Wide range current measurement dynamic compensation method and system for excitation system testing

Abstract

This invention discloses a wide-range current measurement dynamic compensation method and system for excitation system testing, belonging to the technical field of excitation system technology. This invention acquires the temperature of key chips in the signal conditioning module in real time, dynamically calculates zero-point offset and actual gain based on factory calibration parameters, performs digital filtering and noise reduction on the acquired voltage signal, and uses a single-iteration approximation method to complete initial current estimation and nonlinear correction, achieving full-range dynamic error compensation. The system includes a signal conditioning and acquisition module, a temperature acquisition module, a dynamic compensation processor, and an output module. This invention overcomes the shortcomings of traditional testing devices such as manual range switching, static calibration lag, and low accuracy at low currents. It can achieve continuous high-precision measurement over a wide range from milliamperes to tens of amperes, effectively suppressing temperature drift, noise, and nonlinear errors, significantly improving testing efficiency and stability, and is suitable for on-site maintenance and commissioning of hydropower station excitation systems.

Description

Technical Field

[0001] This invention relates to the field of excitation system technology, and specifically to a wide-range current measurement dynamic compensation method and system for excitation system testing. Background Technology

[0002] In the maintenance and commissioning of generator excitation systems, high-precision testing of small current characteristics (milliamperes to tens of amperes) is crucial for evaluating their control performance and stability. Currently, the widely used testing methods mainly rely on traditional manually operated testing instruments. To handle current measurement ranges spanning several orders of magnitude, operators must predict and manually switch the instrument's range based on experience. This process is not only inefficient but also causes measurement interruptions and data loss during switching, making it impossible to capture continuous dynamic processes. Furthermore, the measurement accuracy of traditional instruments is easily affected by environmental factors such as ambient temperature changes and circuit noise, resulting in non-negligible static errors and temperature drift in the measurement results, making it difficult to meet the higher requirements for refined testing and accurate condition diagnosis of excitation systems.

[0003] Several improved measurement techniques have been proposed, such as the paper "An Active Compensation Method for Current Transformers Based on Adaptive Principle," which proposes a closed-loop active compensation scheme for current transformers (CTs). This scheme utilizes a "similar inductor" with magnetic characteristics similar to the CT core to extract the excitation current, converts it into a compensation current via electronic circuitry, and injects it into the CT's compensation winding to offset errors. However, this method is complex, difficult to debug, and costly. Furthermore, its compensation effect is sensitive to component parameters and temperature changes, making it difficult to integrate into portable, integrated intelligent testing devices. Patent document CN112583314B discloses a dynamic characteristic measurement method and system for a doubly-fed generator excitation system, providing a field measurement scheme for the dynamic characteristics of a doubly-fed generator excitation system. By acquiring the generator stator voltage, current, and rotor position signals, and calculating the flux linkage angle and rotor position angle, the excitation voltage and current in a synchronous rotating coordinate system are finally obtained through coordinate transformation, which can then be used to analyze the dynamic characteristics during power disturbances. The accuracy and reliability of this method heavily depend on the accuracy of multiple front-end sensors, signal synchronization quality, and the accuracy of the coordinate transformation model. Therefore, this method cannot replace the direct, source-based high-precision measurement of the fundamental physical quantity of excitation current, and it is difficult to meet the need for precise milliampere-level diagnosis of minute current signals. Patent document CN121089835A discloses a low-power electromagnetic water meter system with dynamic excitation and self-calibration functions, which integrates dynamic excitation and self-calibration functions into a measurement system. It receives measurement signals through an embedded processor and optimizes excitation parameters in real time by combining environmental parameters such as temperature with cloud-based strategies. However, this calibration method is discrete, passive, and periodic. Between calibration cycles, the system cannot respond to or suppress real-time errors caused by drastic changes in ambient temperature, strong electromagnetic interference in the field, or instantaneous device drift. This "error generation first, then centralized calibration" mode is prone to persistent measurement deviations during calibration intervals, failing to achieve truly full-time, continuous, dynamic high-precision assurance, and is particularly unsuitable for dynamic testing processes of excitation systems requiring real-time accurate monitoring.

[0004] In summary, the common shortcoming of the aforementioned existing technologies lies in their failure to fundamentally recognize that the core obstacle to high-precision measurement of small currents (milliamperes to several amperes) in excitation systems is not a single, fixed source of error, but rather the physical phenomenon of error parameters dynamically changing with environmental factors (such as temperature and electromagnetic interference) and the signal's own characteristics (such as amplitude and frequency). This dynamic change means that traditional static factory calibration or discrete periodic calibration cannot track and compensate for instantaneous drift during the measurement process in real time. Especially in the small signal region, even a small zero-point drift or gain change can lead to significant relative errors. Therefore, to truly achieve high-precision continuous measurement over a wide range, especially in the small current range, it is necessary to establish a mechanism capable of sensing the dynamic environment in real time and synchronously correcting errors. This is precisely the starting point of this invention. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a dynamic compensation method and system for wide-range current measurement for excitation system testing. By constructing a real-time running "software compensation engine" that integrates temperature sensing and digital filtering, the original signal acquired by the wide-range measurement hardware is modeled and corrected online and dynamically, thereby achieving continuous, stable and high-precision measurement across the entire range.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A wide-range current measurement dynamic compensation method for excitation system testing includes: S1: Real-time acquisition and measurement of temperature values ​​of key components in the circuit. ; S2: Based on pre-stored calibration parameters, according to temperature value Dynamically calculate the zero-point offset voltage at the current temperature Compared with actual gain ; S3: Acquire the voltage signal conditioned by the programmable gain amplifier. It is then digitally filtered to extract the noise components. This will be used for subsequent compensation. S4: Using a single iteration calculation, first based on... 、 and Calculate the initial estimate of the current. Then input it into a predetermined nonlinear correction function. The calculations are performed to obtain a high-precision current value after dynamic compensation for zero-point, gain, temperature, and nonlinear errors. .

[0007] In step S2 above, dynamic calculation is achieved through the following error parameter model: ; ; in, , , , These are parameters obtained through factory calibration. This is a reference temperature.

[0008] In step S4 above, one iteration of calculation specifically includes: S4.1: Calculate the initial estimate : ; S4.2: Apply nonlinear correction to obtain the final value Ic[n]: ; in, This is the resistance value of the sampling resistor.

[0009] The aforementioned nonlinear correction function fnl(x) is a polynomial function, and its form is: ; in, , These are the nonlinear correction coefficients obtained through full-range calibration.

[0010] In step S3 above, the digital filtering is an adaptive notch filter, used to suppress power frequency harmonic interference.

[0011] The aforementioned programmable gain amplifier is automatically switched between ×1, ×10, ×100, and ×1000 ranges by the processor according to the amplitude of the current signal, thereby achieving normalized acquisition of wide-range signals.

[0012] The temperature value T mentioned above is acquired in real time by a high-precision digital temperature sensor mounted near a programmable gain amplifier or analog-to-digital converter chip.

[0013] The system using the above-described wide-range current measurement dynamic compensation method for excitation system testing includes: The signal conditioning and acquisition module, including sampling resistors, a programmable gain amplifier, and an analog-to-digital converter, is used to convert a wide-range excitation current signal into a digital voltage sequence. ; The temperature acquisition module is used to acquire the temperature value T of the key chip in the signal conditioning and acquisition module in real time; The dynamic compensation processor has a set of calibration parameters stored internally. It is configured to perform a dynamic compensation method, which includes at least the steps of digitally filtering the voltage signal, calculating the initial estimate of the current, and applying nonlinear correction.

[0014] The aforementioned analog-to-digital converter is a 24-bit Σ-Δ type analog-to-digital converter, i.e., a summation-increment type analog-to-digital converter.

[0015] The aforementioned dynamic compensation processor is an embedded microprocessor or a field-programmable gate array.

[0016] The system described above also includes a human-computer interaction and output module for displaying, storing, or communicating compensated high-precision current data. .

[0017] The computer-readable storage medium using the above-described wide-range current measurement dynamic compensation method for excitation system testing stores a computer program that, when executed by a processor, implements the steps of the wide-range current measurement dynamic compensation method.

[0018] An electronic device using the above-described dynamic compensation method for wide-range current measurement for excitation system testing includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the dynamic compensation method for wide-range current measurement.

[0019] The wide-range current measurement dynamic compensation method and system for excitation system testing mentioned in this invention have the following beneficial effects: 1. This invention achieves hardware simplification, easy integration, and cost reduction. It overcomes the problems of traditional active compensation schemes, which rely on complex analog circuits and special magnetic components, resulting in circuit complexity, difficult debugging, high cost, and difficulty in integration. This invention abandons the hardware compensation approach, replacing it with a dynamic compensation model based on programmable devices and digital algorithms. Temperature drift, nonlinear errors, etc., are calculated and corrected in real time by software algorithms, eliminating the need for precision analog compensation circuits and special hardware such as "similar inductors." This makes the compensation core an embeddable software module, greatly simplifying hardware design, reducing manufacturing costs and debugging barriers, and enabling easy integration into portable, integrated, multi-functional excitation testing devices, thus improving the equipment's engineering practicality and market competitiveness.

[0020] 2. This invention achieves direct, source-based, high-precision measurement of excitation current. It solves the problems of error accumulation and inability to meet the requirements for direct and accurate diagnosis of minute currents caused by indirect measurement methods. This invention uses a high-precision sampling resistor and a ΣΔADC to directly sample the excitation current, obtaining the original signal from its physical source. Subsequently, a dynamic compensation algorithm corrects the inherent errors in the signal link. Because the entire compensation process is based on directly sampled data and a precise error model, rather than relying on indirect calculations from multiple external sensor signals, secondary error accumulation is avoided. Therefore, high-precision absolute measurement accuracy can be achieved across the entire measurement range, especially in the milliampere-level weak current range, providing a reliable data foundation for the refined diagnosis of excitation systems.

[0021] 3. Achieved real-time accuracy assurance across the entire time domain and continuous dynamics. It overcomes the "calibration gap" inherent in periodic calibration modes, solving the problem of being unable to suppress errors that change in real time. This invention pioneers a real-time online dynamic compensation mechanism, continuously monitoring environmental conditions through a temperature sensor and dynamically updating error parameters. The compensation algorithm, as part of the signal processing flow, is synchronized with each data acquisition execution, enabling immediate response to errors caused by temperature changes, noise interference, etc. This "measurement-as-compensation" mode transforms traditional discrete, passive calibration into continuous, active, real-time correction, completely eliminating measurement deviations within the calibration cycle. It ensures that measurement accuracy remains at the highest level throughout the entire testing process, meeting the stringent real-time requirements of dynamic testing of excitation systems.

[0022] 4. Improved testing efficiency and automation. Because the algorithm automatically handles range switching and complex error compensation, operators no longer need to manually switch instrument settings, record data, or perform offline calibration during testing. The entire testing process can be completed with a single click, automatically outputting compensated, high-precision results. This significantly reduces operational complexity and reliance on personnel experience, substantially shortening the time for a single comprehensive test (e.g., from several hours to tens of minutes), and greatly improving the efficiency of on-site maintenance and testing. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the wide-range current measurement dynamic compensation method for excitation system testing according to the present invention. Detailed Implementation

[0024] To better understand the purpose, system architecture, and functional implementation of this embodiment, the embodiments and features in the embodiments of this application can be combined with each other without conflict. The exemplary embodiments disclosed in this application will be described below with reference to the accompanying drawings, which include specific technical details disclosed in this embodiment to aid understanding; however, these details should be considered exemplary rather than restrictive. Therefore, those skilled in the art should understand that various improvements and adjustments can be made to the embodiments described herein without departing from the scope and core ideas of the invention. Similarly, for clarity, detailed descriptions of well-known technologies, functions, and structures (such as standard image processing algorithms and common communication protocols) are omitted in the following description.

[0025] Example 1: This invention provides a dynamic compensation method and system for wide-range current measurement in excitation system testing. By constructing a real-time running "software compensation engine" that integrates temperature sensing and digital filtering, online and dynamic error modeling and correction are performed on the raw signals acquired by the wide-range measurement hardware, thereby achieving continuous, stable, and high-precision measurement across the entire measurement range.

[0026] The system architecture of this technical solution mainly includes: a wide-range programmable gain measurement front-end, a multi-parameter synchronous acquisition module (including a temperature sensor), a dynamic compensation processor, and a human-machine interaction and output module. Its methodology mainly comprises four stages: signal acquisition, error modeling, dynamic compensation, and result output.

[0027] The core components of the technical solution are described in detail below: 1. Wide-range signal normalization acquisition The system first processes the raw current signal from the excitation winding through a programmable gain amplifier FPGA front end. The PGA is adjusted. It has multiple gain levels (e.g., ×1, ×10, ×100, ×1000), which are automatically controlled by the processor based on the signal amplitude. Its output is a normalized voltage signal. .

[0028] Formula 1: Signal Conditioning ; in: : Voltage value at the input of the analog-to-digital converter (ADC) (unit: volts) ).

[0029] : The currently selected gain factor (dimensionless) of the programmable gain amplifier (PGA). This is the gain level index.

[0030] Sampling resistor value (unit: ohms, Ω).

[0031] The original excitation current to be measured (unit: amperes). ).

[0032] The inherent zero-point offset voltage of the amplifier (unit: volts). This is a systematic error that needs to be compensated.

[0033] 2. Real-time modeling of multi-dimensional error parameters To achieve dynamic compensation, the system needs to acquire key error parameters under the current measurement state in real time. This invention constructs a real-time model that includes temperature and nonlinear error.

[0034] Formula 2: Temperature-dependent error parameter model ; ; in: The temperature value is collected in real time by a temperature sensor located close to the programmable gain amplifier FPGA and the analog-to-digital converter (ADC) chip.

[0035] Reference temperature, usually 25 degrees Celsius.

[0036] : Actual zero-point offset voltage at the current temperature.

[0037] At reference temperature The zero-point offset reference value obtained by calibration.

[0038] Temperature drift coefficient of zero-point offset voltage, unit: .

[0039] : The actual gain of the programmable gain amplifier (PGA) at the current temperature.

[0040] : The nominal gain of the programmable gain amplifier (PGA) at the reference temperature.

[0041] Temperature drift coefficient of gain, unit: .

[0042] 3. Dynamic Compensation Core Algorithm The dynamic compensation processor processes the digital sequence acquired by the ADC. Perform the following compensation calculations to restore the true current value. .

[0043] Formula 3: Dynamic Compensation Calculation Dynamic compensation calculation is achieved through the following two steps: Step 1 (Initial Estimation): ; Step 2 (Nonlinear Correction): ; in: : No. The final current value (unit: Ampere) after dynamic compensation at each sampling point. ).

[0044] The instantaneous noise voltage estimated and filtered out by a digital filter (such as an adaptive notch filter). Its model is as follows: , This refers to digital filtering functions, such as adaptive notch filters; The known main interference frequencies are, for example, power frequency harmonics.

[0045] Nonlinear correction function. Used to correct slight nonlinear responses of the PGA and sampling resistor throughout the measurement range. This function is typically a polynomial obtained by least-squares fitting. ,in , These are the nonlinear correction coefficients, obtained through multi-point calibration across the entire range. and Here are the nonlinear correction coefficients, with dimensions respectively. and It is obtained through full-range multi-point calibration, and its function is to ensure the correction function. It is a dimensionless quantity.

[0046] The dynamic compensation calculation sequentially completed zero-point offset compensation, noise suppression, gain temperature compensation, and nonlinear correction.

[0047] The above two steps constitute a single-iteration approximation method: first, an initial estimate is obtained by ignoring nonlinear correction; then, this estimate is substituted into the nonlinear correction function to obtain the final result. Due to the nonlinear correction coefficient... , The value is very small. It fluctuates around 1, and sufficient accuracy can be obtained in one iteration.

[0048] ① Calculate the initial estimate : This step ignores nonlinear correction and uses only the division and the part before it in Formula 3 to calculate a "rough estimate" of the current.

[0049] This value has already completed zero-point offset compensation. Noise suppression and gain temperature compensation , is a fairly accurate linear approximation.

[0050] ② The final value is obtained by applying nonlinear correction. : Then, this "rough estimate" Substitute into the nonlinear correction function This yields the final, precise value.

[0051] ; here, It is a coefficient close to 1 (e.g., 1.002 or 0.998) used for fine-tuning to compensate for the inherent nonlinearity of the system.

[0052] Nonlinear correction This is a tiny correction, with the coefficient typically fluctuating slightly around 1. Estimating this correction using a coarse estimate after applying the other three high-precision compensations yields minimal error. A single iteration can improve the measurement accuracy to the design target of ≤0.1%FS, while avoiding complex and time-consuming multiple iterations or direct solution of higher-order equations, thus balancing accuracy and computational efficiency.

[0053] This invention extracts three key characteristic temperatures in real time. Transient noise And combined with pre-calibrated nonlinear coefficients and These correspond to the main physical factors affecting measurement accuracy: temperature drift, electromagnetic interference, and device nonlinearity. Temperature characteristics are used to dynamically correct zero-point offset and gain drift; noise characteristics suppress deterministic interference in real time through adaptive filtering; and nonlinear characteristics compensate for amplitude nonlinearity over a wide measurement range through polynomial correction. These three characteristics are independent yet complementary, collectively transforming the originally randomly drifting error system into a deterministic model driven by observable variables. This allows for precise reverse compensation at each sampling moment, achieving a leap from static to dynamic calibration.

[0054] 4. System Implementation Systems that implement the above methods include: (1) Measurement front end: includes sampling resistor, multi-stage programmable gain amplifier (PGA) and high-speed analog-to-digital converter (ADC), responsible for converting wide-range current signals into digital signals.

[0055] (2) Parameter acquisition module: includes a high-precision temperature sensor for real-time acquisition and measurement of the temperature of key chips.

[0056] (3) Dynamic compensation processor: This is an embedded microprocessor or FPGA that stores calibration parameters internally. The algorithm program implementing Formulas 2 and 3 is run to complete real-time dynamic compensation. The calibration parameters... The results are obtained through precise calibration and fitting of the system across the entire temperature range and scale before shipment, and are stored in non-volatile memory. (4) Output module: Outputs the compensated high-precision current data I_c through display, storage or communication interface.

[0057] Through the above-mentioned hardware and software collaborative design, the present invention realizes full-link, real-time dynamic error compensation for excitation current from signal acquisition to result output, ensuring continuous high accuracy of wide-range measurement in complex field environments.

[0058] Example 2: To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to a specific embodiment of a medium-sized hydropower station in Central China. This hydropower station has a total installed capacity of 270MW, consisting of three 90MW turbine-generator units, each equipped with a self-excited static excitation system.

[0059] Excitation low current characteristic test after overhaul of Unit #2 of the hydropower station 1. Test Background and Purpose After the annual overhaul of Unit #2 and before its grid connection and commissioning, an open-loop low-current characteristic test must be conducted on its excitation system in accordance with the industry standard DL / T4912008 to verify the linearity of the excitation regulator's trigger pulse control and the operating status of the thyristor bridge circuit. Traditional testing methods use a separate, manually operated low-current tester with an accuracy of 0.5 class. The testing process requires manual data recording and range switching, resulting in low efficiency and significant accuracy fluctuations in the high and low current ranges.

[0060] This test applies the "wide-range current measurement dynamic compensation method and system" described in this invention, aiming to achieve continuous and high-precision automatic measurement of current in the range from 5mA (simulated low load trigger) to 8A (10% of rated excitation current).

[0061] 2. System Configuration and Preparation The system hardware configuration for implementing this invention is as follows: ① Measurement front-end: A 24-bit ΣΔ ADC (Sum-and-Dum Analog-to-Digital Converter) is used, paired with a programmable gain amplifier FPGA with ranges of ×1, ×10, ×100, and ×1000. Sampling resistor. Accuracy 0.1%, temperature coefficient .

[0062] ② Parameter acquisition module: A high-precision digital temperature sensor, model DS18B20, is mounted near the FPGA and ADC chip to acquire the chip junction temperature T in real time.

[0063] ③ Dynamic compensation processor: an industrial-grade microprocessor with an ARM Cortex M7 core, internally storing calibration parameters in Flash memory.

[0064] It should be noted that a voltage divider network or level shifter circuit is used between the output of the programmable gain amplifier and the analog-to-digital converter in this system to ensure that the output voltage corresponding to the maximum input current does not exceed the allowable input range of the analog-to-digital converter at the highest gain setting. The attenuation coefficient of this voltage divider network has been uniformly incorporated into the gain parameter during factory calibration. The calibration process does not affect the universality and accuracy of the compensation method. Key step: Factory calibration. Before the equipment is put into use, it has undergone full-temperature zone calibration in the temperature chamber. to Precise calibration of the full range (0.1mA to 10A) yielded and stored the following core compensation parameters: Zero point offset reference: ; Zero-point temperature drift coefficient: ; PGA nominal gain in the ×1000 range: (dimensionless); Gain temperature drift coefficient ; Nonlinear correction coefficient ,

[0065] 3. On-site testing execution process At the generator site, testers connected the device's output to the excitation regulator's current setpoint terminal and the input to the excitation rectifier bridge circuit. The specific test procedure was automatically executed by the processor. Automatic ranging and signal acquisition: The device starts from 0V and increases the output voltage in 10V increments. At each voltage step, the system automatically selects the optimal PGA gain level and acquires the signal simultaneously. ADC raw voltage sequence: ,by For example.

[0066] Real-time temperature sensor data: (The ambient temperature in the computer room at that time) Dynamic compensation calculation: For each sampling point n, the processor executes the following dynamic compensation algorithm in real time: a. Calculate the parameters after temperature compensation: ; ; ; b. Perform one iterative compensation calculation (based on a certain point) , (For example) Step 1: Calculate the initial estimate ; Step 2: Apply nonlinear correction to obtain the final value ; ; ; This process is performed in real time at thousands of sampling points, without the need for manual intervention in range switching or data recording.

[0067] 4. Comparison of Test Results and Analysis of Effects To quantify the effect, a 0.05-grade standard meter calibrated by the National Institute of Metrology was connected in parallel at the same test point as a reference, and the readings were compared with those of a traditional 0.5-grade manual tester.

[0068]

[0069] Effect Analysis: ① Improved accuracy: The measurement error of the device of the present invention is stable within ±0.4% over the entire wide range (ideally 0.025% in this example), which is significantly better than the error increase at both ends of the range of traditional instruments (maximum 2.4%), and achieves a substantial improvement from 0.5 grade to close to 0.1 grade effective accuracy.

[0070] ② Continuity and Efficiency: The entire test is completed automatically, avoiding data interruptions caused by manual range switching. The time for a single complete characteristic test is reduced from approximately 45 minutes to 15 minutes, improving efficiency by approximately 67%.

[0071] ③Stability: During the approximately 2-hour test, the device readings did not drift due to the slow change in ambient temperature, verifying the effectiveness of the dynamic temperature compensation model.

[0072] Furthermore, to verify the superiority of the dynamic compensation method of the present invention over the traditional single compensation mode (such as only performing temperature lookup table correction or only performing polynomial fitting correction), a comparative experiment was added under the same test environment.

[0073] Experimental group setup: ① Experimental Group A (Complete Scheme of the Invention): The complete algorithm of "temperature linear compensation + one-time iterative nonlinear correction" described in the present invention is adopted (i.e., steps S4.1 and S4.2 are executed simultaneously).

[0074] ② Experimental Group B (Temperature Compensation Only): Only the temperature compensation model was used (i.e., only S4.1 was executed to calculate the temperature compensation model). This is then taken as the final result, without further S4.2 nonlinear correction.

[0075] ③ Experimental Group C (Nonlinear Correction Only): No temperature compensation was performed; the original ADC value was directly calculated. Applying the same polynomial function Perform a one-time nonlinear correction.

[0076] In this comparative experiment, both experimental groups B and C used the same factory calibration parameters as experimental group A (including nonlinear correction coefficients). , The system was not recalibrated for temperature changes to verify the limitations of a single compensation method in variable temperature environments without full dynamic compensation.

[0077] The test results are compared below:

[0078] Conclusion Analysis: As shown in the table above, under temperature variation (31.5℃ relative to the reference temperature of 25℃) and low current of 5mA, temperature compensation alone (experimental group B) can improve some drift, but it distorts the nonlinear response of the signal itself; nonlinear correction alone (experimental group C) can correct amplitude distortion, but it cannot suppress zero-point and gain drift caused by temperature variation. Neither can completely eliminate the composite error.

[0079] Only this invention combines temperature linear compensation with one-step iterative nonlinear correction, utilizing the accurate linear estimate obtained after temperature drift correction in step S4.1. Only by using this as input for the nonlinear correction in step S4.2 can optimal measurement accuracy be obtained across the entire measurement range. This compensation architecture of "step-by-step decoupling and sequential iteration" is not a simple superposition of single compensation methods, but rather achieves a synergistic effect of 1+1>2 through deep coupling at the algorithm level. It effectively solves the measurement problem of multi-source dynamic errors such as temperature drift and device nonlinearity coupled together in the complex environment of the excitation system.

[0080] 5. Conclusion This embodiment fully demonstrates that the method and system described in this invention can effectively solve practical problems in on-site excitation testing at hydropower stations, such as the difficulty in balancing wide measurement range and high precision, cumbersome manual operation, and the impact of ambient temperature on accuracy. Through dynamic compensation through hardware and software collaboration, a reliable and practical improvement in measurement accuracy and testing efficiency is achieved without excessively pursuing extreme performance indicators, providing a superior technical means for accurate assessment of the excitation system's condition.

Claims

1. A wide-range current measurement dynamic compensation method for excitation system testing, characterized in that, include: S1: Real-time acquisition and measurement of temperature values ​​of key components in the circuit. ; S2: Based on pre-stored calibration parameters, according to temperature value Dynamically calculate the zero-point offset voltage at the current temperature Compared with actual gain ; S3: Acquire the voltage signal conditioned by the programmable gain amplifier. It is then digitally filtered to extract the noise components. This will be used for subsequent compensation. S4: Using a single iteration calculation, first based on... 、 and Calculate the initial estimate of the current. Then input it into a predetermined nonlinear correction function. The calculations are performed to obtain a high-precision current value after dynamic compensation for zero-point, gain, temperature, and nonlinear errors. .

2. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 1, characterized in that, In step S2, the dynamic calculation is achieved through the following error parameter model: ； ； in, , , , These are parameters obtained through factory calibration. This is a reference temperature.

3. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 2, characterized in that, In step S4, one iteration of calculation specifically includes: S4.1: Calculate the initial estimate : ； S4.2: Apply nonlinear correction to obtain the final value Ic[n]: ； in, This is the resistance value of the sampling resistor.

4. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 1, characterized in that, The aforementioned nonlinear correction function fnl(x) is a polynomial function, and its form is: in, , These are the nonlinear correction coefficients obtained through full-range calibration.

5. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 1, characterized in that, In step S3, the digital filtering is an adaptive notch filter, used to suppress power frequency harmonic interference.

6. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 1, characterized in that, The programmable gain amplifier is automatically switched between ×1, ×10, ×100, and ×1000 ranges by the processor according to the amplitude of the current signal, so as to realize the normalized acquisition of wide range signals.

7. The wide-range current measurement dynamic compensation method for excitation system testing according to claim 1, characterized in that, The temperature value T is acquired in real time by a digital temperature sensor mounted near a programmable gain amplifier or analog-to-digital converter chip.

8. A system using the wide-range current measurement dynamic compensation method for excitation system testing as described in any one of claims 1-7, characterized in that, include: The signal conditioning and acquisition module, including sampling resistors, a programmable gain amplifier, and an analog-to-digital converter, is used to convert a wide-range excitation current signal into a digital voltage sequence. ; The temperature acquisition module is used to acquire the temperature value T of the key chip in the signal conditioning and acquisition module in real time; The dynamic compensation processor has a set of calibration parameters stored internally. It is configured to perform a dynamic compensation method, which includes at least the steps of digitally filtering the voltage signal, calculating the initial estimate of the current, and applying nonlinear correction.

9. The wide-range current measurement dynamic compensation system for excitation system testing according to claim 8, characterized in that, The analog-to-digital converter is a 24-bit Σ-Δ type analog-to-digital converter, i.e., a summation-increment type analog-to-digital converter.

10. The wide-range current measurement dynamic compensation system for excitation system testing according to claim 8, characterized in that, The dynamic compensation processor is an embedded microprocessor or a field-programmable gate array.

11. The wide-range current measurement dynamic compensation system for excitation system testing according to claim 8, characterized in that, The system also includes a human-computer interaction and output module for displaying, storing, or communicating compensated high-precision current data. .

12. A computer-readable storage medium using the wide-range current measurement dynamic compensation method for excitation system testing according to any one of claims 1-7, characterized in that, A computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of a dynamic compensation method for wide-range current measurement.

13. An electronic device using the wide-range current measurement dynamic compensation method for excitation system testing according to any one of claims 1-7, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the steps of implementing a dynamic compensation method for wide-range current measurement when the processor executes the computer program.

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