Accurate data acquisition device of lightning arrester on-line monitoring system

Abstract

The invention relates to a precise data acquisition device of a lightning arrester on-line monitoring system, and the device comprises a sensor unit which is used for obtaining a three-phase leakage current signal of a lightning arrester and a voltage signal of a corresponding phase in real time; a signal conditioning unit; a micro-current amplification circuit; a dynamic gain control circuit; a multi-stage active filter circuit; an electromagnetic shielding housing; a synchronous sampling unit; a data processing unit; a self-energy-taking power supply unit; and an intelligent communication unit. The beneficial effects are that through the high-linearity current transformer and the partial pressure type voltage sensor of the sensor unit, three-phase leakage current signals and corresponding-phase voltage signals of the lightning arrester can be accurately obtained; a micro-current amplification circuit, a dynamic gain control circuit and a multi-order active filter circuit in the signal conditioning unit work cooperatively, weak leakage current signals are effectively processed, the signal-to-noise ratio is improved, and it is ensured that the signals can still keep high precision in a complex electromagnetic environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system monitoring, in particular to a precise data acquisition device of a lightning arrester online monitoring system. BACKGROUND

[0002] In modern power systems, with the continuous expansion of the power grid scale and the increasing of voltage level, the safe and stable operation of power equipment is crucial. As a key over-voltage protection device, lightning arrester is widely used in power plants, substations and transmission lines. Its main function is to limit lightning over-voltage and operating over-voltage, protect electrical equipment from over-voltage damage, and ensure the safe and reliable operation of the power system.

[0003] According to the search, the patent with the Chinese patent number CN103197134A discloses an online data acquisition and monitoring device for lightning arrester in power system, which comprises a pulse input interface circuit, a single-chip microcomputer, a data transmission communication module including a clock and a Flash data storage circuit, an isolation and data transmission circuit, a wireless communication module, and a key and liquid crystal display circuit, a signal sampling circuit composed of three-phase identical circuit structures, a leakage current amplification and arrangement circuit composed of three-phase identical circuit structures, and a same-phase voltage signal amplification and arrangement circuit composed of three-phase identical circuit structures, a phase-locked loop circuit, an ADC conversion circuit, and a power supply circuit. The present application has the characteristics of full function, stable and reliable performance, strong real-time performance, real-time online monitoring of lightning arrester without power interruption, timely detection of defects in lightning arrester, effective improvement of the efficiency of lightning arrester safety management in power departments, especially effective monitoring of the working condition of lightning arrester in remote areas, reduction of line lightning outage accidents, and wide application range.

[0004] However, the signal sampling circuit in the above-mentioned patent, such as the sampling circuit composed of three diodes in series and the amplification and arrangement circuit, can process leakage current and voltage signals, but does not solve the signal-to-noise ratio problem of weak current in complex electromagnetic environment. For example, the leakage current amplification and arrangement circuit relies on TVS tube and switching diode for clamping protection, which may cause signal distortion and affect the accurate capture of small current changes. In addition, the synchronous sampling of the conversion circuit can process 6-way signals, but does not integrate a high-precision calibration mechanism, which is easy to introduce errors in the field of high interference environment. Based on this, the present application designs a precise data acquisition device of a lightning arrester online monitoring system to solve the above problems. SUMMARY

[0005] (I) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a precise data acquisition device of a lightning arrester online monitoring system, which solves the technical problem of insufficient monitoring data precision and reliability.

[0007] (II) Technical Solution

[0008] To achieve the above object, the main technical scheme adopted by the present application comprises:

[0009] A precise data acquisition device of an on-line monitoring system of a lightning arrester, comprising:

[0010] A sensor unit for acquiring real-time three-phase leakage current signals of the lightning arrester and voltage signals of corresponding phases, the sensor unit comprising a high-linearity current transformer and a voltage divider type voltage sensor integrated with the body of the lightning arrester;

[0011] A signal conditioning unit connected to the output end of the sensor unit for processing weak leakage current signals, the configuration of which comprises:

[0012] A micro-current amplification circuit for primary amplification of microampere-level leakage current signals;

[0013] A dynamic gain control circuit for disturbance-free switching of amplification gain according to the real-time amplitude of the leakage current signals to prevent signal saturation;

[0014] A multi-stage active filter circuit for noise suppression of the power frequency characteristic band;

[0015] An electromagnetic shielding shell for completely covering the circuit board and components of the signal conditioning unit with a continuous welded metal cavity to effectively isolate external electromagnetic interference;

[0016] A synchronous sampling unit with a phase-locked loop circuit, the reference signal being taken from the power frequency voltage signal output by the voltage sensor to ensure that the sampling clock is strictly synchronized with the power grid power frequency; a temperature-compensated high-stability clock source is configured; a differential input structure is used to perform equal-phase interval sampling on the analog signals of the three-phase current and three-phase voltage to suppress common-mode interference;

[0017] A data processing unit integrating a high-resolution analog-to-digital converter and an embedded microprocessor;

[0018] A self-powered power supply unit magnetically or capacitively coupled to the grounding circuit of the lightning arrester to convert leakage current energy into a direct current power source, and a storage element is configured to maintain the continuity of system power supply when the energy is temporarily insufficient;

[0019] An intelligent communication unit supporting wireless and wired interfaces, with a built-in data encryption module, normally in a low-power sleep state, which can be awakened by leakage current out-of-limit events or external commands for data transmission.

[0020] Preferably, the data processing unit executes the following strategies:

[0021] Dynamic baseline calibration, automatically update signal zero point reference based on preset period or environmental changes, eliminate long-term drift of sensor and circuit;

[0022] Environmental parameter compensation, apply temperature and humidity compensation algorithm to correct the measurement deviation of leakage current caused by environmental factors;

[0023] Fault feature analysis, execute fault discrimination algorithm based on the change trend of leakage current harmonic components.

[0024] Preferably, the multi-stage active filter circuit in the signal conditioning unit is a low-pass filter with adjustable cutoff frequency, whose cutoff frequency f(c) is dynamically adjusted according to the real-time monitored power frequency f(0), satisfying the following formula:

[0025] f(c) = n·f(0);

[0026] Where n is an integer between 2 and 5, used to ensure effective filtering of high-frequency noise while completely retaining the fundamental frequency and key harmonic components.

[0027] Preferably, the dynamic gain control circuit in the signal conditioning unit is implemented using a program-controlled gain amplifier, whose gain value G and input leakage current effective value Im satisfy a nonlinear mapping relationship:

[0028] G = k·lg(Im) + b, where k and b are constants set according to circuit characteristics.

[0029] Preferably, in the fault feature analysis performed by the data processing unit, when the ratio H(n) / H(l) of the specific harmonic content H(n) to the fundamental content H(l) exceeds the preset threshold, a corresponding multi-level warning signal is generated and actively uploaded through the intelligent communication unit.

[0030] Preferably, the sensor unit further integrates a temperature and humidity sensing module installed close to the arrester core or the surface of the silicone rubber umbrella skirt, for real-time monitoring of the local environmental temperature and humidity of the arrester body, and providing the collected temperature and humidity data Te and He to the data processing unit as input for the environmental parameter compensation algorithm.

[0031] Preferably, the environmental parameter compensation algorithm executed by the data processing unit uses Te and He provided by the temperature and humidity sensing module to correct the measured original leakage current value in real time according to the pre-established leakage current temperature drift model:

[0032] ΔI = f(Te, He) and humidity influence factor.

[0033] Preferably, the self-powered power supply unit includes a high-efficiency energy collection circuit and a large-capacity energy storage element, which is designed to ensure that when the arrester leakage current is as low as tens of microamperes, sufficient energy can still be collected to maintain the device in a minimum power consumption standby mode, and trigger the intelligent communication unit to send a low power reminder when the energy storage element voltage is below the working threshold.

[0034] Preferably, further comprising an impulse full-wave capture module, which is directly connected to the high-speed output terminals of the voltage sensor and the current transformer, and is configured with an independent wideband signal conditioning link;

[0035] When an overvoltage condition is detected, the data processing unit triggers the module to synchronously record the voltage waveform and the current waveform flowing through the arrester at a high sampling rate, while bypassing the multi-stage active filter circuit; the data processing unit extracts key feature parameters from the original waveform, including the turning voltage and the residual voltage.

[0036] The wideband signal conditioning link of the impulse full-wave capture module includes:

[0037] High-speed operational amplifier (bandwidth ≥ 10 MHz);

[0038] Transient voltage suppressor protection circuit;

[0039] Anti-aliasing filter (cutoff frequency ≥ 500 kHz);

[0040] Ensure complete capture of high-frequency features of the waveform during overvoltage events, while being isolated from the power frequency monitoring channel.

[0041] Preferably, further comprising a self-diagnosis and redundant sampling channel: a set of miniature redundant current transformers and redundant voltage sensors are added inside the sensor unit, whose outputs are connected to the data processing unit through independent signal conditioning links; the data processing unit periodically compares the amplitude difference and phase offset of the main channel and the redundant channel, and if the deviation exceeds the set tolerance, it automatically marks the main channel as abnormal and switches to the redundant channel for continuous operation.

[0042] (Three) beneficial effects

[0043] 1. The present application, through the high linearity current transformer and the voltage divider type voltage sensor of the sensor unit, can accurately obtain the three-phase leakage current signal of the arrester and the voltage signal of the corresponding phase; the micro-current amplification circuit, the dynamic gain control circuit and the multi-stage active filter circuit in the signal conditioning unit work cooperatively, effectively processing the weak leakage current signal, improving the signal-to-noise ratio, and ensuring that the signal can still maintain high precision in complex electromagnetic environment.

[0044] 2. The application, the synchronous sampling unit built-in phase-locked loop circuit, the power frequency voltage signal output by the reference voltage sensor, ensures that the sampling clock is strictly synchronized with the power grid power frequency; The temperature compensation type high stability clock source and the differential input structure are configured, which further improves the sampling precision and effectively suppresses the common mode interference.

[0045] 3. The application, the data processing unit integrates high-resolution analog-to-digital converter and embedded microprocessor, executes dynamic baseline calibration, environmental parameter compensation and fault feature analysis and various strategies; Through real-time updating of signal zero point reference, correction of measurement deviation caused by environmental factors, and fault discrimination algorithm based on leakage current harmonic component change trend, the accuracy and timeliness of fault diagnosis are improved. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The system and signal overall architecture diagram of the accurate data acquisition device of the lightning arrester online monitoring system of the application;

[0047] Figure 2 The signal conditioning unit working flow chart of the accurate data acquisition device of the lightning arrester online monitoring system of the application;

[0048] Figure 3 The synchronous sampling timing diagram of the accurate data acquisition device of the lightning arrester online monitoring system of the application. DETAILED DESCRIPTION

[0049] In order to better explain the application, so as to be understood, the application will be described in detail in combination with the specific embodiments and the drawings. In this paper, the orientation of "up", "down" and other orientation terms is referred to as the orientation of the drawing. Figure 1 .

[0050] The embodiment of the application proposes the technical problem of insufficient monitoring data precision and reliability, through the high linearity current transformer of the sensor unit and the voltage divider type voltage sensor, the application can accurately obtain the three-phase leakage current signal of the lightning arrester and the voltage signal of the corresponding phase; The micro-current amplification circuit, dynamic gain control circuit and multi-stage active filter circuit in the signal conditioning unit work cooperatively, effectively process the weak leakage current signal, improve the signal-to-noise ratio, and ensure that the signal can still maintain high precision in complex electromagnetic environment.

[0051] In order to better understand the above technical solution, the exemplary embodiments of the application will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the application are shown in the drawings, it should be understood that the application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer, more thorough understanding of the application and to convey the complete scope of the application to those skilled in the art.

[0052] Embodiment 1;

[0053] Please refer to Figures 1-3 In the embodiment of the present application, a precise data acquisition device of an online monitoring system of a lightning arrester comprises:

[0054] A sensor unit is used to acquire real-time three-phase leakage current signals of the lightning arrester and voltage signals of corresponding phases, and the sensor unit comprises a high-linearity current transformer and a voltage divider type voltage sensor which form an integrated structure with the lightning arrester body.

[0055] A signal conditioning unit is connected to the output end of the sensor unit and is used to process weak leakage current signals, and the configuration of the signal conditioning unit comprises:

[0056] A micro-current amplification circuit is used to perform primary amplification on the microampere-level leakage current signals.

[0057] A dynamic gain control circuit is used to switch the amplification gain without disturbance according to the real-time amplitude of the leakage current signals, so as to prevent signal saturation.

[0058] A multi-stage active filter circuit is used to suppress noise for the power frequency characteristic frequency band.

[0059] An electromagnetic shielding shell is used to completely cover the circuit board and components of the signal conditioning unit by using a continuous welded metal cavity, so as to effectively isolate external electromagnetic interference.

[0060] A synchronous sampling unit is internally provided with a phase-locked loop circuit, the reference signal is taken from the power frequency voltage signal output by the voltage sensor, and the sampling clock is strictly synchronized with the power grid power frequency; a temperature compensation type high-stability clock source is configured; a differential input structure is used to perform equal-phase interval sampling on the analog signals of the three-phase current and three-phase voltage, so as to suppress common-mode interference.

[0061] A data processing unit is integrated with a high-resolution analog-to-digital converter and an embedded microprocessor.

[0062] A self-powered power supply unit is magnetically coupled or capacitively coupled to the grounding loop of the lightning arrester, converts the leakage current energy into a direct current power supply, and configures an energy storage element to maintain the continuity of system power supply when the energy is temporarily insufficient.

[0063] An intelligent communication unit supports wireless and wired interfaces, is internally provided with a data encryption module, is in a low-power sleep state under normal conditions, and can be awakened by a leakage current out-of-limit event or an external instruction to perform data transmission.

[0064] The data processing unit executes the following strategies: dynamic baseline calibration, automatic updating of signal zero point reference based on preset period or environmental changes, eliminating long-term drift of sensors and circuits; environmental parameter compensation, applying temperature and humidity compensation algorithm to correct the measurement deviation of leakage current caused by environmental factors; fault feature analysis, executing fault discrimination algorithm based on the change trend of leakage current harmonic component.

[0065] The multi-stage active filter circuit in the signal conditioning unit is a low-pass filter with adjustable cutoff frequency, and the cutoff frequency f(c) is dynamically adjusted according to the real-time monitored power frequency f(0), satisfying the following formula:

[0066] f(c)=n·f(0);

[0067] Where n is an integer between 2 and 5, used to ensure effective filtering of high-frequency noise while completely retaining the fundamental frequency and key harmonic components.

[0068] The dynamic gain control circuit in the signal conditioning unit uses a program-controlled gain amplifier to achieve, and its gain value G and input leakage current effective value Im satisfy a nonlinear mapping relationship:

[0069] G=k·lg(Im)+b, where k, b are constants set according to the circuit characteristics. In the fault feature analysis executed by the data processing unit, when the ratio H(n) / H(l) of the specific harmonic content H(n) to the fundamental content H(l) exceeds the preset threshold, the corresponding multi-level warning signal is generated and actively uploaded through the intelligent communication unit.

[0070] The working principle of the embodiment of the application is: the working process starts from the sensor unit, the high linearity current transformer and the voltage divider type voltage sensor are closely attached to the arrester body, continuously acquiring three-phase leakage current and corresponding phase voltage signals, and transmitting the signals to the signal conditioning unit; the micro-current amplification circuit receives the signals and performs primary amplification to enhance the signal strength. Subsequently, the dynamic gain control circuit dynamically adjusts the amplification gain according to the leakage current signal amplitude to prevent signal saturation and ensure signal integrity.

[0071] The amplified signal is input into the multi-stage active filter circuit, which can dynamically adjust the cutoff frequency according to the power frequency, filter out high-frequency noise while retaining the fundamental frequency and key harmonics; the entire signal conditioning process is carried out under the protection of an electromagnetic shielding shell, which uses a continuous welded metal cavity to isolate external electromagnetic interference and ensure signal accuracy.

[0072] The synchronous sampling unit uses a phase-locked loop circuit to lock the power frequency, realizing strict synchronization between the sampling clock and the power frequency; the temperature-compensated clock source provides a stable time reference, and the differential input structure samples the three-phase current and voltage signals with the same phase to suppress common-mode interference.

[0073] The analog-to-digital converter of the data processing unit converts the analog signal into a digital signal, and the embedded microprocessor executes multiple algorithms: dynamic baseline calibration eliminates long-term drift, environmental parameter compensation corrects measurement deviation, and fault feature analysis identifies leakage current harmonic changes; when the specific harmonic ratio exceeds the standard, a warning signal is generated and uploaded through the intelligent communication unit.

[0074] The intelligent communication unit has wireless and wired interfaces and data encryption functions, and is normally in a low-power sleep state and can be awakened by events or instructions; the self-powered power supply unit takes power from the leakage current through magnetic or capacitive coupling, and the energy storage element ensures continuous system power supply in case of energy shortage.

[0075] Embodiment 2;

[0076] Please refer to Figures 1-3 In the embodiment of the present application, the sensor unit further integrates a temperature and humidity sensing module installed close to the core of the lightning arrester or the surface of the silicone rubber umbrella skirt, which is used to monitor the local environmental temperature and humidity of the lightning arrester body in real time, and provide the collected temperature and humidity data Te and He to the data processing unit as the input of the environmental parameter compensation algorithm.

[0077] The environmental parameter compensation algorithm executed by the data processing unit uses Te and He provided by the temperature and humidity sensing module to correct the measured original leakage current value in real time according to the pre-established leakage current temperature drift model: and the humidity influence factor. The self-powered power supply unit includes an efficient energy harvesting circuit and a large-capacity energy storage element, which ensures that the device can still collect enough energy to maintain it in the lowest power standby mode when the leakage current of the lightning arrester is as low as tens of microamperes, and trigger the intelligent communication unit to send a low power reminder when the voltage of the energy storage element is lower than the working threshold.

[0078] The device includes an impulse full-wave capture module that is directly connected to the high-speed output terminals of the voltage sensor and the current transformer, and is configured with an independent wideband signal conditioning link;

[0079] When an overvoltage condition is detected, the data processing unit triggers the module to record the voltage waveform and the current waveform flowing through the lightning arrester at a high sampling rate, while bypassing the multi-stage active filter circuit; the data processing unit extracts key feature parameters from the original waveform, including the turning voltage and the residual voltage.

[0080] The wideband signal conditioning link of the impulse full-wave capture module includes:

[0081] A high-speed operational amplifier (bandwidth ≥ 10 MHz);

[0082] A transient voltage suppressor protection circuit;

[0083] An anti-aliasing filter (cutoff frequency ≥ 500 kHz);

[0084] Ensure the complete capture of waveform high-frequency characteristics in overvoltage events, while being isolated from the power frequency monitoring channel.

[0085] The device also includes self-diagnosis and redundant sampling channels: a set of miniature redundant current transformers and redundant voltage sensors are added inside the sensor unit, and their outputs are connected to the data processing unit through independent signal conditioning links; the data processing unit periodically compares the amplitude difference and phase offset of the main channel and the redundant channel, and if the deviation exceeds the set tolerance, the main channel is automatically marked as abnormal, and the redundant channel is switched to continue working.

[0086] The working principle of the embodiment of the application is that a temperature and humidity sensing module is added to the sensor unit, which is closely attached to the surface of the surge arrester to monitor the local environmental temperature and humidity in real time, and the data is transmitted to the data processing unit; the data processing unit uses a leakage current temperature drift model and a humidity influence factor to correct the original leakage current value in real time, further improving the measurement accuracy.

[0087] The self-powered power supply unit is equipped with a high-efficiency energy harvesting circuit and a large-capacity energy storage element, which can still maintain the device in standby mode when the leakage current is as low as tens of microamperes, and trigger the intelligent communication unit to alarm when the power is low; the impact full-wave capture module is connected to the high-speed output end, which is started by the data processing unit when overvoltage is detected, and synchronously records the voltage and current waveforms to extract key parameters to support fault analysis.

[0088] The system introduces self-diagnosis and redundant sampling channels, and the output of the miniature redundant sensor is connected to the data processing unit through an independent link; the data processing unit regularly compares the data difference between the main and redundant channels, and automatically switches to the redundant channel when the deviation exceeds the standard, ensuring the reliability of the monitoring data; overall, the units of the device work closely to realize accurate and real-time monitoring of the status of the surge arrester, effectively improving the operation reliability of the surge arrester and providing protection for the stable operation of the power system.

[0089] Embodiment 3;

[0090] Please refer to Figures 1-3 , which provides a specific embodiment;

[0091] The sensor unit collects the leakage currents of the three-phase surge arrester A / B / C (example values: A phase 120 μA, B phase 95 μA, C phase 110 μA) and the corresponding bus voltage (220 kV) in real time, and synchronously records the temperature and humidity data of the umbrella skirt surface (example: temperature 32℃, humidity 75% RH); the micro-current amplification circuit amplifies the B phase signal to 9.5 mV, and the dynamic gain control circuit adaptively adjusts the gain to 4.2 to prevent signal saturation; the active filter dynamically sets the cutoff frequency to 150 Hz (n=2) according to the real-time power frequency 50.02 Hz, and filters out high-frequency noise > 150 Hz.

[0092] The phase-locked loop controls the analog-to-digital converter to synchronously sample the three-phase signal at 512 points per cycle, and the data processing unit executes the environmental compensation algorithm: the compensated output of the original current of phase B is 102.6 mu A; the harmonic analysis module separates the resistive current component, detects the 3rd harmonic ratio H(3) / H(1) of phase A is 0.18, which exceeds the preset threshold 0.15, triggering a secondary warning.

[0093] The intelligent communication unit is awakened by the warning event, and the encrypted data packet is uploaded to the monitoring platform through LoRa (data format: {phase: A, harmonic ratio: 0.18, time: 2025-07-21 11:45:30}); the self-powered unit is powered by the leakage current of phase C, and the conversion efficiency is 87%, and the super capacitor voltage is maintained at 4.1V, and the system is in standby state.

[0094] The miniature redundant current transformer periodically verifies the main channel data, and if the amplitude difference is greater than 2% or the phase offset is out of limit, it automatically switches to the redundant channel (in this example, the deviation is 0.8%, and the switching is not triggered).

[0095] In this embodiment, the leakage current measurement error is compressed to within ±1% by dynamic gain control and environmental parameter compensation algorithm; early fault warning is realized based on harmonic ratio threshold criterion, and the response time is less than 5 minutes; the passive energy harvesting design supports continuous operation under microampere-level current, and is suitable for unattended substations in the wild; the double-CT structure can distinguish between internal aging and surface contamination faults of the surge arrester, and improve the diagnosis specificity.

[0096] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0097] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0098] In the present application, unless otherwise explicitly specified and limited, a first feature is "on" or "under" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature is "over", "above" and "on top of" a second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. A first feature is "under", "below" and "underneath" a second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0099] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0100] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A precise data acquisition device for an arrester online monitoring system, characterized in that: include: A sensor unit, used to obtain the three-phase leakage current signal of the arrester and the voltage signal of the corresponding phase in real time, the sensor unit includes a high-linearity current transformer and a voltage divider voltage sensor that form an integrated structure with the arrester body; A signal conditioning unit is connected to the output end of the sensor unit and is used to process a weak leakage current signal. The configuration thereof includes: A micro-current amplifier circuit is used to perform primary amplification on micro-ampere leakage current signals; Dynamic gain control circuit, which switches the amplification gain without disturbance according to the real-time amplitude of the leakage current signal to prevent signal saturation; Multi-stage active filter circuit, which suppresses noise in the characteristic frequency band of power frequency; An electromagnetic shielding shell, which uses a continuously welded metal cavity to completely cover the circuit board and components of the signal conditioning unit, effectively isolating external electromagnetic interference; The synchronous sampling unit has a built-in phase-locked loop circuit. The reference signal is taken from the power frequency voltage signal output by the voltage sensor, ensuring that the sampling clock is strictly synchronized with the power frequency of the power grid. It is equipped with a temperature-compensated and highly stable clock source. The differential input structure is used to sample the analog signals of the three-phase current and three-phase voltage at equal phase intervals to suppress common-mode interference. Data processing unit, integrating high-resolution analog-to-digital converter and embedded microprocessor; The self-powered power supply unit is magnetically or capacitively coupled to the arrester grounding circuit, converting leakage current energy into DC power. It is also equipped with energy storage elements to maintain the continuity of system power supply when energy is insufficient. The intelligent communication unit supports wireless and wired interfaces, has a built-in data encryption module, and is in a low-power sleep state under normal circumstances. It can be awakened by leakage current limit events or external commands for data transmission.

2. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: The data processing unit implements the following strategies: Dynamic baseline calibration automatically updates the signal zero reference based on a preset period or environmental changes to eliminate long-term drift of sensors and circuits; Environmental parameter compensation: Apply temperature and humidity compensation algorithm to correct leakage current measurement deviation caused by environmental factors; Fault signature analysis, executing a fault discrimination algorithm based on the changing trend of the harmonic components of the leakage current.

3. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: The multi-order active filter circuit in the signal conditioning unit is a low-pass filter with an adjustable cutoff frequency. Its cutoff frequency f(c) is dynamically adjusted according to the real-time monitored power grid frequency f(0), satisfying the following formula: f(c)=n·f(0); Where n is an integer between 2 and 5, which is used to ensure that high-frequency noise is effectively filtered out while completely retaining the power frequency fundamental wave and key harmonic components.

4. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: The dynamic gain control circuit in the signal conditioning unit is implemented using a programmable gain amplifier, and the gain value G and the input leakage current effective value Im satisfy a nonlinear mapping relationship: G=k·lg(Im)+b, where k and b are constants set according to circuit characteristics.

5. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: In the fault feature analysis performed by the data processing unit, when it is detected that the ratio H(n) / H(l) of the specific subharmonic content H(n) to the fundamental wave content H(l) exceeds the preset threshold, a corresponding multi-level warning signal is generated and actively uploaded through the intelligent communication unit.

6. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: The sensor unit further integrates a temperature and humidity sensing module installed close to the arrester core or the surface of the silicone rubber shed, which is used to monitor the local ambient temperature and humidity of the arrester body in real time, and provide the collected temperature and humidity data Te and He to the data processing unit as input to the environmental parameter compensation algorithm.

7. The precise data acquisition device for an arrester online monitoring system according to claim 6, characterized in that: The environmental parameter compensation algorithm executed by the data processing unit utilizes Te and He provided by the temperature and humidity sensing module according to a pre-established leakage current temperature drift model: ΔI=f(Te,He) and humidity influence factor are used to make real-time corrections to the measured original leakage current value.

8. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: The self-powered power supply unit includes a high-efficiency energy collection circuit and a large-capacity energy storage element. Its design ensures that when the lightning arrester leakage current is as low as tens of microamperes, it can still collect sufficient energy to maintain the device in the lowest power consumption standby mode, and trigger the intelligent communication unit to send a low-battery reminder when the voltage of the energy storage element is lower than the working threshold.

9. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: It further includes an impulse full-wave capture module, which is directly connected to the high-speed output terminals of the voltage sensor and the current transformer and is configured with an independent wide-band signal conditioning link; When an overvoltage condition is detected, the data processing unit triggers the module to synchronously record the voltage waveform at both ends of the lightning arrester and the current waveform flowing through it at a high sampling rate, while bypassing the multi-order active filter circuit; the data processing unit extracts key characteristic parameters from the original waveform, including the turning voltage and residual voltage.

10. The precise data acquisition device for an arrester online monitoring system according to claim 1, characterized in that: It further includes self-diagnosis and redundant sampling channels: a set of micro redundant current transformers and redundant voltage sensors are added inside the sensor unit, and their outputs are connected to the data processing unit through an independent signal conditioning link; the data processing unit periodically compares the amplitude difference and phase offset between the main channel and the redundant channel. If the deviation exceeds the set tolerance, the main channel is automatically marked as abnormal and switched to the redundant channel to continue working.

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