time monitoring system and method, it is related to surge protector technical field.The system includes signal acquisition module, signal processing module, microcontroller module, communication module and power module.Signal acquisition module is connected in series with the ground wire of SPD or using current transformer non-contact coupling, leakage current signal is collected and converted into voltage signal;Signal processing module includes filter circuit and amplifier circuit, and the signal is filtered and amplified;The analog signal is converted into digital quantity by the built-in ADC of microcontroller module, and the effective value of leakage current is calculated, and the built-in algorithm analyzes the trend;Communication module uploads monitoring data to remote monitoring center.The application can monitor the leakage current of SPD in real time, realize early fault warning, support remote data transmission, solve the problem that existing SPD cannot monitor leakage current in real time online, cannot early warning performance degradation and lack remote monitoring capability.

Description

Technical Field

[0001] This invention relates to the field of surge protector technology, specifically to a real-time monitoring system and method for surge protection devices (SPDs). Background Technology

[0002] A surge protector (SPD), also known as a lightning arrester, is an electronic device that provides safety protection for various electronic devices, instruments, and communication lines. The main function of an SPD is to provide a discharge path in the event of lightning strikes or operational overvoltages, protecting downstream equipment. Its core components are nonlinear elements such as varistors (MOVs) or gas discharge tubes.

[0003] Currently, most SPDs lack online monitoring capabilities or are only equipped with simple mechanical tripping indicator windows (such as "green-red" color codes) to show whether the SPD has physically disconnected due to overheating. In existing technologies, such as Chinese patent CN210572671U, a leakage current detection device based on an SPD is disclosed. This device collects signals through a microampere-level leakage current transformer, processes them through a filtering module, an amplification module, a first-order RC low-pass filter module, and a resistor divider module, and then outputs the signal to an MCU for detection. However, this solution still has the following technical problems: (1) Functional limitations: The mechanical indicator can only show whether the SPD has completely failed (tripped), and cannot monitor the leakage current changes during its operation in real time. Leakage current is a key early indicator reflecting the aging, moisture and performance degradation of the SPD. Although CN210572671U realizes leakage current detection, its signal processing link is relatively simple, only using a first-order RC low-pass filter, and its anti-interference ability is limited.

[0004] (2) Delayed warning: When the mechanical indicator is activated, the SPD is usually close to or completely failed, loses its protective capability, and cannot provide warning before the failure, causing the protected equipment to be exposed to risk.

[0005] (3) Cannot be remotely monitored: Traditional SPDs require manual periodic inspections to check the status of indicators, which is inefficient and cannot meet the needs of smart grids, Internet of Things and other technologies for remote and real-time monitoring of equipment status.

[0006] (4) Lack of quantitative data: It is impossible to obtain the specific value of leakage current, making it difficult to conduct trend analysis, life prediction and precise maintenance.

[0007] In view of this, we propose a real-time monitoring system and method for SPD. Summary of the Invention

[0008] The purpose of this invention is to provide a real-time SPD monitoring system and method to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A real-time monitoring system and method for SPD includes: a signal acquisition module, a signal processing module, a microcontroller module (MCU module), a communication module, and a power supply module.

[0010] The signal acquisition module is connected in series with the SPD's grounding wire or coupled non-contactly using a high-precision current transformer (CT) to acquire the minute leakage current signal generated by the SPD under operating voltage and convert it into a voltage signal. Preferably, a high-precision current transformer is used to achieve non-contact coupling acquisition, avoiding any impact on the original SPD circuitry.

[0011] The signal processing module is connected to the signal acquisition module and includes a filtering circuit and an amplification circuit. It is used to filter (remove high-frequency interference) and amplify the acquired weak signal to make it suitable for the input range of the microcontroller's analog-to-digital converter (ADC).

[0012] The filtering employs a dual anti-interference approach using both analog and digital filtering to eliminate aliasing distortion and prevent high-frequency signals from folding into low-frequency bands; it also enhances electromagnetic interference resistance, reduces power consumption, improves stability, and eliminates signal jitter. Amplification is achieved through the PGA gain setting of the acquisition chip, with selectable amplification factors of 1, 2, 8, and 16, and a default current gain of 16. Specifically, a 0-1mA current signal is sampled, configured to 16 times gain via the internal PGA, and then amplified to 0-80mV. This is followed by a voltage divider resistor to output 0-40mV, which is then fed into the current input point of the acquisition chip. After passing through the PGA, the signal is amplified to 0-640mV. Using the full-scale range minimizes quantization error, improves measurement accuracy, and enables the detection of microcurrents at the μA level.

[0013] The microcontroller module is connected to the signal processing module. Its built-in ADC converts the processed analog voltage signal into a digital quantity. The MCU calculates the digital signal to obtain the real-time effective value of the leakage current and can analyze its changing trend using built-in algorithms.

[0014] Specifically, the microcontroller module sends a read command to the metering chip (such as the RN8209G) via the SPI communication interface, and the chip returns 24-bit raw ADC data. This raw data represents the digital value of the current signal after internal amplification and analog-to-digital conversion. During reading, the high 8 bits, middle 8 bits, and low 8 bits need to be acquired separately and then combined into a 24-bit signed integer. The 24-bit raw data is multiplied by the chip's full-scale voltage value of 1000mV, and then divided by the 24-bit ADC's full-scale value (0x800000, i.e., 8388608) to obtain the actual voltage value of the current signal, in millivolts (mV). The calculation formula is: Voltage (mV) = Raw data × 1000 ÷ 8388608. The internal ADC reading reflects the voltage value, which needs to be multiplied by the system's total gain coefficient to obtain the actual current value. The overall gain coefficient is determined by the front-end circuit gain and the internal PGA gain of the chip: Overall gain = front-end voltage divider ratio × internal PGA gain, actual current = RMS voltage × overall gain, ensuring a complete conversion process from the ADC raw data to the final effective current value.

[0015] The communication module is connected to the MCU and has an optional RS-485 communication interface, which is used to upload the monitored leakage current data and early warning information (such as exceeding the standard or rising sharply) to the remote monitoring center or cloud platform.

[0016] The power module provides a stable power supply for the entire device, and can draw power from the monitoring line or use an independent power supply.

[0017] The present invention also provides a real-time monitoring method for SPD, comprising the following steps: Step 1: Acquire the leakage current signal generated by the SPD under the operating voltage through the signal acquisition module and convert it into a voltage signal; Step 2: The acquired voltage signal is filtered and amplified by the signal processing module; Step 3: The processed analog voltage signal is converted into a digital quantity by the ADC built into the microcontroller module, and the effective value of the leakage current is calculated from the digital quantity. Step 4: Upload the monitored leakage current data to the remote monitoring center via the communication module.

[0018] The beneficial effects of this invention are as follows: (1) Real-time online monitoring: It can monitor the leakage current change of SPD in real time and detect early fault signs such as SPD aging, moisture, and performance degradation in a timely manner.

[0019] (2) Early warning: By analyzing the leakage current change trend through the built-in algorithm, a warning message is issued before the SPD completely fails, so as to avoid the protected equipment being exposed to risks.

[0020] (3) Remote monitoring: The monitoring data is uploaded to the remote monitoring center through communication interfaces such as RS-485 to meet the needs of smart grids, Internet of Things and other technologies for remote real-time monitoring of equipment status.

[0021] (4) Precise quantification: Obtain the specific value of leakage current to facilitate trend analysis, life prediction and precise maintenance.

[0022] (5) High-precision detection: It adopts dual anti-interference technology of analog filtering and digital filtering, combined with PGA programmable gain amplification, which can detect micro leakage current at the μA level, with high detection accuracy and good stability. Attached Figure Description

[0023] Figure 1 This is a block diagram illustrating the overall structural principle of the present invention; Figure 2 This is the circuit schematic of the MCU in this invention; Figure 3 This is a circuit schematic diagram of the signal acquisition module and the signal processing module in this invention; Figure 4 This is a circuit diagram of the power supply module in this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figures 1-4 As shown, the present invention provides a technical solution: A real-time monitoring system and method for SPD includes: a signal acquisition module, a signal processing module, a microcontroller (MCU), a communication module, and a power supply module.

[0026] The signal acquisition module is connected in series with the SPD's grounding wire or coupled non-contactly using a high-precision current transformer (CT) to acquire the minute leakage current signal generated by the SPD under operating voltage and convert it into a voltage signal. In this embodiment, a high-precision current transformer is preferably used to achieve non-contact coupling acquisition, avoiding any impact on the original SPD circuit and ensuring that the normal protection function of the SPD is not interfered with.

[0027] The signal processing module is connected to the signal acquisition module and includes a filtering circuit and an amplification circuit. It is used to filter (remove high-frequency interference) and amplify the acquired weak signal to make it suitable for the input range of the microcontroller's analog-to-digital converter (ADC).

[0028] The filtering employs both analog and digital filtering methods to eliminate aliasing distortion and prevent high-frequency signals from folding into low-frequency bands; it also enhances electromagnetic interference resistance, reduces power consumption, improves stability, eliminates signal jitter, and makes the system more stable.

[0029] Signal amplification maximizes the utilization of the ADC range by amplifying small signals, improving ADC efficiency; full-scale operation minimizes quantization error and enhances measurement accuracy; it can detect microcurrents at the μA level, enhancing small signal detection capabilities. The PGA gain setting on the acquisition chip allows for amplification factors of 1, 2, 8, or 16, with a default current gain of 16. Specifically, a 0-1mA current signal is sampled, configured to 16x gain via the internal PGA, amplified to 0-80mV, then output as 0-40mV via a voltage divider resistor and connected to the current input point of the acquisition chip. After passing through the PGA, the signal is amplified to 0-640mV.

[0030] like Figure 2 The diagram shown is the circuit schematic of the MCU in this invention. The MCU connects to the metering chip (such as RN8209G) via an SPI communication interface to read the ADC conversion data and perform calculations.

[0031] like Figure 3 The diagram shown is a circuit schematic of the signal acquisition module and signal processing module in this invention. The signal acquisition module converts the leakage current signal into a voltage signal, then filters it to remove high-frequency interference, and finally amplifies the weak signal to a range suitable for ADC acquisition using an amplifier circuit.

[0032] like Figure 4 The diagram shown is a circuit schematic of the power supply module in this invention. The power supply module provides a stable operating power supply for the entire device, and can draw power from the monitoring line or use an independent power supply.

[0033] The microcontroller module (MCU module) connects to the signal processing module. Its built-in ADC converts the processed analog voltage signal into a digital value. The MCU calculates the digital signal to obtain the real-time effective value of the leakage current and can analyze its changing trend using built-in algorithms.

[0034] The control method is as follows: The MCU sends a read command to the RN8209G chip via the SPI communication interface, and the chip returns 24-bit raw ADC data. This raw data represents the digital value of the current signal after internal amplification and analog-to-digital conversion. During reading, the high 8 bits, middle 8 bits, and low 8 bits need to be obtained separately and then combined into a 24-bit signed integer. The 24-bit raw data is multiplied by the chip's full-scale voltage value of 1000mV, and then divided by the 24-bit ADC's full-scale value (0x800000, i.e., 8388608) to obtain the actual voltage value of the current signal, in millivolts (mV). The calculation formula is: Voltage (mV) = Raw data × 1000 ÷ 8388608. The internal ADC reading reflects the voltage value, which needs to be multiplied by the system's total gain coefficient to obtain the actual current value. The total gain coefficient is determined by both the front-end circuit gain and the chip's internal PGA gain. Total gain = Front-end voltage divider ratio × Internal PGA gain. Actual current = RMS voltage × total gain, ensuring a complete conversion process from the ADC raw data to the final effective current value, guaranteeing both the accuracy of the calculation and a balance between real-time performance and resource efficiency.

[0035] The communication module connects to the MCU and has an optional RS-485 communication interface, which is used to upload the monitored leakage current data and early warning information (such as exceeding the standard or rising sharply) to the remote monitoring center or cloud platform.

[0036] The power module provides a stable power supply for the entire device, and can draw power from the monitoring line or use an independent power supply.

[0037] The SPD real-time monitoring system and method of the present invention acquires the leakage current signal of the SPD in real time through the signal acquisition module, and after filtering and amplification by the signal processing module, the MCU performs accurate calculation to obtain the effective value of the leakage current and its changing trend. The communication module realizes remote data transmission and early warning, which effectively solves the technical problems of existing SPDs that cannot monitor leakage current online in real time, cannot provide early warning of performance degradation, and lack remote monitoring capabilities.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A real-time monitoring system for SPD, characterized in that, include: The signal acquisition module is connected in series with the grounding wire of the SPD or coupled non-contactly using a current transformer. It is used to acquire the leakage current signal generated by the SPD under the operating voltage and convert it into a voltage signal. The signal processing module, connected to the signal acquisition module, includes a filtering circuit and an amplification circuit, and is used to filter and amplify the acquired voltage signal. The microcontroller module is connected to the signal processing module. Its built-in ADC converts the processed analog voltage signal into a digital quantity. The microcontroller module calculates the effective value of the leakage current from the digital quantity. A communication module, connected to the microcontroller module, is used to upload the monitored leakage current data to a remote monitoring center; The power module is used to provide operating power for the entire system.

2. The SPD real-time monitoring system according to claim 1, characterized in that, The signal acquisition module uses a high-precision current transformer to achieve non-contact coupling acquisition.

3. The SPD real-time monitoring system according to claim 1, characterized in that, The filtering circuit includes an analog filtering circuit and a digital filtering circuit, and uses a dual anti-interference method of analog filtering and digital filtering to eliminate aliasing distortion.

4. The SPD real-time monitoring system according to claim 1, characterized in that, The amplifier circuit amplifies the signal by setting the PGA gain of the acquisition chip, with the current gain set to 16 times by default.

5. The SPD real-time monitoring system according to claim 4, characterized in that, The 0-1mA current signal is sampled, configured to be multiplied by 16 by the internal PGA, and then amplified to output 0-80mV. After passing through the voltage divider resistor, the output is 0-40mV and connected to the current input point of the acquisition chip. After passing through the PGA, the signal is amplified to 0-640mV.

6. The SPD real-time monitoring system according to claim 1, characterized in that, The microcontroller module sends a read command to the metering chip via the SPI communication interface. The chip returns 24-bit raw ADC data. The actual voltage value of the current signal is obtained by multiplying the 24-bit raw data by the chip's full-scale voltage value of 1000mV and then dividing it by the full-scale value of the 24-bit ADC. The unit is mV. Actual current = RMS voltage × total gain, where total gain = front-end voltage divider ratio × internal PGA gain.

7. The SPD real-time monitoring system according to claim 1, characterized in that, The communication module is an RS-485 communication interface.

8. The SPD real-time monitoring system according to claim 1, characterized in that, The microcontroller module has a built-in trend analysis algorithm to analyze the changing trend of leakage current and generate early warning information.

9. A method for real-time monitoring of SPD, characterized in that, Includes the following steps: Step 1: Acquire the leakage current signal generated by the SPD under the operating voltage through the signal acquisition module and convert it into a voltage signal; Step 2: The acquired voltage signal is filtered and amplified by the signal processing module; Step 3: The processed analog voltage signal is converted into a digital quantity by the ADC built into the microcontroller module, and the effective value of the leakage current is calculated from the digital quantity. Step 4: Upload the monitored leakage current data to the remote monitoring center via the communication module.

10. The SPD real-time monitoring method according to claim 9, characterized in that, The specific method for calculating the effective value of leakage current in step 3 is as follows: The microcontroller sends a read command to the metering chip via the SPI communication interface to obtain 24-bit raw ADC data; Multiply the 24-bit raw data by the chip's full-scale voltage value of 1000mV and then divide by the full-scale value of the 24-bit ADC to obtain the actual voltage value of the current signal. The actual current value is obtained by multiplying the actual voltage value by the total gain factor.

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