Thermal power generating unit frequency modulation and peak regulation control method and system based on fused salt heat storage system

Abstract

The invention belongs to the field of thermal power generation and energy storage, and discloses a thermal power generating unit frequency modulation and peak regulation control method and system based on a fused salt heat storage system.The method comprises the steps that firstly, power deviation is calculated based on a power grid AGC instruction collected in real time and actual power of a thermal power generating unit, and then an electric heater power regulation instruction is output through a PID algorithm; and finally outputting a switching signal in combination with the time-of-use electricity price signal of the power grid and the liquid level state of the molten salt tank. The frequency modulation and peak regulation requirements can be accurately mastered by calculating the power deviation, a proper power regulation instruction can be efficiently output through a PID algorithm, and reasonable power regulation of the electric heater is ensured; a switching signal is output by combining the time-of-use electricity price and the molten salt tank liquid level state, and the economical efficiency and the equipment state can be comprehensively considered. By adopting the method, the technical potential of fused salt heat storage is fully excavated, intelligent and precise heat storage / release mode switching and electric heater power adjustment are achieved, the problems existing in an existing thermal power generating unit control system are effectively solved, and the thermal power generating unit is assisted to better complete frequency modulation and peak regulation tasks.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation and energy storage, and particularly relates to a frequency and peak regulation control method and system for a thermal power unit based on a molten salt heat storage system. Background Art

[0002] In the current power industry, with the continuous expansion of renewable energy integration, the power system's supply and demand balance faces even more severe challenges. To ensure stable and reliable power supply, the power grid places extremely high demands on the frequency and peak-shaving capabilities of thermal power units. Traditional thermal power units play a vital role in the overall power system, but their operating characteristics struggle to adapt to the new reality. During the heating season, the coupled thermal-electric nature of the units leads to a mutual constraint between power generation and heating, making it impossible to flexibly adjust power generation according to grid load fluctuations, severely limiting peak-shaving capabilities. During the non-heating season, the minimum stable combustion limit makes it difficult for the units to operate stably under low load conditions, resulting in frequent zero-price electricity. This inability to demonstrate the expected flexibility in the electricity spot market and meet the market's demand for fast and precise power regulation. Furthermore, the DCS system, as the "nerve center" of the thermal power unit, plays a critical role in unit operation and control, and its performance directly impacts the overall operation of the unit.

[0003] Faced with the lack of flexibility faced by thermal power plants, existing energy storage technologies have attempted to address this, but each has its own shortcomings. While electrochemical energy storage has a fast response speed and can theoretically assist thermal power plants in frequency and peak regulation, its cost remains high, and its battery life is short. Performance deteriorates significantly after frequent charging and discharging, making large-scale application difficult due to both economic and technical obstacles. Pumped storage technology is relatively mature, but its construction is highly dependent on specific geographical conditions and requires suitable upper and lower reservoir sites, making it difficult to promote and apply in areas with restricted topographical conditions. Molten salt thermal storage technology has been relatively maturely applied in the field of solar thermal power generation, demonstrating advantages such as large heat storage capacity and stable temperature. However, when attempting to deeply couple it with thermal power plants to achieve frequency and peak regulation, a comprehensive control method is lacking. Most existing thermal power unit control systems fail to fully tap the potential of molten salt heat storage technology. They are unable to comprehensively consider multiple factors such as real-time grid command changes, time-of-use electricity price fluctuations, and the liquid level status of the molten salt tank, and are unable to achieve intelligent and precise storage / release mode switching and electric heater power regulation. As a result, thermal power units still face many difficulties in the critical task of frequency and peak regulation. Summary of the Invention

[0004] The present invention provides a frequency regulation and peak regulation control method and system for thermal power units based on a molten salt heat storage system. Relying on a DCS system, the method and system collect power grid AGC instructions, actual power generation of the thermal power units, power grid time-of-use electricity price signals, and the liquid level status of the molten salt tank in real time. A PID algorithm is used to accurately output power regulation instructions for electric heaters to adjust the power of the electric heaters, and a switching signal is reasonably output to switch the storage / release mode of the molten salt heat storage system. This method fully taps the potential of molten salt heat storage technology, improves the frequency regulation and peak regulation capabilities of thermal power units, and ensures the stability and reliability of the power system.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

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

[0007] The power deviation is calculated based on the real-time collected grid AGC instructions and the actual power generated by the thermal power units;

[0008] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment instruction, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater;

[0009] Combined with the real-time collected power 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 heat storage system.

[0010] Furthermore, before calculating the power deviation based on the real-time collected grid AGC instructions and the actual power generated by the thermal power unit, the method further includes:

[0011] Through the communication interface between the DCS system and the power grid dispatching center, the grid AGC instructions are obtained in real time at a preset sampling period. The actual power generation of the thermal power unit is collected in real time at a preset sampling period through the power sensor installed at the generator outlet of the thermal power unit.

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

[0013]

[0014] Where, P filtered Represents the data after filtering, P i Represents the original data of the current moment and the previous n-1 moments; n represents the filter window size.

[0015] Furthermore, the power deviation is calculated based on the real-time collected grid AGC command and the actual power generated by the thermal power unit, including:

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

[0017] ΔP=P AGC -P actual

[0018] Where ΔP represents the power deviation; P AGC Indicates the grid AGC instruction after filtering; P actual Indicates the actual generated power after filtering.

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

[0020] According to the power deviation, the PID algorithm is used to calculate the power adjustment amount of the electric heater. The specific formula is as follows:

[0021]

[0022] Where, ΔP heater Indicates the power adjustment of the electric heater; K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively; ΔP represents the power deviation; Integral term representing power deviation; is the differential term of power deviation;

[0023] The power adjustment amount of the electric heater is limited as follows:

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

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

[0026] Where, ΔP max , ΔP min Respectively represent the upper and lower limits of the electric heater power adjustment;

[0027] According to the power adjustment amount of the electric heater after the limiting process and the current output power of the electric heater, the electric heater power adjustment instruction is generated. The specific formula is as follows:

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

[0029] Where, P heater-command Indicates the electric heater power adjustment instruction; P heater-current Indicates the current output power of the electric heater.

[0030] Furthermore, the method combines the real-time collected power grid time-of-use electricity price signal and the liquid level status of the molten salt tank to output a switching signal, wherein the switching signal is used to switch the storage / release mode of the molten salt heat storage system, including:

[0031] Determine the electricity price period according to the collected power grid time-of-use electricity price signal, wherein the electricity price period includes the power grid valley 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 liquid level status of the high molten salt tank, a corresponding switching signal is output.

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

[0034] Based on the electricity price period and the liquid level status of the low molten salt tank or the liquid level status of the high molten salt tank, the following judgment is made:

[0035] The first case: When the power grid is in the off-peak period and the liquid level of the low-temperature molten salt tank is greater than the minimum liquid level threshold of the low-temperature molten salt tank, it is determined that it is necessary to switch to the heat storage mode and output the heat storage mode switching signal;

[0036] The second case: when it is during the peak period of the power grid and the liquid level of 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 case, when neither the first case nor the second case is satisfied, the current operation mode of the molten salt heat storage system is maintained and no switching signal is output.

[0038] Furthermore, the control method further includes:

[0039] Based on the comparison results of the current temperature with the high temperature threshold and the low temperature threshold, the electric heater is started or stopped;

[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 salt drainage tank is controlled to automatically recover the molten salt and isolate the fault area.

[0042] A frequency and peak regulation control system for a thermal power unit based on a molten salt heat storage system, comprising:

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

[0044] a second calculation module, configured to output an electric heater power adjustment instruction using a PID algorithm based on the power deviation, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater;

[0045] The switching module is used to combine the real-time collected power grid time-sharing electricity price signal 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 heat storage system.

[0046] A device comprising:

[0047] memory for storing computer programs;

[0048] A processor is used to implement the steps of the above-mentioned method for frequency and peak regulation control of a thermal power unit based on a molten salt heat storage system when executing the computer program.

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

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

[0051] The present invention provides a frequency regulation and peak regulation control method for thermal power units based on a molten salt heat storage system. First, the power deviation is calculated based on the real-time collected grid AGC instructions and the actual power output of the thermal power unit. Then, the PID algorithm is used to output the power regulation instruction of the electric heater. Finally, the switching signal is output in combination with the time-of-use electricity price signal of the grid and the liquid level status of the molten salt tank. By calculating the power deviation, the frequency regulation and peak regulation requirements can be accurately grasped. The PID algorithm can efficiently output the appropriate power regulation instruction to ensure the reasonable regulation of the electric heater power. The switching signal is output in combination with the time-of-use electricity price and the liquid level status of the molten salt tank, which can comprehensively consider the economic efficiency and equipment status. The use of this method fully taps the potential of molten salt heat storage technology, realizes intelligent and precise storage / release mode switching and electric heater power regulation, effectively solves the problems existing in the existing thermal power unit control system, and helps the thermal power unit to better complete the frequency regulation and peak regulation tasks.

[0052] In the present invention, preferably, before calculating power deviation, real-time data is acquired through the DCS system's communication interface with the power grid dispatch center and power sensors, and a moving average filter is applied. This ensures the accuracy and reliability of the acquired data, reduces noise interference, and improves the accuracy of subsequent power deviation calculations. This in turn makes the power regulation instructions for the electric heater more precise, helping the thermal power unit respond more stably and effectively to power grid frequency and peak regulation instructions, thereby improving the performance and reliability of the entire control system.

[0053] In the present invention, the specific process of outputting an electric heater power adjustment command using a PID algorithm based on power deviation preferably includes calculating the power adjustment amount, limiting the amount, 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 process ensures that the electric heater power is adjusted within a safe range, and the generated command, combined with the current output power, achieves precise control. This makes electric heater power regulation more reasonable and stable, effectively improving the dynamic response capability of the thermal power unit's frequency and peak regulation.

[0054] In the present invention, a switching signal is preferably output based on the grid's time-of-use electricity price signal and the molten salt tank liquid level status, thereby switching the molten salt heat storage system's storage / release mode. By taking into account electricity price periods, heat can be stored during low-price periods and released during peak periods, reducing operating costs. In combination with the molten salt tank liquid level status, the safety and feasibility of storage / release operations can be ensured. This mode switching approach, which comprehensively considers economic and equipment conditions, improves the operating efficiency and economic benefits of the molten salt heat storage system and enhances the comprehensive performance of frequency and peak regulation of thermal power units.

[0055] In the present invention, preferably, based on the electricity price period and the liquid level status of the low molten salt tank or the liquid level status of the high molten salt tank, it is determined whether to output the corresponding switching signal; in different electricity price periods and molten salt tank liquid level states, the mode is accurately switched, which can not only meet the frequency and peak regulation needs of the power grid, but also ensure the safety and economy of the system operation, and further improve the effect of the collaborative work of the thermal power unit and the molten salt heat storage system.

[0056] In the present invention, the method preferably also incorporates a protection mechanism that activates or deactivates the electric heater based on temperature comparison results, controls the linkage between the molten salt pump and valve based on abnormal operating condition feedback signals, and controls the salt drain tank to automatically recover molten salt and isolate the faulty area based on leakage feedback signals. These features 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 and peak regulation, and improving the stability and availability of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic diagram of the structure of a molten salt heat storage system connected to a thermal power unit provided by an embodiment of the present invention;

[0058] Figure 2 A power response curve diagram of a thermal power unit following an AGC instruction provided by an embodiment of the present invention;

[0059] Figure 3 AGC frequency modulation response curve diagram of the molten salt heat storage system auxiliary thermal power unit provided in an embodiment of the present invention;

[0060] Figure 4 A flow chart of a method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system provided by an embodiment of the present invention;

[0061] Figure 5 A schematic structural diagram of a frequency and peak regulation control system for a thermal power unit based on a molten salt heat storage system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to further understand the content of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0063] The following is an explanation of the technical terms involved in the present invention:

[0064] AGC: The full name is Automatic Generation Control. As the core functional module of the power system energy management system (EMS), AGC maintains the stability of the grid frequency by adjusting the output of the generator sets in real time, and achieves an economic match between power generation and load demand.

[0065] Illustratively, this embodiment provides a method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system, comprising:

[0066] The power deviation is calculated based on the real-time collected grid AGC instructions and the actual power generated by the thermal power units;

[0067] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment instruction, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater;

[0068] Combined with the real-time collected power 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 heat storage system.

[0069] The control method provided by this embodiment is further explained below with reference to the accompanying drawings:

[0070] like Figure 1As shown in the figure, the molten salt thermal storage system is planned to be connected to the thermal power unit system. The electrical access structure is mainly composed of a high-voltage transformer, a plant power bus, a 6kV molten salt bus, an energy storage system power regulating cabinet and a molten salt heater, including:

[0071] High-voltage transformer: There are No. 1 high-voltage transformer and No. 2 high-voltage transformer, which are the power source of the entire system and provide power for subsequent equipment.

[0072] The auxiliary power busbar is divided into sections 1A, 1B, 2A, and 2B. The No. 1 high-voltage transformer connects sections 1A and 1B, while the No. 2 high-voltage transformer connects sections 2A and 2B, distributing and transmitting electricity.

[0073] 6kV Molten Salt Busbar: There are 6kV Molten Salt Busbar Section A and 6kV Molten Salt Busbar Section B. Auxiliary power sections 1A, 1B, 2A, and 2B are connected to the 6kV Molten Salt Busbar Sections A and B via switches for further distribution of power.

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

[0075] The overall electrical access structure presents an electric energy transmission and distribution path from the high-voltage plant transformer through the plant power bus, 6kV molten salt bus, to the energy storage system power regulating cabinet and molten salt heater, ensuring the power supply of related production links such as molten salt heating.

[0076] In order to ensure the stable, safe and reliable operation of the molten salt heat storage system connected to the thermal power generation system, this embodiment provides a frequency and peak regulation control method for the thermal power generation system based on the molten salt heat storage system, which specifically includes:

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

[0078] S2, Power Deviation Calculation: The power deviation is calculated by comparing the difference between the filtered grid AGC command and the actual generated power. For example, if a thermal power unit is responsible for grid load regulation, the filtered grid AGC command is 500MW, while the filtered actual generated power is 480MW. This results in a power deviation of 20MW, indicating that the thermal power unit needs to increase its generated power to meet grid demand.

[0079] S3, Electric Heater Power Adjustment Command Generation Stage: Based on the power deviation, the PID algorithm is used to calculate the electric heater power adjustment variable. The PID controller's proportional, integral, and differential coefficients are determined through on-site commissioning or through simulation optimization based on the thermal power unit and molten salt heat storage system model. The calculated power adjustment variable is limited to prevent over-adjustment of the electric heater. The limiting thresholds, i.e., the upper and lower limits of the electric heater power adjustment, are set based on the electric heater's rated power and the safe operating range of the molten salt heat storage system. Finally, the adjustment command is generated based on the electric heater's current output power. If the electric heater's current output power is 30 MW and the power adjustment variable after limiting is 5 MW, the generated electric heater power adjustment command is 35 MW.

[0080] According to the power deviation, the PID algorithm is used to calculate the power adjustment amount of the electric heater. The specific formula is as follows:

[0081]

[0082] Where, ΔP heater Indicates the power adjustment of the electric heater; K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively; ΔP represents the power deviation; Integral term representing power deviation; is the differential term of power deviation;

[0083] The power adjustment amount of the electric heater is limited as follows:

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

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

[0086] Where, ΔP max , ΔP min Respectively represent the upper and lower limits of the electric heater power adjustment;

[0087] According to the power adjustment amount of the electric heater after the limiting process and the current output power of the electric heater, the electric heater power adjustment instruction is generated. The specific formula is as follows:

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

[0089] Where, P heater-command Indicates the electric heater power adjustment instruction; P heater-current Indicates the current output power of the electric heater.

[0090] S4, heat storage / release mode switching phase: The power grid's time-of-use electricity price signal is collected, and the electricity price period is determined based on the timestamp and electricity price information in the signal. The liquid level status of the low-temperature molten salt tank and the high-temperature molten salt tank is monitored in real time with the help of liquid level sensors. The sensors are installed at appropriate locations on the tank body to accurately measure the liquid level. The switching signal is output according to the electricity price period and the molten salt tank level status. During the off-peak period of the power grid, if the liquid level of the low-temperature molten salt tank is higher than the minimum liquid level threshold, the heat storage mode switching signal is output; during the peak period of the power grid, if the liquid level of the high-temperature molten salt tank is higher than the minimum liquid level threshold, the 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 using temperature sensors and compared with high 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. If the system experiences abnormal operating conditions, such as abnormal pipeline pressure or sudden flow changes, the control system receives feedback signals and controls the molten salt pump and valves to shut off the molten salt flow, ensuring system safety. If a molten salt leak is detected, the control system automatically controls the salt drain tank to recover the molten salt based on the leak feedback signal and isolates the faulty area to prevent further leakage.

[0092] The control method provided in this embodiment is further described below with reference to specific examples:

[0093] Example 1:

[0094] In this example, the installed capacity of the thermal power plant is 600MW, and the capacity of the molten salt thermal storage system is 300MWh. The specific implementation steps are as follows:

[0095] Data acquisition and preprocessing: Set the sampling period to every minute, obtain the grid AGC instructions and the actual power of the thermal power units in real time through the DCS system, and perform moving average filtering.

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

[0097] PID algorithm adjustment: The PID algorithm is used to calculate the power adjustment of the electric heater and perform amplitude limiting. The proportional coefficient, integral coefficient, and differential 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 the off-peak period and the liquid level of the low-temperature molten salt tank is greater than 50%, the heat storage mode switching signal is output; when the power grid is in the peak period and the liquid level of the high-temperature molten salt tank is greater than 30%, the heat release mode switching signal is output.

[0099] Safety protection: High-temperature thresholds are set at 550°C and low-temperature thresholds at 250°C. When the temperature exceeds or falls below these thresholds, the electric heater is activated or deactivated. The system also monitors abnormal operating conditions and leaks in real time and takes appropriate protective measures.

[0100] Example 2:

[0101] In this example, the installed capacity of the thermal power plant 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, and the grid AGC instructions and the actual power of the thermal power units are obtained in real time through the DCS system, and moving average filtering is performed.

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

[0104] PID algorithm adjustment: The PID algorithm is used to calculate the electric heater power adjustment amount and perform amplitude limiting. The proportional coefficient, integral coefficient, and differential coefficient of the PID controller are set to 0.6, 0.08, and 0.03, respectively.

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

[0106] Safety protection: High-temperature thresholds are set at 600°C and low-temperature thresholds at 200°C. When the temperature exceeds or falls below these thresholds, the electric heater is activated or deactivated. Simultaneously, the system monitors abnormal operating conditions and leaks in real time and takes appropriate protective measures. Furthermore, a molten salt tank pressure monitoring function has been added to ensure that the molten salt thermal storage system operates at a safe pressure.

[0107] This demonstrates that using this control method, thermal power units quickly respond to grid AGC commands, reducing power deviations and improving grid stability. By storing excess electricity during off-peak hours, the system converts excess electricity into stored thermal energy. This stored thermal energy can then be used to assist in power generation during peak hours, improving the economic efficiency and peak-shaving capabilities of the thermal power units.

[0108] This embodiment differs from normal unit control in that the power generated by this thermal power unit consists of two components: the unit load commanded by the AGC, and the electrical heating power. For example, if the load command assigned to the unit is 200MW and the electrical heating power is 20MW, the actual unit output should be 180MW. Using the frequency modulation data of a thermal power unit for modeling and analysis, the thermal power unit's response curve to the AGC command is shown in Figure 2. Figure 2 In the figure, the blue curve is the AGC frequency regulation instruction, and the red curve is the actual power generated by the unit. The frequency regulation performance of the Qiguang Power Plant unit is good, and the trend of the unit power curve is the same as the trend of the AGC instruction curve, but the unit response speed and response accuracy still have a lot of room for improvement. After configuring 40MW molten salt energy storage, the unit frequency regulation performance is greatly improved. The energy storage-assisted unit AGC frequency regulation response curve is shown in Figure 3; after adding molten salt energy storage, the green curve is the sum of the actual power generated by the unit and the molten salt system power. It can be seen from the above figure that the sum of the actual power generated by the unit and the molten salt system power (green curve) and the AGC instruction (blue curve) basically coincide, indicating that the frequency regulation performance of the unit has been greatly improved; at the same time, the control method provided in this embodiment can ensure the stable, reliable and safe operation of the unit.

[0109] For example, Figure 4 As shown, this embodiment provides a frequency and peak regulation control method for a thermal power unit based on a molten salt heat storage system, comprising the following steps:

[0110] The power deviation is calculated based on the real-time collected grid AGC instructions and the actual power generated by the thermal power units;

[0111] Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment instruction, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater;

[0112] Combined with the real-time collected power 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 heat storage system.

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

[0114] Through the communication interface between the DCS system and the power grid dispatching center, the grid AGC instructions are obtained in real time at a preset sampling period. The actual power generation of the thermal power unit is collected in real time at a preset sampling period through the power sensor installed at the generator outlet of the thermal power unit.

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

[0116]

[0117] Where, P filtered Represents the data after filtering, P i Represents the original data of the current moment and the previous n-1 moments; n represents the filter window size.

[0118] In this embodiment, the power deviation is calculated based on the real-time collected grid AGC command and the actual power generated by the thermal power unit, including:

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

[0120] ΔP=P AGC -P actual

[0121] Where ΔP represents the power deviation; P AGC Indicates the grid AGC instruction after filtering; P actual Indicates the actual generated power after filtering.

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

[0123] According to the power deviation, the PID algorithm is used to calculate the power adjustment amount of the electric heater. The specific formula is as follows:

[0124]

[0125] Where, ΔP heater Indicates the power adjustment of the electric heater; K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively; ΔP represents the power deviation; Integral term representing power deviation; is the differential term of power deviation;

[0126] The power adjustment amount of the electric heater is limited as follows:

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

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

[0129] Where, ΔP max , ΔP min Respectively represent the upper and lower limits of the electric heater power adjustment;

[0130] According to the power adjustment amount of the electric heater after the limiting process and the current output power of the electric heater, the electric heater power adjustment instruction is generated. The specific formula is as follows:

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

[0132] Where, P heater-command Indicates the electric heater power adjustment instruction; P heater-current Indicates the current output power of the electric heater.

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

[0134] Determine the electricity price period according to the collected power grid time-of-use electricity price signal, wherein the electricity price period includes the power grid valley 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 liquid level status of the high molten salt tank, a corresponding switching signal is output.

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

[0137] Based on the electricity price period and the liquid level status of the low molten salt tank or the liquid level status of the high molten salt tank, the following judgment is made:

[0138] The first case: When the power grid is in the off-peak period and the liquid level of the low-temperature molten salt tank is greater than the minimum liquid level threshold of the low-temperature molten salt tank, it is determined that it is necessary to switch to the heat storage mode and output the heat storage mode switching signal;

[0139] The second case: when it is during the peak period of the power grid and the liquid level of 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 case, when neither the first case nor the second case is satisfied, the current operation mode of the molten salt heat 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 of the current temperature with the high temperature threshold and the low temperature threshold, the electric heater is started or stopped;

[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 salt drainage tank is controlled to automatically recover the molten salt and isolate the fault area.

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

[0146] The present invention also provides a device, comprising: a memory for storing a computer program; and a processor for implementing the steps of the frequency and peak regulation control method of a thermal power unit based on a molten salt heat storage system when executing the computer program.

[0147] When the processor executes the computer program, it implements the steps of frequency and peak regulation control of the thermal power unit based on the molten salt heat storage system, for example: based on the real-time collected grid AGC instructions and the actual power generated by the thermal power unit, a power deviation is calculated; based on the power deviation, a PID algorithm is used to output an electric heater power adjustment instruction, and the electric heater power adjustment instruction is used to adjust the output power of the electric heater; in combination 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, and the switching signal is used to switch the storage / release mode of the molten salt heat storage system.

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

[0149] Exemplarily, the computer program can be divided into one or more modules / units, and the one or more modules / units 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 that can complete preset functions, and the instruction segments are used to describe the execution process of the computer program in the frequency and peak regulation control device of the thermal power unit based on the molten salt heat 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 collected grid AGC instruction and the actual power generated by the thermal power unit; the second calculation module is used to output the electric heater power adjustment instruction based on the power deviation using the PID algorithm, and the electric heater power adjustment instruction is used to adjust the output power of the electric heater; the switching module is used to combine the real-time collected grid time-of-use electricity price signal and the liquid level status of the molten salt tank to output a switching signal, and the switching signal is used to switch the storage / release mode of the molten salt heat storage system.

[0150] The frequency regulation and peak regulation control device for thermal power generation units based on the molten salt heat storage system can be a computing device such as a desktop computer, a notebook computer, a PDA, and a cloud server. The frequency regulation and peak regulation control device for thermal power generation units based on the molten salt heat storage system may include, but is not limited to, a processor and a memory. Those skilled in the art will understand that the above examples of frequency regulation and peak regulation control devices for thermal power generation units based on the molten salt heat storage system do not constitute a limitation on frequency regulation and peak regulation control devices for thermal power generation units based on the molten salt heat storage system. The device may include more components than the above, or a combination of certain components, or different components. For example, the frequency regulation and peak regulation control device for thermal power generation units based on the molten salt heat storage system may also include input and output devices, network access devices, buses, etc.

[0151] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. The processor is the control center of the frequency and peak regulation control of the thermal power unit based on the molten salt heat storage system, and utilizes various interfaces and lines to connect various parts of the frequency and peak regulation control equipment of the thermal power unit based on the molten salt heat storage system.

[0152] The memory can be used to store the computer program and / or module, and the processor realizes various functions of the frequency and peak regulation control device of the thermal power unit based on the molten salt heat 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 mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, at least one application required for a function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created based on the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory and may also include a non-volatile memory, such as a hard disk, internal memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0154] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the frequency and peak regulation control method of a thermal power unit based on a molten salt heat storage system.

[0155] If the integrated module / unit of the frequency and peak regulation control system of the thermal power unit based on the molten salt heat storage system is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0156] Based on this understanding, the present invention implements all or part of the process steps in the above-mentioned method for frequency and peak regulation control of a thermal power plant based on a molten salt heat storage system. This process can also be accomplished by instructing related hardware through a computer program. 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 method for frequency and peak regulation control of a thermal power plant based on a molten salt heat storage system. The computer program includes computer program code, which can be in source code form, object code form, executable file, or a preset intermediate form.

[0157] The computer-readable storage medium may include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, 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 can be appropriately increased or decreased according to the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practices, computer-readable storage media do not include electrical carrier signals and telecommunication signals.

[0159] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by 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, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A frequency regulation and peak regulation control method for thermal power units based on a molten salt heat storage system, applied to a DCS system, characterized in that: include: The power deviation is calculated based on the real-time collected grid AGC instructions and the actual power generated by the thermal power units; Based on the power deviation, a PID algorithm is used to output an electric heater power adjustment instruction, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater; Combined with the real-time collected power 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 heat storage system.

2. The method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system according to claim 1 is characterized in that, before calculating the power deviation based on the real-time collected grid AGC instructions and the actual power generated by the thermal power unit, the method further comprises: Through the communication interface between the DCS system and the power grid dispatching center, the grid AGC instructions are obtained in real time at a preset sampling period; The actual power generation of the thermal power unit is collected in real time at a preset sampling period through a power sensor installed at the generator outlet of the thermal power unit; The grid AGC command and actual power generation are processed by moving average filtering respectively. The specific formula is as follows: Where, P filtered Represents the data after filtering, P i Represents the original data of the current moment and the previous n-1 moments; n represents the filter window size.

3. The method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system according to claim 2, wherein the power deviation is calculated based on the real-time collected grid AGC instructions and the actual power generated by the thermal power unit, including: Calculate the difference between the filtered grid AGC command and the actual generated power to obtain the power deviation. The specific formula is as follows: ΔP=P AGC -P actual Where ΔP represents the power deviation; P AGC Indicates the grid AGC instruction after filtering; P actual Indicates the actual generated power after filtering.

4. The method for frequency and peak regulation control of a thermal power unit based on a molten salt heat storage system according to claim 1 is characterized in that the method adopts a PID algorithm to output an electric heater power regulation instruction based on the power deviation, comprising: According to the power deviation, the PID algorithm is used to calculate the power adjustment amount of the electric heater. The specific formula is as follows: Where ΔP heater Indicates the power adjustment of the electric heater; K p , K i , K d They represent the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively; ΔP represents the power deviation; Integral term representing power deviation; is the differential term of power deviation; The power adjustment amount of the electric heater is limited as follows: When ΔP heater >ΔP max When ΔP heater =ΔP max ; When ΔP heater <ΔP min When ΔP heater =ΔP min ; Where ΔP max , ΔP min Respectively represent the upper and lower limits of the electric heater power adjustment; According to the power adjustment amount of the electric heater after the limiting process and the current output power of the electric heater, the electric heater power adjustment instruction is generated. The specific formula is as follows: P heater-command =P heater-current +ΔP heater Where, P heater-command Indicates the electric heater power adjustment instruction; P heater-current Indicates the current output power of the electric heater.

5. The method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system according to claim 1 is characterized in that the method combines 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, wherein the switching signal is used to switch the storage / release mode of the molten salt heat storage system, and comprises: Determine the electricity price period according to the collected power grid time-of-use electricity price signal, wherein the electricity price period includes the power grid valley 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 liquid level status of the high molten salt tank, a corresponding switching signal is output.

6. The method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system according to claim 5, wherein the step of outputting a corresponding switching signal based on the electricity price period and the liquid level of the low molten salt tank or the liquid level of the high molten salt tank comprises: Based on the electricity price period and the liquid level status of the low molten salt tank or the liquid level status of the high molten salt tank, the following judgment is made: The first case: When the power grid is in the off-peak period and the liquid level of the low-temperature molten salt tank is greater than the minimum liquid level threshold of the low-temperature molten salt tank, it is determined that it is necessary to switch to the heat storage mode and output the heat storage mode switching signal; The second case: when it is during the peak period of the power grid and the liquid level of 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 case, when neither the first case nor the second case is satisfied, the current operation mode of the molten salt heat storage system is maintained and no switching signal is output.

7. The method for controlling frequency and peak regulation of a thermal power unit based on a molten salt heat storage system according to claim 1, characterized in that: The control method further includes: Based on the comparison results of the current temperature with the high temperature threshold and the low temperature threshold, the electric heater is started or stopped; 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 salt drainage tank is controlled to automatically recover the molten salt and isolate the fault area.

8. A frequency and peak regulation control system for thermal power units based on a molten salt heat storage system, characterized in that: include: The first calculation module is used to calculate the power deviation based on the real-time collected power grid AGC command and the actual power generated by the thermal power unit; a second calculation module, configured to output an electric heater power adjustment instruction using a PID algorithm based on the power deviation, wherein the electric heater power adjustment instruction is used to adjust the output power of the electric heater; The switching module is used to combine the real-time collected power grid time-sharing electricity price signal 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 heat storage system.

9. A device, characterized in that include: Memory for storing computer programs; A processor, configured to implement the steps of the method for frequency and peak regulation control of a thermal power unit based on a molten salt heat storage system according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it is used to implement the steps of the frequency and peak regulation control method of a thermal power unit based on a molten salt heat storage system according to any one of claims 1 to 7.

Images