A portable scanner for power quality analysis and diagnosis

Abstract

The present invention proposes a portable scanner for power quality analysis and diagnosis, comprising a data acquisition module, an analysis and diagnosis software module, and a main control chip. The data acquisition module's signal output is connected to the main control chip's signal input, and the main control chip is equipped with the analysis and diagnosis software module. The analysis and diagnosis software module performs relevant power quality analysis and diagnosis. The present invention, combined with portable installation, can collect accurate power quality data from 380V distribution substations. Based on the collected accurate data, the backend automatically establishes a topology model. Relying on topology module data and collected equipment operation data, and using big data mining and analysis algorithms, it accurately locates the location and cause of power quality issues, provides professional and reliable decision support, and provides a theoretical basis for operation and maintenance inspections for grassroots maintenance personnel.

Description

Technical Field

[0001] The invention relates to a portable scanner for power quality analysis and diagnosis, and belongs to the field of power quality analysis and diagnosis. Background Art

[0002] With the rapid development of power electronics technology, a large number of nonlinear and impact loads have been put into use, and power quality problems such as harmonic interference, voltage fluctuation, and flicker have been significantly aggravated. Power quality issues have inevitably come into people's attention. On the other hand, with the development of information technology, more and more sensitive loads have higher and higher requirements for power quality. Therefore, it is particularly important to develop and design an instrument that can accurately calculate and display power quality parameters in real time.

[0003] Faults that cause power quality degradation in power systems can be divided into internal faults and external faults. Short circuit faults are internal faults, while lightning, human operational errors, external equipment failures, or changes in operating conditions during normal operation can also cause power quality problems. There are many sources that affect the power quality of power systems, and the harm caused by power quality problems will also have a reverse effect on the power system while also affecting the performance of external equipment. The harm is manifested in the following points: 1) Due to the generation of harmonics, component losses in the power network are greater than normal operating losses, which will also accelerate equipment aging, shortening its service life and limiting equipment performance. 2) Due to the presence of harmonics, the power network will resonate, and the increased current will cause capacitors and reactance to burn out. This phenomenon greatly reduces the safety of electricity use and even creates fire hazards such as fire. 3) Unnecessary relay protection caused by fluctuations, flicker, etc., and even power outages will lead to stagnation in the production process. 4) Voltage instability and harmonics will cause noise interference and information loss during communication, so communication quality cannot be guaranteed.

[0004] The power quality monitoring device can be regarded as a data acquisition system. It collects parameters such as voltage and current through sensors, uses signal conditioning circuits to perform a series of processing such as amplification and noise reduction, and then sends them to a high-precision AD converter to obtain digital signals. Finally, the data is processed by a signal processor. The significance of power quality monitoring lies in: first, it can provide corresponding technical support for the stable operation of the power grid, monitor the operation of the power system in real time, effectively detect the source of hidden dangers at the first time, and provide accurate and effective information when taking measures; second, with the popularization of electric energy today, power quality directly affects the quality of life of users. Therefore, monitoring power quality can effectively improve service quality and bring convenience to the production and life of the whole society.

[0005] The power quality scanner is an indirect access (through a mutual inductor) power quality parameter analysis and measurement instrument. It is a dedicated portable product for detecting and analyzing the quality of power grid operation. It can provide harmonic analysis and power quality analysis during system operation, and can conduct long-term data collection and monitoring of power grid operation. It is currently widely used in quality supervision system energy centers, power plants, power grid companies, energy-saving monitoring systems, and large and medium-sized enterprises. It is a large-scale and widely used metering equipment with a great impact on the field of measurement and detection. It plays an important role in technical support and data guarantee for the troubleshooting of various faults in power work, safe production, energy conservation and emission reduction. Summary of the Invention

[0006] The present invention proposes a portable scanner for power quality analysis and diagnosis, and aims to design an instrument that can analyze and diagnose power quality problems.

[0007] The technical solution of the present invention is: a portable scanner for power quality analysis and diagnosis, whose structure includes a data acquisition module, an analysis and diagnosis software module, and a main control chip; wherein the signal output end of the data acquisition module is connected to the signal input end of the main control chip, and the main control chip is equipped with the analysis and diagnosis software module; the analysis and diagnosis software module performs relevant power quality analysis and diagnosis.

[0008] Furthermore, the data acquisition module includes a frequency module, a harmonic module, and a three-phase imbalance module; the signal output end of the frequency module, the signal output end of the harmonic module, and the signal output end of the three-phase imbalance module are respectively connected to the signal input end of the main control chip.

[0009] Furthermore, a portable scanner for power quality analysis and diagnosis also includes a power supply system, a display and input device, and an artificial intelligence expansion card; wherein the electrical output end of the power supply system is connected to the electrical input end of the main control chip, the first signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the display and input device, the second signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the artificial intelligence expansion, and the signal output end of the artificial intelligence expansion card is connected to the signal input end of the data acquisition module; the analysis and diagnosis software module completes relevant power quality analysis and diagnosis, and the relevant power quality analysis and diagnosis include frequency analysis, harmonic analysis, and three-phase imbalance analysis.

[0010] Furthermore, the frequency module includes a single-chip microcomputer, a mutual inductor, a low-pass filter circuit, a voltage follower, a band-pass filter circuit, and a comparator; wherein, the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the low-pass filter circuit, the signal output end of the low-pass filter circuit is connected to the signal input end of the voltage follower, the signal output end of the voltage follower is connected to the signal input end of the band-pass filter circuit, the signal output end of the band-pass filter circuit is connected to the signal input end of the comparator, the signal output end of the comparator is connected to the signal input end of the single-chip microcomputer, and the signal output end of the single-chip microcomputer is connected to the signal input end of the main control chip; the mutual inductor includes a voltage mutual inductor and a current mutual inductor.

[0011] Furthermore, the harmonic module includes a mutual inductor, a signal conditioning circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the signal conditioning circuit, the signal output end of the signal conditioning circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductor includes a voltage mutual inductor and a current mutual inductor.

[0012] Furthermore, the three-phase imbalance module includes a mutual inductor, a phase detection circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the phase detection circuit, the signal output end of the phase detection circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductors in the three-phase imbalance module are three groups, and each group of mutual inductors includes a voltage mutual inductor and a current mutual inductor.

[0013] Furthermore, the frequency analysis includes measuring the frequency. The frequency measurement process includes: the voltage, current and other values of the power grid are converted into analog electrical signals after passing through the mutual inductor, the analog electrical signals are filtered out of the high-frequency components through a low-pass filter, and then the signals are isolated through a voltage follower. The fundamental component in the signal is extracted through a band-pass filter circuit, and a square wave signal is generated through a comparator and sent to the microcontroller for frequency calculation.

[0014] Furthermore, the harmonic analysis includes measuring harmonics. The process of measuring harmonics includes: the voltage, current and other values of the power grid are converted into analog electrical signal quantities after passing through a mutual inductor, and then more accurately converted through a signal conditioning circuit, that is, first high-frequency filtering is performed on the harmonic voltage and current to determine the measurement range, and then the DC component is isolated, and then the filtered and isolated signal is amplified in multiple stages using an operational amplifier, and then output to the main control chip after A / D conversion by an A / D converter. The main control chip uses a fast Fourier transform algorithm to calculate the harmonics of the input signal.

[0015] Furthermore, the three-phase imbalance analysis includes measuring the three-phase imbalance. The process of measuring the three-phase imbalance includes: using three sets of voltage transformers and current transformers to sample the three-phase voltage and current of the power grid, and then using the phase detection circuit to complete the detection of the three-phase phase, and transmitting the detected result data to the main control chip through the A / D converter. The main control chip reads the A / D conversion result and uses the symmetrical component method to calculate the three-phase voltage and current imbalance.

[0016] Furthermore, the signal output end of the artificial intelligence expansion card is respectively connected to the signal input end of the frequency module, the signal input end of the harmonic module, and the signal input end of the three-phase imbalance module; the artificial intelligence expansion card includes an SD card and an artificial intelligence acceleration card; the artificial intelligence acceleration card adopts artificial intelligence AI expansion card technology to realize reference level adaptive measurement; the reference level adaptive measurement specifically includes the following steps:

[0017] 1. Real-time grid voltage and current input; the real-time grid voltage and current input specifically includes: grid voltage and current signals are input into the data acquisition module via a portable scanner probe;

[0018] 2. Data acquisition module identification processing: The data acquisition module identification processing is specifically: the grid voltage and current signals are recognized through the mutual inductor in the data acquisition module;

[0019] 3. BP neural network algorithm training; the specific process of the BP neural network algorithm training includes: first, inputting normalized voltage and current signal samples into the BP neural network; then initializing parameters, including: maximum number of iterations, learning accuracy, initial weights of hidden nodes, threshold, and initial learning rate; then calculating the input and output values of each layer; and finally calculating the output layer error E(q);

[0020] 4. Determine the reference level; if E(q) < ε, proceed to step 5; if not, modify the weights and thresholds and return to step 3; ε is the error threshold;

[0021] 5. Output the reference level value to the main control chip.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) This invention combines portable installation with the ability to collect accurate power quality data for 380V distribution stations. Based on this collected data, the backend automatically builds a topology model. Relying on topology module data and collected equipment operation data, and using big data mining and analysis algorithms, it accurately locates the location and cause of power quality problems, provides professional and reliable decision support, and provides a theoretical basis for operation and maintenance inspections for grassroots maintenance personnel.

[0024] 2) The portable scanner of the present invention is designed based on modularization and functional conversion. Each module is designed as an integrated whole and coordinated through built-in software to achieve functional conversion. In this way, different functional modules can be used according to different power quality issues in actual field applications, which improves portability and flexibility and also makes the scanner scalable to a certain extent.

[0025] 3) The adaptive signal level measurement described in the present invention includes adaptively measuring the reference level using an artificial neural network algorithm. Specifically, the Stratix 10SX FPGA programmable accelerator card developed by Intel is used to identify the reference level in different scenarios using a BP neural network algorithm. At the same time, it complements and improves any data loss that may occur during the measurement process.

[0026] 4) The present invention supports multiple fixed modes and two power supply modes: battery / power supply, meeting two different usage scenarios: short-term testing and long-term deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Attachment Figure 1 This is a system structure diagram of a portable scanner.

[0028] Attachment Figure 2 It is a flow chart of realizing adaptive measurement of reference level by artificial neural network algorithm.

[0029] Attachment Figure 3 It is a structural diagram of the frequency module.

[0030] Attachment Figure 4 This is a structural diagram of the harmonic module.

[0031] Attachment Figure 5 It is a structural diagram of the three-phase imbalance module. DETAILED DESCRIPTION

[0032] A portable scanner for power quality analysis and diagnosis, comprising a data acquisition module, an analysis and diagnosis software module, and a main control chip; wherein the signal output end of the data acquisition module is connected to the signal input end of the main control chip, and the main control chip is equipped with the analysis and diagnosis software module; the analysis and diagnosis software module performs relevant power quality analysis and diagnosis.

[0033] The portable scanner for power quality analysis and diagnosis is suitable for power quality analysis and diagnosis in 380V distribution station areas.

[0034] The data acquisition module includes a frequency module, a harmonic module, and a three-phase imbalance module; the signal output end of the artificial intelligence expansion card is respectively connected to the signal input end of the frequency module, the signal input end of the harmonic module, and the signal input end of the three-phase imbalance module; the signal output end of the frequency module, the signal output end of the harmonic module, and the signal output end of the three-phase imbalance module are respectively connected to the signal input end of the main control chip.

[0035] The portable scanner for power quality analysis and diagnosis also includes a power supply system, a display and input device, and an artificial intelligence expansion card; wherein the electrical output end of the power supply system is connected to the electrical input end of the main control chip, the first signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the display and input device, the second signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the artificial intelligence expansion, and the signal output end of the artificial intelligence expansion card is connected to the signal input end of the data acquisition module; the display and input device is preferably a touch screen.

[0036] The analysis and diagnosis software module performs relevant power quality analysis and diagnosis, which includes frequency analysis, harmonic analysis, and three-phase imbalance analysis.

[0037] The frequency module is a frequency measurement circuit formed with a single-chip microcomputer as the control core; the frequency module includes a single-chip microcomputer, a mutual inductor, a low-pass filter circuit, a voltage follower, a band-pass filter circuit, and a comparator; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the low-pass filter circuit, the signal output end of the low-pass filter circuit is connected to the signal input end of the voltage follower, the signal output end of the voltage follower is connected to the signal input end of the band-pass filter circuit, the signal output end of the band-pass filter circuit is connected to the signal input end of the comparator, the signal output end of the comparator is connected to the signal input end of the single-chip microcomputer, and the signal output end of the single-chip microcomputer is connected to the signal input end of the main control chip; the single-chip microcomputer is preferably an AT89C51 single-chip microcomputer; the voltage follower realizes the functions of voltage following and signal isolation; the mutual inductor includes a voltage mutual inductor and a current mutual inductor; the signal acquisition end of the mutual inductor collects the voltage and current information of the power grid.

[0038] The harmonic module includes a mutual inductor, a signal conditioning circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the signal conditioning circuit, the signal output end of the signal conditioning circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductor includes a voltage mutual inductor and a current mutual inductor; the signal acquisition end of the mutual inductor collects grid voltage and current information.

[0039] The three-phase imbalance module includes a mutual inductor, a phase detection circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the phase detection circuit, the signal output end of the phase detection circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductors in the three-phase imbalance module are three groups, each group of mutual inductors includes a voltage mutual inductor and a current mutual inductor; the signal acquisition ends of the three groups of mutual inductors respectively correspond to the three-phase voltage and current information collected in the power grid.

[0040] The frequency module, harmonic module and three-phase imbalance module each have their own mutual inductor; the harmonic module and three-phase imbalance module each have their own A / D converter.

[0041] The frequency analysis and frequency measurement process are as follows: the voltage, current and other values of the power grid are converted into analog electrical signals after passing through a mutual inductor. The analog electrical signals are filtered out of high-frequency components through a low-pass filter, and then pass through a voltage follower to achieve signal isolation. The fundamental component of the signal is then extracted through a band-pass filter circuit, and a square wave signal is generated through a comparator and sent to the microcontroller for frequency calculation.

[0042] The harmonic analysis method measures harmonics in the following manner: the voltage and current values of the power grid are converted into analog electrical signals through mutual inductors, and then more accurately converted through signal conditioning circuits. First, the harmonic voltage and current are subjected to high-frequency filtering to determine the measurement range. The DC components are then isolated. The filtered and isolated signals are then amplified in multiple stages using an operational amplifier. After A / D conversion by an A / D converter, the signals are output to a main control chip, which calculates the harmonics of the input signals using a commonly used fast Fourier transform (FFT) algorithm.

[0043] The three-phase imbalance analysis and the process of measuring the three-phase imbalance are as follows: using three sets of voltage transformers and current transformers to sample the three-phase voltage and current of the power grid, and then using a phase detection circuit to complete the detection of the three-phase phase. The detected result data is transmitted to the main control chip through an A / D converter. The main control chip reads the A / D conversion result and uses the conventional symmetrical component method to calculate the three-phase voltage and current imbalance.

[0044] The main control chip preferably adopts a DSP+ARM structure.

[0045] The portable scanner for power quality analysis and diagnosis also includes a scanner probe, which is used to collect voltage and current signals in the power grid and input them into the data acquisition module.

[0046] The artificial intelligence expansion card includes an SD card and an artificial intelligence acceleration card (i.e., an AI acceleration card).

[0047] The artificial intelligence acceleration card uses artificial intelligence AI expansion card technology to achieve adaptive measurement of reference level. In different measurement scenarios, due to different input voltage and current, the reference level for the data acquisition module is also different. The present invention uses an artificial intelligence acceleration card (i.e., AI acceleration card) to achieve adaptive measurement of reference level. The AI acceleration card is preferably the Stratix 10SX FPGA programmable acceleration card developed by INTEL, which uses the BP neural network algorithm to achieve adaptive measurement of signal level, simplifying the measurement steps. The specific algorithm flow chart is shown below. Figure 2 As shown in the figure, when the real-time grid voltage and current signals are input, the signal acquisition is completed through the voltage and current transformers. The collected signals are continuously learned and adapted by the BP neural network algorithm to solve the reference level of the current measurement value, and finally realize the adaptive measurement of the signal level.

[0048] The adaptive reference level measurement is mainly aimed at the data acquisition module of the scanner. In order to improve the measurement accuracy and thus be used to calculate and analyze information such as frequency, harmonics, and three-phase imbalance, when measuring the voltage and current signals of the power grid, the corresponding reference level can be automatically matched according to the different voltage and current signals. In this way, the signal can be converted into specific voltage and current values, which is achieved through artificial intelligence acceleration card technology. For example, the Stratix 10SX FPGA programmable acceleration card developed by INTEL is used to identify the reference level in different scenarios with the BP neural network algorithm, while also supplementing and improving any data loss that may occur during the measurement process.

[0049] The reference level adaptive measurement specifically comprises the following steps:

[0050] 1. Real-time grid voltage and current input; the real-time grid voltage and current input specifically includes: grid voltage and current signals are input into the data acquisition module via a portable scanner probe;

[0051] 2. Data acquisition module identification processing: The data acquisition module identification processing is specifically: the grid voltage and current signals are recognized through the mutual inductor in the data acquisition module;

[0052] 3. BP neural network algorithm training; BP neural network is a feedforward neural network with self-adaptation and self-learning capabilities. It adapts to environmental changes by adjusting its own parameters and can meet the needs of processing multiple types of information. The specific process of BP neural network algorithm training is as follows: first, normalized voltage and current signal samples are input into the BP neural network; then the parameters are initialized, including the maximum number of iterations, learning accuracy, initial weights of the number of hidden nodes, threshold, and initial learning rate; then the input and output values of each layer are calculated; finally, the output layer error E(q) is calculated;

[0053] 4. Determine the reference level; if E(q) < ε, proceed to step 5; if not, modify the weight and threshold, and return to step 3; ε is the error threshold; ε is preferably 10 -3 ;

[0054] 5. Output the reference level value to the main control chip.

[0055] When the present invention is in use, the real-time voltage and current signals are collected through the data acquisition module. Different from the conventional power quality scanner, the present invention adopts the idea of modularization and function conversion. In the specific implementation process, the software and hardware are combined with each other. For example, in order to solve the harmonic problem in the power quality problem, considering that the dynamic range of the power grid harmonics is large, the corresponding harmonic module is inserted into the data acquisition module. At the same time, the corresponding harmonic analysis software is written into the analysis and diagnosis software module by sharing or on-site downloading. In this way, the data acquisition module and the analysis and diagnosis software module can be matched one by one, realizing the flexibility of the scanner. In addition, the portable scanner for power quality analysis and diagnosis has There is a built-in SD card slot, which can be used to expand the software content, thereby improving the scalability of the scanner; the data acquisition module of the portable scanner used for power quality analysis and diagnosis of the present invention can simultaneously collect voltage and current signals, and at the same time adopts artificial intelligence AI expansion card technology to automatically identify the reference level in different measurement scenarios, thereby realizing the adaptive measurement function of the signal level; the present invention can also provide different fixing methods and power supply methods. For short-term testing, the operator can perform measurements in a handheld manner, and the built-in battery of the scanner is used for power supply. For long-term deployment, it can be fixed in two independent ways, namely, a clip and a bracket, and powered by an external power supply.

[0056] The present invention can adopt different fixing methods and power supply methods. For short-term testing, the operator can measure by hand-held mode, and the built-in battery of the scanner is powered. For long-term deployment, it can be fixed by two independent methods, namely clips and brackets, and powered by an external power supply.

Claims

1. A portable scanner for power quality analysis and diagnosis, characterized by It includes a data acquisition module, an analysis and diagnosis software module, a main control chip, a power supply system, a display and input device, and an artificial intelligence expansion card; wherein, the signal output end of the data acquisition module is connected to the signal input end of the main control chip, and the main control chip is equipped with an analysis and diagnosis software module; the analysis and diagnosis software module performs relevant power quality analysis and diagnosis; the electrical output end of the power supply system is connected to the electrical input end of the main control chip, the first signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the display and input device, the second signal input and output end of the main control chip is correspondingly connected to the signal output and input end of the artificial intelligence expansion card, and the signal output end of the artificial intelligence expansion card is connected to the signal input end of the data acquisition module; the analysis and diagnosis software module performs relevant power quality analysis and diagnosis, and the relevant power quality analysis and diagnosis include frequency analysis, harmonic analysis, and three-phase imbalance analysis; The signal output end of the artificial intelligence expansion card is respectively connected to the signal input end of the frequency module, the signal input end of the harmonic module, and the signal input end of the three-phase imbalance module; the artificial intelligence expansion card includes an SD card and an artificial intelligence acceleration card; the artificial intelligence acceleration card adopts artificial intelligence AI expansion card technology to realize reference level adaptive measurement; the reference level adaptive measurement specifically includes the following steps: 1) Real-time grid voltage and current input; the real-time grid voltage and current input is specifically: the grid voltage and current signals are input into the data acquisition module via the portable scanner probe; 2) Data acquisition module identification processing: The data acquisition module identification processing is specifically: the grid voltage and current signals are recognized through the mutual inductor in the data acquisition module; 3) BP neural network algorithm training; the specific process of BP neural network algorithm training includes: first, inputting normalized voltage and current signal samples into the BP neural network; then initializing parameters, including: maximum number of iterations, learning accuracy, initial weights of hidden nodes, threshold, initial learning rate; then calculating the input and output values of each layer; finally calculating the output layer error ; 4) Determine the reference level; if it meets , then proceed to step 5. If it is not satisfied, modify the weight and threshold and return to step 3; is the error threshold; 5) Output the reference level value to the main control chip.

2. A portable scanner for power quality analysis and diagnosis according to claim 1, characterized in that The data acquisition module includes a frequency module, a harmonic module, and a three-phase imbalance module; the signal output end of the frequency module, the signal output end of the harmonic module, and the signal output end of the three-phase imbalance module are respectively connected to the signal input end of the main control chip.

3. A portable scanner for power quality analysis and diagnosis according to claim 2, characterized in that The frequency module includes a single-chip microcomputer, a mutual inductor, a low-pass filter circuit, a voltage follower, a band-pass filter circuit, and a comparator; wherein, the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the low-pass filter circuit, the signal output end of the low-pass filter circuit is connected to the signal input end of the voltage follower, the signal output end of the voltage follower is connected to the signal input end of the band-pass filter circuit, the signal output end of the band-pass filter circuit is connected to the signal input end of the comparator, the signal output end of the comparator is connected to the signal input end of the single-chip microcomputer, and the signal output end of the single-chip microcomputer is connected to the signal input end of the main control chip; the mutual inductor includes a voltage mutual inductor and a current mutual inductor.

4. A portable scanner for power quality analysis and diagnosis according to claim 2, characterized in that The harmonic module includes a mutual inductor, a signal conditioning circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the signal conditioning circuit, the signal output end of the signal conditioning circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductor includes a voltage mutual inductor and a current mutual inductor.

5. A portable scanner for power quality analysis and diagnosis according to claim 2, characterized in that The three-phase imbalance module includes a mutual inductor, a phase detection circuit, and an A / D converter; wherein the signal input end of the mutual inductor is connected to the signal output end of the artificial intelligence expansion card, the signal output end of the mutual inductor is connected to the signal input end of the phase detection circuit, the signal output end of the phase detection circuit is connected to the signal input end of the A / D converter, and the signal output end of the A / D converter is connected to the signal input end of the main control chip; the mutual inductors in the three-phase imbalance module are three groups, and each group of mutual inductors includes a voltage mutual inductor and a current mutual inductor.

6. A portable scanner for power quality analysis and diagnosis according to claim 1, characterized in that The frequency analysis includes measuring frequency. The frequency measurement process includes: the voltage, current and other values of the power grid are converted into analog electrical signals after passing through a mutual inductor, the analog electrical signals are filtered out of high-frequency components through a low-pass filter, and then the signals are isolated by a voltage follower. The fundamental component of the signal is extracted through a band-pass filter circuit, and a square wave signal is generated through a comparator and sent to a single-chip microcomputer for frequency calculation.

7. A portable scanner for power quality analysis and diagnosis according to claim 1, characterized in that The harmonic analysis includes measuring harmonics. The process of measuring harmonics includes: the voltage, current and other values of the power grid are converted into analog electrical signals after passing through a mutual inductor, and then more accurately converted through a signal conditioning circuit. That is, first, the harmonic voltage and current are high-frequency filtered to determine the measurement range, and then the DC component is isolated. Then, the filtered and isolated signals are amplified in multiple stages using an operational amplifier, and after A / D conversion by an A / D converter, they are output to the main control chip. The main control chip uses a fast Fourier transform algorithm to calculate the harmonics of the input signal.

8. A portable scanner for power quality analysis and diagnosis according to claim 1, characterized in that The three-phase imbalance analysis includes measuring the three-phase imbalance. The process of measuring the three-phase imbalance includes: using three sets of voltage transformers and current transformers to sample the three-phase voltage and current of the power grid, and then using a phase detection circuit to complete the detection of the three-phase phase. The detected result data is transmitted to the main control chip through an A / D converter. The main control chip reads the A / D conversion result and uses the symmetrical component method to calculate the three-phase voltage and current imbalance.

Images