A portable three-phase power quality field diagnosis method

Abstract

The application discloses a kind of portable three-phase power quality field diagnosis method, the application is first with 0.1~1Hz low-speed acquisition voltage, current signal of the three-phase alternating current loop to be measured, synchronous acquisition ambient temperature and complete phase shift compensation;Current waveform high-order statistical feature is extracted again to realize load type identification, corresponding power quality evaluation threshold is matched and core index is calculated, index is judged as power quality disturbance when threshold, generate local diagnosis prompt and trigger 3.2~12.8kHz high-speed sampling.High-speed sampling stage real-time detects communication link state, link is normal then real-time upload data, interrupt then data is cached to local storage, link recovers after breakpoint and completes supplement transmission;Diagnosis whole process carries out FIFO management to local storage capacity, and high-speed sampling data is preferentially retained.The application realizes local intelligent diagnosis and adaptive sampling, solves the problem that traditional equipment is poor in portability, has no local diagnosis capability, data is easy to lose, sampling strategy is rigid.

Description

Technical Field

[0001] This invention relates to a portable on-site diagnostic method for three-phase power quality. Background Technology

[0002] With the widespread integration of industrial automation and distributed energy, three-phase AC power quality monitoring is of great significance for ensuring the safe and stable operation of electrical equipment and achieving industrial energy conservation and energy efficiency management. Currently, power measurement devices are mainly divided into fixed-installation online monitoring equipment and laboratory-grade precision instruments. The former is costly and inconvenient to deploy, while the latter is bulky and lacks portability, making it difficult to meet the needs of rapid on-site inspections and mobile diagnostics.

[0003] To address the aforementioned issues, existing portable power measurement devices typically include a signal acquisition module, a power metering chip, a main control unit, and a wireless communication module. These devices non-invasively acquire three-phase voltage and current signals via current transformers. After processing by the power metering chip, the main control unit wirelessly uploads basic electrical parameters (such as voltage, current, and active power) to a remote platform, thus achieving, to a certain extent, portable measurement and remote monitoring of power parameters.

[0004] However, existing technical solutions still have the following technical shortcomings:

[0005] First, the functionality is limited, lacking local intelligent diagnostic capabilities. Existing devices only function as data acquisition and forwarding terminals, uploading raw sampled data or simple statistics to the cloud for centralized analysis. In scenarios lacking network coverage or requiring immediate fault location, the devices cannot locally identify the type of currently connected load (such as asynchronous motors, frequency converters, switching power supplies, etc.) based on current waveform characteristics, nor can they perform real-time comparison and diagnostic prompts for power quality evaluation thresholds for specific loads. This makes it difficult for maintenance personnel to quickly determine the cause of power quality problems, resulting in low diagnostic efficiency.

[0006] Second, there is a lack of data integrity assurance mechanisms. Portable application scenarios (such as underground power distribution rooms, remote outdoor equipment, and mobile vehicles) often face problems such as unstable or intermittent wireless network signals. Existing devices lack effective local data caching strategies when communication links are interrupted, resulting in the permanent loss of critical data in measurement blind spots; and there is no mechanism for resuming transmission after the link is restored, which cannot guarantee the continuity and data integrity of the monitoring time series.

[0007] Third, the sampling strategy is rigid, making it difficult to balance battery life and data accuracy. Most existing devices use a fixed sampling rate. While high-speed continuous sampling can capture short-term power quality disturbances, it leads to a surge in power consumption and rapid depletion of storage space, failing to meet the needs of long-term portable operation. On the other hand, if low-speed sampling is used to reduce power consumption, transient power quality events such as voltage drops and current surges are easily missed, failing to meet the needs of on-site fault tracing and detailed analysis. Summary of the Invention

[0008] This invention provides a portable on-site three-phase power quality diagnostic method to address the problems existing in the prior art. This invention enables local load type identification and real-time power quality diagnosis, possesses reliable data caching and resume capabilities during network interruptions, and employs an adaptive sampling strategy to balance battery life and event capture accuracy, thus overcoming the shortcomings of existing technologies.

[0009] The technical solutions adopted in this invention are as follows:

[0010] A portable on-site diagnostic method for three-phase power quality, based on a portable terminal integrating a signal acquisition module, a power metering chip, a main control unit, a local storage unit, and a wireless communication module, includes the following steps:

[0011] S1: The main control unit control signal acquisition module is connected to the three-phase AC circuit under test, and the three-phase voltage and three-phase current waveform data of the circuit are acquired in real time at the first sampling rate;

[0012] S2: The main control unit extracts high-order statistical features based on the acquired current waveform, and identifies the type of the currently connected load based on the high-order statistical features;

[0013] S3: The main control unit matches the corresponding power quality evaluation threshold according to the identified load type, calculates the current power quality index, and determines whether the power quality index exceeds the threshold. If it exceeds the threshold, it determines that there is a power quality disturbance, generates a local diagnostic prompt, and triggers a high-speed sampling control command.

[0014] S4: The main control unit responds to the high-speed sampling control command and controls the power metering chip to collect the three-phase current waveform data of the circuit at a second sampling rate;

[0015] S5: The main control unit detects the communication link status of the wireless communication module. If the communication link is normal, the three-phase current waveform data collected at the second sampling rate is uploaded to the remote platform in real time. If the communication link is interrupted, the three-phase current waveform data collected at the second sampling rate is written to the local storage unit and the link recovery status is continuously monitored. After the communication link is restored, the data cached in the local storage unit is retransmitted to the remote platform.

[0016] Furthermore, the signal acquisition module includes a voltage transformer, a current transformer, and a signal conditioning circuit. The voltage transformer and the current transformer are used for non-invasive coupling to the three-phase AC circuit under test.

[0017] Furthermore,

[0018] The first sampling rate is 0.1 Hz to 1 Hz;

[0019] The second sampling rate is from 3.2 kHz to 12.8 kHz.

[0020] Furthermore, the higher-order statistical features include current waveform peak factor, peak factor, total harmonic distortion rate, and waveform asymmetry.

[0021] Furthermore, the load types include linear resistive loads, asynchronous motor loads, variable frequency speed control loads, and switching power supply loads.

[0022] Furthermore, the power quality indicators include total harmonic distortion of current, power factor, voltage deviation, and three-phase imbalance.

[0023] Furthermore, the local diagnostic prompts include a load type identifier, an over-threshold indicator name, and recommended maintenance measures.

[0024] Furthermore, the power quality disturbance includes one of the following situations: a voltage drop exceeding 10% of the rated voltage, a current surge exceeding 50% of the rated current, or a power factor change exceeding 0.1.

[0025] Furthermore, the main control unit detects the communication link status by periodically sending heartbeat packets and monitoring response signals, or by detecting whether the wireless signal strength indicator value is lower than a preset threshold.

[0026] Furthermore, when the remaining capacity of the local storage unit is lower than a preset capacity threshold, the main control unit prioritizes retaining the waveform data acquired at the second sampling rate and overwrites the earliest stored sampling data at the first sampling rate.

[0027] Furthermore, the portable terminal also includes a temperature sensor. The main control unit acquires the ambient temperature data collected by the temperature sensor and performs phase error compensation on the voltage and current signals acquired by the signal acquisition module based on the temperature-phase drift compensation model.

[0028] Furthermore, the portable terminal also includes a display module, and the main control unit outputs the local diagnostic prompts to the display module in real time for visualization.

[0029] Furthermore, the main control unit monitors the storage status of the local storage unit. When the storage space is insufficient, it adopts a first-in-first-out strategy to overwrite historical data in order to store waveform data acquired at the new second sampling rate.

[0030] The present invention has the following beneficial effects:

[0031] (1) By identifying the load type and matching the corresponding power quality evaluation threshold locally based on the high-order statistical features of the current waveform, local diagnostic prompts can be generated for the power quality status of a specific load without relying on real-time communication with the cloud, thus improving the timeliness of on-site fault location.

[0032] (2) When power quality disturbances are detected, the event triggering mechanism switches to the second sampling rate to collect waveform data. The data is uploaded in real time when the communication link is normal, written to the local storage unit cache when interrupted, and retransmitted after recovery. This reduces the loss of key data due to network instability or signal blind spots and ensures the integrity and continuity of the monitoring time series.

[0033] (3) By distinguishing the usage scenarios of the first sampling rate and the second sampling rate, the system power consumption and storage resource occupation are reduced by sampling at a lower frequency during non-disturbance periods, and waveform details are captured by sampling at a higher frequency during disturbance periods. While meeting the battery life requirements of portable terminals, the ability to trace short-term power quality events is retained.

[0034] (4) By monitoring the ambient temperature through a temperature sensor and compensating for the phase error of the acquired signal based on the temperature-phase drift compensation model, the phase drift error of the transformer caused by the temperature change of the portable working environment is reduced, and the accuracy of power quality index calculation under complex working conditions is improved. Attached Figure Description

[0035] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] This invention provides a portable on-site diagnostic method for three-phase power quality, which is based on a portable terminal integrating a signal acquisition module, a power metering chip, a main control unit, a local storage unit, a wireless communication module, a temperature sensor, and a display module.

[0038] The signal acquisition module is equipped with a ZMPT107-1 voltage transformer and a ZMCT103C current transformer.

[0039] The power metering chip uses the ATT7022 high-precision dedicated chip;

[0040] The main control unit is an STM32F103ZET6 chip;

[0041] The wireless communication module selected is the ESP8266 WIFI module;

[0042] The temperature sensor uses a DS18B20 single-bus digital sensor;

[0043] The local storage unit is a W25Q64 series non-volatile FLASH memory chip;

[0044] The display module is a TFT high-definition touch LCD screen.

[0045] Each module is electrically connected to the main control unit, which completes the overall command issuance, data interaction, and logic processing. The power metering chip and the main control unit achieve high-speed data interaction via SPI communication. The wireless communication module and the main control unit complete command and data transmission via serial communication. The communication baud rate can be flexibly configured according to on-site requirements. The voltage transformer and current transformer convert the current signal into a weak voltage signal adapted to the input of the power metering chip through 11Ω and 10Ω sampling resistors, respectively, laying the hardware foundation for subsequent signal acquisition and processing.

[0046] The voltage and current transformers of the signal acquisition module are connected to the three-phase AC circuit under test through a non-intrusive coupling method. The matching signal conditioning circuit can perform filtering, amplification, differential conversion and other processing on the raw electrical signals acquired by the transformers, so that the processed signals are accurately adapted to the input specifications of the power metering chip.

[0047] The local storage unit has a storage capacity of 64MB and supports data retention even when power is off, enabling reliable caching of sampled data. The wireless communication module uses WIFI communication as its core, enabling bidirectional data transmission with the remote monitoring platform. The temperature sensor has an acquisition accuracy of ±0.5℃, which can accurately acquire the ambient temperature of the portable terminal in real time. The display module can visualize various electrical parameters, waveform data, load types, and diagnostic prompts. The power metering chip has the basic functions of three-phase electrical signal acquisition, processing, and preliminary calculation of power quality indicators. It can accurately identify core indicators such as total harmonic distortion and power factor. Each hardware module works together based on its own characteristics to form a stable hardware support system, realizing portable on-site diagnosis of the power quality of the three-phase AC circuit under test.

[0048] Combination Figure 1In actual field diagnostic operations, the main control unit first outputs control commands to schedule the signal acquisition module to non-intrusively couple the voltage transformer and current transformer into the three-phase AC circuit under test. Under the unified control of the main control unit, the signal acquisition module collects the three-phase voltage and three-phase current waveform data of the three-phase AC circuit under test in real time at the first sampling rate. The first sampling rate can be flexibly configured in the range of 0.1Hz to 1Hz according to the endurance requirements of the field operation.

[0049] Simultaneously with signal acquisition, the temperature sensor continuously collects the ambient temperature of the portable terminal's operating environment and transmits the collected ambient temperature data to the main control unit in real time via a single bus. After receiving the raw voltage and current signals transmitted by the signal acquisition module, the main control unit immediately calls the pre-stored temperature-phase drift compensation model. Based on the ambient temperature data collected by the temperature sensor, it performs phase error compensation on the raw voltage and current signals. Specifically, according to the current ambient temperature value, it matches the phase drift correction coefficients of the voltage transformer and current transformer at that temperature, which are pre-calibrated in the compensation model. The correction coefficients are then used to accurately correct the phase parameters of the voltage and current signals, eliminating the measurement error caused by the phase drift of the transformers due to changes in the ambient temperature, and further improving the accuracy of electrical signal acquisition.

[0050] The main control unit performs high-order statistical feature extraction processing on the three-phase current waveform data after phase error compensation. The extracted high-order statistical features specifically include current waveform peak factor, peak coefficient, total harmonic distortion rate, and waveform asymmetry.

[0051] The peak factor is the ratio of the peak value to the effective value of the current waveform, the crest coefficient is the ratio of the peak value to the average value of the current waveform, the total harmonic distortion rate is obtained by performing a Fourier transform on the current waveform to complete harmonic decomposition and then calculating it according to the calculation method specified in the national standard, and the waveform asymmetry is obtained by calculating the difference between the positive and negative half-waves of the current waveform. The power metering chip can assist the main control unit in completing the preliminary calculation of some harmonic data, effectively improving the efficiency of feature extraction.

[0052] After extracting the aforementioned high-order statistical features, the main control unit matches each extracted feature value with a pre-stored load feature threshold library. This load feature threshold library pre-stores threshold ranges for each of the four load types—linear resistive loads, asynchronous motor loads, variable frequency speed control loads, and switching power supply loads—based on the power consumption characteristics of common three-phase loads in industrial sites. By matching and comparing the real-time extracted feature values ​​with the threshold ranges of each load type, the main control unit accurately identifies the load type connected to the current three-phase AC circuit under test. The identified load type result is transmitted to the display module for visualization in real time and simultaneously stored in the local storage unit for subsequent data traceability and retrieval.

[0053] After identifying the load type, the main control unit matches the corresponding exclusive power quality evaluation threshold from the locally stored power quality evaluation threshold library based on the identification result. The power quality evaluation threshold library presets reasonable threshold ranges for four core power quality indicators, namely total harmonic distortion rate, power factor, voltage deviation, and three-phase imbalance, according to the power consumption characteristics and quality requirements of different load types.

[0054] Based on the phase-compensated three-phase voltage and current waveform data, combined with the electrical parameter data collected by the power metering chip, the main control unit calculates the current values ​​of the above four power quality indicators in real time according to the calculation standards stipulated by the national standard. Then, it compares the current value of each indicator with the matched exclusive power quality evaluation threshold one by one to determine whether there is a power quality indicator exceeding the corresponding threshold. If it is determined that at least one indicator exceeds the corresponding threshold, it is further determined that there is a power quality disturbance in the three-phase AC circuit under test. The specific criteria for judging power quality disturbance are any one of the following: voltage drop exceeding 10% of rated voltage, current rise exceeding 50% of rated current, or power factor change exceeding 0.1.

[0055] After determining that there is a power quality disturbance in the circuit under test, the main control unit immediately generates a local diagnostic prompt. This local diagnostic prompt includes the currently identified load type identifier, the name of the power quality indicator that exceeds the threshold, and the corresponding equipment maintenance suggestions. The maintenance suggestions are pre-stored in the main control unit based on the common fault patterns and operation and maintenance experience of different load types. The main control unit matches the corresponding targeted suggestions to different over-threshold indicators and load types. After the local diagnostic prompt is generated, the main control unit will immediately output it to the display module for visualization, so that the on-site operation and maintenance personnel can view and grasp the fault situation in real time. At the same time, the main control unit will immediately generate and trigger a high-speed sampling control command to start the subsequent high-precision high-speed sampling process.

[0056] The main control unit responds in real-time to the triggered high-speed sampling control command, immediately sending a rate switching command to the signal acquisition module and the power metering chip. This commands the two components to work together, switching the data acquisition rate from the original first sampling rate to a second sampling rate. This second sampling rate can be flexibly configured within the range of 3.2kHz to 12.8kHz according to the severity of the power quality disturbances on site. The power metering chip itself supports high-speed synchronous sampling and can form a precise sampling coordination with voltage transformers and current transformers. At this sampling rate, the signal acquisition module and the power metering chip can perform high-precision, high-frequency real-time acquisition of the three-phase current waveform data of the tested three-phase AC circuit. This accurately captures the complete waveform details of transient power quality disturbances such as voltage drops and current surges, providing accurate and comprehensive waveform data support for subsequent fault tracing and detailed analysis.

[0057] During the acquisition process at the second sampling rate, the temperature sensor continues to collect the ambient temperature. The main control unit continues to perform phase error compensation on the acquired current signal based on the temperature-phase drift compensation model. At the same time, the local storage unit will cache all waveform data acquired at this sampling rate in real time to avoid data loss from the source.

[0058] While acquiring three-phase current waveform data at the second sampling rate, the main control unit continuously monitors the communication link status between the wireless communication module and the remote platform in real time. This monitoring can be achieved in two ways: First, the main control unit controls the wireless communication module to send heartbeat packets to the remote platform at preset time intervals and monitors the platform's response signal in real time. If a response signal is received within the preset time, the link is considered normal; otherwise, it is considered interrupted. Second, the main control unit monitors the wireless signal strength indicator value of the wireless communication module in real time. If this value is higher than a preset threshold, the link is considered normal; otherwise, it is considered interrupted. The main control unit can flexibly switch between these two monitoring methods based on the on-site network environment.

[0059] If the main control unit detects that the communication link is normal, it immediately controls the wireless communication module to upload the three-phase current waveform data collected at the second sampling rate and after phase compensation to the remote platform in real time. The remote platform then performs further analysis, storage, and display of the data, achieving remote real-time monitoring of power quality. If the main control unit detects that the communication link is interrupted, it immediately controls the wireless communication module to stop uploading data to the remote platform, while simultaneously controlling the local storage unit to continuously write and cache the three-phase current waveform data collected at the second sampling rate. During this period, the main control unit continues to monitor the communication link recovery status of the wireless communication module at preset time intervals until it detects that the link has been restored. After the communication link is restored, the main control unit immediately controls the wireless communication module to completely retransmit all the three-phase current waveform data at the second sampling rate cached in the local storage unit to the remote platform according to the time acquisition sequence, ensuring the continuity and integrity of the power quality monitoring data time series in all aspects.

[0060] During the signal acquisition and data caching phase of the entire diagnostic process, the main control unit continuously monitors the remaining storage capacity of the local storage unit in real time. When the remaining capacity is detected to be lower than the preset capacity threshold, the main control unit immediately activates the storage optimization strategy, prioritizing the retention of waveform data acquired at the second sampling rate. Following the first-in-first-out principle, the earliest stored sampling data at the first sampling rate in the local storage unit is overwritten. If there is no sampling data at the first sampling rate in the local storage unit, the earliest stored waveform data at the second sampling rate is overwritten according to the first-in-first-out principle, ensuring that the local storage unit always reserves sufficient storage space for the latest transient power quality disturbance waveform data.

[0061] Meanwhile, the main control unit displays the remaining capacity status of the local storage unit on the display module in real time. When the remaining capacity falls below the capacity threshold, a capacity warning prompt is generated on the display module to promptly remind on-site maintenance personnel to process the stored data and prevent the loss of critical data due to insufficient storage capacity. Based on the above connection and operation mode, the various hardware modules, in conjunction with the software logic control of the main control unit, form a complete portable three-phase power quality on-site diagnostic system. This system enables accurate, efficient, and real-time diagnosis of the power quality of the three-phase AC circuit under test, providing reliable data support and decision-making basis for on-site maintenance work.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A portable on-site diagnostic method for three-phase power quality, based on a portable terminal integrating a signal acquisition module, a power metering chip, a main control unit, a local storage unit, and a wireless communication module, characterized in that: Includes the following steps: S1: The main control unit control signal acquisition module is connected to the three-phase AC circuit under test, and the three-phase voltage and three-phase current waveform data of the circuit are acquired in real time at the first sampling rate; S2: The main control unit extracts high-order statistical features based on the acquired current waveform, and identifies the type of the currently connected load based on the high-order statistical features; S3: The main control unit matches the corresponding power quality evaluation threshold according to the identified load type, calculates the current power quality index, and determines whether the power quality index exceeds the threshold. If it exceeds the threshold, it determines that there is a power quality disturbance, generates a local diagnostic prompt, and triggers a high-speed sampling control command. S4: The main control unit responds to the high-speed sampling control command and controls the power metering chip to collect the three-phase current waveform data of the circuit at a second sampling rate; S5: The main control unit detects the communication link status of the wireless communication module. If the communication link is normal, the three-phase current waveform data collected at the second sampling rate is uploaded to the remote platform in real time. If the communication link is interrupted, the three-phase current waveform data collected at the second sampling rate is written to the local storage unit and the link recovery status is continuously monitored. After the communication link is restored, the data cached in the local storage unit is retransmitted to the remote platform.

2. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The signal acquisition module includes a voltage transformer, a current transformer, and a signal conditioning circuit. The voltage transformer and the current transformer are used for non-invasive coupling to the three-phase AC circuit under test.

3. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The first sampling rate is 0.1 Hz to 1 Hz; The second sampling rate is from 3.2 kHz to 12.8 kHz.

4. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The higher-order statistical features include current waveform peak factor, peak factor, total harmonic distortion rate, and waveform asymmetry.

5. The portable three-phase power quality on-site diagnostic method as described in claim 1 or 4, characterized in that: The load types include linear resistive loads, asynchronous motor loads, variable frequency speed control loads, and switching power supply loads.

6. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The power quality indicators include total harmonic distortion of current, power factor, voltage deviation, and three-phase imbalance.

7. The portable three-phase power quality on-site diagnostic method as described in claim 1 or 6, characterized in that: The local diagnostic prompts include load type identifier, over-threshold indicator name, and recommended maintenance measures.

8. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The power quality disturbance includes one of the following situations: a voltage drop exceeding 10% of the rated voltage, a current surge exceeding 50% of the rated current, or a power factor change exceeding 0.

1.

9. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: The main control unit detects the communication link status by periodically sending heartbeat packets and monitoring response signals, or by detecting whether the wireless signal strength indicator value is lower than a preset threshold.

10. The portable three-phase power quality on-site diagnostic method as described in claim 1, characterized in that: When the remaining capacity of the local storage unit is lower than the preset capacity threshold, the main control unit prioritizes retaining the waveform data collected at the second sampling rate and overwrites the earliest stored sampling data at the first sampling rate.

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