Novel frequency modulation method and system for fused salt energy storage coupling thermal power generating unit

Abstract

The invention discloses a novel frequency modulation method and system for a fused salt energy storage coupling thermal power generating unit, and the method comprises the steps: monitoring the frequency of a power grid through a frequency detection module, and carrying out the grading according to the deviation amplitude; the parameter acquisition module is used for acquiring data, de-noising processing is performed, and the frequency modulation control module is used for primary frequency modulation; frequency signals are decomposed through a wavelet packet decomposition method, and the thermal power generating unit and the fused salt energy storage module work cooperatively to perform secondary frequency modulation; high and low frequency components are separated by using an ensemble empirical mode decomposition method, and the thermal power generating unit and the fused salt energy storage module cooperatively perform three-level frequency modulation; frequency fluctuation and output conditions are recorded through a data recording and feedback module, and parameters are adjusted according to feedback data; monitoring the state of each module in real time, and starting a fault detection and standby module if the fluctuation exceeds a safety range or a fault occurs; after the frequency is stable, the system gradually quits the frequency modulation mode and recovers to the initial monitoring state, and all modules enter a standby state. The power grid frequency modulation response speed and stability are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid frequency regulation, and in particular to a novel frequency regulation method and system for a molten salt energy storage coupled thermal power unit. Background Art

[0002] Combined frequency regulation of thermal power generation and storage can significantly improve the frequency regulation performance of thermal power units and can quickly and effectively reduce the system frequency regulation capacity shortage. Traditional frequency regulation methods mainly rely on the rapid response capability of thermal power units, but are limited by the response speed and regulation flexibility of thermal power units themselves, and cannot meet the rapid response requirements of modern power grids to frequency fluctuations. This results in the traditional frequency regulation method being difficult to maintain the stability of the power grid under large frequency fluctuations, and having defects such as low frequency regulation accuracy and long response time.

[0003] At present, in practical applications, the frequency regulation effect of molten salt energy storage modules and thermal power units is easily affected by multiple factors such as the operating status of the equipment, the frequency and amplitude of frequency fluctuations; the current frequency regulation system lacks a flexible hierarchical response mechanism, resulting in insufficient precision in frequency regulation control, making it difficult to achieve effective regulation under different frequency deviation amplitudes.

[0004] In view of the above problems, the present invention provides a new frequency modulation method and system for molten salt energy storage coupled thermal power units, which realizes real-time frequency monitoring through the frequency detection module, combines advanced algorithms such as wavelet packet decomposition and ensemble empirical mode decomposition, decomposes the frequency signal, and flexibly allocates the frequency modulation demand to the thermal power units and molten salt energy storage modules. Under different frequency fluctuation conditions, the system can realize hierarchical frequency modulation and adaptive adjustment, ensuring that the system has higher frequency modulation accuracy and response speed. Summary of the invention

[0005] In view of the above problems, the present invention provides a new frequency modulation method and system for molten salt energy storage coupled with thermal power units to solve the problem that the frequency modulation effect of existing molten salt energy storage modules and thermal power units is easily affected by multiple factors such as equipment operating status, frequency fluctuation frequency and amplitude.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: The present invention provides a novel frequency modulation method for a molten salt energy storage coupled thermal power unit, which is characterized by comprising: Step S1, monitoring the grid frequency through a frequency detection module and classifying the frequency according to the deviation amplitude; Wherein step S1 also includes the following sub-steps: S1-1, through the frequency detection module, uses the synchronized phasor measurement device to monitor the changes of voltage and current in real time, captures the slight frequency fluctuations, and continuously detects the frequency fluctuations of the power grid; S1-2, frequency levels are divided according to the frequency deviation amplitude, and the fluctuation is divided into three levels, as follows: Level 1: Mild frequency fluctuation, with deviation within 0.1Hz; Level 2: Moderate frequency fluctuation, with a deviation between 0.1-0.2 Hz; Level 3: High frequency fluctuation, deviation exceeds 0.2Hz.

[0007] Step S2, collecting data through the parameter collection module, performing denoising, and performing primary frequency modulation using the frequency modulation control module; Wherein step S2 also includes the following sub-steps: S2-1, obtaining temperature, pressure, speed and power parameters through the temperature sensor, pressure sensor, speed sensor and power sensor in the parameter acquisition module; S2-2, the double threshold method is combined with the sliding average filter to remove noise, and the three sigma rule is combined with the local anomaly factor algorithm to detect outliers, identify and remove or correct abnormal data points, as shown in formula (1) to formula (4): Formula (1) Formula (2) Formula (3) Formula (4) in, is a data point in the original data sequence, is the data point processed by the double threshold method, , are the upper and lower thresholds, is invalid data; is the smoothed data value after sliding average filtering, The size of the sliding window, i is the relative position of the data point, The window used to initialize the filter, is the data point processed by the double threshold method, the data point at time ti; is the mean of the data, is the standard deviation, is a data point in the data set; is the local outlier factor of point p, k is the number of neighbors, is the set of k neighbors of point p, o is a neighbor of point p, is the local reachability density of point p, is the local reachability density of point o; S2-3, through the frequency modulation control module, uses the fuzzy adaptive PID algorithm to dynamically adjust according to different frequency deviation conditions, as shown in formula (5): Formula (5) in, is the error value, It is the parameter that the fuzzy controller automatically adjusts according to the real-time frequency error; S2-4, return to monitoring mode after frequency adjustment is completed.

[0008] Step S3, decomposing the frequency signal by wavelet packet decomposition method, and the thermal power unit and the molten salt energy storage module work together to perform secondary frequency modulation; Wherein step S3 also includes the following sub-steps: S3-1, according to the frequency fluctuation signal, the frequency regulation demand is allocated to the thermal power unit module and the molten salt energy storage module. The thermal power unit module is responsible for preliminary regulation, and the molten salt energy storage module is responsible for frequency stability; S3-2, using wavelet packet decomposition technology to decompose the frequency modulation signal into high-frequency and low-frequency components, the high-frequency part is responded by the thermal power unit module, and the low-frequency part is borne by the molten salt energy storage module, as shown in formula (6)-formula (7): Formula (6) Formula (7) Among them, the number of decomposition layers is n, the wavelet packet decomposition coefficient is d, the frequency band node number is j, the low-pass filter coefficient is b, the high-pass filter coefficient is a, the low-pass filter coefficient is l, and the frequency band number is k; S3-3, the thermal power unit module undertakes the task of rapid frequency regulation to cope with instantaneous frequency fluctuations; the molten salt energy storage module provides support for low-frequency components; S3-4, monitor the frequency recovery in real time and adjust the output of the molten salt energy storage module according to the frequency change.

[0009] Step S4, using the ensemble empirical mode decomposition method to separate high and low frequency components, the thermal power unit module and the molten salt energy storage module work together, and the cogeneration module and the molten salt energy storage module coordinate and adjust to perform three-level frequency modulation in response to large fluctuations; Wherein step S4 also includes the following sub-steps: S4-1, through the ensemble empirical mode decomposition method, the load command is decomposed into high-frequency signals and low-frequency signals, as shown in formula (8) to formula (10): Formula (8) Formula (9) Formula (10) in, is the signal to be decomposed, is the original signal The natural mode components of order, To decompose the remainder, is the decomposition order; Represents a high frequency signal, represents low-frequency signal, d represents wavelet packet decomposition coefficient; Formula (9) is the order less than or equal to The sum of the natural modal components of is the higher frequency part; Formula (10) is the order greater than The sum of the natural modal components and the remainder is the lower frequency part; S4-2, the thermal power unit module and the molten salt energy storage module work together, the molten salt energy storage module provides long-term output to cope with continuous low-frequency fluctuations, and the thermal power unit module responds to short-term high-frequency fluctuations; S4-3, when the grid frequency continues to fluctuate significantly, the heat energy of the molten salt energy storage module is transferred to the grid through the thermoelectric conversion device; S4-4, the molten salt energy storage module adjusts the heat output through the cogeneration module, and uses the feedforward control strategy to link the demand of the heating end with the output of the molten salt energy storage module.

[0010] Step S5, recording the frequency fluctuation and output status through the data recording and feedback module, and adjusting the parameters according to the feedback data; Wherein, in step S5, the following sub-steps are also included: S5-1, through the data recording and feedback module, the frequency fluctuation and the output data of the thermal power unit module and the molten salt energy storage module are recorded in real time during the frequency modulation process; S5-2, based on real-time monitoring data, using data feedback mechanism and intelligent control algorithm, adjust the output parameters of the thermal power unit module and the molten salt energy storage module.

[0011] Step S6, monitor the status of each module in real time, and immediately start the fault detection and backup module if the fluctuation exceeds the safety range or the fault occurs; Wherein, in step S6, the following sub-steps are also included: S6-1, through the fault detection and backup module, real-time monitoring of the operating status of the thermal power unit module and the molten salt energy storage module, to determine whether there is an abnormal operating status; S6-2, using the over-limit judgment mechanism, starts the backup energy storage device when it is detected that the frequency fluctuation meets the third-level standard or the equipment fails.

[0012] Step S7, through the reset and recovery module, after the frequency is stabilized, the system gradually exits the frequency modulation mode and returns to the initial monitoring state, and all modules enter the standby state.

[0013] Wherein, in step S7, the following sub-steps are also included: S7-1, after the frequency is restored to a stable state through the reset and recovery module, a phased exit method is adopted to gradually reduce the output of the molten salt energy storage module and the thermal power unit module and return to the initial monitoring mode; S7-2, after detecting that the data remains within the normal range for a period of time, triggers the automatic reset mechanism in the reset and recovery module, so that each module returns to the standby state after the frequency modulation task is completed.

[0014] Furthermore, a new frequency regulation system for molten salt energy storage coupled with thermal power generation units includes: Frequency detection module, parameter acquisition module, frequency modulation control module, thermal power unit module, molten salt energy storage module, combined heat and power module, data recording and feedback module, fault detection and backup module, reset and recovery module; The frequency detection module is used to continuously monitor the grid frequency to obtain grid frequency deviation information, and transmit the detected frequency data to the system to trigger the corresponding frequency modulation response; The parameter acquisition module includes temperature, pressure, speed and power sensors, which are used to collect the operating parameters of the thermal power unit module and the molten salt energy storage module in real time; The frequency modulation control module includes a fuzzy adaptive PID controller and an algorithm processor, which triggers corresponding frequency modulation operations according to different levels of frequency deviation, and is used to analyze data and adjust the output parameters of the thermal power unit module and the molten salt energy storage module; The thermal power unit module is used to quickly respond to high-frequency frequency fluctuations. When the grid frequency fluctuates instantaneously, the output power is quickly adjusted to help the grid return to a stable state; The molten salt energy storage module is used to handle low-frequency fluctuations and long-term frequency stability, provide continuous power output, and provide additional power support to the system through thermoelectric conversion equipment when the grid frequency fluctuates; The cogeneration module is connected to the molten salt energy storage module, and can adjust the heat output according to the fluctuation of the power grid frequency, and link the heat demand with the power output of the energy storage system through feedforward control; The data recording and feedback module is used to record and store various data of the system during the frequency modulation process, including frequency fluctuations, output conditions of the thermal power unit module and the molten salt energy storage module; The fault detection and backup module is used to monitor the status of the entire system in real time. When it is detected that the frequency fluctuation in the system exceeds the safety range or a module fails, the backup energy storage device is immediately started; The reset and recovery module is responsible for gradually exiting the frequency modulation mode, returning the system to the initial monitoring state, setting all modules to standby state, and gradually restoring the heat of the molten salt energy storage module to normal levels in preparation for the next frequency modulation demand.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The novel frequency modulation method of the molten salt energy storage coupled thermal power unit of the present invention comprises: monitoring the grid frequency through a frequency detection module, and dividing the levels according to the deviation amplitude; collecting data through a parameter acquisition module, performing denoising processing, and performing primary frequency modulation using a frequency modulation control module; decomposing the frequency signal through a wavelet packet decomposition method, and the thermal power unit and the molten salt energy storage module work together to perform secondary frequency modulation; using a collective empirical mode decomposition method to separate high and low frequency components, the thermal power unit module and the molten salt energy storage module work together, and the cogeneration module and the molten salt energy storage module cooperate to adjust to cope with large fluctuations to perform third-level frequency modulation; recording frequency fluctuations and output conditions through a data recording and feedback module, and adjusting parameters according to feedback data; real-time monitoring of the status of each module, and immediately starting the fault detection and standby module if the fluctuation exceeds the safety range or a fault occurs; through a reset and recovery module, after the frequency is stable, the system gradually exits the frequency modulation mode and returns to the initial monitoring state, and all modules enter a standby state.

[0016] The new frequency regulation system of molten salt energy storage coupled with thermal power units includes: frequency detection module, parameter acquisition module, frequency regulation control module, thermal power unit module, molten salt energy storage module, cogeneration module, data recording and feedback module, fault detection and backup module, reset and recovery module.

[0017] The present invention performs hierarchical processing on frequency signals through algorithms such as wavelet packet decomposition and ensemble empirical mode decomposition, and leaves high-frequency fluctuations to thermal power units for response, while low-frequency fluctuations are smoothly adjusted by molten salt energy storage modules. This hierarchical frequency modulation strategy effectively improves the accuracy and response speed of frequency modulation, and can better cope with the regulation needs of different frequency fluctuation amplitudes.

[0018] During the frequency modulation process, the system of the present invention records the frequency fluctuation and output conditions in real time through the data recording and feedback module, and dynamically adjusts the output of the thermal power unit and the molten salt energy storage module according to the feedback data, ensuring that the system can automatically optimize the frequency modulation parameters according to the real-time situation, thereby further improving the frequency modulation effect and system stability.

[0019] The present invention introduces a fault detection and backup module. When the frequency fluctuation in the system exceeds the safe range or an equipment failure occurs, the system will immediately start the backup energy storage device to prevent large fluctuations in the grid frequency due to equipment failure, effectively improving the reliability and safety of the system and ensuring the frequency stability of the grid in emergency situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It is understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 is a flow chart of the method of the present invention; Figure 2 It is a system architecture diagram of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but is only for selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0023] Please refer to Figure 1 This is a flow chart of a new frequency modulation method for a molten salt energy storage coupled thermal power unit provided by an embodiment of the present invention, comprising the following steps: Step S1, monitoring the grid frequency through a frequency detection module and classifying the frequency according to the deviation amplitude; Wherein step S1 also includes the following sub-steps: S1-1, through the frequency detection module, uses the synchronized phasor measurement device to monitor the changes of voltage and current in real time, captures the slight frequency fluctuations, and continuously detects the frequency fluctuations of the power grid; S1-2, frequency levels are divided according to the frequency deviation amplitude, and the fluctuation is divided into three levels, as follows: Level 1: Mild frequency fluctuation, with deviation within 0.1Hz; Level 2: Moderate frequency fluctuation, with a deviation between 0.1-0.2 Hz; Level 3: High frequency fluctuation, deviation exceeds 0.2Hz.

[0024] It should be noted that the synchronized phasor measurement unit (PMU) performs synchronous measurement of the voltage and current phasors at each node in the power grid based on the precise time signal provided by the global positioning system; PMU measures the amplitude and phase angle of voltage and current in real time, generating accurate phasor data. These phasors represent the instantaneous state of the power grid and can quickly reflect the dynamic changes of the power system. When a power grid fails, PMU can quickly locate the fault by analyzing abnormal changes in phasor data, helping the power grid system to isolate the fault and reduce the scope of the accident.

[0025] Step S2, collecting data through the parameter collection module, performing denoising, and performing primary frequency modulation using the frequency modulation control module; Wherein step S2 also includes the following sub-steps: S2-1, obtaining temperature, pressure, speed and power parameters through the temperature sensor, pressure sensor, speed sensor and power sensor in the parameter acquisition module; S2-2, the double threshold method is combined with the sliding average filter to remove noise, and the three sigma rule is combined with the local anomaly factor algorithm to detect outliers, identify and remove or correct abnormal data points, as shown in formula (1) to formula (4): Formula (1) Formula (2) Formula (3) Formula (4) in, is a data point in the original data sequence, is the data point processed by the double threshold method, , are the upper and lower thresholds, is invalid data; is the smoothed data value after sliding average filtering, The size of the sliding window, i is the relative position of the data point, The window used to initialize the filter, is the data point processed by the double threshold method, the data point at time ti; is the mean of the data, is the standard deviation, is a data point in the data set; is the local outlier factor of point p, k is the number of neighbors, is the set of k neighbors of point p, o is a neighbor of point p, is the local reachability density of point p, is the local reachability density of point o; S2-3, through the frequency modulation control module, uses the fuzzy adaptive PID algorithm to dynamically adjust according to different frequency deviation conditions, as shown in formula (5): Formula (5) in, is the error value, It is the parameter that the fuzzy controller automatically adjusts according to the real-time frequency error; S2-4, return to monitoring mode after frequency adjustment is completed.

[0026] It should be noted that the double threshold method combined with the moving average filter to remove noise is used to process the noise signal in the data and enhance the stability and accuracy of the signal: the moving average filter smoothes the data by taking the average value of a set of continuous data points, thereby reducing the impact of random noise, and calculates the local average value of the current data point by continuously moving the window, making the data smoother. The double threshold method introduces two thresholds, usually a high threshold and a low threshold. When processing data, if a data point exceeds the high threshold, it is considered that the fluctuation of the point may be a signal, and the point is retained instead of noise; if the data point is lower than the low threshold, it is considered that the fluctuation is not significant and may be noise, so the point is filtered out; values ​​between the high and low thresholds need to be further processed, retained or smoothed.

[0027] The three sigma rule is combined with the local anomaly factor algorithm for outlier detection to detect outliers in data and identify abnormal system states or faults: the three sigma rule is based on the normal distribution assumption, which considers data within three times the standard deviation above and below the mean as normal data, and data outside this range as abnormal data; the local anomaly factor algorithm is an unsupervised anomaly detection algorithm, which determines whether each data point is an anomaly by comparing the density of other points in its neighborhood; the three sigma rule combined with the local anomaly factor algorithm can eliminate noise interference in a timely manner when obvious global anomalies are detected, and identify potential local abnormal data at the same time.

[0028] The fuzzy adaptive PID algorithm is an intelligent control algorithm that combines fuzzy logic and PID control. It can automatically adjust the parameters of the PID controller according to the system state and is suitable for nonlinear or dynamically changing systems. The fuzzy controller first obtains the current error of the system (the difference between the actual value and the target value) and the rate of change of the error. These two values ​​are used as input variables to judge the state of the system. Based on the preset fuzzy rule base, the error and the rate of change of the error are converted into fuzzy language variables, and the combination of these variables is used to determine the increment of the PID parameters. The fuzzy controller calculates the appropriate PID parameter adjustment amount through fuzzy reasoning based on the rule base and input variables. These adjustments are processed in the steps of fuzzification, reasoning and defuzzification, and the specific output is output. value; apply the result of fuzzy reasoning to the PID controller and update it in real time The value of can make the PID controller better adapt to the current state of the system.

[0029] Step S3, decomposing the frequency signal by wavelet packet decomposition method, and the thermal power unit and the molten salt energy storage module work together to perform secondary frequency modulation; Wherein step S3 also includes the following sub-steps: S3-1, according to the frequency fluctuation signal, the frequency regulation demand is allocated to the thermal power unit module and the molten salt energy storage module. The thermal power unit module is responsible for preliminary regulation, and the molten salt energy storage module is responsible for frequency stability; S3-2, using wavelet packet decomposition technology to decompose the frequency modulation signal into high-frequency and low-frequency components, the high-frequency part is responded by the thermal power unit module, and the low-frequency part is borne by the molten salt energy storage module, as shown in formula (6)-formula (7): Formula (6) Formula (7) Among them, the number of decomposition layers is n, the wavelet packet decomposition coefficient is d, the frequency band node number is j, the low-pass filter coefficient is b, the high-pass filter coefficient is a, the low-pass filter coefficient is l, and the frequency band number is k; S3-3, the thermal power unit module undertakes the task of rapid frequency regulation to cope with instantaneous frequency fluctuations; the molten salt energy storage module provides support for low-frequency components; S3-4, monitor the frequency recovery in real time and adjust the output of the molten salt energy storage module according to the frequency change.

[0030] It should be noted that after the initial signal (0, 0) is collected, the high-frequency signal (1, 1) and the low-frequency signal (1, 0) are obtained through wavelet packet decomposition technology. The two signals are decomposed by wavelet packets again, and this process is repeated three times; finally, the frequencies of each sub-signal are arranged according to the high and low frequencies.

[0031] The thermal power unit module is characterized by fast response speed and the ability to adjust the output power in a short time. It is suitable for handling instantaneous frequency fluctuations, that is, changes in high-frequency components. When the grid frequency suddenly experiences a small but rapid fluctuation, the thermal power unit module can respond immediately and adjust its own output to quickly balance the power demand of the grid and prevent excessive frequency deviation.

[0032] The advantages of molten salt energy storage modules are their large energy storage capacity and stable energy output, which are suitable for coping with slow changes in frequency, that is, fluctuations in low-frequency components. Low-frequency fluctuations are usually caused by large and continuous load changes and require long-term power balance. Molten salt energy storage modules provide smooth power output by slowly releasing or absorbing energy, helping the system to cope with such long-term frequency fluctuations and maintain the frequency stability of the power grid.

[0033] Step S4, using the ensemble empirical mode decomposition method to separate high and low frequency components, the thermal power unit module and the molten salt energy storage module work together, and the cogeneration module and the molten salt energy storage module coordinate and adjust to perform three-level frequency modulation in response to large fluctuations; Wherein step S4 also includes the following sub-steps: S4-1, through the ensemble empirical mode decomposition method, the load command is decomposed into high-frequency signals and low-frequency signals, as shown in formula (8) to formula (10): Formula (8) Formula (9) Formula (10) in, is the signal to be decomposed, is the original signal The natural mode components of order, To decompose the remainder, is the decomposition order; Represents a high frequency signal, represents low-frequency signal, d represents wavelet packet decomposition coefficient; Formula (9) is the order less than or equal to The sum of the natural modal components of is the higher frequency part; Formula (10) is the order greater than The sum of the natural modal components and the remainder is the lower frequency part; S4-2, the thermal power unit module and the molten salt energy storage module work together, the molten salt energy storage module provides long-term output to cope with continuous low-frequency fluctuations, and the thermal power unit module responds to short-term high-frequency fluctuations; S4-3, when the grid frequency continues to fluctuate significantly, the heat energy of the molten salt energy storage module is transferred to the grid through the thermoelectric conversion device; S4-4, the molten salt energy storage module adjusts the heat output through the cogeneration module, and uses the feedforward control strategy to link the demand of the heating end with the output of the molten salt energy storage module.

[0034] It should be noted that ensemble empirical mode decomposition is a signal processing method, which is an improvement on empirical mode decomposition. It is often used to decompose complex signals into multiple intrinsic mode functions. It can better handle the noise and unstable components in the signal and analyze the frequency components and characteristics of the signal more finely.

[0035] The load command is a control signal issued by the system to adjust the power output of each module to meet the needs of the power grid. During the power grid frequency regulation process, the load command is used to instruct the thermal power unit or energy storage module to increase or decrease the power output to achieve frequency stability. These commands are usually generated by the frequency regulation control module based on real-time frequency deviation, load demand and system status information.

[0036] The process of the feedforward control strategy is as follows: the system predicts future heating demand by monitoring the parameters of the heating end; based on the predicted demand, the system adjusts the output of the molten salt energy storage module without waiting for actual changes to occur, ensuring that the heating end can obtain the required heat when changes occur; the output of the heating end and the molten salt energy storage module are linked under the feedforward control strategy to achieve rapid response, reduce fluctuations at the heating end, and improve the stability of the system's heating and power regulation.

[0037] Step S5, recording the frequency fluctuation and output status through the data recording and feedback module, and adjusting the parameters according to the feedback data; Wherein, in step S5, the following sub-steps are also included: S5-1, through the data recording and feedback module, the frequency fluctuation and the output data of the thermal power unit module and the molten salt energy storage module are recorded in real time during the frequency modulation process; S5-2, based on real-time monitoring data, using data feedback mechanism and intelligent control algorithm, adjust the output parameters of the thermal power unit module and the molten salt energy storage module.

[0038] It should be noted that when a grid frequency fluctuation is detected, the system analyzes the amplitude and frequency components of the fluctuation to determine the high-frequency components that require a quick response and the low-frequency components that require continuous regulation; The thermal power unit module is mainly responsible for responding to short-term high-frequency fluctuations. By adjusting its output power, that is, speeding up or slowing down the fuel supply, it can quickly increase or decrease power generation to help the power grid cope with instantaneous frequency changes; the molten salt energy storage module is suitable for coping with low-frequency fluctuations and long-term frequency stability requirements. By adjusting its thermoelectric conversion output, the molten salt energy storage module can provide continuous power support and gradually restore the frequency to a stable state.

[0039] Step S6, monitor the status of each module in real time, and immediately start the fault detection and backup module if the fluctuation exceeds the safety range or the fault occurs; Wherein, in step S6, the following sub-steps are also included: S6-1, through the fault detection and backup module, real-time monitoring of the operating status of the thermal power unit module and the molten salt energy storage module, to determine whether there is an abnormal operating status; S6-2, using the over-limit judgment mechanism, starts the backup energy storage device when it is detected that the frequency fluctuation meets the third-level standard or the equipment fails.

[0040] It should be noted that the over-limit judgment mechanism is a monitoring and control method used to detect whether system parameters exceed the preset safety thresholds. By setting a set of upper and lower limit thresholds, it is determined whether the key parameters of the system exceed the allowable range; when the parameters exceed these thresholds, the system will trigger an alarm or protective measures to ensure safety and stability.

[0041] Frequency fluctuations are divided into different levels, among which exceeding 0.2Hz is defined as level three fluctuations, which is the highest level of frequency fluctuations; the system divides frequency deviations into multiple thresholds, level one, level two and level three; each level corresponds to a different frequency deviation range, level three is the highest level (exceeding 0.2Hz), indicating that the system is in a state of large fluctuations; the frequency detection module in the system will continuously monitor the grid frequency and compare it with the set threshold level in real time; if the detected frequency deviation reaches or exceeds 0.2Hz, that is, exceeds level two, the system will judge it as a level three fluctuation state. Once the over-limit judgment mechanism detects level three fluctuations (that is, exceeding 0.2Hz), the system will immediately initiate the corresponding emergency response to quickly balance the grid to reduce the impact of frequency deviation.

[0042] Step S7, through the reset and recovery module, after the frequency is stabilized, the system gradually exits the frequency modulation mode and returns to the initial monitoring state, and all modules enter the standby state.

[0043] Wherein, in step S7, the following sub-steps are also included: S7-1, after the frequency is restored to a stable state through the reset and recovery module, a phased exit method is adopted to gradually reduce the output of the molten salt energy storage module and the thermal power unit module and return to the initial monitoring mode; S7-2, after detecting that the data remains within the normal range for a period of time, triggers the automatic reset mechanism in the reset and recovery module, so that each module returns to the standby state after the frequency modulation task is completed.

[0044] It should be noted that the phased exit method is a strategy for the frequency modulation system to gradually reduce the output of each module when the frequency fluctuation gradually returns to stability, so that the system can smoothly transition to the initial monitoring state; when the grid frequency returns to a safe range, the system will not immediately stop the frequency modulation operation completely, but will gradually reduce the power output of the thermal power units and molten salt energy storage modules through the reset and recovery module to avoid the sudden change of the system again. The system will reduce the frequency modulation output step by step according to the amplitude and stability trend of the frequency deviation, from a higher power regulation to a lower compensation amount, until the frequency deviation is close to zero; at each stage, the system will confirm the stability of the frequency before continuing to reduce the output; this phased exit process ensures a smooth transition during the frequency modulation exit and prevents secondary fluctuations or instantaneous frequency offsets caused by rapid switching.

[0045] The automatic reset mechanism means that after the frequency modulation task is completed, each module of the system can automatically restore to the standby state in order to prepare for the next frequency modulation demand; when the frequency returns to stability and exits the frequency modulation mode, the reset and recovery module will gradually reduce the temperature and power output of the molten salt energy storage module through the automatic reset mechanism, and restore it to the standby state; during the reset process, the system will monitor the energy status of the energy storage module to ensure that it is full of energy reserves and provide sufficient support for the next frequency fluctuation, which includes monitoring the power or heat recovery of the energy storage module to ensure that the reserve status is normal; the thermal power unit and other auxiliary modules will also be restored to the standby state according to the automatic reset mechanism to ensure that the entire system has the ability to respond quickly at any time.

[0046] Please refer to Figure 2 This is a new frequency modulation system architecture diagram of a molten salt energy storage coupled with a thermal power unit provided by an embodiment of the present invention, including: Frequency detection module, parameter acquisition module, frequency modulation control module, thermal power unit module, molten salt energy storage module, combined heat and power module, data recording and feedback module, fault detection and backup module, reset and recovery module; The frequency detection module is used to continuously monitor the grid frequency to obtain grid frequency deviation information, and transmit the detected frequency data to the system to trigger the corresponding frequency modulation response; The parameter acquisition module includes temperature, pressure, speed and power sensors, which are used to collect the operating parameters of the thermal power unit module and the molten salt energy storage module in real time; The frequency modulation control module includes a fuzzy adaptive PID controller and an algorithm processor, which triggers corresponding frequency modulation operations according to different levels of frequency deviation, and is used to analyze data and adjust the output parameters of the thermal power unit module and the molten salt energy storage module; The thermal power unit module is used to quickly respond to high-frequency frequency fluctuations. When the grid frequency fluctuates instantaneously, the output power is quickly adjusted to help the grid return to a stable state; The molten salt energy storage module is used to handle low-frequency fluctuations and long-term frequency stability, provide continuous power output, and provide additional power support to the system through thermoelectric conversion equipment when the grid frequency fluctuates; The cogeneration module is connected to the molten salt energy storage module, and can adjust the heat output according to the fluctuation of the power grid frequency, and link the heat demand with the power output of the energy storage system through feedforward control; The data recording and feedback module is used to record and store various data of the system during the frequency modulation process, including frequency fluctuations, output conditions of the thermal power unit module and the molten salt energy storage module; The fault detection and backup module is used to monitor the status of the entire system in real time. When it is detected that the frequency fluctuation in the system exceeds the safety range or a module fails, the backup energy storage device is immediately started; The reset and recovery module is responsible for gradually exiting the frequency modulation mode, returning the system to the initial monitoring state, setting all modules to standby state, and gradually restoring the heat of the molten salt energy storage module to normal levels in preparation for the next frequency modulation demand.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention has various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A new frequency modulation method for molten salt energy storage coupled with thermal power units, characterized in that: The following steps are involved: Step S1, monitoring the grid frequency through a frequency detection module and classifying the frequency according to the deviation amplitude; Step S2, collecting data through the parameter collection module, performing denoising, and performing primary frequency modulation using the frequency modulation control module; Step S3, decomposing the frequency signal by wavelet packet decomposition method, and the thermal power unit module and the molten salt energy storage module work together to perform secondary frequency modulation; Step S4, using the ensemble empirical mode decomposition method to separate high and low frequency components, the thermal power unit module and the molten salt energy storage module work together, and the cogeneration module and the molten salt energy storage module coordinate and adjust to perform three-level frequency modulation in response to large fluctuations; Step S5, recording the frequency fluctuation and output status through the data recording and feedback module, and adjusting the parameters according to the feedback data; Step S6, monitor the status of each module in real time, and immediately start the fault detection and backup module if the fluctuation exceeds the safety range or the fault occurs; Step S7, through the reset and recovery module, after the frequency is stabilized, the system gradually exits the frequency modulation mode and returns to the initial monitoring state, and all modules enter the standby state.

2. According to claim 1, a novel frequency modulation method for molten salt energy storage coupled with a thermal power unit is characterized in that: Wherein step S1 also includes the following sub-steps: S1-1, through the frequency detection module, uses the synchronized phasor measurement device to monitor the changes of voltage and current in real time, captures the slight frequency fluctuations, and continuously detects the frequency fluctuations of the power grid; S1-2, frequency levels are divided according to the frequency deviation amplitude, and the fluctuation is divided into three levels, as follows: Level 1: Mild frequency fluctuation, with deviation within 0.1Hz; Level 2: Moderate frequency fluctuation, with a deviation between 0.1-0.2 Hz; Level 3: High frequency fluctuation, deviation exceeds 0.2Hz.

3. According to claim 1, a novel frequency modulation method for molten salt energy storage coupled with a thermal power unit is characterized in that: Wherein step S2 also includes the following sub-steps: S2-1, obtaining temperature, pressure, speed and power parameters through the temperature sensor, pressure sensor, speed sensor and power sensor in the parameter acquisition module; S2-2, the double threshold method is combined with the sliding average filter to remove noise, and the three sigma rule is combined with the local anomaly factor algorithm to detect outliers, identify and remove or correct abnormal data points, as shown in formula (1) to formula (4): Formula (1) Formula (2) Formula (3) Formula (4) in, is a data point in the original data sequence, is the data point processed by the double threshold method, , are the upper and lower thresholds, is invalid data; is the smoothed data value after sliding average filtering, The size of the sliding window, i is the relative position of the data point, The window used to initialize the filter, is the data point processed by the double threshold method, the data point at time ti; is the mean of the data, is the standard deviation, is a data point in the data set; is the local outlier factor of point p, k is the number of neighbors, is the set of k neighbors of point p, o is a neighbor of point p, is the local reachability density of point p, is the local reachability density of point o; S2-3, through the frequency modulation control module, uses the fuzzy adaptive PID algorithm to dynamically adjust according to different frequency deviation conditions, as shown in formula (5): Formula (5) in, is the error value, It is the parameter that the fuzzy controller automatically adjusts according to the real-time frequency error; S2-4, return to monitoring mode after frequency adjustment is completed.

4. According to claim 1, a novel frequency modulation method for molten salt energy storage coupled with a thermal power unit is characterized in that: Wherein step S3 also includes the following sub-steps: S3-1, according to the frequency fluctuation signal, the frequency regulation demand is allocated to the thermal power unit module and the molten salt energy storage module. The thermal power unit module is responsible for preliminary regulation, and the molten salt energy storage module is responsible for frequency stability; S3-2, using wavelet packet decomposition technology to decompose the frequency modulation signal into high-frequency and low-frequency components, the high-frequency part is responded by the thermal power unit module, and the low-frequency part is borne by the molten salt energy storage module, as shown in formula (6)-formula (7): Formula (6) Formula (7) Among them, the number of decomposition layers is n, the wavelet packet decomposition coefficient is d, the frequency band node number is j, the low-pass filter coefficient is b, the high-pass filter coefficient is a, the low-pass filter coefficient is l, and the frequency band number is k; S3-3, the thermal power unit module undertakes the task of rapid frequency regulation to cope with instantaneous frequency fluctuations; the molten salt energy storage module provides support for low-frequency components; S3-4, monitor the frequency recovery in real time and adjust the output of the molten salt energy storage module according to the frequency change.

5. According to claim 1, a novel frequency modulation method for molten salt energy storage coupled with a thermal power unit is characterized in that: Wherein step S4 also includes the following sub-steps: S4-1, through the ensemble empirical mode decomposition method, the load command is decomposed into high-frequency signals and low-frequency signals, as shown in formula (8) to formula (10): Formula (8) Formula (9) Formula (10) in, is the signal to be decomposed, is the original signal The natural mode components of order, To decompose the remainder, is the decomposition order; Represents a high frequency signal, represents low-frequency signal, d represents wavelet packet decomposition coefficient; Formula (9) is the order less than or equal to The sum of the natural modal components of is the higher frequency part; Formula (10) is the order greater than The sum of the natural modal components and the remainder is the lower frequency part; S4-2, the thermal power unit module and the molten salt energy storage module work together, the molten salt energy storage module provides long-term output to cope with continuous low-frequency fluctuations, and the thermal power unit module responds to short-term high-frequency fluctuations; S4-3, when the grid frequency continues to fluctuate significantly, the heat energy of the molten salt energy storage module is transferred to the grid through the thermoelectric conversion device; S4-4, the molten salt energy storage module adjusts the heat output through the cogeneration module, and uses the feedforward control strategy to link the demand of the heating end with the output of the molten salt energy storage module.

6. A novel frequency modulation method for molten salt energy storage coupled with thermal power generation units according to claim 1, characterized in that: Wherein, in step S5, the following sub-steps are also included: S5-1, through the data recording and feedback module, the frequency fluctuation and the output data of the thermal power unit module and the molten salt energy storage module are recorded in real time during the frequency modulation process; S5-2, based on real-time monitoring data, using data feedback mechanism and intelligent control algorithm, adjust the output parameters of the thermal power unit module and the molten salt energy storage module.

7. A novel frequency modulation method for molten salt energy storage coupled with thermal power generation units according to claim 1, characterized in that: Wherein, in step S6, the following sub-steps are also included: S6-1, through the fault detection and backup module, real-time monitoring of the operating status of the thermal power unit module and the molten salt energy storage module, to determine whether there is an abnormal operating status; S6-2, using the over-limit judgment mechanism, starts the backup energy storage device when it is detected that the frequency fluctuation meets the third-level standard or the equipment fails.

8. A novel frequency modulation method for molten salt energy storage coupled with thermal power generation units according to claim 1, characterized in that: Wherein, in step S7, the following sub-steps are also included: S7-1, after the frequency is restored to a stable state through the reset and recovery module, a phased exit method is adopted to gradually reduce the output of the molten salt energy storage module and the thermal power unit module and return to the initial monitoring mode; S7-2, after detecting that the data remains within the normal range for a period of time, triggers the automatic reset mechanism in the reset and recovery module, so that each module returns to the standby state after the frequency modulation task is completed.

9. A new frequency modulation system for molten salt energy storage coupled with thermal power units, characterized in that: include: Frequency detection module, parameter acquisition module, frequency modulation control module, thermal power unit module, molten salt energy storage module, combined heat and power module, data recording and feedback module, fault detection and backup module, reset and recovery module; The frequency detection module is used to continuously monitor the grid frequency to obtain grid frequency deviation information, and transmit the detected frequency data to the system to trigger the corresponding frequency modulation response; The parameter acquisition module includes temperature, pressure, speed and power sensors, which are used to collect the operating parameters of the thermal power unit module and the molten salt energy storage module in real time; The frequency modulation control module includes a fuzzy adaptive PID controller and an algorithm processor, which triggers corresponding frequency modulation operations according to different levels of frequency deviation, and is used to analyze data and adjust the output parameters of the thermal power unit module and the molten salt energy storage module; The thermal power unit module is used to quickly respond to high-frequency frequency fluctuations. When the grid frequency fluctuates instantaneously, the output power is quickly adjusted to help the grid return to a stable state; The molten salt energy storage module is used to handle low-frequency fluctuations and long-term frequency stability, provide continuous power output, and provide additional power support to the system through thermoelectric conversion equipment when the grid frequency fluctuates; The cogeneration module is connected to the molten salt energy storage module, and can adjust the heat output according to the fluctuation of the power grid frequency, and link the heat demand with the power output of the energy storage system through feedforward control; The data recording and feedback module is used to record and store various data of the system during the frequency modulation process, including frequency fluctuations, output conditions of the thermal power unit module and the molten salt energy storage module; The fault detection and backup module is used to monitor the status of the entire system in real time. When it is detected that the frequency fluctuation in the system exceeds the safety range or a module fails, the backup energy storage device is immediately started; The reset and recovery module is responsible for gradually exiting the frequency modulation mode, returning the system to the initial monitoring state, setting all modules to standby state, and gradually restoring the heat of the molten salt energy storage module to normal levels in preparation for the next frequency modulation demand.

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