Microgrid complex transient frequency rapid measurement method and measurement device thereof

Abstract

The invention discloses a micro-grid complex transient frequency rapid measurement method and a measurement device thereof, and relates to the field of micro-grid transient measurement. In order to solve the defects that an existing micro-grid is insufficient in harmonic robustness, rigid in calculation power distribution and unbalanced in transient response, harmonic amplitude aliasing is restrained through a low-pass filter, and harmonic waves are compensated; then, the signal fluctuation intensity of the frequency measurement task is evaluated in real time through the voltage second-order difference change rate R, and a calculation mode is dynamically selected; selecting data of a current point and adjacent points, and executing Taylor expansion; a double-buffer synchronization technology is adopted, a frequency measurement task and a control task respectively access different buffers, and conflict-free synchronization is realized through an interrupt flag bit; and through multi-channel redundancy check, a result is written into double buffer areas, and other real-time tasks are notified. The method is mainly used for measuring the complex transient frequency of the micro-grid.

Description

Technical Field

[0001] The present invention relates to the field of microgrid transient measurement, and particularly to a method and device for rapidly measuring the complex transient frequency of a microgrid. Background Art

[0002] With the rapid popularization of distributed energy, new power systems represented by microgrids have put forward different requirements for the real-time performance and anti-interference ability of frequency measurement. The traditional power system has relatively loose requirements for the sampling rate of frequency. Taking 2 kHz as an example (40 points per cycle, sampling period 0.5 ms), the frequency change is gentle (ROCOF < 0.5 Hz / s) and the harmonic content is low (total harmonic distortion THD < 10%) under the steady-state operation scenario. Existing frequency measurement schemes can meet the basic control requirements by virtue of mature filtering algorithms and dedicated hardware. However, in new small and medium-power microgrids, the frequent switching of distributed power sources gives rise to a large number of complex transient processes, making the frequency measurement technology at the traditional 2 kHz sampling rate expose multiple adaptability problems, specifically as follows: 1. Steady-state optimization algorithms are difficult to adapt to transient high-frequency changes; Traditional frequency measurement algorithms (such as the fixed-window interpolation method) are designed for steady-state signals. During the transient process of the microgrid (such as the rapid charge and discharge of the energy storage system, ROCOF can reach 5 Hz / s), due to insufficient information in the data window of the 3-point interpolation method at a 2 kHz sampling rate, the frequency tracking error increases significantly with the increase of the change rate. The actual measurement of a certain photovoltaic microgrid shows that when using the traditional scheme, the frequency measurement delay in the island mode reaches 1.5 ms, causing a lag in the PCS power adjustment, resulting in an increase in the probability that the voltage fluctuation amplitude exceeds the national standard limit (±10% ) by 30%.

[0003] 2. Traditional anti-aliasing designs cannot cope with new harmonic scenarios; The anti-aliasing filter cut-off frequency of traditional measurement and control devices is mostly set to 500 Hz, which is suitable for scenarios mainly composed of power frequency signals. However, in new microgrids, characteristic harmonics such as 250 Hz and 350 Hz generated by photovoltaic inverters and power electronic devices (the amplitude can reach 15% of the fundamental wave) are prone to aliasing distortion after 2 kHz sampling. The on-site test of a certain wind power microgrid shows that when the total harmonic distortion THD = 20%, the frequency error of the traditional 5-point interpolation method breaks through ±0.25 Hz, exceeding 2.5 times the microgrid transient measurement standard (±0.1 Hz), directly resulting in an increase in the rejection rate of the synchronization device to 18%.

[0004] 3. There are blind spots in the adaptation of low-amplitude signal processing; The traditional frequency measurement process defaults that the line voltage amplitude is in the normal operation range above 50V. However, in a new type of microgrid, under conditions such as single-phase grounding faults and sudden load drops, the line voltage often drops below 10V, and the zero-crossing density increases by 2-3 times compared to the steady state. This causes the traditional calculation formula to fail because the denominator approaches zero. A backup microgrid in a data center once misjudged the frequency as 45Hz during a main grid fault due to such problems, triggering the incorrect switching of the backup power supply and resulting in a cumulative 10-minute interruption of data processing.

[0005] 4. The computing power bottleneck of the low-cost hardware platform becomes prominent; To control costs, the new type of microgrid generally adopts a hardware combination of a general medium-cost processor (72MHz) + 16-bit ADC (total cost < $15). However, the traditional frequency measurement algorithm is not optimized for the fixed-point operation characteristics of such chips. The single-cycle calculation time of the 4th-order Taylor expansion reaches 200μs, occupying more than 60% of the MCU computing power, resulting in a response delay of more than 50μs for real-time tasks such as fault protection and communication protocols, and being unable to meet the real-time requirements of the fast control of the microgrid (such as power synchronization adjustment during grid connection and disconnection switching). At the same time, the relatively serious computing power occupation will have unpredictable effects on control tasks.

[0006] Due to the trends of "transient complexity" and "low-cost hardware" in the new type of power system, the frequency measurement technology at the traditional 2kHz sampling rate has changed from "steady-state applicable" to "transient ineffective". The existing solutions, limited by the insufficient adaptability of "fixed algorithm + general hardware" and their defects in computing power allocation, anti-aliasing, and low-amplitude adaptability, have become the key technical bottlenecks for the stable operation of the microgrid.

[0007] Therefore, a fast measurement method and its measurement device for the complex transient frequency of a microgrid that can adaptively allocate computing power, have high anti-aliasing ability, and strong low-amplitude adaptability are needed. Summary of the Invention

[0008] To solve the deficiencies of the existing microgrid in terms of insufficient harmonic robustness, rigid computing power allocation, and unbalanced transient response, the present invention provides a fast measurement method and its measurement device for the complex transient frequency of a microgrid that can adaptively allocate computing power, have high anti-aliasing ability, and strong low-amplitude adaptability.

[0009] A fast measurement method for the complex transient frequency of a microgrid according to the present invention includes the following steps: S1. Composite anti-aliasing processing: Suppress the harmonic amplitude aliasing through a low-pass filter and compensate for the harmonics; S2. Transient feature extraction: Evaluate the signal fluctuation intensity of the frequency measurement task in real time through the voltage second-order difference change rate R, and dynamically select the calculation mode; S3. Dynamic hierarchical calculation: Select the data of the current point and adjacent points according to the calculation mode, and perform Taylor expansion; S4. Multi-task cooperative scheduling: Adopt the double-buffer synchronization technology, where the frequency measurement task and the control task access different buffers respectively, and achieve conflict-free synchronization through the interrupt flag bit.

[0010] Further: In S1, the specific steps of the composite anti-aliasing processing are as follows: Hardware-level filtering: Deploy a low-pass filter between the PT sensor and the AD converter of the measurement device to suppress the harmonic amplitude; Software-level filtering: Perform cubic spline interpolation on the sampled values to generate virtual sampled data; Harmonic frequency compensation: Add a harmonic correction term to the Taylor expansion; S5. Result output and verification: Through multi-channel redundant verification, write the result into the double buffer and notify other real-time tasks.

[0011] Further: In S2, the specific process of evaluating the signal fluctuation intensity in real time according to the voltage second-order difference change rate R includes: Dynamically select the calculation mode: If the voltage second-order difference change rate R is less than or equal to the preset threshold, it is determined as a gentle transient; if the voltage second-order difference change rate R is greater than the preset threshold, it is determined as a severe transient.

[0012] Further: In S3, the specific steps of the dynamic hierarchical calculation are as follows: Gentle transient: Adopt the 3-point lightweight calculation mode, select the current point and the data of the previous two points, and perform 2nd-order Taylor expansion; Severe transient: Adopt the 5-point high-precision calculation mode, select the current point and the data of two points before and after respectively, and perform 4th-order Taylor expansion and combine with the fundamental frequency pre-estimation optimization.

[0013] Further: The 3-point lightweight calculation mode is as follows: Sampling point selection: Select the current point and the previous 2 points , , and the data window is 1.5 ms; The 2nd-order Taylor expansion formula is: ; is to predict the next point.

[0014] Further: The 5-point high-precision calculation mode is as follows: Sampling point selection: The current point and 2 points before and after respectively , , , , the data window is 2.5 ms; 4th-order Taylor expansion optimization: Introduce fundamental frequency pre-estimation , narrow the polynomial variable range to .

[0015] Furthermore: In S4, the multi-task collaborative scheduling further includes dynamic computing power allocation. The processor task scheduler assigns variable priorities to the frequency measurement tasks, specifically including: Gentle transient: The priority is reduced to the lowest, and the computing power will be released to the control task; Severe transient: The priority is raised to the highest to ensure exclusive computing resources and improve the task switching speed.

[0016] Furthermore: The multi-channel redundancy check is specifically as follows: When the deviation of the three-phase frequency measurement results is greater than the preset threshold, recalculation is triggered. When the deviation of the three-phase frequency measurement results is less than the preset threshold, redundancy check is passed.

[0017] The measurement device for implementing the disclosed method for rapid measurement of complex transient frequency in a microgrid includes a transient perception module, a dynamic calculation module, and a multi-task collaborative module; The transient perception module is used to evaluate the working conditions of the frequency measurement task in real time through the second-order differential change rate of voltage and dynamically select the calculation mode; The dynamic calculation module is used to calculate the frequency measurement task according to the selected calculation mode and switch the hierarchical calculation mode as needed; The multi-task collaborative module is used to synchronize the frequency measurement results with the control results through a double buffer to ensure that the control instructions have no delay.

[0018] The beneficial effects of the present invention are: Aiming at the special requirements of the new power system, without increasing the hardware cost and sampling rate, through the adaptive algorithm reconstruction of the dynamic calculation module, the present invention achieves a breakthrough in transient frequency measurement performance on the same hardware platform, provides core technical support for the efficient access and reliable control of distributed energy, and has significant engineering application value and industry universality. Through dynamic calculation driven by working condition perception + anti-aliasing design of hardware and software collaboration, on a general hardware platform with a sampling rate of 2 kHz, the present invention realizes a leapfrog improvement in measurement accuracy, computing power efficiency, transient response, and hardware adaptability in frequency measurement technology, effectively solves the core technical problems such as insufficient frequency measurement accuracy, rigid computing power allocation mechanism, and multi-index imbalance of transient response in the harmonic scenario of frequency measurement in a new microgrid, and has both technical innovation and engineering practicability.

[0019] Through the collaborative optimization of dynamic algorithms and hardware, the present invention realizes a cross-generation improvement in frequency measurement performance without significantly increasing costs. Based on the frequency compensation algorithm based on harmonic amplitude, the anti-aliasing ability is improved by 40% compared with the traditional scheme.

[0020] Through dynamic algorithm reconstruction + hardware co - optimization, for the first time on a low - cost platform with a sampling rate of 2 kHz, a tripartite breakthrough in computing power efficiency, measurement accuracy, and transient response is achieved, filling the industry gap in the new type of micro - grid frequency measurement technology, providing core support for the efficient access and reliable control of distributed energy, and having significant engineering application value and technological innovation significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the frequency measurement architecture. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The following embodiments are only used to explain the present invention and cannot be construed as a limitation of the present invention. The protection scope of the present invention should be based on the protection scope of the claims. The embodiments of the present invention are described in detail below. For the convenience of describing the present invention and simplifying the description, the technical terms used in the specification of the present invention should be interpreted in a broad sense, including but not limited to conventional replacement schemes not mentioned in this application, and including both direct implementation methods and indirect implementation methods.

[0023] Embodiment 1 Combined with Figure 1 To illustrate this embodiment, a method for rapid measurement of complex transient frequency in a micro - grid disclosed in this embodiment includes the following steps: S1. Composite anti - aliasing processing: Suppress harmonic amplitude aliasing through a low - pass filter and compensate for harmonics; The anti - aliasing scheme combining hardware filtering and software interpolation is an integrated design of a front - end low - pass filter and an ADC. The software uses a cubic spline interpolation method to generate virtual sampling points for software correction.

[0024] Adapt to low - cost hardware, adapt the fixed - point operation optimization algorithm for general - purpose processors (such as STM32 / DSP) and 16 - bit ADCs. The cost of a single set of modules is < 800 yuan, reducing the hardware cost by 90% compared with the dedicated chip solution, filling the gap in low - cost and high - performance frequency measurement technology for medium - and small - power micro - grids.

[0025] Hardware - level filtering: Deploy an 8 - th - order Butterworth low - pass filter between the PT sensor and the AD converter of the measuring device, with a cut - off frequency , transfer function: ; Among them, S is the amplitude - frequency domain variable; The attenuation of the 250Hz harmonic reaches 30dB, suppressing its amplitude to less than 5% of the fundamental wave.

[0026] Software-level filtering: Cubic spline interpolation is performed on 5 sampling values to generate 10 virtual sampling data points (equivalent to a sampling rate of 4kHz), and a harmonic frequency compensation term is introduced to further suppress the influence of higher-order harmonics. Through cubic spline interpolation, the 5-point sampling is virtually extended to 10 points (equivalent to a sampling rate of 4kHz). Combining with the harmonic frequency compensation term, when the total harmonic distortion THD = 20%, the frequency measurement accuracy reaches ±0.1Hz, breaking through the anti-aliasing limit of a 2kHz sampling rate.

[0027] Interpolation formula:

[0028] where are the piecewise polynomial coefficients, respectively, and are solved by least squares fitting.

[0029] Add 3rd and 5th harmonic correction terms in the Taylor expansion:

[0030] Coefficient , is dynamically calculated through the harmonic amplitudes of the first 5 cycles.

[0031] This embodiment breaks the traditional mode of "high-performance frequency measurement relying on dedicated chips" and is compatible with mainstream low-cost processors and ADCs. It is adapted to general-purpose processors. Through fixed-point operation optimization and instruction pipeline design, the cost of a single set of frequency measurement modules is <800 yuan (a 90% reduction compared to the FFT scheme); by using the built-in PGA of the ADC (such as the ×16 gain of ADS1115), a wide amplitude input of 0.1V - 20V is achieved, eliminating the need for an additional signal conditioning circuit, and reducing the hardware complexity by 30%.

[0032] Break through the harmonic suppression limit at a 2kHz sampling rate and meet the high-precision frequency measurement requirements in scenarios with a total harmonic distortion THD = 20%. Deploy an LC filter with a cut-off frequency of 900Hz at the hardware front end to attenuate the 250Hz harmonic by 30dB and weaken the source of aliasing distortion; perform cubic spline interpolation (virtual 10 points) on the 5 sampling values in software, equivalently increasing the sampling rate to 4kHz. After testing with a microgrid semi-physical simulation system, the aliasing error is reduced from 0.8% to 0.3%, and the total error is ≤±0.1Hz when the total harmonic distortion THD = 20%; introduce a harmonic frequency compensation term (based on the initial frequency estimation of the zero-crossing point) in the Taylor expansion to further suppress the spectral leakage caused by higher-order harmonics, that is, suppress the influence of the 3rd and 5th harmonics, and improve the anti-aliasing ability by 40% compared to the traditional scheme.

[0033] S2. Transient feature extraction: Real-time evaluation of signal fluctuation intensity through voltage second-order differential change rate R; intelligent switching between two calculation modes; Based on the working condition judgment logic of the voltage second-order differential change rate R, the calculation formula of the voltage second-order differential change rate R is: ; in, is the voltage value of the kth sampling point, is the voltage value of the k+1th sampling point, is the voltage value of the k-1th sampling point, is the sampling period, ΔT=0.5ms.

[0034] The second-order differential change rate R of the voltage is used in this embodiment to determine the severity of the voltage change at the current sampling moment. The MATLAB Simulink semi-physical simulation is used to simulate different transient scenarios of the microgrid operation, and the statistical R value distribution is shown in Table 1.

[0035] Table 1: R value distribution table;

[0036] Un is the system rated voltage.

[0037] Threshold screening logic: The middle value between the maximum R value of gentle transient (0.25V / ms2) and the minimum R value of severe transient (0.35V / ms2), i.e. 0.3V / ms2, is selected to ensure reliable distinction between the two types of working conditions.

[0038] For power usage scenarios with drastic load changes or relatively wide transient characteristics requirements, the R value can be changed according to actual needs.

[0039] Real-time evaluation of signal fluctuation intensity based on the voltage second-order differential change rate R specifically includes: dynamically selecting a calculation mode: if the voltage second-order differential change rate R is less than or equal to a preset threshold, it is determined to be a gentle transient; if the voltage second-order differential change rate R is greater than the preset threshold, it is determined to be a severe transient.

[0040] When the preset threshold is 0.3, the calculation mode is dynamically selected according to the voltage second-order differential change rate R: When , it is judged as a gentle transient state; when When , it is judged as severe transient; Switching threshold: When the transient state is smooth (such as load gradient): enable 3-point sampling + 2nd-order Taylor series expansion; computing power usage is reduced to 25%; ensure that the processor runs 3 real-time tasks (such as control tasks, fault detection, and communication) at the same time; During severe transients (such as grid connection / disconnection switching): Enable 5-point sampling + 4th-order Taylor expansion; optimize the Taylor expansion in combination with fundamental frequency pre-estimation, and cooperate with hardware multiplication acceleration (such as the MAC instruction of DSP) to control the error within ±0.1 Hz when the total harmonic distortion (THD) = 20%, and the computing power occupancy is stably within 50%. Ensure that the frequency measurement task runs in parallel with real-time tasks such as control tasks and fault detection, and the multi-task timing deviation < 50 μs, meeting the stringent requirements of the microgrid controller for computing power allocation.

[0041] Computing power intelligent allocation driven by transient intensity; Construct a transient self-adaptive computing power allocation mechanism, solve the contradiction between computing power waste and computing power overload caused by fixed algorithms, and achieve intelligent scheduling of processor resources.

[0042] S3. Dynamic hierarchical calculation: To solve the problems of zero-crossing frequency measurement response lag and poor dynamic adaptability of Taylor expansion, covering a wide ROCOF range of 0.1 - 5 Hz / s. Select the data of the current point and adjacent points and perform Taylor expansion; When in a gentle transient ( ), adopt a 3-point lightweight calculation mode for fast calculation, with a response time < 1.5 ms, which is 6 times faster than the zero-crossing scheme (10 ms); achieve a 40% improvement in computing power efficiency. Select the current point and the first two previous points of data (1.5 ms data window) and perform 2nd-order Taylor expansion, and the computing power occupancy is reduced to 25%.

[0043] Sampling point selection: the current point and the first 2 previous points , , with a data window of 1.5 ms; The 2nd-order Taylor expansion formula is: ; To predict the next point, obtain it through linear extrapolation; Computing power optimization: Omit absolute value operations and high-order multiplications, with the number of single-cycle calculation instructions < 200, and the computing power occupancy ≤ 25%.

[0044] When in a severe transient ( ), enable 5-point high-precision calculation, cooperate with the harmonic frequency compensation term, control the tracking error under rapid frequency changes within ±0.1 Hz, meet the control margin requirements for grid connection / disconnection switching (200 ms cycle), and achieve stable frequency measurement under wide-range transient conditions.

[0045] Select the data of the current point and two points before and after it (2.5 ms data window), perform 4th-order Taylor expansion and optimize it in combination with fundamental frequency pre-estimation, and control the computing power occupancy within 50%.

[0046] 5-point high-precision calculation mode (severe transient): Sampling point selection: the current point and 2 points before and after it , , , , the data window is 2.5 ms; 4th-order Taylor expansion optimization: Introduce fundamental frequency pre-estimation (from the results of the previous cycle), narrow the range of polynomial variables to , reduce the number of iterations, and the calculation time is reduced by 30% compared with the traditional scheme.

[0047] S4. Multi-task collaborative scheduling: Adopt dual-buffer (A / B) synchronization technology, and let the frequency measurement task and the control task access different buffers respectively, and achieve conflict-free synchronization through the interrupt flag bit.

[0048] Set up "frequency measurement result buffer A / B", the frequency measurement task and the control task access different buffers respectively, and achieve synchronization through the interrupt flag bit (FLAG_FREQ_READY) to eliminate critical section competition.

[0049] Dynamically adjust task priorities: Reduce the priority of the frequency measurement task during gentle transients to release computing power; increase the priorities of the frequency measurement task and the control task during severe transients to ensure exclusive access to computing resources.

[0050] Allocate variable priorities for the frequency measurement task through the processor task scheduler (such as FreeRTOS): Gentle transient: the priority is reduced to the lowest (release computing power to the control task); Severe transient: the priority is increased to the highest (ensure exclusive access to computing resources), and the task switching delay < 10 μs.

[0051] The dual-buffer architecture and the dynamic priority scheduling strategy are conflict-free synchronization methods for the dual buffer of the frequency measurement results; the dynamic adjustment technology of task priorities based on transient strength controls the multi-task time sequence deviation within 50 μs.

[0052] S5. Result output and verification: Through multi-channel redundant verification (recalculate when the three-phase frequency measurement result deviation > 0.5 Hz), ensure the reliability of the result and then write it into the buffer, and notify other real-time tasks.

[0053] Embodiment 2 This embodiment is described in combination with Embodiment 1. The specific implementation steps of a microgrid complex transient frequency rapid measurement method disclosed in this embodiment are as follows, Signal acquisition stage: The ADC samples the three-phase line voltage at a rate of 2 kHz and stores it in a circular buffer (depth 10 points). Every time 3 points are sampled (1.5 ms), the transient intensity detection module is triggered.

[0054] Operating condition judgment stage: Calculate the second-order difference change rate R of the current 3 points of voltage, and determine whether to use the 3-point / 5-point calculation mode. If it is the 5-point mode, supplement the first 2 points of historical data to the calculation window.

[0055] Frequency calculation stage: 3-point mode: Perform a second-order Taylor expansion, with a time consumption of <80 μs. 5-point mode: Perform a fourth-order Taylor expansion + harmonic compensation, with a time consumption of <150 μs. Both modes perform anti-aliasing correction on the sampling points through cubic spline interpolation.

[0056] Result output stage: Multi-channel redundancy check (recalculation is triggered when the deviation of the three-phase frequency measurement results > 0.5 Hz). The results are written into a double buffer, and control tasks, fault detection and other tasks are notified through interrupts.

[0057] Comparison of key technical parameters in MATLAB simulation:

[0058] Example 2 Combined with Figure 1 To illustrate this embodiment, the measurement device disclosed in this embodiment for implementing the method for rapid measurement of complex transient frequency in a microgrid includes a transient perception module, a dynamic calculation module, and a multi-task coordination module. The transient perception module is used to evaluate the operating condition of the frequency measurement task in real time through the second-order difference change rate of the voltage and dynamically select the calculation mode. The dynamic calculation module is used to calculate the frequency measurement task according to the selected calculation mode and switch the hierarchical calculation mode as needed. The multi-task coordination module is used to synchronize the frequency measurement results with the control results through a double buffer to ensure that there is no delay in the control instructions.

Claims

1. A rapid measurement method for the complex transient frequency of a microgrid, characterized in that, It includes the following steps: S1. Composite anti-aliasing processing: Suppress the harmonic amplitude aliasing through a low-pass filter and compensate for the harmonics; S2. Transient feature extraction: Evaluate the signal fluctuation intensity of the frequency measurement task in real time through the voltage second-order difference change rate R, and dynamically select the calculation mode; S3. Dynamic hierarchical calculation: Select the data of the current point and adjacent points according to the calculation mode, and perform Taylor expansion; S4. Multi-task collaborative scheduling: Adopt the double-buffer synchronization technology, enable the frequency measurement task and the control task to access different buffers respectively, and achieve conflict-free synchronization through the interrupt flag bit.

2. A method for rapid measurement of complex transient frequency of a microgrid according to claim 1, characterized in that In S1, the specific steps of the composite anti-aliasing processing are as follows: Hardware-level filtering: Deploy a low-pass filter between the PT sensor and the AD converter of the measurement device to suppress the harmonic amplitude; Software-level filtering: Perform cubic spline interpolation on the sampled values to generate virtual sampled data; Harmonic frequency compensation: Add a harmonic correction term to the Taylor expansion; S5. Result output and verification: Through multi-channel redundancy verification, write the result into the double buffer and notify other real-time tasks.

3. A fast measurement method for the complex transient frequency of a microgrid according to claim 1, characterized in that, In S2, the real-time evaluation of the signal fluctuation intensity according to the voltage second-order difference change rate R specifically includes: dynamically selecting the calculation mode: if the voltage second-order difference change rate R is less than or equal to the preset threshold, it is determined as a gentle transient; if the voltage second-order difference change rate R is greater than the preset threshold, it is determined as a severe transient.

4. A method for rapidly measuring the complex transient frequency of a microgrid according to claim 3, characterized in that, In S3, the specific steps of the dynamic hierarchical calculation are as follows: Gentle transient: Adopt a 3-point lightweight calculation mode, select the data of the current point and the first two points, and perform a 2nd-order Taylor expansion; Severe transient: Adopt a 5-point high-precision calculation mode, select the data of the current point and the two points before and after, and perform a 4th-order Taylor expansion and combine it with the fundamental frequency pre-estimation optimization.

5. A method for rapid measurement of complex transient frequency of a microgrid according to claim 4, characterized in that, The 3-point lightweight calculation mode is: Sampling point selection: Select the current point and the previous 2 points , , with a data window of 1.5 ms; The 2nd-order Taylor expansion formula is: ； To predict the next point.

6. A method for rapid measurement of complex transient frequency in a microgrid according to claim 4, characterized in that The 5-point high-precision calculation mode is: Sampling point selection: the current point and two points before and after it , , , , the data window is 2.5 ms; 4th-order Taylor expansion optimization: Introduce fundamental frequency pre-estimation , narrow down the polynomial variable range to .

7. A method for rapid measurement of complex transient frequency of a microgrid according to claim 1, characterized in that, In S4, the multi-task collaborative scheduling further includes dynamic computing power allocation. The processor task scheduler assigns variable priorities to the frequency measurement task, specifically including: Gentle transient: The priority is reduced to the lowest, and the computing power is released to the control task; Severe transient: The priority is increased to the highest to ensure exclusive computing resources and improve the task switching speed.

8. A rapid measurement method for the complex transient frequency of a microgrid according to claim 1, characterized in that The multi-channel redundancy verification is specifically as follows: When the deviation of the three-phase frequency measurement results is greater than the preset threshold, trigger a recalculation; when the deviation of the three-phase frequency measurement results is less than the preset threshold, pass the redundancy verification.

9. A measuring device for implementing a method for quickly measuring the complex transient frequency of a microgrid as described in any one of claims 1-8, characterized in that, It includes a transient perception module, a dynamic calculation module and a multi-task collaborative module; The transient perception module is used to evaluate the working condition of the frequency measurement task in real time through the voltage second-order difference change rate and dynamically select the calculation mode; The dynamic calculation module is used to calculate the frequency measurement task according to the selected calculation mode and switch the hierarchical calculation mode as needed; The multi-task collaborative module is used to synchronize the frequency measurement result with the control result through the double buffer to ensure that the control instruction has no delay.

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