A peak shaving and frequency modulation system coupling electricity storage and heat storage and a control method thereof

Abstract

The application discloses a peak regulation and frequency modulation system coupled with electricity storage and heat storage and a control method. The peak regulation and frequency modulation system comprises a heat storage system, an electricity storage system, a thermal power generating unit, a generator, a DCS system, a joint peak regulation and frequency modulation controller and an AGC system. The joint peak regulation and frequency modulation controller receives instructions from the AGC system. The joint peak regulation and frequency modulation controller sends the instructions to the DCS system, the electricity storage system and the heat storage system. The AGC system sends the instructions to the DCS system. The DCS system sends the instructions to the joint peak regulation and frequency modulation controller. The joint peak regulation and frequency modulation controller sends the instructions to the thermal power generating unit, the electricity storage system and the heat storage system after re-distribution, so that the flexibility of energy storage participating in peak regulation and frequency modulation is improved, and the thermal power generating unit can quickly and accurately complete the peak regulation and frequency modulation task.

Description

Technical Field

[0001] This application relates to the field of thermal power generation technology, and more specifically, to a peak-shaving and frequency regulation system and control method that couples energy storage and thermal storage. Background Technology

[0002] With the continuous development of the social economy, the peak-to-valley difference in the power grid is widening, and the randomness of electricity load is increasing, leading to a greater demand for peak-shaving capacity in the power grid. Furthermore, with my country's goals of achieving carbon peaking and carbon neutrality, new energy power generation technologies such as solar and wind power are developing rapidly. However, due to the uncertainty and volatility of their output, large-scale grid connection will have a significant impact on the power grid, affecting its safe and stable operation and increasing the pressure on frequency regulation.

[0003] Energy storage technology has multiple application values ​​in theory, such as improving the quality of new energy power generation, reducing grid pressure, and participating in the electricity market to provide ancillary services. In recent years, energy storage participation in peak shaving and frequency regulation has gradually become a hot topic.

[0004] On the one hand, with the continuous development of energy storage technology, the investment cost of energy storage is constantly decreasing, creating conditions for its effective peak shaving and valley filling and for facilitating the consumption of new energy power generation. On the other hand, the continuous introduction of relevant policies has further promoted the development of energy storage technology. Driven by both market demand and policies, the installed capacity of energy storage will gradually increase in the future.

[0005] In terms of power structure, thermal power is the primary power source in my country, and given the current low proportion of peak-shaving power, it needs to undertake the main tasks of peak and frequency regulation. Constructing energy storage projects on the generation side is of great significance for addressing the problem of insufficient peak and frequency regulation resources on a large scale.

[0006] In terms of energy storage technology types, power energy storage technologies can be mainly divided into pumped hydro storage, electrochemical energy storage, molten salt energy storage, flywheel energy storage, and compressed air energy storage. Electrochemical energy storage is currently the most widely used and has the greatest development potential. It has a fast response speed and is suitable for participating in the regulation of rapid load fluctuations on a shorter time scale. Molten salt energy storage has better thermal stability and a larger specific heat capacity compared to other thermal storage technologies. Its biggest advantage over electrochemical energy storage is its large energy storage capacity and low unit energy storage cost. However, it has a certain inertia, and its flexibility is obviously not as good as electrochemical energy storage. It is suitable for participating in the regulation of large load changes on a longer time scale.

[0007] Therefore, how to provide a peak-shaving and frequency regulation system that combines electrochemical energy storage and molten salt energy storage to improve the peak-shaving and frequency regulation capabilities of thermal power units is a technical problem that needs to be solved. Summary of the Invention

[0008] This invention discloses a peak-shaving and frequency regulation system that couples energy storage and thermal storage, in order to solve the technical problem of poor flexibility in peak-shaving and frequency regulation of thermal power units in the prior art. The peak-shaving and frequency regulation system includes:

[0009] A thermal energy storage system is used to recover heat from or release heat to a thermal power unit according to instructions from a joint peak-shaving and frequency-regulating controller. The thermal energy storage system includes a molten salt thermal storage tank, a molten salt high-temperature pump, a molten salt low-temperature pump, a heat exchanger, a first valve, a second valve, a third valve, and a fourth valve.

[0010] An electric energy storage system is used to perform charging and discharging operations according to the instructions of the joint peak-shaving and frequency-modulation controller;

[0011] The thermal power unit is used to drive the generator to generate electricity according to the instructions of the DCS system, and recover heat to the thermal energy storage system or receive heat released by the thermal energy storage system. The thermal power unit includes a boiler, a steam turbine, a deaerator, a heater, a feedwater pump, a fifth valve, a sixth valve, a seventh valve and an eighth valve.

[0012] The generator is used to supply power to the power grid system and to supply power to the energy storage system;

[0013] The DCS system is used to control the thermal power unit according to the instructions of the joint peak shaving and frequency regulation controller and the instructions of the AGC system, and to send the instructions of the AGC system to the joint peak shaving and frequency regulation controller.

[0014] The combined peak shaving and frequency regulation controller is used to control the DCS system, the thermal energy storage system and the electrical energy storage system according to the instructions of the AGC system;

[0015] The AGC system is used to control the DCS system and the joint peak shaving and frequency modulation controller;

[0016] The high-temperature output of the molten salt thermal storage tank is connected to the high-temperature input of the heat exchanger via the high-temperature molten salt pump and the first valve. The high-temperature input of the heat exchanger is connected to the high-temperature input of the molten salt thermal storage tank via the second valve. The low-temperature output of the molten salt thermal storage tank is connected to the low-temperature input of the heat exchanger via the low-temperature molten salt pump and the third valve. The low-temperature input of the heat exchanger is connected to the low-temperature input of the molten salt thermal storage tank via the fourth valve. The heat is drawn from the boiler and reheated. One path of the steam pipeline is connected to the input end of the intermediate-pressure cylinder of the steam turbine via the fifth valve. Another path of the hot section reheat steam pipeline drawn from the boiler is connected to the working fluid side input end of the heat exchanger via the sixth valve. One path of the water side output end of the deaerator is connected to the low-temperature sensor input end of the heater via the seventh valve. The other path of the water side output end of the deaerator is connected to the working fluid side input end of the heat exchanger via the eighth valve. The working fluid side output end of the heat exchanger is connected to the high-temperature sensor input end of the heater. The output end of the heater is connected to the boiler via the feedwater pump.

[0017] In some embodiments of this application, the peak-shaving and frequency regulation system further includes a first transformer, a second transformer, a third transformer, and a rectifier, wherein,

[0018] The generator is connected to the low-voltage side of the first transformer and the high-voltage side of the second transformer, respectively. The high-voltage side of the first transformer is connected to the power grid system, the low-voltage side of the second transformer is connected to the high-voltage side of the third transformer, and the low-voltage side of the third transformer is connected to the energy storage system via the rectifier.

[0019] In some embodiments of this application, the thermal power unit further includes a condenser, a superheated steam pipe drawn from the boiler is connected to the input end of the high-pressure cylinder of the steam turbine, the output end of the high-pressure cylinder enters the boiler through a cold section reheat pipe, the output end of the intermediate-pressure cylinder is connected to the input end of the low-pressure cylinder of the steam turbine and the steam-side input end of the deaerator, and the output end of the low-pressure cylinder is connected to the water-side input end of the deaerator through the condenser.

[0020] In some embodiments of this application, the joint peak-shaving and frequency-modulating controller is specifically used for:

[0021] The system receives instructions from the AGC system and decomposes these instructions into high-frequency, medium-frequency, and low-frequency instructions. It then controls the electrical energy storage system based on the high-frequency instructions, the thermal energy storage system based on the medium-frequency instructions, and the DCS system based on the low-frequency instructions.

[0022] In some embodiments of this application, the energy storage system includes a lithium-ion battery, a lead-acid battery, or a flow battery.

[0023] In some embodiments of this application, the molten salt in the molten salt storage tank includes nitro-type binary molten salt or nitro-type ternary molten salt.

[0024] This invention also proposes a peak-shaving and frequency-modulation control method that couples energy storage and heat storage, applied to the peak-shaving and frequency-modulation system described above. The method includes:

[0025] If the joint peak shaving and frequency regulation controller receives a first instruction from the AGC system that heat needs to be recovered, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the first instruction, so that the thermal energy storage system performs a first set of preset operations, and at the same time the DCS system controls the thermal power unit to perform a second set of preset operations.

[0026] The first set of preset operations includes running the molten salt cryogenic pump, opening the second and third valves, and closing the first and fourth valves to send the cryogenic molten salt from the lower part of the molten salt storage tank into the heat exchanger, and after heat exchange, it enters the upper part of the molten salt storage tank. The second set of preset operations includes adjusting the opening of the fifth and sixth valves and closing the eighth valve to allow a portion of the hot section reheat steam to be extracted into the heat exchanger. After heat exchange, the extracted steam enters the heater, mixes and heats with the feedwater from the deaerator, and then enters the boiler through the feedwater pump.

[0027] In some embodiments of this application, the method further includes:

[0028] If the joint peak shaving and frequency regulation controller receives a second instruction from the AGC system that heat needs to be released, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the second instruction, so that the thermal energy storage system performs a third set of preset operations, and at the same time the DCS system controls the thermal power unit to perform a fourth set of preset operations.

[0029] The third set of preset operations includes running the molten salt high-temperature pump, opening the first valve and the fourth valve, and closing the second valve and the third valve to send the high-temperature molten salt from the upper part of the molten salt storage tank into the heat exchanger, and after heat exchange, it enters the lower part of the molten salt storage tank; the fourth set of preset operations includes adjusting the opening of the seventh valve and the eighth valve, and closing the sixth valve, so that a portion of the feedwater enters the heat exchanger, and the high-temperature feedwater after heat exchange enters the heater, mixes and heats with another portion of the feedwater from the deaerator, and then enters the boiler through the feedwater pump.

[0030] In some embodiments of this application, the method further includes:

[0031] If the joint peak shaving and frequency regulation controller receives a third instruction from the AGC system requiring charging and discharging, the joint peak shaving and frequency regulation controller controls the energy storage system according to the third instruction, so that when the power to be generated in the third instruction exceeds the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the current maximum charging and discharging power, and when the power to be generated does not exceed the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the power to be generated.

[0032] By applying the above technical solutions, the peak-shaving and frequency regulation system that couples electric and thermal energy storage includes a thermal energy storage system, an electric energy storage system, a thermal power unit, a generator, a DCS system, a joint peak-shaving and frequency regulation controller, and an AGC system. The joint peak-shaving and frequency regulation controller receives instructions from the AGC system; the joint peak-shaving and frequency regulation controller sends instructions to the DCS system, the electric energy storage system, and the thermal energy storage system; the AGC system sends instructions to the DCS system; the DCS system sends instructions to the joint peak-shaving and frequency regulation controller; the joint peak-shaving and frequency regulation controller redistributes the instructions and sends them to the thermal power unit, the electric energy storage system, and the thermal energy storage system, thereby improving the flexibility of energy storage in participating in peak-shaving and frequency regulation and helping thermal power units to quickly and accurately complete peak-shaving and frequency regulation tasks. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This diagram illustrates the structure of a peak-shaving and frequency-modulating system that couples energy storage and heat storage, as proposed in an embodiment of the present invention.

[0035] Figure 2 The following is a schematic diagram of the thermal energy storage system and thermal power unit structure in an embodiment of the present invention;

[0036] Figure 3 The diagram shows a flowchart of a peak-shaving and frequency-modulation control method for coupled energy storage and heat storage proposed in an embodiment of the present invention.

[0037] Figure 1 and Figure 2The components are as follows: 1. AGC system; 2. DCS system; 3. Thermal power unit; 4. Thermal energy storage system; 5. Generator; 6. First transformer; 7. Power grid system; 8. Second transformer; 9. Third transformer; 10. Rectifier; 11. Electric energy storage system; 12. Joint peak-shaving and frequency regulation controller; 13. Boiler; 14. High-pressure cylinder; 15. Medium-pressure cylinder; 16. Low-pressure cylinder; 17. Condenser; 18. Deaerator; 19. Heater; 20. Feedwater pump; 21. Molten salt thermal storage tank; 22. Molten salt high-temperature pump; 23. Molten salt low-temperature pump; 24. Heat exchanger; 25. First valve; 26. Second valve; 27. Third valve; 28. Fourth valve; 29. ​​Fifth valve; 30. Sixth valve; 31. Seventh valve; 32. Eighth valve. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] This application provides a peak-shaving and frequency-regulating system that couples energy storage and heat storage, such as... Figure 1 and Figure 2 As shown, the peak shaving and frequency modulation system includes:

[0041] The thermal energy storage system 4 is used to recover heat from the thermal power unit 3 or release heat to the thermal power unit 3 according to the instructions of the joint peak shaving and frequency regulation controller 12. The thermal energy storage system 4 includes a molten salt thermal storage tank 21, a molten salt high temperature pump 22, a molten salt low temperature pump 23, a heat exchanger 24, a first valve 25, a second valve 26, a third valve 27 and a fourth valve 28.

[0042] The energy storage system 11 is used to perform charging and discharging operations according to the instructions of the joint peak-shaving and frequency-modulation controller 12;

[0043] The thermal power unit 3 is used to drive the generator 5 to generate electricity according to the instructions of the DCS system 2, and recover the heat to the thermal energy storage system 4 or receive the heat released by the thermal energy storage system 4. The thermal power unit 3 includes a boiler 13, a steam turbine (including a high-pressure cylinder 14, an intermediate-pressure cylinder 15 and a low-pressure cylinder 16), a deaerator 18, a heater 19, a feed water pump 20, a fifth valve 29, a sixth valve 30, a seventh valve 31 and an eighth valve 32.

[0044] Generator 5 is used to supply power to the power grid system 7 and the energy storage system 11;

[0045] DCS system 2 is used to control thermal power unit 3 according to the instructions of joint peak shaving and frequency regulation controller 12 and AGC system 1, and to send the instructions of AGC system 1 to joint peak shaving and frequency regulation controller 12.

[0046] The joint peak shaving and frequency regulation controller 12 is used to control the DCS system 2, thermal energy storage system 4 and electrical energy storage system 11 according to the instructions of the AGC system 1;

[0047] AGC system 1 is used to control DCS system 2 and joint peak shaving and frequency modulation controller 12;

[0048] The high-temperature output end of the molten salt heat storage tank 21 is connected to the high-temperature input end of the heat exchanger 24 via the molten salt high-temperature pump 22 and the first valve 25. The high-temperature input end of the heat exchanger 24 is connected to the high-temperature input end of the molten salt heat storage tank 21 via the second valve 26. The low-temperature output end of the molten salt heat storage tank 21 is connected to the low-temperature input end of the heat exchanger 24 via the molten salt low-temperature pump 23 and the third valve 27. The low-temperature input end of the heat exchanger 24 is connected to the low-temperature input end of the molten salt heat storage tank 21 via the fourth valve 28. The heat drawn from the boiler 13... One path of the reheat steam pipeline is connected to the input end of the intermediate pressure cylinder 15 of the steam turbine via the fifth valve 29. Another path of the hot section reheat steam pipeline drawn from the boiler 13 is connected to the working fluid side input end of the heat exchanger 24 via the sixth valve 30. One path of the water side output end of the deaerator 18 is connected to the low temperature sensor input end of the heater 19 via the seventh valve 31. Another path of the water side output end of the deaerator 18 is connected to the working fluid side input end of the heat exchanger 24 via the eighth valve 32. The working fluid side output end of the heat exchanger 24 is connected to the high temperature sensor input end of the heater 19. The output end of the heater 19 is connected to the boiler 13 via the feedwater pump 20.

[0049] To ensure that generator 5 can normally supply power to the power grid system 7 and the energy storage system 11, as shown in Figure 1, the peak-shaving and frequency regulation system also includes a first transformer 6, a second transformer 8, a third transformer 9, and a rectifier 10.

[0050] Generator 5 is connected to the low-voltage side of the first transformer 6 and the high-voltage side of the second transformer 8. The high-voltage side of the first transformer 6 is connected to the power grid system 7. The low-voltage side of the second transformer 8 is connected to the high-voltage side of the third transformer 9. The low-voltage side of the third transformer 9 is connected to the energy storage system 11 via rectifier 10.

[0051] To ensure the reliability of thermal power units, in some embodiments of this application, such as... Figure 2 As shown, the thermal power unit 3 also includes a condenser 17. The superheated steam pipe led out from the boiler 13 is connected to the input end of the high-pressure cylinder 14 of the steam turbine. The output end of the high-pressure cylinder 14 enters the boiler 13 through the cold section reheat pipe. The output end of the intermediate-pressure cylinder 15 is connected to the input end of the low-pressure cylinder 16 of the steam turbine and the steam-side input end of the deaerator 18, respectively. The output end of the low-pressure cylinder 16 is connected to the water-side input end of the deaerator 18 through the condenser 17.

[0052] To improve system reliability, in some embodiments of this application, the joint peak-shaving and frequency-modulating controller 12 is specifically used for:

[0053] It receives instructions from AGC system 1, decomposes the instructions from AGC system 1 into high-frequency instructions, medium-frequency instructions and low-frequency instructions according to frequency, and controls the electric energy storage system 11 based on the high-frequency instructions, controls the thermal energy storage system 4 based on the medium-frequency instructions, and controls the DCS system 2 based on the low-frequency instructions.

[0054] In this embodiment, the joint peak shaving and frequency regulation controller 12 receives the instructions from the AGC system 1 and decomposes the instructions into high-frequency instructions, medium-frequency instructions, and low-frequency instructions according to different frequencies. These instructions are then sent to the electric energy storage system 11, the thermal energy storage system 4, and the DCS system 2, respectively. The DCS system 2 then sends the low-frequency instructions to the thermal power unit 3. This allows the thermal power unit 3, the thermal energy storage system 4, and the electric energy storage system 11 to coordinate and cooperate, controlling the output of the corresponding energy storage systems. This fully utilizes the characteristics of the thermal energy storage system (large capacity but slow response) and the electric energy storage system (fast response but small capacity), enabling the rapid and accurate completion of peak shaving and frequency regulation tasks.

[0055] To ensure the reliability of the energy storage system 11, in some embodiments of this application, the energy storage system 11 includes a lithium-ion battery, a lead-acid battery, or a flow battery.

[0056] Those skilled in the art may use other energy storage technologies as needed, which does not affect the scope of protection of this application.

[0057] To ensure the reliability of the thermal energy storage system 4, in some embodiments of this application, the molten salt in the molten salt storage tank 21 includes nitro-type binary molten salt or nitro-type ternary molten salt.

[0058] In this embodiment, in the molten salt storage tank 21, high-temperature molten salt is stored in the upper part and low-temperature molten salt is stored in the lower part. There is a natural stratification with a large temperature gradient and a very thin layer between the high-temperature molten salt and the low-temperature molten salt, namely the sloping temperature layer. The buoyancy formed by the density difference of the molten salt at different temperatures maintains the thermal stratification and separates the high and low temperature molten salt regions.

[0059] Nitro-type binary molten salts or nitro-type ternary molten salts can be selected according to the actual working temperature of high-temperature molten salts and low-temperature molten salts. For example, nitro-type binary molten salts are 40% KNO3 + 60% NaNO3 or 55% KNO3 + 45% NaNO2, and nitro-type ternary molten salts are 53% KNO3 + 7% NaNO3 + 40% NaNO2.

[0060] Those skilled in the art may use other types of molten salts as needed, which does not affect the scope of protection of this application.

[0061] By applying the above technical solutions, the peak-shaving and frequency regulation system that couples electric and thermal energy storage includes a thermal energy storage system, an electric energy storage system, a thermal power unit, a generator, a DCS system, a joint peak-shaving and frequency regulation controller, and an AGC system. The joint peak-shaving and frequency regulation controller receives instructions from the AGC system; the joint peak-shaving and frequency regulation controller sends instructions to the DCS system, the electric energy storage system, and the thermal energy storage system; the AGC system sends instructions to the DCS system; the DCS system sends instructions to the joint peak-shaving and frequency regulation controller; the joint peak-shaving and frequency regulation controller redistributes the instructions and sends them to the thermal power unit, the electric energy storage system, and the thermal energy storage system, thereby improving the flexibility of energy storage in participating in peak-shaving and frequency regulation and helping thermal power units to quickly and accurately complete peak-shaving and frequency regulation tasks.

[0062] This application also proposes a peak-shaving and frequency-modulation control method that couples energy storage and heat storage, applied to the peak-shaving and frequency-modulation system described above, such as... Figure 3 As shown, the method includes the following steps:

[0063] Step S101: If the joint peak shaving and frequency regulation controller receives a first instruction from the AGC system that heat needs to be recovered, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the first instruction, so that the thermal energy storage system performs a first set of preset operations, and at the same time, the DCS system controls the thermal power unit to perform a second set of preset operations.

[0064] Among them, such as Figure 2As shown, the first set of preset operations includes running the molten salt cryogenic pump 23, opening the second valve 26 and the third valve 27, and closing the first valve 25 and the fourth valve 28 to send the cryogenic molten salt in the lower part of the molten salt heat storage tank 21 into the heat exchanger 24, and after heat exchange, it enters the upper part of the molten salt heat storage tank 21; the second set of preset operations includes adjusting the opening of the fifth valve 29 and the sixth valve 30, and closing the eighth valve 32, so that a portion of the hot section reheat steam is extracted into the heat exchanger 24, and the extracted steam after heat exchange enters the heater 19, mixes and heats with the feedwater from the deaerator 18, and then enters the boiler 13 through the feedwater pump 20.

[0065] To ensure that the thermal energy storage system reliably releases heat to the thermal power unit, in some embodiments of this application, the method further includes:

[0066] If the joint peak shaving and frequency regulation controller receives a second instruction from the AGC system that heat needs to be released, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the second instruction, so that the thermal energy storage system performs a third set of preset operations, and at the same time the DCS system controls the thermal power unit to perform a fourth set of preset operations.

[0067] Among them, such as Figure 2 As shown, the third set of preset operations includes running the molten salt high-temperature pump 21, opening the first valve 25 and the fourth valve 28, and closing the second valve 26 and the third valve 27 to send the high-temperature molten salt in the upper part of the molten salt heat storage tank 21 into the heat exchanger 24, and after heat exchange, it enters the lower part of the molten salt heat storage tank 21; the fourth set of preset operations includes adjusting the opening of the seventh valve 31 and the eighth valve 32, and closing the sixth valve 30, so that a part of the feedwater enters the heat exchanger 24, and the high-temperature feedwater after heat exchange enters the heater 19, and after mixing and heating with another part of the feedwater from the deaerator 18, it enters the boiler 13 through the feedwater pump 20.

[0068] To ensure the reliable charging and discharging operation of the energy storage system, in some embodiments of this application, the method further includes:

[0069] If the joint peak shaving and frequency regulation controller receives a third instruction from the AGC system requiring charging and discharging, the joint peak shaving and frequency regulation controller controls the energy storage system according to the third instruction, so that when the power to be generated in the third instruction exceeds the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the current maximum charging and discharging power, and when the power to be generated does not exceed the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the power to be generated.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A peak-shaving and frequency-regulating system that couples energy storage and heat storage, characterized in that, The peak-shaving and frequency modulation system includes: A thermal energy storage system is used to recover heat from or release heat to a thermal power unit according to instructions from a joint peak-shaving and frequency-regulating controller. The thermal energy storage system includes a molten salt thermal storage tank, a molten salt high-temperature pump, a molten salt low-temperature pump, a heat exchanger, a first valve, a second valve, a third valve, and a fourth valve. An electric energy storage system is used to perform charging and discharging operations according to the instructions of the joint peak-shaving and frequency-modulation controller; The thermal power unit is used to drive the generator to generate electricity according to the instructions of the DCS system, and recover heat to the thermal energy storage system or receive heat released by the thermal energy storage system. The thermal power unit includes a boiler, a steam turbine, a deaerator, a heater, a feedwater pump, a fifth valve, a sixth valve, a seventh valve and an eighth valve. The generator is used to supply power to the power grid system and to supply power to the energy storage system; The DCS system is used to control the thermal power unit according to the instructions of the joint peak shaving and frequency regulation controller and the instructions of the AGC system, and to send the instructions of the AGC system to the joint peak shaving and frequency regulation controller. The combined peak shaving and frequency regulation controller is used to control the DCS system, the thermal energy storage system and the electrical energy storage system according to the instructions of the AGC system; The AGC system is used to control the DCS system and the joint peak shaving and frequency modulation controller; The high-temperature output of the molten salt thermal storage tank is connected to the high-temperature input of the heat exchanger via the high-temperature molten salt pump and the first valve. The high-temperature input of the heat exchanger is connected to the high-temperature input of the molten salt thermal storage tank via the second valve. The low-temperature output of the molten salt thermal storage tank is connected to the low-temperature input of the heat exchanger via the low-temperature molten salt pump and the third valve. The low-temperature input of the heat exchanger is connected to the low-temperature input of the molten salt thermal storage tank via the fourth valve. The heat is drawn from the boiler and reheated. One path of the steam pipeline is connected to the input end of the intermediate-pressure cylinder of the steam turbine via the fifth valve. Another path of the hot section reheat steam pipeline drawn from the boiler is connected to the working fluid side input end of the heat exchanger via the sixth valve. One path of the water side output end of the deaerator is connected to the low-temperature sensor input end of the heater via the seventh valve. The other path of the water side output end of the deaerator is connected to the working fluid side input end of the heat exchanger via the eighth valve. The working fluid side output end of the heat exchanger is connected to the high-temperature sensor input end of the heater. The output end of the heater is connected to the boiler via the feedwater pump.

2. The peak-shaving and frequency-modulating system as described in claim 1, characterized in that, The peak-shaving and frequency regulation system also includes a first transformer, a second transformer, a third transformer, and a rectifier, wherein, The generator is connected to the low-voltage side of the first transformer and the high-voltage side of the second transformer, respectively. The high-voltage side of the first transformer is connected to the power grid system, the low-voltage side of the second transformer is connected to the high-voltage side of the third transformer, and the low-voltage side of the third transformer is connected to the energy storage system via the rectifier.

3. The peak-shaving and frequency-modulating system as described in claim 1, characterized in that, The thermal power unit also includes a condenser. A superheated steam pipe drawn from the boiler is connected to the input end of the high-pressure cylinder of the turbine. The output end of the high-pressure cylinder enters the boiler through a cold section reheat pipe. The output end of the intermediate-pressure cylinder is connected to the input end of the low-pressure cylinder of the turbine and the steam-side input end of the deaerator, respectively. The output end of the low-pressure cylinder is connected to the water-side input end of the deaerator through the condenser.

4. The peak-shaving and frequency-modulating system as described in claim 1, characterized in that, The combined peak-shaving and frequency-modulating controller is specifically used for: The system receives instructions from the AGC system and decomposes these instructions into high-frequency, medium-frequency, and low-frequency instructions. It then controls the electrical energy storage system based on the high-frequency instructions, the thermal energy storage system based on the medium-frequency instructions, and the DCS system based on the low-frequency instructions.

5. The peak-shaving and frequency-modulating system as described in claim 1, characterized in that, The energy storage system includes lithium-ion batteries, lead-acid batteries, or flow batteries.

6. The peak-shaving and frequency-modulating system as described in claim 1, characterized in that, The molten salt in the molten salt storage tank includes either nitro-type binary molten salt or nitro-type ternary molten salt.

7. A peak-shaving and frequency-modulation control method that couples energy storage and heat storage, characterized in that, Applied to the peak-shaving and frequency modulation system as described in any one of claims 1-6, the method comprises: If the joint peak shaving and frequency regulation controller receives a first instruction from the AGC system that heat needs to be recovered, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the first instruction, so that the thermal energy storage system performs a first set of preset operations, and at the same time the DCS system controls the thermal power unit to perform a second set of preset operations. The first set of preset operations includes running the molten salt cryogenic pump, opening the second and third valves, and closing the first and fourth valves to send the cryogenic molten salt from the lower part of the molten salt storage tank into the heat exchanger, and after heat exchange, it enters the upper part of the molten salt storage tank. The second set of preset operations includes adjusting the opening of the fifth and sixth valves and closing the eighth valve to allow a portion of the hot section reheat steam to be extracted into the heat exchanger. After heat exchange, the extracted steam enters the heater, mixes and heats with the feedwater from the deaerator, and then enters the boiler through the feedwater pump.

8. The method as described in claim 7, characterized in that, The method further includes: If the joint peak shaving and frequency regulation controller receives a second instruction from the AGC system that heat needs to be released, the joint peak shaving and frequency regulation controller controls the thermal energy storage system and the DCS system according to the second instruction, so that the thermal energy storage system performs a third set of preset operations, and at the same time the DCS system controls the thermal power unit to perform a fourth set of preset operations. The third set of preset operations includes running the molten salt high-temperature pump, opening the first valve and the fourth valve, and closing the second valve and the third valve to send the high-temperature molten salt from the upper part of the molten salt storage tank into the heat exchanger, and after heat exchange, it enters the lower part of the molten salt storage tank; the fourth set of preset operations includes adjusting the opening of the seventh valve and the eighth valve, and closing the sixth valve, so that a portion of the feedwater enters the heat exchanger, and the high-temperature feedwater after heat exchange enters the heater, mixes and heats with another portion of the feedwater from the deaerator, and then enters the boiler through the feedwater pump.

9. The method as described in claim 7, characterized in that, The method further includes: If the joint peak shaving and frequency regulation controller receives a third instruction from the AGC system requiring charging and discharging, the joint peak shaving and frequency regulation controller controls the energy storage system according to the third instruction, so that when the power to be generated in the third instruction exceeds the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the current maximum charging and discharging power, and when the power to be generated does not exceed the current maximum charging and discharging power, the energy storage system performs charging and discharging operations at the power to be generated.

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