An online calibration device for a three-phase electrical parameter analyzer

Abstract

This invention discloses an online calibration device for a three-phase electrical parameter analyzer, belonging to the field of calibration equipment technology. The calibration signal injection module is used to generate standard calibration voltages and currents for the three phases, and superimposes the standard calibration signals onto the voltage measurement channel and current measurement channel of the three-phase analyzer according to a predetermined timing sequence via a programmable solid-state relay. This invention achieves contactless switching injection of calibration signals through the calibration signal injection module, solving the problems of traditional offline calibration requiring power outages and low accuracy under simulated loads, enabling zero-downtime online calibration, supporting high-order harmonic scenarios, and improving accuracy.

Description

Technical Field

[0001] This invention relates to the field of calibration equipment technology, specifically to an online calibration device for a three-phase electrical parameter analyzer. Background Technology

[0002] Traditional three-phase electrical parameter analyzers mostly rely on offline calibration or simulated load comparison methods, which require manual intervention, result in long downtime, and lack sufficient calibration accuracy for complex operating conditions such as harmonic enrichment and unbalanced loads. During long-term operation, sensor drift, changes in ambient temperature and humidity, and component aging lead to the accumulation of measurement errors, seriously affecting the reliability and accuracy of power grid monitoring and energy management.

[0003] Patent CN107860953B discloses a three-phase power metering module and its calibration method. The above patent realizes the self-calibration of channels with deviations, thereby improving the measurement accuracy.

[0004] The aforementioned patents solve the problem of inaccurate measurements that may occur in existing three-phase power metering modules, and improve the measurement accuracy of three-phase power metering modules. However, the calibration of the three-phase power metering modules disclosed in the aforementioned patents relies on offline power outages or simulated load comparison methods, which require manual intervention and involve long downtime.

[0005] Therefore, this application proposes an online calibration device for a three-phase electrical parameter analyzer that enables contactless switching and injection of calibration signals. Summary of the Invention

[0006] The purpose of this invention is to provide an online calibration device for a three-phase electrical parameter analyzer, so as to solve the technical problems mentioned in the background art, which require power outages and have low accuracy in simulating loads.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an online calibration device for a three-phase electrical parameter analyzer, comprising a calibration signal injection module, a main measurement module, a calibration measurement module, a seamless switching control unit, and an adaptive compensation calculation unit. The calibration signal injection module is used to generate standard calibration voltage and current for three-phase signals, and to superimpose the standard calibration signals onto the voltage measurement channel and current measurement channel of the three-phase analyzer according to a predetermined timing sequence via a programmable solid-state relay.

[0008] The calibration signal injection module includes:

[0009] A set of three-phase DACs, each corresponding to a three-phase voltage calibration source;

[0010] A set of three-phase programmable current sources;

[0011] The output of each DAC and current source is connected to the channel under test via an SSR;

[0012] For high-order harmonic calibration scenarios, the DAC supports multi-frequency synthesis output mode.

[0013] Preferably, the adaptive compensation calculation unit is based on the least squares method and adaptive filtering algorithm, and uses the synchronously acquired data of the main measurement module and the calibration measurement module to calculate the gain error, bias error and phase error of each measurement channel in real time, and adjust the correction coefficient of the main measurement module.

[0014] The adaptive compensation calculation unit is implemented by a DSP processor, and its internal program modules include:

[0015] The data preprocessing module performs noise reduction and normalization on the collected raw data;

[0016] The error identification module identifies channel gain and bias error based on the least squares method.

[0017] Adaptive filtering module, dynamically filters out measurement noise and environmental drift;

[0018] The correction coefficient update module writes the calculated correction coefficients into the coefficient storage area of ​​the main measurement module in real time.

[0019] Preferably, the seamless switching control unit is used to perform millisecond-level switching between the main measurement module and the calibration measurement module to ensure that the continuity of the main measurement data is not affected during the injection of calibration signals;

[0020] The seamless switching control unit is composed of an FPGA and a high-speed analog switch array, with a switching delay of ≤3ms, and performs closed-loop self-checks on timing and channel status before and after each switching.

[0021] Preferably, the main measurement module is electrically connected to the input terminal of the three-phase electrical parameter analyzer, and is used to collect the three-phase voltage and current of the circuit under test, as well as the active power, reactive power, and power factor parameters calculated therefrom.

[0022] Preferably, the calibration measurement module is electrically connected to the calibration signal injection module, and is used to acquire the injected standard calibration signal and output the corresponding measurement value during calibration.

[0023] Preferably, the calibration device further includes a phase-locked loop (PLL) module for automatically tracking the fundamental phase and frequency of the power grid, so that the phase and frequency of the calibration signal are in phase and frequency with the power grid under test.

[0024] The phase-locked loop (PLL) module includes a digital phase-locked algorithm and a hardware loop filter, with phase error controlled within ±0.005 degrees and frequency tracking accuracy reaching ±0.001Hz.

[0025] Preferably, the calibration device further includes a remote communication and cloud comparison module, which is used to upload historical calibration data, real-time calibration results and device status to the cloud via the network, and receive calibration algorithms and firmware upgrade packages sent from the cloud;

[0026] The cloud-based comparison module integrates a big data statistical learning engine on the cloud platform. By performing machine learning on the historical calibration records of multiple devices of the same model, it generates cross-batch calibration models and synchronously distributes the models to the on-site calibration devices to optimize local adaptive compensation.

[0027] Preferably, the calibration device further includes an electromagnetic compatibility (EMC) design unit, which includes a metal shielding isolation layer, multi-layer PCB partitions, and a common-mode filter to suppress external electromagnetic interference and reduce the interference of injected signals on the signal under test.

[0028] The electromagnetic compatibility (EMC) design unit specifically includes:

[0029] A grounding isolation shield is installed inside the casing to physically isolate calibration and measurement;

[0030] All high-frequency signal lines and power measurement lines are double-braided aluminum foil shielded.

[0031] Common-mode and differential-mode filters and surge suppressors are configured at both the power inlet and the injection channel inlet.

[0032] Preferably, the calibration device further includes a dynamic calibration frequency scheduling unit, which is used to intelligently adjust the calibration interval, calibration signal amplitude and calibration duration according to load current fluctuations and changes in ambient temperature and humidity, so as to obtain the optimal calibration effect under different operating conditions.

[0033] Preferably, the mechanical structure of the calibration device adopts a modular pluggable design, and all functional modules are connected through a transducer slot and a connector with hot-swap protection, so that on-site maintenance does not require interruption of system power.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. This invention achieves contactless switching injection of calibration signals through a calibration signal injection module, solving the problems of traditional offline calibration requiring power outages and low accuracy of simulated loads, realizing zero-downtime online calibration, supporting high-order harmonic scenarios, and improving accuracy;

[0036] 2. This invention achieves millisecond-level switching and closed-loop self-testing by switching control units, solving the problems of data interruption and large switching errors during calibration, ensuring the continuity of main measurement data during calibration, and eliminating errors introduced by switching;

[0037] 3. This invention uses an adaptive compensation calculation unit to identify and compensate for gain, bias and phase errors in real time, solving the problem of decreased measurement accuracy caused by long-term drift and environmental changes. It also dynamically updates the correction coefficients, automatically compensates for long-term drift, and improves the stability of measurement accuracy.

[0038] 4. This invention uses a cloud-based big data comparison and model distribution module to achieve cross-batch calibration data, solving the problem of poor consistency in calibration results between different batches of equipment, optimizing parameters and reducing maintenance costs. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the calibration process of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Please see Figure 1 This invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The adaptive compensation calculation unit, based on the least squares method and adaptive filtering algorithm, utilizes synchronously acquired data from the main measurement module and the calibration measurement module to calculate the gain error, bias error, and phase error of each measurement channel in real time, and adjusts the correction coefficients of the main measurement module. The adaptive compensation calculation unit is implemented by a DSP processor, and its internal program modules include: a data preprocessing module for denoising and normalizing the acquired raw data; an error identification module for identifying channel gain and bias errors based on the least squares method; an adaptive filtering module for dynamically filtering out measurement noise and environmental drift; and a correction coefficient update module for writing the calculated correction coefficients into the coefficient storage area of ​​the main measurement module in real time.

[0042] Furthermore, assume that a three-phase electrical parameter analyzer is monitoring a set of loads online, with an actual three-phase voltage of approximately 230V and a current of approximately 5A; in order to calibrate the A-phase channel, a calibration voltage signal with a known amplitude of 1V and a calibration current signal of 0.1A are superimposed on this channel;

[0043] The raw ADC value of phase A voltage acquired by the main measurement module is U. raw (n), the original ADC value of phase A current is I raw (n); The calibration measurement module simultaneously acquires the ADC value after superimposing the calibration signal, denoted as U. cal (n), I cal(n), sampling frequency f s =10kHz, synchronously acquire N=1024 points for a complete calibration calculation;

[0044] Noise reduction: for U raw (n), U cal (n), I raw (n), I cal (n) Apply Hamming windowing and then perform fast Fourier transform to remove harmonic components higher than 2kHz, and then perform inverse transform to obtain the time-domain cleaned signal;

[0045] Normalization: Divide the denoised voltage and current samples by their respective full-scale range to map them to the -1, 1 interval to obtain the normalized waveform;

[0046] Model assumptions: The main measurement channel corresponds to the true signal U true (n) There exists a linear gain error k and a bias error b, i.e., U' raw (n) = k·U true (n) + b; The signal obtained from calibration measurement approximates the true signal U. true (n), therefore, the calibration channel data is used as a reference;

[0047] Least squares estimation: constructing matrix equations

[0048]

[0049] Using the standard least squares formula

[0050]

[0051] Calculate the initial gain error k'-1 and bias error b' of phase A voltage channel.

[0052] The purpose of the adaptive filtering module is to further filter out environmental drift and measurement noise, making the error coefficient more stable.

[0053] Implementation: A first-order exponential smoothing filter k is used. new =α·k'+(1-α)·k old b new =α·b'+(1-α)·b old ;

[0054] Where α = 0.3, and k has been stored in the previous cycle. old =1.003、b old =0.0015, then k new =1.0036, b new =0.00165;

[0055] k new b new Through DSPI 2 The C interface writes the coefficient register to the main measurement module; after the update is complete, the main channel processes all subsequent sampled data according to U... corrected (n) = (U' raw (n)-b new ) / k new Perform real-time correction output.

[0056] Please see Figure 1 This invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The calibration signal injection module generates standard calibration voltages and currents for the three phases and superimposes these standard calibration signals onto the voltage and current measurement channels of the three-phase analyzer via programmable solid-state relays (SSRs) according to a predetermined timing sequence. The calibration signal injection module includes: a set of three-phase DACs, each corresponding to a three-phase voltage calibration source; a set of three-phase programmable current sources; the output terminals of each DAC and current source are connected to the channel under test via an SSR; for high-order harmonic calibration scenarios, the DACs support multi-frequency synthesis output mode.

[0057] Furthermore, a multi-channel DAC (such as AD5766) with 16-bit resolution and a 100kS / s update rate was selected, and the three voltage calibration channels were respectively controlled by the DAC. A DAC B DAC C Provides an amplitude range of 0-5V corresponding to a nominal mains voltage of 0-300V; uses a linear constant current source chip (such as TI OPA462 driving an external power resistor array), with a current output range of 0-1A. The target current setpoint is sent to the current source DAC via the SPI bus on the microcontroller (MCU); each DAC and current source output are connected in series with an SSR (such as Panasonic AQW214EH) for switching with the measured channel. The SSR drive signal is controlled by the FPGA and provided to each relay after opto-isolation to ensure electrical isolation between the measurement and injection circuits; the core uses an FPGA (such as Xilinx Spartan-7) and is implemented through internal logic.

[0058] The injection timing is calibrated to an accuracy of 1 μs.

[0059] The SSR drive pulse is synchronized with the DAC output.

[0060] Output waveform distortion detection and protection.

[0061] The DAC has a built-in multiplexer that can simultaneously output a superimposed signal of the fundamental frequency and higher harmonics; for example, it can generate a 50Hz fundamental frequency + 5kHz fifth harmonic combination: V out(t) = V1sin(2π·50t) + V5sin(2π·250t), corresponding SPI command configuration register, set the amplitude coefficient of each harmonic;

[0062] Output filtering: A 10μH coil and a 0.1μF ceramic capacitor are connected in parallel at the output terminals of the DAC and SSR to form an LC filter to suppress switching transient spikes;

[0063] Distortion detection: The voltage is divided by the differential sampling resistor before the DAC output and fed back to the ADC in the FPGA. The output amplitude and phase are monitored in real time. When the output exceeds the preset threshold, the injection is automatically interrupted and a fault is reported.

[0064] Please see Figure 1 This invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The seamless switching control unit performs millisecond-level switching between the main measurement module and the calibration measurement module to ensure the continuity of the main measurement data is unaffected during calibration signal injection. The seamless switching control unit is composed of an FPGA and a high-speed analog switch array, with a switching delay ≤3ms, and performs closed-loop self-checks on timing and channel status before and after each switching. The main measurement module is electrically connected to the input terminal of the three-phase electrical parameter analyzer and is used to acquire the three-phase voltage and current of the circuit under test, as well as the active power, reactive power, and power factor parameters calculated therefrom. The calibration measurement module is electrically connected to the calibration signal injection module and is used to acquire the injected standard calibration signal during calibration and output the corresponding measurement value.

[0065] Furthermore, the high-speed analog switch array employs 8-channel double-pole double-throw analog switches. Each phase voltage and current line is controlled by two sets of switch arrays: the main channel switch group is normally closed to the main measurement module; the calibration channel switch group is normally open, receiving signals after calibration injection. The FPGA receives the calibration cycle signal, generates a switching preparation pulse, and before the FPGA commands the analog switches to open, it reads the status feedback pins of the main channel and calibration channel to confirm that all switches are in a ready-to-switch, controllable state and there are no fault alarms. The FPGA drives the analog switch control pins, simultaneously opening the main channel switch and closing the calibration channel, with a switching delay of 1.8ms. During this period, the FPGA suppresses the output of the upper-level measurement algorithm to avoid misreading. The FPGA reads the status feedback of each switch again to confirm that the main and calibration channels have switched successfully and that there are no short circuits or open circuits in any line. If the self-test fails, the fault isolation logic is immediately triggered: the system returns to the main channel, local calibration is disabled, and the fault event is recorded.

[0066] The main measurement module is connected to a 24-bit Δ-Σ ADC via a high-precision voltage divider network with a sampling rate of 10kHz. It employs a current transformer and a precision sampling resistor, followed by the 24-bit Δ-Σ ADC with a sampling frequency of 10kHz. The FPGA handles real-time synchronization of the FIFO buffer, from which the DSP reads data and calculates: Active power: P = ΣUn I n cosφ; Reactive power: Q=ΣU n I n sinφ; Power factor: cosφ is obtained by phase difference measurement; The calculation result is transmitted to the main control MCU through the SPI interface, and then the MCU uploads it to the cloud or displays it locally;

[0067] After the calibration measurement module analog switch is switched, the calibration module is connected to the same sampling channel and ADC hardware as the main measurement. The FPGA simultaneously caches the data of the calibration channel to a dedicated calibration FIFO within the calibration window. The DSP reads the FIFO in the adaptive compensation calculation unit and processes it in parallel with the main channel data for error identification and coefficient calculation. When the calibration measurement channel is switched off, the FPGA first cuts off the ADC sampling trigger and then switches the switch to ensure a glitch-free power-on.

[0068] Please see Figure 1 This invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The calibration device further includes a phase-locked loop (PLL) module for automatically tracking the fundamental phase and frequency of the power grid, ensuring that the phase and frequency of the calibration signal are in phase and frequency with the measured power grid. The PLL module includes a digital phase-locked algorithm and a hardware loop filter, controlling the phase error within ±0.005 degrees and achieving a frequency tracking accuracy of ±0.001Hz. The calibration device also includes a remote communication and cloud comparison module for uploading historical calibration data, real-time calibration results, and device status to the cloud via a network, and receiving calibration algorithms and firmware upgrade packages from the cloud. The cloud comparison module integrates a big data statistical learning engine on the cloud platform, performing machine learning on historical calibration records of multiple devices of the same model to generate cross-batch calibration models, and synchronously distributing these models to the on-site calibration device to optimize local adaptive compensation.

[0069] Furthermore, the digital signal processing unit uses a DSP shared with the adaptive compensation, with a built-in high-speed fixed-point arithmetic unit for executing the phase-locked loop algorithm; the analog loop filter uses a second-order active filter with a cutoff frequency of 10Hz to balance speed and suppress high-frequency noise, and low-noise operational amplifiers are selected as key components to ensure that the filter phase error is <0.01°; the phase detector internally implements digital phase detection: the input fundamental signal under test is compared with the local reference signal of the PLL.

[0070] At startup, the DSP reads multi-cycle grid voltage samples from the ADC to quickly estimate the fundamental phase and frequency. Each main loop executes: Phase error calculation: Δφ(n) = φgrid(n) - φPLL(n); Loop filtering: Among them, K p K i Derived from bandwidth design, Ts =100μs; Reference phase update: φPLL(n+1) = φPLL(n) + 2Π(f0 + e(n))T s Where f0 = 50Hz;

[0071] Phase error control: After loop parameter tuning, the steady-state phase error |Δφ| ≤ 0.005°; Frequency tracking: Tracking within 10ms during ±0.1Hz sudden changes, with a steady-state accuracy of ±0.001Hz; The DSP sends the value of φPLL(n) that is the same as the required fundamental phase to the DAC, driving the calibration signal to be in phase and frequency with the power grid, and the higher harmonic components are superimposed on this reference phase.

[0072] Please see Figure 1 This invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The calibration device further includes an electromagnetic compatibility (EMC) design unit, which comprises a metal shielding layer, multi-layer PCB partitions, and common-mode and differential-mode filters to suppress external electromagnetic interference and reduce interference from injected signals to the measured signal. Specifically, the EMC design unit includes: a grounded isolation shielding plate inside the housing to physically isolate calibration from measurement; double-layer braided aluminum foil shielding for all high-frequency signal lines and power measurement lines; and common-mode and differential-mode filters and surge suppressors at both the power inlet and the injection channel inlet.

[0073] Furthermore, the outer casing is made of aluminum alloy profile with an anodized surface treatment, which provides both good conductivity and shielding performance as well as corrosion resistance and durability; Grounding isolation shielding plate: A stainless steel shielding plate is vertically installed in the center of the chassis, with calibration modules and measurement modules installed on both sides respectively. The two ends of the plate are fastened to the chassis shell with M4 conductive bolts and connected to the system grounding busbar through an independent grounding wire; The front compartment (measurement area) and the rear compartment (calibration area) are electrically isolated, and the front and rear compartments are only connected through a filtered differential signal and control signal channel;

[0074] Double-braided aluminum foil shielded cable: Each high-frequency signal line and power measurement line uses a double-braided + aluminum foil composite shield.

[0075] The inner braided copper mesh is attached to the outside of the insulation layer; the outer aluminum foil strip covers the copper mesh and is welded to the overall shielding aluminum shell at the circuit end; the shielding layer is grounded at one end and open at the other end to prevent loop current interference;

[0076] Common-mode and differential-mode filtering and surge suppression: Power input filtering is connected in parallel at the device power input line.

[0077] Common-mode inductor (DL=2mH, two-phase) to suppress common-mode interference;

[0078] Y capacitor (0.1μF / 275VAC), two phases to ground;

[0079] Differential mode inductance (2mH), phase-to-phase;

[0080] X capacitor (0.01μF / 250VAC), phase-to-phase;

[0081] MOV surge absorber (MOV-14D471K), clamping voltage ~300VAC, protects against overvoltage surges;

[0082] Each phase injection channel inlet is configured with a calibration channel inlet filter:

[0083] A common-mode choke (1mH) with a 50Ω damping network is used to suppress high-frequency common-mode noise.

[0084] Differential-mode Π-type filter: 10μF ceramic capacitors at both ends, and 100μF differential-mode inductor in the middle;

[0085] Transient voltage suppression diode, clamping voltage ~400V, to prevent accidental high voltage surges;

[0086] PCB layered design: 6-layer PCB is used.

[0087] Top layer - Analog signal layout; Power layer - High-power and filtering network; Ground layer - Complete continuous copper layer, with analog ground AGND and digital ground DGND respectively; Signal layer - Low-speed digital and control signals; Power return layer; Bottom layer - Calibration and measurement digital circuitry;

[0088] Zoned grounding: AGND and DGND are connected on the PCB only through a single-point grounding bus, and shielded isolation slots are used between analog and digital areas to reduce coupling.

[0089] Please see Figure 1 The present invention provides an embodiment of an online calibration device for a three-phase electrical parameter analyzer. The calibration device further includes a dynamic calibration frequency scheduling unit, which is used to intelligently adjust the calibration interval, calibration signal amplitude, and calibration duration according to load current fluctuations and changes in ambient temperature and humidity, so as to obtain the optimal calibration effect under different operating conditions. The mechanical structure of the calibration device adopts a modular pluggable design, and all functional modules are connected through a transducer slot and a connector with hot-swap protection, so that on-site maintenance does not require interruption of system power.

[0090] Furthermore, regarding temperature and humidity: a digital temperature and humidity sensor is selected, with a measurement range of -40℃ to +125℃, 0-100%RH, and an accuracy of ±1.5%RH / ±0.1℃; the RMS values ​​of the A / B / C three-phase currents from the autonomous measurement module are sampled, and the load fluctuation rate is calculated in real time.

[0091]

[0092] Where N corresponds to the data point 1 minute ago;

[0093] It uses an ARM Cortex-M7 with a built-in floating-point unit, which is responsible for the interface between the scheduling algorithm and the adaptive compensation control unit.

[0094] Scheduling algorithm flow:

[0095] The equipment is factory-calibrated with a reference calibration cycle T0=60s, a standard injection amplitude V0=1V / 0.1A, and a standard duration D0=500ms; temperature and humidity T are read every 30s. env H env and load volatility ΔI;

[0096] If T env >60℃ or H env If the value is greater than 85%, increase the calibration frequency T=max(T0 / 2, 30s);

[0097] Otherwise, if the environment is stable, T env -T ref <5℃ and |H env -H ref If | <10%, the period can be appropriately extended: T=min(T0×1.5, 120s);

[0098] If ΔI > 10%, it indicates a drastic change in load, requiring an increase in the injection amplitude and duration:

[0099] V=min (V0×1.2, 1.5V), D=min (D0×1.5, 800ms);

[0100] If ΔI < 2%, injection disturbances can be reduced:

[0101] V=max (V0×0.8, 0.5V), D=max (D0×0.8, 300ms);

[0102] The MCU sends the newly calculated T, V, D parameters to the FPGA and DAC current source module via SPI. After each calibration, the scheduling unit compares the main channel measurement variance before and after calibration. If the variance does not decrease significantly, the amplitude and duration will be increased by 10% next time.

[0103] Working principle: The system has a built-in high-precision three-phase DAC and a programmable current source. Through programmable solid-state relays, the known amplitude, same frequency and phase calibration voltage and current signals are superimposed on the measurement channels of each phase of the circuit under test to ensure the stability and repeatability of the injected signals.

[0104] The main measurement channel and calibration channel are switched at millisecond level using an FPGA and a high-speed analog switch array. Closed-loop self-test is performed before and after the switching moment to ensure continuous and uninterrupted data transmission. After the switching, the main measurement and calibration measurement channels acquire the same signal simultaneously, forming dual-channel parallel data.

[0105] The DSP uses the least squares method combined with an adaptive filtering algorithm to identify gain, bias, and phase errors in the data synchronously acquired by the main and calibration channels, and updates the correction coefficients in real time. It uses a PLL to ensure that the calibration signal is in phase and frequency with the fundamental frequency of the power grid, thus achieving accurate phase compensation.

[0106] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A three-phase electric parameter analyzer online calibration device, comprising a calibration signal injection module, a main measurement module, a calibration measurement module, a seamless switching control unit and an adaptive compensation calculation unit, characterized in that: The calibration signal injection module is used to generate standard calibration voltages and currents of three-phase signals, and superimposes the standard calibration signals on the voltage measurement channel and the current measurement channel of the three-phase analyzer according to a predetermined timing sequence through programmable solid-state relays; The calibration signal injection module comprises: a set of three-phase DACs corresponding to three-phase voltage calibration sources respectively; a set of three-phase programmable current sources; the output ends of each DAC and current source are connected to the measured channel through SSRs; For high harmonic calibration scenarios, the DAC supports multi-frequency synthesis output mode; The adaptive compensation calculation unit uses the synchronous acquisition data of the main measurement module and the calibration measurement module to calculate the gain error, bias error and phase error of each measurement channel in real time based on the least square method and the adaptive filtering algorithm, and adjusts the correction coefficient of the main measurement module; The adaptive compensation calculation unit is realized by a DSP processor, and the internal program modules comprise: a data preprocessing module for denoising and normalizing the acquired original data; an error identification module for identifying the channel gain and bias error based on the least square method; an adaptive filtering module for dynamically filtering measurement noise and environmental drift; a correction coefficient updating module for writing the calculated correction coefficient into the coefficient storage area of the main measurement module in real time; The seamless switching control unit is used to perform millisecond-level switching between the main measurement module and the calibration measurement module to ensure the continuity of the main measurement data during the injection of the calibration signal is not affected; The seamless switching control unit is composed of FPGA and high-speed analog switch array, and the switching delay is ≤3ms, and the timing and channel state are closed-loop self-checked before and after each switching.

2. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The main measurement module is electrically connected with the input end of the three-phase electric parameter analyzer, and is used to acquire the three-phase voltage, current and active power, reactive power and power factor parameters calculated therefrom of the to-be-measured line.

3. The device for online calibration of a three-phase electric parameter analyzer according to claim 1, characterized in that: The calibration measurement module is electrically connected with the calibration signal injection module, and is used to acquire the injected standard calibration signal and output the corresponding measurement value during calibration.

4. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The calibration device further comprises a phase-locked loop (PLL) phase-locked module for automatically tracking the fundamental wave phase and frequency of the power grid, so that the phase and frequency of the calibration signal are the same as those of the measured power grid. The phase-locked loop (PLL) phase-locked module comprises a digital phase-locked algorithm and a hardware loop filter, and the phase error is controlled within ±0.005 degrees, and the frequency tracking accuracy reaches ±0.001 Hz.

5. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The calibration device further comprises a remote communication and cloud comparison module for uploading historical calibration data, real-time calibration results and equipment states to the cloud through a network, and receiving calibration algorithms and firmware upgrade packages issued by the cloud; The cloud comparison module integrates a big data statistical learning engine on the cloud platform, learns the historical calibration records of multiple devices of the same type, generates a cross-batch correction model, and synchronously issues the model to the on-site calibration device to optimize the local adaptive compensation.

6. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The calibration device further comprises an electromagnetic compatibility (EMC) design unit, which comprises a metal shielding isolation layer, a multi-layer PCB partition and a common differential mode filter to suppress external electromagnetic interference and reduce the interference of the injected signal on the measured signal. The EMC design unit specifically comprises: A ground isolation shielding plate is arranged in the shell to physically separate the calibration from the measurement; All high-frequency signal lines and power measurement lines are shielded by double-layer braided aluminum foil; A common-mode and differential-mode filter and a surge suppressor are configured at the power inlet and the injection channel inlet.

7. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The calibration device further comprises a dynamic calibration frequency scheduling unit, which is configured to intelligently adjust a calibration interval, a calibration signal amplitude and a calibration duration according to load current fluctuation and environmental temperature and humidity change, so as to obtain optimal calibration effect under different working conditions.

8. The on-line calibration device for a three-phase electric parameter analyzer according to claim 1, characterized in that: The mechanical structure of the calibration device adopts a modular plug-in design, and all functional modules are connected through a standardized plug-in slot and a connector with hot plug protection, so that on-site maintenance does not need to interrupt the system power supply.

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