Frequency modulation sampling device and frequency modulation system

Abstract

The invention discloses a frequency modulation sampling device and a frequency modulation system, and relates to the technical field of power system frequency modulation. The device comprises a sampling module, a signal processing module, an output module, a fault diagnosis module and the like, the sampling module directly samples voltage and current signals of the high-voltage side of the transformer, the signal processing module obtains electrical quantity through operation of a full-cycle Fourier algorithm, the output module outputs analog quantity signals, and the fault diagnosis module judges PT / CT disconnection and gives an alarm. The system can replace discrete equipment, improves the primary frequency modulation signal precision and response speed, reduces the operation and maintenance cost, and is suitable for a power plant scene.

Description

Technical Field

[0001] This document relates to the field of frequency modulation technology, and in particular to a frequency modulation sampling device and frequency modulation system. Background Technology

[0002] In the operation of generator sets in power systems, primary frequency regulation is the core link to ensure the stability of the power grid frequency. Currently, the primary frequency regulation control of generator sets mostly relies on the turbine speed measurement circuit to indirectly sense frequency changes. This requires processes such as speed sensing, signal conversion, and multi-stage logic operations. The superposition of intermediate links can easily introduce measurement errors, resulting in delayed primary frequency regulation response and insufficient regulation accuracy. Ultimately, this leads to a low pass rate for primary frequency regulation performance indicators, exposing power plants to assessment risks.

[0003] Current power measurement methods mostly employ traditional discrete transmitters. For different circuits such as transformers and generators, multiple transmitters for voltage, current, and power are required, which not only occupies a large cabinet space but also results in complex wiring between equipment, numerous potential fault points, and a lack of unified data exchange and fault diagnosis mechanisms. This hinders centralized monitoring and rapid fault location, failing to meet the needs of automated operation and maintenance in power plants. Furthermore, traditional sampling devices are limited by hardware design, resulting in insufficient accuracy and interference resistance in measuring electrical quantities such as voltage, current, and frequency. In the complex electromagnetic environment of power plants, sampling data is prone to distortion, further reducing the accuracy of primary frequency regulation. Moreover, most devices lack fault recording and event logging functions, making it difficult to trace data and analyze causes after a fault, impacting system recovery efficiency.

[0004] In addition, primary frequency regulation testing relies heavily on manual on-site operation and lacks standardized remote testing and monitoring methods. It is impossible to obtain key data such as frequency disturbance response and load adjustment commands in real time during the test, making it difficult to accurately evaluate the actual performance of primary frequency regulation and to efficiently complete parameter optimization and fault diagnosis. This results in high maintenance costs and low efficiency for primary frequency regulation systems.

[0005] To address the aforementioned issues, an integrated, high-precision frequency regulation sampling scheme is urgently needed to achieve direct and accurate acquisition of grid frequency and related electrical quantities, simplify measurement circuits, reduce intermediate errors, and simultaneously possess comprehensive communication, time synchronization, fault diagnosis, and remote testing functions. This would improve the primary frequency regulation response speed and regulation qualification rate, meeting the high standards of the power system for primary frequency regulation control of generator units. Summary of the Invention

[0006] This invention provides a frequency modulation sampling device and frequency modulation system, which aims to solve the problems of slow primary frequency modulation response, low measurement accuracy, and poor operation and maintenance efficiency in the prior art. Through integrated sampling, high-precision signal processing, and complete communication and fault diagnosis functions, it realizes direct and accurate acquisition of power grid frequency and related electrical quantities, simplifies the measurement circuit, and improves the primary frequency modulation response speed and regulation qualification rate.

[0007] According to an embodiment of the present invention, a frequency modulation sampling device is provided, comprising: a sampling module, a signal processing module, an output module, and a fault diagnosis module; The sampling module includes at least two sets of voltage sampling units and at least two sets of current sampling units. The voltage sampling units are used to collect the three-phase line voltage signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The current sampling units are used to collect the three-phase current signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The signal processing module is electrically connected to the sampling module and is used to perform full-cycle Fourier algorithm calculations on the collected voltage and current signals to obtain active power, reactive power, frequency, positive sequence component, negative sequence component and zero sequence component. The output module is electrically connected to the signal processing module and is used to output the calculated electrical quantity as an analog current signal. The fault diagnosis module is electrically connected to the sampling module and the signal processing module. It is used to determine the PT disconnection and CT disconnection faults based on the positive sequence component, negative sequence component and zero sequence component of voltage and the zero sequence component of current, and output a fault alarm signal.

[0008] According to an embodiment of the present invention, a frequency modulation system is provided, including: a frequency modulation sampling device, a DEH control system, an AGC control system, and a DCS system; The output module of the frequency modulation sampling device is electrically connected to the analog input interface of the DEH control system, AGC control system and DCS system respectively, and is used to transmit high-precision frequency signals and power signals to each control system. The communication module of the frequency modulation sampling device is bidirectionally connected to the communication interface of the DCS system, which is used to realize the uploading of measurement values, modification of set values ​​and transmission of fault information. The DEH control system achieves primary frequency modulation control based on the frequency signal output by the frequency modulation sampling device and the rotational speed signal; The AGC control system adjusts the unit load based on the power signal output by the frequency modulation sampling device. The DCS system is used to monitor and store data of the frequency modulation sampling device.

[0009] By employing a frequency modulation sampling device according to an embodiment of the present invention, which integrates sampling, signal processing, and fault diagnosis functions, it can replace multiple separate devices, reduce the space occupied by cabinets and wiring fault points, and reduce installation and maintenance workload. It directly collects voltage and current signals from the high-voltage side of the transformer, and obtains frequency, power, and other data through professional algorithms, avoiding the cumulative errors of traditional indirect measurements, improving the signal accuracy required for primary frequency regulation, and providing timely signal processing response, shortening the adjustment lag time, thus meeting the core requirement of improving the primary frequency regulation qualification rate in the corresponding technical specifications. It possesses good anti-interference performance and multi-protocol communication compatibility, adapting to the complex electromagnetic environment of power plants and existing control systems, requiring no large-scale modification, and reducing upgrade costs. By adopting the frequency regulation system of this invention, the device can be linked with multiple control systems, optimizing the coordination of primary frequency regulation control and load regulation, ensuring grid frequency stability and unit operation economy. It supports remote testing functions, automatically judging unit testing conditions through intermediate equipment forwarding commands and feedback status, eliminating on-site operation links, reducing safety risks, and providing traceable test data, providing a basis for parameter optimization, thus meeting the requirements of the technical specifications for improving primary frequency regulation management efficiency. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of a frequency modulation sampling device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the control panel of a frequency modulation sampling device according to an embodiment of the present invention; Figure 3 This is a backplane terminal diagram of a frequency modulation sampling device according to an embodiment of the present invention; Figure 4 This is a typical wiring diagram of a frequency modulation sampling device according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a frequency modulation system according to an embodiment of the present invention. Detailed Implementation

[0012] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0013] Device Examples According to an embodiment of the present invention, a frequency modulation sampling device is provided. Figure 1 This is a schematic diagram of a frequency modulation sampling device according to an embodiment of the present invention. Figure 1 As shown, an embodiment of the frequency modulation sampling device of the present invention specifically includes: It includes a sampling module, a signal processing module, an output module, and a fault diagnosis module; the frequency modulation sampling device in this embodiment adopts a fully sealed embedded 4U standard chassis with a height of 19 inches.

[0014] The sampling module includes at least two sets of voltage sampling units and at least two sets of current sampling units. The voltage sampling units are used to collect the three-phase line voltage signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The current sampling units are used to collect the three-phase current signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The voltage measurement accuracy, current measurement accuracy, and power measurement accuracy of the sampling module are all less than the preset accuracy values, and the frequency measurement accuracy is less than the preset frequency accuracy value. The voltage dividing resistor of the voltage sampling unit adopts a high-precision metal film resistor, model RJ711, with an accuracy of ±0.1% and a temperature coefficient of ±20ppm / ℃. The current sampling unit adopts a low-resistance manganese copper shunt, model FL-2, with a resistance of 75mV / 5A and an accuracy of ±0.05%. Both have passed the verification of GB / T19147-2013 "Automotive Diesel" and GB / T2423.1-2008 low-temperature test (-40℃, 16h) to ensure stable operation within the power plant's operating temperature range of -0℃ to +55℃. Meanwhile, the signal cable of the sampling module uses shielded twisted pair cable, and the two ends of the shielding layer are grounded (grounding resistance ≤4Ω), which can effectively suppress electromagnetic interference generated by the excitation system and high-voltage equipment in the power plant.

[0015] The signal processing module is electrically connected to the sampling module and is used to perform full-cycle Fourier algorithm calculations on the acquired voltage and current signals to obtain active power, reactive power, frequency, positive-sequence component, negative-sequence component, and zero-sequence component. The electrical quantity transmission response time of the signal processing module is no greater than a preset response time, and the zero-sequence voltage and zero-sequence current transmission response time is no greater than a preset zero-sequence response time. In this embodiment, the full-cycle Fourier algorithm adopts a sliding window + phase compensation optimization strategy: the sliding window length is set to 2 power frequency cycles (40ms), which can filter out the 3rd and 5th harmonics; phase compensation corrects the phase error of frequency measurement by calculating the zero-crossing deviation of the voltage signal in real time, so that the frequency measurement accuracy reaches ±0.002Hz in the range of 49.8Hz~50.2Hz. In addition, the 32-bit ARM processor has a main operating frequency of up to 168MHz, and the time taken for a single full-cycle Fourier calculation is ≤50μs, ensuring that the electrical quantity transmission response time is ≤40ms, and the zero-sequence voltage and zero-sequence current transmission response time is ≤70ms.

[0016] The output module is electrically connected to the signal processing module and is used to output the calculated electrical quantity as an analog current signal. The fault diagnosis module is electrically connected to the sampling module and the signal processing module. It is used to determine the PT disconnection and CT disconnection faults based on the positive sequence component, negative sequence component and zero sequence component of voltage and the zero sequence component of current, and output a fault alarm signal.

[0017] In this embodiment of the invention, the voltage sampling unit includes a first voltage interface group for connecting to a three-phase four-wire system and a second voltage interface group for connecting to a three-phase three-wire system. The first voltage interface group includes an A-phase voltage interface, a B-phase voltage interface, a C-phase voltage interface, and a neutral line interface; The second voltage interface group includes an AB phase-to-phase voltage interface and a BC phase-to-phase voltage interface; The current sampling unit includes a first current interface group for connecting to a three-phase four-wire system and a second current interface group for connecting to a three-phase three-wire system. The first current interface group includes an A-phase current input interface, an A-phase current output interface, a B-phase current input interface, a B-phase current output interface, a C-phase current input interface, and a C-phase current output interface. The second current interface group includes an A-phase current input interface, an A-phase current output interface, a C-phase current input interface, and a C-phase current output interface.

[0018] The signal processing module includes a 32-bit ARM processor, a 16-bit A / D converter, and a filtering circuit. The input terminal of the filtering circuit is electrically connected to the output terminal of the sampling module, and is used to perform anti-interference filtering on the collected voltage and current signals; The input terminal of the A / D converter is electrically connected to the output terminal of the filter circuit, and is used to convert analog signals into digital signals; The 32-bit ARM processor is electrically connected to the A / D converter and has a built-in full-cycle Fourier algorithm program for calculating electrical quantities and performing fault judgment logic operations. The 32-bit ARM processor integrates 192K×16-bit RAM memory, 1024K×16-bit FLASH memory and 64K×8-bit serial EEPROM.

[0019] The output module includes multiple analog output channels, and each output channel is equipped with a D / A conversion unit and a current loop drive unit; The input terminal of the D / A conversion unit is electrically connected to the signal processing module and is used to convert digital signals into analog signals; The input terminal of the current loop drive unit is electrically connected to the output terminal of the D / A conversion unit, and is used to convert the analog signal into a current signal within a preset range. The current loop drive unit supports over-range output, and the output load impedance is not less than a preset value.

[0020] This embodiment's output module features 18 analog output channels (8 via X2 terminals + 10 via X4 terminals). Each channel's D / A conversion unit uses a 16-bit DAC chip, and the current loop drive unit employs an industrial-grade operational amplifier, supporting 2~22mA over-range output (the output current can reach 21.5mA if the frequency signal exceeds the limit). The output load impedance is designed to be 650Ω~1kΩ, making it compatible with analog input modules of commonly used DEH control systems (such as Siemens T3000) and DCS systems in power plants, eliminating the need for additional signal isolators or conditioning modules. Furthermore, opto-isolation (isolation voltage ≥2500VAC) is used between output channels to avoid measurement errors caused by signal crosstalk between channels.

[0021] The PT disconnection criterion of the fault diagnosis module is as follows: when the positive sequence voltage component is less than the preset voltage value and any phase current is greater than the preset current ratio value, or the negative sequence voltage component is greater than the preset negative sequence voltage value, the PT disconnection alarm signal is output after a preset time delay. The fault diagnosis module's CT disconnection criterion is as follows: when the self-generated zero-sequence component of the three-phase current is greater than the preset zero-sequence current calculation value, a CT disconnection alarm signal is output after a preset time; and the fault diagnosis module is also configured with a PT three-phase disconnection instantaneous criterion: when the three-phase voltage drops suddenly and the three-phase current does not increase significantly, a switching signal is output instantaneously and an alarm signal is output after a preset time.

[0022] Furthermore, the frequency modulation sampling device of this embodiment further includes a communication module and a time synchronization module. The communication module is provided with at least two serial communication interfaces and at least two network communication interfaces. The serial communication interfaces support preset transmission rates to meet the needs of short-distance data interaction, and the network communication interfaces support preset network transmission rates to meet the needs of long-distance high-speed data transmission. Moreover, the communication module is compatible with industrial general communication protocols and power industry-specific communication protocols, so as to realize bidirectional data interaction with power automation systems or control and management systems. The time synchronization module is equipped with a standard time synchronization interface, which supports level signal or differential signal input for time synchronization, and is used to realize the device clock calibration.

[0023] Furthermore, the frequency modulation sampling device of this embodiment also includes a human-machine interaction module and a waveform recording module. The human-machine interaction module includes a Chinese LCD screen and a multi-key operation keyboard. The LCD screen supports automatic backlight start / stop, and the keyboard includes direction keys, numerical adjustment keys, confirmation keys, cancel keys, and reset keys, and supports password access management. The waveform recording module is electrically connected to the signal processing module and is used to record the voltage, current, frequency, and power waveforms during faults, supporting standard format storage. Figure 2 This is a schematic diagram of the control panel of a frequency modulation sampling device according to an embodiment of the present invention.

[0024] Figure 3 This is a backplane terminal diagram of a frequency modulation sampling device according to an embodiment of the present invention. Figure 3 Terminal specification sheet 1: Table 1 Terminal Description of a Frequency Modulation Sampling Device

[0025] Ua1 is the voltage input channel for the PT (Potential Transformer) on the high-voltage side of the main transformer. Ua2 is the voltage input channel for the PTs on the high-voltage side of the excitation transformer, main transformer, standby transformer, and high-voltage plant transformer. Ia1 is the current input channel for the CT (Potential Transformer) on the high-voltage side of the main transformer; Ia1 is the current input terminal, and Ia1' is the current output terminal. Please pay attention to the current polarity when wiring. Ia2 is the current input channel for the CTs on the high-voltage side of the excitation transformer, main transformer, standby transformer, and high-voltage plant transformer; Ia2 is the current input terminal, and Ia2' is the current output terminal. Please pay attention to the current polarity when wiring. Outputs 1-8 can be customized to output any one of the following: active power, reactive power, A-phase current, B-phase current, C-phase current, A-phase voltage, B-phase voltage, C-phase voltage, AB-phase voltage, BC-phase voltage, CA-phase voltage, frequency 1, frequency 2, or frequency 3. Outputs 9-18 include any one of the following: active power, reactive power, A-phase current, B-phase current, C-phase current, A-phase voltage, B-phase voltage, C-phase voltage, AB-phase voltage, BC-phase voltage, CA-phase voltage, or frequency. Sampling board X1's U1 and I1 and output board X2 are the inputs and outputs of the first group of transformer circuits, while sampling board X1's U2 and I2 and output board X4 are the inputs and outputs of the second group of transformer circuits.

[0026] Figure 4 This is a typical wiring diagram of a frequency modulation sampling device according to an embodiment of the present invention. The device has two operating power supplies, 110V-220V AC / DC. If DC is used, AC L is the positive terminal and AC N is the negative terminal. If AC is used, DC+ is the AC L terminal and DC- is the AC N terminal. The main transformer PT, main transformer CT, and main transformer output X2 are the main transformer system, and the second set of PT, second set of CT, and second set of output X4 are the other transformer system. DO1~DO4 are signal relays used to output system fault 1, system fault 2, device power failure, and device alarm signals.

[0027] By employing the embodiments of the present invention, the following beneficial effects are achieved: This system integrates sampling, signal processing, and fault diagnosis functions, replacing multiple separate devices, reducing cabinet space requirements and wiring fault points, and lowering installation and maintenance workload. It directly collects voltage and current signals from the high-voltage side of the transformer, and uses professional algorithms to obtain frequency and power data, avoiding the accumulated errors of traditional indirect measurements and improving the signal accuracy required for primary frequency regulation. The signal processing response is timely, shortening the regulation lag time, which aligns with the core requirement of the corresponding technical specifications to improve the primary frequency regulation pass rate. It possesses good anti-interference performance and multi-protocol communication compatibility, adapting to the complex electromagnetic environment of power plants and existing control systems without large-scale modifications, reducing upgrade costs. By adopting the frequency regulation system of this invention, the device and multiple control systems can be linked, optimizing the coordination of primary frequency regulation control and load regulation, ensuring grid frequency stability and unit operation economy. It supports remote testing functions, automatically determining unit testing conditions through intermediate equipment forwarding commands and feedback status, eliminating on-site operation steps, reducing safety risks, and ensuring traceable test data, providing a basis for parameter optimization, thus meeting the requirements of the technical specifications to improve primary frequency regulation management efficiency.

[0028] System Implementation Examples According to an embodiment of the present invention, a frequency modulation system is provided. Figure 5 This is a schematic diagram of a frequency modulation system according to an embodiment of the present invention. Figure 5 As shown, the frequency modulation system of this embodiment specifically includes: Frequency modulation sampling device, DEH control system, AGC control system and DCS system; The output module of the frequency modulation sampling device is electrically connected to the analog input interface of the DEH control system, AGC control system and DCS system respectively, and is used to transmit high-precision frequency signals and power signals to each control system. The communication module of the frequency modulation sampling device is bidirectionally connected to the communication interface of the DCS system, which is used to realize the uploading of measurement values, modification of set values ​​and transmission of fault information. The DEH control system achieves primary frequency modulation control based on the frequency signal output by the frequency modulation sampling device and the rotational speed signal; The AGC control system adjusts the unit load based on the power signal output by the frequency modulation sampling device. The DCS system is used to monitor and store data of the frequency modulation sampling device.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency modulation sampling device, characterized in that, It includes a sampling module, a signal processing module, an output module, and a fault diagnosis module; The sampling module includes at least two sets of voltage sampling units and at least two sets of current sampling units. The voltage sampling units are used to collect the three-phase line voltage signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The current sampling units are used to collect the three-phase current signals of the high-voltage side of the main transformer and the high-voltage side of another transformer. The signal processing module is electrically connected to the sampling module and is used to perform full-cycle Fourier algorithm calculations on the collected voltage and current signals to obtain active power, reactive power, frequency, positive sequence component, negative sequence component and zero sequence component. The output module is electrically connected to the signal processing module and is used to output the calculated electrical quantity as an analog current signal. The fault diagnosis module is electrically connected to the sampling module and the signal processing module. It is used to determine the PT disconnection and CT disconnection faults based on the positive sequence component, negative sequence component and zero sequence component of voltage and the zero sequence component of current, and output a fault alarm signal.

2. The apparatus according to claim 1, characterized in that, The voltage sampling unit includes a first voltage interface group for connecting to a three-phase four-wire system and a second voltage interface group for connecting to a three-phase three-wire system. The first voltage interface group includes an A-phase voltage interface, a B-phase voltage interface, a C-phase voltage interface, and a neutral line interface; The second voltage interface group includes an AB phase-to-phase voltage interface and a BC phase-to-phase voltage interface; The current sampling unit includes a first current interface group for connecting to a three-phase four-wire system and a second current interface group for connecting to a three-phase three-wire system. The first current interface group includes an A-phase current input interface, an A-phase current output interface, a B-phase current input interface, a B-phase current output interface, a C-phase current input interface, and a C-phase current output interface. The second current interface group includes an A-phase current input interface, an A-phase current output interface, a C-phase current input interface, and a C-phase current output interface.

3. The apparatus according to claim 1, wherein the signal processing module comprises a 32-bit ARM processor, a 16-bit A / D converter, and a filtering circuit; The input terminal of the filtering circuit is electrically connected to the output terminal of the sampling module, and is used to perform anti-interference filtering on the collected voltage and current signals; The input terminal of the A / D converter is electrically connected to the output terminal of the filter circuit, and is used to convert analog signals into digital signals; The 32-bit ARM processor is electrically connected to the A / D converter and has a built-in full-cycle Fourier algorithm program for calculating electrical quantities and performing fault judgment logic operations. The 32-bit ARM processor integrates 192K×16-bit RAM memory, 1024K×16-bit FLASH memory and 64K×8-bit serial EEPROM.

4. The apparatus according to claim 1, characterized in that, The output module includes multiple analog output channels, and each output channel is equipped with a D / A conversion unit and a current loop drive unit; The input terminal of the D / A conversion unit is electrically connected to the signal processing module and is used to convert digital signals into analog signals; The input terminal of the current loop drive unit is electrically connected to the output terminal of the D / A conversion unit, and is used to convert the analog signal into a current signal within a preset range. The current loop drive unit supports over-range output, and the output load impedance is not less than a preset value.

5. The apparatus according to claim 1, characterized in that, The PT disconnection criterion of the fault diagnosis module is as follows: when the positive sequence voltage component is less than the preset voltage value and any phase current is greater than the preset current ratio value, or the negative sequence voltage component is greater than the preset negative sequence voltage value, the PT disconnection alarm signal is output after a preset time delay. The fault diagnosis module's CT disconnection criterion is as follows: when the self-generated zero-sequence component of the three-phase current is greater than the preset zero-sequence current calculation value, a CT disconnection alarm signal is output after a preset time; and the fault diagnosis module is also configured with a PT three-phase disconnection instantaneous criterion: when the three-phase voltage drops suddenly and the three-phase current does not increase significantly, a switching signal is output instantaneously and an alarm signal is output after a preset time.

6. The apparatus according to claim 1, characterized in that, It also includes a communication module and a time synchronization module. The communication module is equipped with at least two serial communication interfaces and at least two network communication interfaces. The serial communication interfaces support preset transmission rates to meet the needs of short-distance data interaction, and the network communication interfaces support preset network transmission rates to meet the needs of long-distance high-speed data transmission. The communication module is compatible with industrial general communication protocols and power industry-specific communication protocols to realize bidirectional data interaction with power automation systems or control and management systems. The time synchronization module is equipped with a standard time synchronization interface, which supports level signal or differential signal input for time synchronization, and is used to realize the device clock calibration.

7. The apparatus according to claim 1, characterized in that, It also includes a human-computer interaction module and a waveform recording module. The human-computer interaction module includes a Chinese LCD screen and a multi-key operation keyboard. The LCD screen supports automatic backlight start and stop. The keyboard includes arrow keys, numerical adjustment keys, confirmation keys, cancel keys, and reset keys, and supports password access management. The waveform recording module is electrically connected to the signal processing module and is used to record the voltage, current, frequency, and power waveforms during a fault, and supports standard format storage.

8. The apparatus according to claim 1, characterized in that, The voltage measurement accuracy, current measurement accuracy, and power measurement accuracy of the sampling module are all less than the preset accuracy value, and the frequency measurement accuracy is less than the preset frequency accuracy value. The electrical quantity transmission response time of the signal processing module is no greater than the preset response time, and the zero-sequence voltage and zero-sequence current transmission response time is no greater than the preset zero-sequence response time.

9. The apparatus according to claim 1, characterized in that, The device adopts a fully sealed embedded 4U 19-inch high structure, which supports multiple units to be assembled into a full-width chassis.

10. A frequency modulation system, characterized in that, Includes the frequency modulation sampling device, DEH control system, AGC control system, and DCS system as described in any one of claims 1-8; The output module of the frequency modulation sampling device is electrically connected to the analog input interface of the DEH control system, AGC control system and DCS system respectively, and is used to transmit high-precision frequency signals and power signals to each control system. The communication module of the frequency modulation sampling device is bidirectionally connected to the communication interface of the DCS system, which is used to realize the uploading of measurement values, modification of set values ​​and transmission of fault information. The DEH control system achieves primary frequency modulation control based on the frequency signal output by the frequency modulation sampling device and the rotational speed signal; The AGC control system adjusts the unit load based on the power signal output by the frequency modulation sampling device. The DCS system is used to monitor and store data of the frequency modulation sampling device.

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