Frequency modulation and peak regulation control method and system for thermal power generating unit based on fused salt heat storage system

Abstract

The present application belongs to the field of thermal power generation and energy storage, and discloses a method and system for frequency modulation and peak shaving control of a thermal power unit based on a molten salt heat storage system. The method first calculates the power deviation based on the real-time collected AGC instruction of the power grid and the actual power output of the thermal power unit, then outputs the power adjustment instruction of the electric heater by using the PID algorithm, and finally outputs the switching signal in combination with the time-of-use electricity price signal and the molten salt tank liquid level state. The power deviation is calculated to accurately grasp the demand for frequency modulation and peak shaving, the PID algorithm can efficiently output the appropriate power adjustment instruction to ensure the reasonable adjustment of the power of the electric heater, and the switching signal is output in combination with the time-of-use electricity price and the molten salt tank liquid level state to comprehensively consider the economy and the equipment state. The method fully taps the potential of the molten salt heat storage technology, realizes the intelligent and accurate switching of heat storage and release modes and the power adjustment of the electric heater, effectively solves the problems existing in the existing control system of the thermal power unit, and helps the thermal power unit to better complete the frequency modulation and peak shaving task.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation and energy storage technology, specifically relating to a frequency regulation and peak shaving control method and system for thermal power units based on molten salt thermal storage system. Background Technology

[0002] In the current power industry, with the continuous expansion of renewable energy grid connection, the power system faces increasingly severe challenges in balancing supply and demand. To ensure the stability and reliability of power supply, the power grid places extremely high demands on the frequency regulation and peak shaving capabilities of thermal power units. Traditional thermal power units occupy an important position in the entire power system; however, their operating characteristics are difficult to adapt to the new situation. During the heating season, the thermoelectric coupling characteristics cause the unit's power generation and heating to be mutually constrained, making it impossible to flexibly adjust power generation according to changes in grid load, severely limiting peak shaving capabilities. During the non-heating season, the minimum stable fuel requirement makes it difficult for the unit to operate stably under low load conditions, leading to frequent zero-price electricity phenomena. This results in a lack of flexibility in the electricity spot market, failing to meet the market's demand for rapid and precise power regulation. Meanwhile, the DCS system, as the "nerve center" of the thermal power unit, plays a crucial role in the unit's operation control, and its performance directly affects the overall operating effect of the thermal power unit.

[0003] Faced with the dilemma of insufficient flexibility in thermal power units, existing energy storage technologies attempt to address this issue, but each has its own shortcomings. While electrochemical energy storage offers fast response and can theoretically assist thermal power units in frequency and peak regulation, its high cost, short battery life, and significant performance degradation after frequent charge-discharge cycles hinder large-scale application due to both economic and technological obstacles. Pumped hydro storage technology is relatively mature; however, its construction is highly dependent on specific geographical conditions, requiring suitable upper and lower reservoir sites, making it difficult to promote in areas with limited terrain. Molten salt thermal energy storage technology has been relatively maturely applied in concentrated solar power (CSP), demonstrating advantages such as large storage capacity and stable temperature. However, when attempting to deeply couple it with thermal power units to achieve frequency and peak regulation functions, a comprehensive control method is lacking. Most existing thermal power unit control systems have failed to fully tap the potential of molten salt thermal energy storage technology. They cannot comprehensively consider factors such as real-time changes in grid commands, time-of-use electricity price fluctuations, and the liquid level status of molten salt tanks to achieve intelligent and precise switching between storage / release modes and adjustment of electric heater power. As a result, thermal power units still face numerous difficulties in the critical tasks of frequency regulation and peak shaving. Summary of the Invention

[0004] This invention provides a frequency regulation and peak shaving control method and system for thermal power units based on a molten salt thermal storage system. Relying on a DCS system, it collects real-time data on grid AGC commands, actual power generation of the thermal power unit, grid time-of-use electricity price signals, and molten salt tank level status. Using a PID algorithm, it accurately outputs power adjustment commands for electric heaters to regulate their power and outputs switching signals to switch the storage / release modes of the molten salt thermal storage system. This fully taps the potential of molten salt thermal storage technology, enhances the frequency regulation and peak shaving capabilities of thermal power units, and ensures the stability and reliability of the power system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A frequency regulation and peak shaving control method for thermal power units based on molten salt thermal storage systems, applied to a DCS system, includes:

[0007] The power deviation is calculated based on the real-time collected AGC commands from the power grid and the actual power output of the thermal power units.

[0008] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment command, which is used to adjust the output power of the electric heater.

[0009] By combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank, a switching signal is output. The switching signal is used to switch the storage / release mode of the molten salt thermal storage system.

[0010] Furthermore, before calculating the power deviation based on the real-time collected power grid AGC commands and the actual power generated by the thermal power unit, the following steps are also included:

[0011] The DCS system communicates with the power grid dispatch center and obtains AGC commands from the power grid in real time at a preset sampling period; the power sensors installed at the generator outlet of the thermal power unit collect the actual power generation of the thermal power unit in real time at a preset sampling period.

[0012] The power grid AGC command and the actual power generation are respectively processed by moving average filtering, and the specific formula is as follows:

[0013]

[0014] In the formula, P filtered P represents the filtered data. i This represents the raw data for the current time step and the previous n-1 time steps; n represents the size of the filtering window.

[0015] Furthermore, the calculation of the power deviation based on the real-time collected power grid AGC commands and the actual power output of the thermal power unit includes:

[0016] The difference between the filtered grid AGC command and the actual power generation is calculated to obtain the power deviation. The specific formula is as follows:

[0017] ΔP=P AGC -P actual

[0018] In the formula, ΔP represents the power deviation; P AGC This indicates the filtered power grid AGC command; P actual This represents the actual power generation after filtering.

[0019] Furthermore, the step of outputting the electric heater power adjustment command based on the power deviation using a PID algorithm includes:

[0020] Based on the power deviation, the power adjustment of the electric heater is calculated using a PID algorithm, and the specific formula is as follows:

[0021]

[0022] In the formula, ΔP heater Indicates the power adjustment amount of the electric heater; K p K i K d These represent the proportional, integral, and derivative coefficients of the PID controller, respectively; ΔP represents the power deviation. The integral term representing the power deviation; This is the differential term of the power deviation;

[0023] The power regulation of the electric heater is limited, as follows:

[0024] When ΔP heater >ΔP max When, then ΔP heater <ΔP max ;

[0025] When ΔP heater <ΔP min When, then ΔP heater =ΔP min ;

[0026] In the formula, ΔP max ΔP min These represent the upper and lower limits for adjusting the power of the electric heater, respectively.

[0027] Based on the power adjustment amount of the electric heater after the limiting process, and combined with the current output power of the electric heater, a power adjustment command for the electric heater is generated. The specific formula is as follows:

[0028] P heater-command =P heater-current +ΔPheater

[0029] In the formula, P heater-command This indicates a power adjustment command for the electric heater; P heater-current This indicates the current output power of the electric heater.

[0030] Furthermore, by combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank, a switching signal is output. This switching signal is used to switch the storage / release mode of the molten salt thermal storage system, including:

[0031] Based on the collected time-of-use electricity price signals from the power grid, the electricity price period is determined, which includes the power grid off-peak period or the power grid peak period;

[0032] Based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank, the corresponding switching signal is output.

[0033] Furthermore, the step of outputting a corresponding switching signal based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank includes:

[0034] The judgment is made based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank:

[0035] The first scenario: When it is during a power grid off-peak period and the liquid level in the cryogenic molten salt tank is greater than the minimum liquid level threshold of the cryogenic molten salt tank, it is determined that it is necessary to switch to the thermal storage mode and output a thermal storage mode switching signal.

[0036] The second scenario: When it is during the peak period of the power grid and the liquid level in the high-temperature molten salt tank is higher than the minimum liquid level threshold of the high-temperature molten salt tank, it is determined that it is necessary to switch to the heat release mode and output the heat release mode switching signal.

[0037] In the third scenario, if neither the first nor the second scenario is met, the current operating mode of the molten salt thermal storage system is maintained, and no switching signal is output.

[0038] Furthermore, the control method further includes:

[0039] Based on the comparison results between the current temperature and the high temperature threshold and the low temperature threshold, start or stop the electric heater;

[0040] Based on the abnormal operating condition feedback signal, the molten salt pump and valve of the molten salt thermal storage system are controlled to cut off the flow of molten salt;

[0041] Based on the leakage feedback signal, the brine tank is controlled to automatically recover molten salt and isolate the faulty area.

[0042] A frequency regulation and peak shaving control system for thermal power units based on a molten salt thermal storage system includes:

[0043] The first calculation module is used to calculate the power deviation based on the real-time collected power grid AGC commands and the actual power generated by the thermal power unit.

[0044] The second calculation module is used to output an electric heater power adjustment command based on the power deviation using a PID algorithm. The electric heater power adjustment command is used to adjust the output power of the electric heater.

[0045] The switching module is used to combine the real-time collected time-of-use electricity price signal of the power grid and the liquid level status of the molten salt tank to output a switching signal, which is used to switch the storage / heat release mode of the molten salt thermal storage system.

[0046] An apparatus comprising:

[0047] Memory, used to store computer programs;

[0048] A processor is used to implement the steps of the above-described frequency regulation and peak shaving control method for thermal power units based on molten salt thermal storage systems when executing the computer program.

[0049] A computer-readable storage medium storing a computer program, which, when executed by a processor, is used to implement the steps of the above-described frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] This invention provides a frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system. First, the power deviation is calculated based on real-time collected grid AGC commands and the actual generated power of the thermal power unit. Then, a PID algorithm is used to output power adjustment commands for the electric heater. Finally, a switching signal is output by combining the grid time-of-use electricity price signal and the molten salt tank level status. By calculating the power deviation, frequency regulation and peak shaving requirements can be accurately grasped. The PID algorithm can efficiently output appropriate power adjustment commands, ensuring reasonable adjustment of the electric heater power. Combining the time-of-use electricity price and the molten salt tank level status to output the switching signal comprehensively considers economic efficiency and equipment status. This method fully taps the potential of molten salt thermal storage technology, achieving intelligent and precise switching between storage / release modes and electric heater power adjustment, effectively solving the problems existing in current thermal power unit control systems, and helping thermal power units better complete frequency regulation and peak shaving tasks.

[0052] In this invention, preferably, before calculating the power deviation, data is acquired in real time through the communication interface between the DCS system and the power grid dispatch center, as well as through power sensors, and then processed using moving average filtering. This operation ensures that the acquired data is accurate and reliable, reduces noise interference, and improves the accuracy of subsequent power deviation calculations. This, in turn, makes the power adjustment commands for the electric heaters more precise, helps thermal power units respond more stably and effectively to grid frequency regulation and peak shaving commands, and enhances the performance and reliability of the entire control system.

[0053] In this invention, preferably, the specific process of outputting electric heater power adjustment commands based on power deviation using a PID algorithm includes calculating the power adjustment amount, limiting processing, and generating the power adjustment command. The PID algorithm can quickly and accurately calculate the appropriate power adjustment amount based on the power deviation, the limiting processing ensures that the electric heater power is adjusted within a safe range, and combined with the current output power command generation, precise control is achieved. This makes the electric heater power adjustment more reasonable and stable, effectively improving the dynamic response capability of thermal power units for frequency regulation and peak shaving.

[0054] In this invention, preferably, the storage / release mode of the molten salt thermal energy storage system is switched by combining the time-of-use electricity price signal from the power grid and the output switching signal of the molten salt tank level status. By considering the electricity price period, heat can be stored during off-peak hours and released during peak hours, reducing operating costs; combining the molten salt tank level status ensures the safety and feasibility of the storage / release operation. This mode switching method, which comprehensively considers economics and equipment status, improves the operating efficiency and economic benefits of the molten salt thermal energy storage system and enhances the overall performance of frequency regulation and peak shaving of thermal power units.

[0055] In this invention, preferably, the corresponding switching signal is output based on the electricity price period and the liquid level status of the low molten salt tank or the high molten salt tank. The accurate switching mode under different electricity price periods and molten salt tank liquid level status can not only meet the frequency regulation and peak shaving requirements of the power grid, but also ensure the safety and economy of the system operation, and further improve the effect of the coordinated work between thermal power units and molten salt thermal storage system.

[0056] In this invention, preferably, the method also includes a protection mechanism: starting or stopping the electric heater based on temperature comparison results; controlling the molten salt pump and valve linkage based on abnormal operating condition feedback signals; and controlling the brine tank to automatically recover molten salt and isolate the fault area based on leakage feedback signals. These functions enhance the safety and reliability of the system, enabling timely handling of various abnormal situations, ensuring the stable operation of the molten salt thermal storage system and thermal power units, reducing the impact of faults on frequency regulation and peak shaving tasks, and improving the stability and availability of the entire system. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the structure of a molten salt thermal energy storage system connected to a thermal power unit according to an embodiment of the present invention;

[0058] Figure 2 This is a power response curve diagram of a thermal power unit following AGC commands, provided in an embodiment of the present invention.

[0059] Figure 3 AGC frequency regulation response curve of the auxiliary thermal power unit of the molten salt thermal storage system provided in the embodiments of the present invention;

[0060] Figure 4 A flowchart of a frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system provided in an embodiment of the present invention;

[0061] Figure 5 This is a schematic diagram of a frequency regulation and peak shaving control system for thermal power units based on a molten salt thermal storage system, provided as an embodiment of the present invention. Detailed Implementation

[0062] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0063] The technical terms involved in this invention are explained below:

[0064] AGC stands for Automatic Generation Control. As a core functional module of the Power System Energy Management System (EMS), AGC maintains grid frequency stability and achieves economic matching between power generation and load demand by adjusting generator output in real time.

[0065] For example, this embodiment provides a frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system, including:

[0066] The power deviation is calculated based on the real-time collected AGC commands from the power grid and the actual power output of the thermal power units.

[0067] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment command, which is used to adjust the output power of the electric heater.

[0068] By combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank, a switching signal is output. The switching signal is used to switch the storage / release mode of the molten salt thermal storage system.

[0069] The control method provided in this embodiment will be further explained below with reference to the accompanying drawings:

[0070] like Figure 1As shown, the proposed molten salt thermal energy storage system will be connected to the thermal power unit system. The electrical connection structure mainly consists of a high-voltage plant transformer, a plant service busbar, a 6kV molten salt busbar, an energy storage system power control cabinet, and a molten salt heater, specifically including:

[0071] High-voltage transformer: There are No. 1 and No. 2 high-voltage transformers, which are the power source for the entire system and supply power to the downstream equipment.

[0072] The plant power busbars are divided into three sections: Plant Power Section 1A, Plant Power Section 1B, Plant Power Section 2A, and Plant Power Section 2B. The No. 1 high-voltage transformer connects Plant Power Sections 1A and 1B, and the No. 2 high-voltage transformer connects Plant Power Sections 2A and 2B, serving to distribute and transmit electrical energy.

[0073] 6kV molten salt busbars: There are 6kV molten salt section A busbars and 6kV molten salt section B busbars. The plant power supply sections 1A, 1B, 2A, and 2B are connected to the 6kV molten salt section A and section B busbars via switches to further distribute electrical energy.

[0074] Energy storage system power control cabinet and molten salt heater: Multiple energy storage system power control cabinets are connected to the 6kV molten salt A and B busbars, and each power control cabinet is connected to a molten salt heater (set power of 5MW). The energy storage system power control cabinet can adjust the power of the molten salt heater to control the molten salt heating process.

[0075] The overall electrical access structure presents a power transmission and distribution path from the high-voltage transformer to the plant's power busbar, the 6kV molten salt busbar, and then to the energy storage system's power control cabinet and the molten salt heater, ensuring the power supply for molten salt heating and other related production processes.

[0076] To ensure the stable, safe, and reliable operation of the molten salt thermal energy storage system integrated into the thermal power unit system, this embodiment provides a frequency regulation and peak shaving control method for thermal power units based on the molten salt thermal energy storage system, specifically including:

[0077] S1. Data Acquisition and Preprocessing Stage: Utilizing the communication interface between the DCS system and the power grid dispatch center, AGC commands from the power grid are stably acquired according to a preset sampling period (e.g., 500 milliseconds) and a communication protocol (e.g., IEC 104 protocol). At the generator outlet of the thermal power unit, actual generated power is collected at the same sampling period using a high-precision power sensor (accuracy up to 0.2 level). The acquired data may fluctuate due to interference. To improve accuracy, a moving average filter is applied to the power grid AGC commands and actual generated power. The filter window size n is set according to the response characteristics of the thermal power unit, typically 5-10. Taking n=5 as an example, when calculating the filtered data at the current moment, the original data from the current moment and the previous four moments need to be added together and then averaged.

[0078] S2. Power Deviation Calculation Stage: The power deviation is calculated by measuring the difference between the filtered grid AGC command and the actual generated power. If the thermal power unit is responsible for grid load regulation, the filtered grid AGC command is 500MW, and the filtered actual generated power is 480MW, resulting in a power deviation of 20MW. This indicates that the thermal power unit needs to increase its generated power to meet grid demand.

[0079] S3. Electric Heater Power Regulation Command Generation Stage: Based on the power deviation, the electric heater power regulation amount is calculated using a PID algorithm. The proportional, integral, and derivative coefficients of the PID controller are determined through on-site commissioning or simulation optimization based on thermal power unit and molten salt thermal storage system models. The calculated power regulation amount needs to be limited to avoid over-regulation of the electric heater. The limiting threshold, i.e., the upper and lower limits of the electric heater power regulation, is set according to the rated power of the electric heater and the safe operating range of the molten salt thermal storage system. Finally, the regulation command is generated based on the current output power of the electric heater. If the current output power of the electric heater is 30MW and the power regulation amount after limiting is 5MW, then the generated electric heater power regulation command is 35MW.

[0080] Based on the power deviation, the power adjustment of the electric heater is calculated using a PID algorithm, and the specific formula is as follows:

[0081]

[0082] In the formula, ΔP heater Indicates the power adjustment amount of the electric heater; K p K i K d These represent the proportional, integral, and derivative coefficients of the PID controller, respectively; ΔP represents the power deviation. The integral term representing the power deviation; This is the differential term of the power deviation;

[0083] The power regulation of the electric heater is limited, as follows:

[0084] When ΔP heater >ΔP max When, then ΔP heater =ΔP max ;

[0085] When ΔP heater <ΔP min When, then ΔP heater =ΔP min ;

[0086] In the formula, ΔP max ΔP min These represent the upper and lower limits for adjusting the power of the electric heater, respectively.

[0087] Based on the power adjustment amount of the electric heater after the limiting process, and combined with the current output power of the electric heater, a power adjustment command for the electric heater is generated. The specific formula is as follows:

[0088] P heater-command =P heater-current +ΔP heater

[0089] In the formula, P heater-command This indicates a power adjustment command for the electric heater; P heater-current This indicates the current output power of the electric heater.

[0090] S4. Storage / Release Mode Switching Phase: Time-of-use electricity price signals from the power grid are collected, and the electricity price period is determined based on the timestamp and price information in the signals. The liquid level status of the low-molten salt tank and the high-molten salt tank is monitored in real time using liquid level sensors installed at appropriate locations on the tanks for accurate level measurement. A switching signal is output based on the electricity price period and the liquid level status of the molten salt tanks. During off-peak hours, if the liquid level in the low-temperature molten salt tank is higher than the minimum liquid level threshold, a heat storage mode switching signal is output; during peak hours, if the liquid level in the high-temperature molten salt tank is higher than the minimum liquid level threshold, a heat release mode switching signal is output; if the above conditions are not met, the current operating mode is maintained.

[0091] S5. Safety and Protection Control Phase: The molten salt temperature is monitored by a temperature sensor, and the measured value is compared with high-temperature and low-temperature thresholds. When the temperature approaches the high-temperature threshold, the electric heater power is reduced or heating is stopped; when it approaches the low-temperature threshold, the electric heater is activated to maintain the fluidity of the molten salt. When abnormal operating conditions occur in the system, such as abnormal pipeline pressure or sudden changes in flow, the control system receives feedback signals and controls the molten salt pump and valves to cut off the flow of molten salt, ensuring system safety. If a molten salt leak is detected, the control system controls the salt recovery tank to automatically recover the molten salt based on the leak feedback signal and isolates the fault area to prevent the leak from spreading.

[0092] The control method provided in this embodiment will be further explained below with reference to specific examples:

[0093] Example 1:

[0094] In this example, the thermal power unit has an installed capacity of 600MW, and the molten salt thermal storage system has a capacity of 300MWh; the specific implementation steps are as follows:

[0095] Data acquisition and preprocessing: The sampling period is set to every minute. The grid AGC command and the actual power generation of thermal power units are obtained in real time through the DCS system and then processed by moving average filtering.

[0096] Power deviation calculation: Calculate the power deviation based on the filtered data.

[0097] PID algorithm regulation: The PID algorithm is used to calculate the power regulation of the electric heater and then limits the adjustment. The proportional coefficient, integral coefficient, and derivative coefficient of the PID controller are set to 0.5, 0.1, and 0.05, respectively.

[0098] Mode switching: When the power grid is in a low-temperature period and the liquid level in the low-temperature molten salt tank is greater than 50%, a thermal storage mode switching signal is output; when the power grid is in a peak period and the liquid level in the high-temperature molten salt tank is greater than 30%, a heat release mode switching signal is output.

[0099] Safety protection: The high-temperature threshold is set at 550℃, and the low-temperature threshold is set at 250℃. When the temperature exceeds or falls below these thresholds, the electric heater will start or stop. Simultaneously, the system monitors abnormal operating conditions and leaks in real time and takes corresponding protective measures.

[0100] Example 2:

[0101] In this example, the installed capacity of the thermal power unit is 1000MW, and the capacity of the molten salt thermal storage system is 500MWh; the specific implementation steps are as follows:

[0102] Data acquisition and preprocessing: The sampling period is set to every 30 seconds. The grid AGC command and the actual power generation of thermal power units are obtained in real time through the DCS system and then processed by moving average filtering.

[0103] Power deviation calculation: Calculate the power deviation based on the filtered data.

[0104] PID algorithm control: The PID algorithm is used to calculate the power adjustment of the electric heater and then limits the adjustment. The proportional, integral, and derivative coefficients of the PID controller are set to 0.6, 0.08, and 0.03, respectively.

[0105] Mode switching: When the power grid is in a low-temperature period and the liquid level in the low-temperature molten salt tank is greater than 60%, a thermal storage mode switching signal is output; when the power grid is in a peak period and the liquid level in the high-temperature molten salt tank is greater than 40%, a heat release mode switching signal is output.

[0106] Safety protection: The high-temperature threshold is set at 600℃, and the low-temperature threshold is set at 200℃. When the temperature exceeds or falls below these thresholds, the electric heater will start or stop. Simultaneously, the system monitors abnormal operating conditions and leaks in real time and takes corresponding protective measures. In addition, a molten salt tank pressure monitoring function has been added to ensure that the molten salt thermal storage system operates under safe pressure.

[0107] Therefore, it is evident that by adopting this control method, thermal power units can quickly respond to grid AGC commands, reduce power deviation, and improve grid stability. During off-peak hours, excess electrical energy is converted into thermal energy for storage, which can then be used to assist in power generation during peak hours, thereby improving the economic efficiency and peak-shaving capacity of thermal power units.

[0108] In this embodiment, the difference from the normal unit control method is that the electrical power generated by this thermal power unit includes two parts: one is the unit load issued by the dispatcher through AGC, and the other is the electric heating power. If the load command issued to the unit by the dispatcher is 200MW and the electric heating power is 20MW, then the actual output of the unit should be 180MW. Based on the frequency regulation data of a certain thermal power unit, the response curve of the thermal power unit following the AGC command is shown in Figure 2. Figure 2 In the diagram, the blue curve represents the AGC frequency regulation command, and the red curve represents the actual power generated by the unit. The Qiguang Power Plant's unit exhibits good frequency regulation performance, with the power curve trending in the same direction as the AGC command curve. However, there is still significant room for improvement in the unit's response speed and accuracy. After configuring 40MW molten salt energy storage, the unit's frequency regulation performance is significantly improved, as shown in Figure 3 of the AGC frequency regulation response curve for the energy storage-assisted unit. With the addition of molten salt energy storage, the green curve represents the sum of the unit's actual power generated and the molten salt system power. As can be seen from the figure above, the sum of the unit's actual power generated and the molten salt system power (green curve) largely coincides with the AGC command (blue curve), indicating a substantial improvement in the unit's frequency regulation performance. Furthermore, the control method provided in this embodiment ensures the stable, reliable, and safe operation of the unit.

[0109] For example, such as Figure 4 As shown in the figure, this embodiment provides a frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system, including the following steps:

[0110] The power deviation is calculated based on the real-time collected AGC commands from the power grid and the actual power output of the thermal power units.

[0111] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment command, which is used to adjust the output power of the electric heater.

[0112] By combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank, a switching signal is output. The switching signal is used to switch the storage / release mode of the molten salt thermal storage system.

[0113] In this embodiment, before calculating the power deviation based on the real-time collected power grid AGC commands and the actual generated power of the thermal power unit, the following steps are also included:

[0114] The DCS system communicates with the power grid dispatch center and obtains AGC commands from the power grid in real time at a preset sampling period; the power sensors installed at the generator outlet of the thermal power unit collect the actual power generation of the thermal power unit in real time at a preset sampling period.

[0115] The power grid AGC command and the actual power generation are respectively processed by moving average filtering, and the specific formula is as follows:

[0116]

[0117] In the formula, P filtered P represents the filtered data. i This represents the raw data for the current time step and the previous n-1 time steps; n represents the size of the filtering window.

[0118] In this embodiment, the calculation of the power deviation based on the real-time collected power grid AGC commands and the actual power output of the thermal power unit includes:

[0119] The difference between the filtered grid AGC command and the actual power generation is calculated to obtain the power deviation. The specific formula is as follows:

[0120] ΔP=P AGC -P actual

[0121] In the formula, ΔP represents the power deviation; P AGC This indicates the filtered power grid AGC command; P actual This represents the actual power generation after filtering.

[0122] In this embodiment, the step of outputting the electric heater power adjustment command based on the power deviation using a PID algorithm includes:

[0123] Based on the power deviation, the power adjustment of the electric heater is calculated using a PID algorithm, and the specific formula is as follows:

[0124]

[0125] In the formula, ΔP heater Indicates the power adjustment amount of the electric heater; K p K i K d These represent the proportional, integral, and derivative coefficients of the PID controller, respectively; ΔP represents the power deviation. The integral term representing the power deviation; This is the differential term of the power deviation;

[0126] The power regulation of the electric heater is limited, as follows:

[0127] When ΔP heater >ΔP max When, then ΔP heater =ΔP max ;

[0128] When ΔP heater <ΔP min When, then ΔP heater =ΔP min ;

[0129] In the formula, ΔP max ΔP min These represent the upper and lower limits for adjusting the power of the electric heater, respectively.

[0130] Based on the power adjustment amount of the electric heater after the limiting process, and combined with the current output power of the electric heater, a power adjustment command for the electric heater is generated. The specific formula is as follows:

[0131] P heater-command =P heater-current +ΔP heater

[0132] In the formula, P heater-command This indicates a power adjustment command for the electric heater; P heater-current This indicates the current output power of the electric heater.

[0133] In this embodiment, the step of combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank to output a switching signal, which is used to switch the storage / release mode of the molten salt thermal storage system, including:

[0134] Based on the collected time-of-use electricity price signals from the power grid, the electricity price period is determined, which includes the power grid off-peak period or the power grid peak period;

[0135] Based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank, the corresponding switching signal is output.

[0136] In this embodiment, the step of outputting a corresponding switching signal based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank includes:

[0137] The judgment is made based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank:

[0138] The first scenario: When it is during a power grid off-peak period and the liquid level in the cryogenic molten salt tank is greater than the minimum liquid level threshold of the cryogenic molten salt tank, it is determined that it is necessary to switch to the thermal storage mode and output a thermal storage mode switching signal.

[0139] The second scenario: When it is during the peak period of the power grid and the liquid level in the high-temperature molten salt tank is higher than the minimum liquid level threshold of the high-temperature molten salt tank, it is determined that it is necessary to switch to the heat release mode and output the heat release mode switching signal.

[0140] In the third scenario, if neither the first nor the second scenario is met, the current operating mode of the molten salt thermal storage system is maintained, and no switching signal is output.

[0141] In this embodiment, the control method further includes:

[0142] Based on the comparison results between the current temperature and the high temperature threshold and the low temperature threshold, start or stop the electric heater;

[0143] Based on the abnormal operating condition feedback signal, the molten salt pump and valve of the molten salt thermal storage system are controlled to cut off the flow of molten salt;

[0144] Based on the leakage feedback signal, the brine tank is controlled to automatically recover molten salt and isolate the faulty area.

[0145] like Figure 5 As shown, this embodiment also provides a frequency regulation and peak shaving control system for thermal power units based on a molten salt thermal storage system, including: a first calculation module, used to calculate the power deviation based on real-time acquired grid AGC commands and the actual power generated by the thermal power unit; a second calculation module, used to output an electric heater power adjustment command based on the power deviation using a PID algorithm, the electric heater power adjustment command being used to adjust the output power of the electric heater; and a switching module, used to output a switching signal by combining real-time acquired grid time-of-use electricity price signals and the liquid level status of the molten salt tank, the switching signal being used to switch the storage / release mode of the molten salt thermal storage system.

[0146] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system.

[0147] When the processor executes the computer program, it implements the above-mentioned steps for frequency regulation and peak shaving control of thermal power units based on molten salt thermal storage systems. For example, based on the real-time collected grid AGC commands and the actual generated power of the thermal power units, the power deviation is calculated; based on the power deviation, a PID algorithm is used to output an electric heater power adjustment command, which is used to adjust the output power of the electric heater; combined with the real-time collected grid time-of-use electricity price signal and the liquid level status of the molten salt tank, a switching signal is output, which is used to switch the storage / release mode of the molten salt thermal storage system.

[0148] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system. For example, the first calculation module is used to calculate the power deviation based on the real-time collected grid AGC command and the actual power generated by the thermal power unit; the second calculation module is used to output the electric heater power adjustment command based on the power deviation using a PID algorithm, the electric heater power adjustment command being used to adjust the output power of the electric heater; and the switching module is used to output a switching signal by combining the real-time collected grid time-of-use electricity price signal and the liquid level status of the molten salt tank, the switching signal being used to switch the storage / release mode of the molten salt thermal storage system.

[0149] Exemplarily, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing preset functions, the instruction segments describing the execution process of the computer program in the frequency regulation and peak shaving control equipment of the thermal power unit based on the molten salt thermal storage system. For example, the computer program can be divided into a first calculation module, a second calculation module, and a switching module; the first calculation module is used to calculate the power deviation based on the real-time acquired grid AGC command and the actual generated power of the thermal power unit; the second calculation module is used to output an electric heater power adjustment command based on the power deviation using a PID algorithm, the electric heater power adjustment command being used to adjust the output power of the electric heater; the switching module is used to output a switching signal by combining the real-time acquired grid time-of-use electricity price signal and the liquid level status of the molten salt tank, the switching signal being used to switch the storage / release mode of the molten salt thermal storage system.

[0150] The frequency regulation and peak shaving control equipment for thermal power units based on molten salt thermal storage systems can be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. This equipment may include, but is not limited to, processors and memory. Those skilled in the art will understand that the above examples of frequency regulation and peak shaving control equipment for thermal power units based on molten salt thermal storage systems do not constitute a limitation on such equipment. It may include more components than described above, or combine certain components, or use different components. For example, the frequency regulation and peak shaving control equipment for thermal power units based on molten salt thermal storage systems may also include input / output devices, network access devices, buses, etc.

[0151] The processor referred to can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor. This processor is the control center for the frequency regulation and peak shaving control of the thermal power unit based on the molten salt thermal storage system, connecting various parts of the entire frequency regulation and peak shaving control equipment for the thermal power unit based on the molten salt thermal storage system through various interfaces and lines.

[0152] The memory can be used to store the computer program and / or module. The processor realizes various functions of the frequency regulation and peak shaving control equipment of the thermal power unit based on the molten salt thermal storage system by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0153] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function (such as sound playback, image playback, etc.). The data storage area may store data created based on the use of the mobile phone (such as audio data, phonebook, etc.). Furthermore, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disks, RAM, plug-in hard disks, SmartMediaCards (SMC), Secure Digital (SD) cards, FlashCards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0154] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the described frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system.

[0155] If the modules / units integrated in the frequency regulation and peak shaving control system of the thermal power unit based on the molten salt thermal storage system are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0156] Based on this understanding, the present invention can implement all or part of the processes in the above-mentioned frequency regulation and peak shaving control method for thermal power units based on molten salt thermal storage systems. This can also be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the above-mentioned frequency regulation and peak shaving control method for thermal power units based on molten salt thermal storage systems. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or preset intermediate forms, etc.

[0157] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0158] It should be noted that the content contained in the computer-readable storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0159] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

[0160] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A frequency regulation and peak shaving control method for thermal power units based on molten salt thermal storage systems, applied to a DCS system, characterized in that, include: The power deviation is calculated based on the real-time collected AGC commands from the power grid and the actual power output of the thermal power units. Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment command, which is used to adjust the output power of the electric heater. By combining the real-time collected time-of-use electricity price signal from the power grid and the liquid level status of the molten salt tank, a switching signal is output. The switching signal is used to switch the storage / release mode of the molten salt thermal storage system. Based on the comparison results between the current temperature and the high temperature threshold and the low temperature threshold, start or stop the electric heater; Based on the abnormal operating condition feedback signal, the molten salt pump and valve of the molten salt thermal storage system are controlled to cut off the flow of molten salt; Based on the leakage feedback signal, the brine tank is controlled to automatically recover molten salt and isolate the faulty area; Before calculating the power deviation based on the real-time collected power grid AGC commands and the actual generated power of the thermal power unit, the following steps are also included: The DCS system communicates with the power grid dispatch center and obtains AGC commands from the power grid in real time at a preset sampling period; the power sensors installed at the generator outlet of the thermal power unit collect the actual power generation of the thermal power unit in real time at a preset sampling period. The power grid AGC command and the actual power generation are respectively processed by moving average filtering, and the specific formula is as follows: In the formula, This represents the data after filtering. This represents the raw data for the current time step and the previous n-1 time steps; n represents the size of the filtering window. The power deviation calculated based on the real-time collected power grid AGC commands and the actual power output of the thermal power units includes: The difference between the filtered grid AGC command and the actual power generation is calculated to obtain the power deviation. The specific formula is as follows: In the formula, Indicates power deviation; This indicates the filtered power grid AGC command; This represents the actual power generation after filtering. The method of outputting electric heater power adjustment commands based on power deviation using a PID algorithm includes: Based on the power deviation, the power adjustment of the electric heater is calculated using a PID algorithm, and the specific formula is as follows: In the formula, This indicates the power adjustment amount of the electric heater; , , These represent the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively. Indicates power deviation; The integral term representing the power deviation; This is the differential term of the power deviation; The power regulation of the electric heater is limited, as follows: when At that time, ; when At that time, ; In the formula, , These represent the upper and lower limits for adjusting the power of the electric heater, respectively. Based on the power adjustment amount of the electric heater after the limiting process, and combined with the current output power of the electric heater, a power adjustment command for the electric heater is generated. The specific formula is as follows: In the formula, This indicates a power adjustment command for the electric heater; This indicates the current output power of the electric heater; The system combines real-time acquired time-of-use electricity price signals from the power grid with the liquid level status of the molten salt tank to output a switching signal. This switching signal is used to switch the storage / release mode of the molten salt thermal storage system, including: Based on the collected time-of-use electricity price signals from the power grid, the electricity price period is determined, which includes the power grid off-peak period or the power grid peak period; Based on the electricity price period and the liquid level status of the low molten salt tank or the high molten salt tank, output the corresponding switching signal; The system outputs a corresponding switching signal based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank, including: The judgment is made based on the electricity price period and the liquid level status of the low-molten salt tank or the high-molten salt tank: The first scenario: When it is during a power grid off-peak period and the liquid level in the cryogenic molten salt tank is greater than the minimum liquid level threshold of the cryogenic molten salt tank, it is determined that it is necessary to switch to the thermal storage mode and output a thermal storage mode switching signal. The second scenario: When it is during the peak period of the power grid and the liquid level in the high-temperature molten salt tank is higher than the minimum liquid level threshold of the high-temperature molten salt tank, it is determined that it is necessary to switch to the heat release mode and output the heat release mode switching signal. In the third scenario, if neither the first nor the second scenario is met, the current operating mode of the molten salt thermal storage system is maintained, and no switching signal is output.

2. A frequency regulation and peak shaving control system for thermal power units based on a molten salt thermal storage system, used to implement the frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system as described in claim 1, comprising: The first calculation module is used to calculate the power deviation based on the real-time collected power grid AGC commands and the actual power generated by the thermal power unit. The second calculation module is used to output an electric heater power adjustment command based on the power deviation using a PID algorithm. The electric heater power adjustment command is used to adjust the output power of the electric heater. The switching module is used to combine the real-time collected time-of-use electricity price signal of the power grid and the liquid level status of the molten salt tank to output a switching signal, which is used to switch the storage / heat release mode of the molten salt thermal storage system.

3. A frequency regulation and peak shaving control device for thermal power units based on a molten salt thermal storage system, characterized in that, include: Memory, used to store computer programs; A processor is used to implement the steps of the frequency regulation and peak shaving control method for thermal power units based on a molten salt thermal storage system as described in claim 1 when executing the computer program.

4. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it is used to implement the steps of the frequency regulation and peak shaving control method for thermal power units based on the molten salt thermal storage system as described in claim 1.

Images