Fused salt energy storage frequency modulation control method of heat supply unit

Abstract

The invention relates to the technical field of heat supply unit control, in particular to a fused salt energy storage frequency modulation control method for a heat supply unit, which comprises the following steps: determining a power generation mode of the heat supply unit, and determining a working mode of a fused salt energy storage system according to the determined power generation mode; detecting the required electric quantity in real time, and judging whether the working mode of the fused salt energy storage system needs to be adjusted or not according to the required electric quantity; for the required electric quantity which does not need to adjust the working mode of the fused salt energy storage system, the working state of the fused salt energy storage system is adjusted in real time in combination with the determined working mode; and re-determining the working mode of the fused salt energy storage system according to the change condition of the required electric quantity for the required electric quantity for adjusting the working mode of the fused salt energy storage system. Due to the addition of the fused salt energy storage system, the unit can maintain operation with lower generated output while meeting external heat supply; and the requirement of external heat supply can be met when the unit generates power in a rated mode.

Description

Technical Field

[0001] The present invention relates to the technical field of heating unit control, and in particular to a molten salt energy storage frequency modulation control method for a heating unit. Background Art

[0002] The new power system has brought severe challenges to the stable operation of the power grid due to the access of a high proportion of renewable energy such as solar energy and wind power. Due to the uncertainty of renewable energy, the power grid has higher and higher requirements for the peak-shaving and frequency-regulating capabilities of thermal power units. Supercritical and ultra-supercritical units are direct-current boilers without steam drums. Limited by the capacity of the boiler-machine coordination system, they generally face the problems of insufficient primary frequency regulation and large fluctuations in main steam parameters. For heating units, due to the limitations of their own "thermal-electric coupling", they have almost no ability to participate in the primary frequency regulation of the power grid. The thermal power unit coupled with molten salt energy storage technology has high safety and low economic cost, and is an effective technical means to assist thermal power units in flexible peak regulation. For heating units, the molten salt system can also solve the stubborn problem of thermal-electric coupling, and can improve the load response speed of the unit, reduce the minimum power output of the unit, maintain the stability of the boiler main steam pressure, and effectively improve the peak-shaving and frequency-regulating capabilities of the unit. Especially for the primary frequency regulation system, the technical route of the coupled molten salt energy storage system is to directly reduce or increase the steam entering the molten salt energy storage system to achieve the purpose of load regulation. Therefore, the load response speed is faster and the frequency regulation capability is stronger than that of ordinary supercritical and ultra-supercritical units that use high and low temperature molten salt heat exchange.

[0003] Chinese Patent Publication No.: CN108534222A discloses a molten salt energy storage heating system with a molten salt static mixer, the system includes a low-temperature molten salt tank, a low-temperature molten salt pump, a molten salt electric heater, a high-temperature molten salt tank, a high-temperature molten salt pump, a mixed salt molten salt pump, a static mixer, a water feed pump, a deaerator, a circulating water pump, a preheater, an evaporator and a heat user; the high-temperature molten salt tank is connected to an inlet of the static mixer through a high-temperature molten salt pump and a corresponding molten salt pipeline, the low-temperature molten salt tank is connected to another inlet of the static mixer through a mixed salt molten salt pump and a corresponding molten salt pipeline, and an outlet of the low-temperature molten salt tank enters the high-temperature molten salt tank after being heated by a molten salt electric heater through a low-temperature molten salt pump; the outlet of the static mixer is connected to the molten salt inlet of the evaporator.

[0004] This shows that the current molten salt energy storage system is not intelligent enough in terms of energy storage regulation and control, and there is still the problem of energy waste. Summary of the invention

[0005] To this end, the present invention provides a molten salt energy storage frequency regulation control method for a heating unit, so as to overcome the problem that the current molten salt energy storage system in the prior art is not intelligent enough for energy storage regulation control and still has energy waste.

[0006] To achieve the above object, the present invention provides a molten salt energy storage frequency modulation control method for a heating unit, comprising:

[0007] Determine the power generation mode of the heating unit, and determine the working mode of the molten salt energy storage system according to the determined power generation mode;

[0008] Detect the power demand in real time and determine whether the working mode of the molten salt energy storage system needs to be adjusted according to the power demand;

[0009] For the power demand that does not require adjustment of the working mode of the molten salt energy storage system, the working state of the molten salt energy storage system is adjusted in real time in combination with the determined working mode;

[0010] For the demand electricity that requires adjustment of the working mode of the molten salt energy storage system, the working mode of the molten salt energy storage system is re-determined according to the changes in the demand electricity.

[0011] Furthermore, the working modes of the molten salt energy storage system include:

[0012] In low power generation mode, the molten salt energy storage system is in a heat storage state and can absorb main steam and hot resteam for heat storage;

[0013] In rated power generation mode, the molten salt system is in the heat release stage;

[0014] In the central power generation working mode, the molten salt energy storage system is in the standby heat absorption state.

[0015] Furthermore, for the molten salt energy storage system in the low power generation working mode, the power generation output can be improved by reducing the steam intake of the molten salt energy storage system.

[0016] Furthermore, for the molten salt energy storage system in the low power generation working mode, when adjusting the steam intake of the molten salt energy storage system, the boiler fuel amount and water supply amount remain unchanged.

[0017] Furthermore, for the molten salt energy storage system in the rated power generation working mode, the heat supply of the molten salt energy storage system is increased by opening the steam inlet valve of the molten salt energy storage system to improve the power generation output.

[0018] Furthermore, for the molten salt energy storage system in the rated power generation working mode, when there is a deep load reduction instruction, the molten salt energy storage system is adjusted by calling the boiler-machine coordination control module to meet the power supply demand.

[0019] The content of calling the boiler-machine coordination control module for adjustment includes reducing one or both of the boiler fuel amount and the feed water amount.

[0020] Furthermore, for the molten salt energy storage system in the central power generation working mode, the load is increased or decreased or the output power of the unit is changed by changing the steam intake of the molten salt energy storage system to meet the power supply demand;

[0021] Among them, the unit output power is regulated by the primary frequency regulation control module.

[0022] Furthermore, if the molten salt energy storage system cannot meet the external heat supply in the central power generation working mode by changing the unit output power through the primary frequency regulation control module, the machine-boiler coordination module is called to meet the external power supply demand by increasing the boiler output.

[0023] Furthermore, a primary frequency regulation control instruction is provided in the primary frequency regulation control module, and the primary frequency regulation control instruction includes, when the grid frequency changes, by adjusting the steam inlet valve of the molten salt energy storage system, changing the steam inlet amount of the molten salt system, and redetermining the boiler output according to the heating pressure parameters on the premise of meeting the primary frequency regulation requirements of the unit.

[0024] Furthermore, when the operating mode of the molten salt energy storage system changes, the steam intake amount of the molten salt energy storage system is determined by re-determining the operating mode.

[0025] Compared with the prior art, the beneficial effect of the present invention is that the molten salt energy storage technology of the heating unit uses the steam of the thermal power plant as the heat source, and first stores the heat in the steam in the molten salt medium when the power generation is low-load, and then releases the heat stored in the molten salt when external steam supply is required and the unit cannot meet the steam supply conditions due to peak operation, generates the required steam, and ensures the normal external steam supply, thereby achieving thermal and electrical decoupling, and improving the flexibility of the unit operation. The addition of the molten salt energy storage system enables the unit to maintain operation at a lower power output while meeting the external heat supply; it can also enable the unit to meet the external heat supply needs when the rated power output.

[0026] Furthermore, by utilizing the steam from a thermal power plant as a heat source, the heat in the steam can be stored in a molten salt medium when power generation is at low load. When external steam supply is required but the unit cannot meet the steam supply conditions due to peak load operation, the heat stored in the molten salt can be released to generate the required steam, thereby ensuring normal external steam supply and effectively realizing thermal and electrical decoupling.

[0027] Furthermore, the addition of the molten salt energy storage system enables the unit to maintain operation at a lower power output while meeting the requirements for external heat supply. For example, during some periods of low load, the unit may have difficulty balancing heat supply and power generation, but with the ability to store and release heat in the molten salt energy storage system, it can better cope with this situation and flexibly adjust the operating status. When the unit is at rated power output, the molten salt energy storage system can also be used to ensure that the demand for external heat supply is met, allowing the unit to better adapt to heating tasks under different power generation conditions, and overall improving the flexibility of the unit's operation to cope with various situations.

[0028] Furthermore, a variety of frequency modulation control methods are adapted to different working modes to meet different external power supply conditions, making external power supply regulation more intelligent.

[0029] In particular, in the low power generation working mode, the power generation output can be improved by reducing the steam intake of the molten salt energy storage system, and when adjusting the steam intake, the boiler fuel amount and water supply remain unchanged. This adjustment method is relatively simple and can specifically improve the power generation output in this mode.

[0030] In particular, in the rated power generation working mode, on the one hand, the power generation output can be improved by opening the steam inlet valve of the molten salt energy storage system and increasing the heat supply of the molten salt energy storage system; on the other hand, when there is a deep-level load reduction instruction, the boiler-machine coordination control module can be called to adjust the molten salt energy storage system by reducing the amount of boiler fuel and / or reducing the water supply to meet the power supply demand, providing a variety of effective adjustment methods.

[0031] In particular, in the central power generation working mode, the power supply demand can be met by changing the steam intake of the molten salt energy storage system to increase or decrease the load or changing the unit output power (the unit output power is regulated by the primary frequency regulation control module). If changing the unit output power cannot meet the external heat supply, the machine-boiler coordination module can also be called to increase the boiler output to meet the external power supply demand. The combination of multiple control methods can better adapt to the complex situation in the central power generation working mode.

[0032] In particular, the present application optimizes the adjustment of parameters such as steam inlet volume. When the working mode of the molten salt energy storage system changes, its steam inlet volume can be determined by re-determining the working mode, so that the key parameter of steam inlet volume can be reasonably adjusted as the working mode switches, ensuring that the entire system can operate efficiently and stably under different working modes, and better realizing the coordination of heating and power generation and the accuracy of frequency regulation control. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the molten salt energy storage frequency modulation control method of the heating unit in the embodiment;

[0034] Figure 2 This is a schematic diagram of the primary frequency modulation control process;

[0035] Figure 3 This is a schematic diagram of the principle of a primary frequency modulation control module;

[0036] Figure 4 It is a schematic diagram of the tracking result of the system setting value of the differential filter in the undesigned embodiment;

[0037] Figure 5 It is a schematic diagram of the system interference immunity test results of the differential filter in the undesigned embodiment;

[0038] Figure 6 Schematic diagram of comparison of system anti-interference test results of the differential filter in the embodiment;

[0039] Figure 7 Schematic diagram of comparison of system anti-interference test results of the differential filter in the embodiment;

[0040] Figure 8 A schematic diagram showing comparison of system anti-interference test results of a first-order filter in an embodiment;

[0041] Fig. 9 Schematic diagram of comparison of system anti-interference test results of the first-order differential filter in the embodiment. DETAILED DESCRIPTION

[0042] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0044] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0045] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] See also Figure 1 As shown, it is a flow chart of the molten salt energy storage frequency modulation control method for the heating unit in the embodiment.

[0047] The present invention provides a molten salt energy storage frequency modulation control method for a heating unit, comprising:

[0048] S1, determining the power generation mode of the heating unit, and determining the working mode of the molten salt energy storage system according to the determined power generation mode;

[0049] S2, real-time detection of power demand, and determination of whether the working mode of the molten salt energy storage system needs to be adjusted according to the power demand;

[0050] S3, for the required power that does not require adjustment of the working mode of the molten salt energy storage system, in combination with the determined working mode, adjusting the working state of the molten salt energy storage system in real time;

[0051] S4, for the demand electricity that needs to adjust the working mode of the molten salt energy storage system, the working mode of the molten salt energy storage system is re-determined according to the change of the demand electricity.

[0052] The molten salt energy storage technology of the heating unit uses the steam of the thermal power plant as the heat source. When the power generation is at low load, the heat in the steam is first stored in the molten salt medium. Then, when external steam supply is required and the unit cannot meet the steam supply conditions due to peak operation, the heat stored in the molten salt is released to generate the required steam, ensuring the normal external steam supply, thereby achieving thermal and electrical decoupling and improving the flexibility of the unit operation. The addition of the molten salt energy storage system enables the unit to maintain operation at a lower power output while meeting the external heat supply; it can also enable the unit to meet the external heat supply needs when the power generation output is rated.

[0053] Specifically, the steam from a thermal power plant is used as a heat source. When power generation is at low load, the heat in the steam can be stored in the molten salt medium. When external steam supply is required but the unit cannot meet the steam supply conditions due to peak operation, the heat stored in the molten salt can be released to generate the required steam, thereby ensuring normal external steam supply and effectively realizing thermal and electrical decoupling.

[0054] The addition of the molten salt energy storage system enables the unit to maintain operation at a lower power output while still meeting the requirements for external heat supply. For example, during some periods of low load, the unit may have difficulty balancing heat supply and power generation, but with the ability to store and release heat in the molten salt energy storage system, it can better cope with this situation and flexibly adjust the operating status.

[0055] When the unit is at rated power generation output, the molten salt energy storage system can also be used to ensure that external heat supply needs are met, allowing the unit to better adapt to heating tasks under different power generation conditions, and overall improving the flexibility of the unit's operation to deal with various situations.

[0056] Specifically, the working modes of the molten salt energy storage system include:

[0057] In the low power generation mode, the molten salt system is in the heat storage stage, absorbing main steam and hot re-steam for heat storage. At this time, the molten salt system can meet the maximum external heat (steam) supply. At this time, it is equivalent to reducing the external power generation output of the unit and increasing the plant power consumption rate. The unit can quickly adapt to the changes in grid power by reducing the steam volume of the molten salt system and increasing the power generation load, achieving the purpose of primary frequency regulation, while reducing the fluctuation of the boiler main steam pressure;

[0058] In the rated power generation mode, the molten salt system is in the heat release stage. At this time, the molten salt system can at least meet the minimum external heat (steam) supply of the unit. When the unit reaches the rated full-load power generation output, the unit can open the molten salt system steam inlet valve to increase the molten salt system heat supply, quickly reduce the power generation load, and quickly adapt to the changes in the power of the power grid to achieve the purpose of primary frequency regulation;

[0059] The intermediate power generation working mode is neither the minimum power generation output nor the rated power generation output: at this time, the external heat (steam) of the unit is supplied by the four-stage exhaust of the steam turbine, and the molten salt energy storage system is in a standby heat absorption state. The unit can quickly adjust the load by increasing or decreasing the steam intake of the molten salt system, and quickly adapt to changes in the power of the power grid to achieve the purpose of primary frequency regulation.

[0060] Specifically, a variety of frequency modulation control methods are adapted to different working modes, meeting different external power supply conditions, making external power supply regulation more intelligent.

[0061] Specifically, in the low power generation working mode, the power generation output can be improved by reducing the steam intake of the molten salt energy storage system, and when adjusting the steam intake, the boiler fuel amount and water supply remain unchanged. This adjustment method is relatively simple and can specifically improve the power generation output in this mode.

[0062] Specifically, the rated power generation working mode: on the one hand, the power generation output can be improved by opening the steam inlet valve of the molten salt energy storage system and increasing the heat supply of the molten salt energy storage system; on the other hand, when there is a deep-level load reduction instruction, the boiler-machine coordination control module can be called to adjust the molten salt energy storage system by reducing the amount of boiler fuel and / or reducing the water supply to meet the power supply demand, providing a variety of effective adjustment methods.

[0063] Specifically, the central power generation working mode: the power supply demand can be met by changing the steam intake of the molten salt energy storage system to increase or decrease the load or changing the unit output power (the unit output power is regulated by the primary frequency regulation control module). If changing the unit output power cannot meet the external heat supply, the machine-boiler coordination module can also be called to increase the boiler output to meet the external power supply demand. The combination of multiple control methods can better adapt to the complex situation under the central power generation working mode.

[0064] This application optimizes the adjustment of parameters such as steam inlet volume. When the working mode of the molten salt energy storage system changes, its steam inlet volume can be determined by re-determining the working mode, so that the key parameter of steam inlet volume can be reasonably adjusted as the working mode switches, ensuring that the entire system can operate efficiently and stably under different working modes, and better realizing the coordination of heating and power generation and the accuracy of frequency regulation control.

[0065] See also Figure 2-Figure 3 As shown, Figure 2 This is a schematic diagram of the primary frequency modulation control process. Figure 3 This is a schematic diagram of the principle of the primary frequency modulation control module. In different working modes, the primary frequency modulation control mode is different.

[0066] In low power generation mode, the system quickly increases power generation output by reducing the steam intake of the molten salt energy storage system. The molten salt energy storage system can maintain the demand for external heat (steam) and the heat supply pressure. Therefore, only one frequency modulation control module is needed to meet the unit output power. There is no need to call the unit boiler coordination control module. The boiler fuel and water supply remain unchanged.

[0067] In the rated power generation mode, the power generation output is rapidly reduced by increasing the steam intake of the molten salt system. The molten salt energy storage system only needs to meet the minimum external heating demand. Therefore, there is no need to call the unit boiler coordination control module. It is only necessary to change the unit output power through the primary frequency modulation control module. When the unit has a deeper load reduction instruction, the unit boiler coordination control module is called again to reduce the amount of boiler fuel and water supply.

[0068] The intermediate power generation working mode is neither the minimum power generation output nor the rated power generation output: the load is quickly increased or decreased by changing the steam inlet of the molten salt energy storage system, and the unit output power is changed through the primary frequency modulation control module. If only the minimum external heat supply is required, there is no need to call the boiler coordination module; if the external heat supply cannot be met, the boiler coordination module needs to be called to increase the boiler output.

[0069] Primary frequency regulation control principle: When the grid frequency changes, the steam inlet volume of the molten salt system is changed by adjusting the steam inlet valve of the molten salt energy storage system to give priority to meeting the primary frequency regulation needs of the unit, and then the boiler output is changed as appropriate based on the heating pressure parameters.

[0070] exist Figure 3 In the equation, R is the droop coefficient, T G is the speed regulator time constant, T CH is the main air intake and the vapor chamber time constant, T RH is the reheater time constant, F HP is the output power ratio of the high-pressure cylinder, J is the inertia time constant, D is the damping coefficient, ΔP L is load disturbance, and AGC is the dispatching instruction from the automatic power generation control system.

[0071] The PI controller expression is as shown in formula (1),

[0072] Fc(s) is a first-order filter, as shown in formula (2),

[0073] Fr(s) is a first-order differential filter, as shown in formula (3).

[0074] The control structure of PI controller + first-order filter Fc(s) is mainly aimed at improving the system's anti-disturbance capability and accelerating the system's adjustment speed, but there is a certain overshoot in the initial stage of set value tracking.

[0075] The PI controller + first-order filter Fc(s) can be regarded as a PID implementation form of the error-based first-order linear auto-disturbance rejection (E-LADRC).

[0076] The main purpose of designing the first-order differential filter Fr(s) is to reduce the overshoot of the system.

[0077]

[0078] Simulation example:

[0079] Figure 3 The parameters of the primary frequency modulation transfer function model are as follows:

[0080] R is 5, T G is 0.15, T CH is 0.2, T RHis 11, F HP is 0.3, J is 6, and D is 0.1.

[0081] The common PID controller is as shown in formula (4), and the parameters are:

[0082] K i =1.12,K p =0.05,K d =4,K d / N=1

[0083]

[0084] Primary frequency modulation control module parameters: K i =9.12,K p =0.174, f0=10, f1=14.8, T1=3, T2=0.1.

[0085] As a set of comparative experiments, Figure 4 It is a schematic diagram of the tracking result of the system setting value of the differential filter in the undesigned embodiment; Figure 5 It is a schematic diagram of the system interference immunity test results of the differential filter in the undesigned embodiment;

[0086] Only the PI controller and the first-order filter Fc(s) are designed, and no differential filter Fr(s) is added to the system, that is, Fr(s)=1.

[0087] At this time, the control system set value tracking ability test results are as follows: Figure 4 , a step disturbance with an amplitude of -1 is added at the simulation time of 100s. The test results of the system's anti-disturbance ability are as follows Figure 5 .

[0088] Depend on Figure 4 , Figure 5 It can be seen that the structure of PI controller + first-order filter Fc(s) can greatly improve the response speed and anti-disturbance ability of the system, but there is a certain overshoot in the initial trial stage of set value tracking, which is a problem that needs to be solved. For this purpose, a differential filter Fr(s) is designed.

[0089] As another set of comparative experiments, Figure 6 Schematic diagram of comparison of system anti-interference test results of the differential filter in the embodiment; Figure 7 Schematic diagram of comparison of system anti-interference test results of the differential filter in the embodiment.

[0090] The control structure proposed by the present invention is adopted to add a differential filter Fr(s).

[0091] The simulation results of the control system setpoint tracking capability are as follows: Figure 6, a step disturbance with an amplitude of -1 is added at the simulation time of 100s. The disturbance test results are as follows Figure 7 It can be seen that the control structure proposed in the present invention has a much better adjustment speed and anti-disturbance capability than ordinary PID control, and has no overshoot.

[0092] Figure 8 A schematic diagram showing comparison of system anti-interference test results of a first-order filter in an embodiment; Fig. 9 Schematic diagram of comparison of system anti-interference test results of the first-order differential filter in the embodiment.

[0093] Figure 8 and Fig. 9 The frequency control of the unit using PID is compared with the frequency control of the unit using PI+first-order filter Fc(s) proposed in the present invention, and the frequency control with the differential filter Fr(s) added. It can be clearly seen that the control of PI+first-order filter Fc(s) has a faster response speed than PID control, a stronger disturbance suppression capability, and a much smaller disturbance variation amplitude than PID control, but there is a relatively serious overshoot in the early stage of control. On this basis, adding the differential filter Fr(s) can completely suppress the overshoot in the early stage of control, and at the same time, the response speed and anti-interference capability of the system are very outstanding.

[0094] If the method proposed in the present invention is not adopted and ordinary PID control is still used, not only the response speed is slow and there is overshoot, but also the disturbance suppression ability is very poor and the disturbance variation range is large, which is difficult to meet the needs of the production site.

[0095] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A molten salt energy storage frequency modulation control method for a heating unit, characterized in that: include, Determine the power generation mode of the heating unit, and determine the working mode of the molten salt energy storage system according to the determined power generation mode; Detect the power demand in real time and determine whether the working mode of the molten salt energy storage system needs to be adjusted according to the power demand; For the power demand that does not require adjustment of the working mode of the molten salt energy storage system, the working state of the molten salt energy storage system is adjusted in real time in combination with the determined working mode; For the demand electricity that requires adjustment of the working mode of the molten salt energy storage system, the working mode of the molten salt energy storage system is re-determined according to the changes in the demand electricity.

2. The molten salt energy storage frequency modulation control method of the heating unit according to claim 1 is characterized in that: The working modes of the molten salt energy storage system include: In low power generation mode, the molten salt energy storage system is in a heat storage state and can absorb main steam and hot resteam for heat storage; In rated power generation mode, the molten salt system is in the heat release stage; In the central power generation working mode, the molten salt energy storage system is in the standby heat absorption state.

3. The molten salt energy storage frequency modulation control method of the heating unit according to claim 2 is characterized in that: For the molten salt energy storage system in the low power generation working mode, the power generation output can be improved by reducing the steam intake of the molten salt energy storage system.

4. The molten salt energy storage frequency modulation control method of the heating unit according to claim 3 is characterized in that: For the molten salt energy storage system in the low power generation working mode, when adjusting the steam intake of the molten salt energy storage system, the boiler fuel amount and water supply amount remain unchanged.

5. The molten salt energy storage frequency modulation control method of the heating unit according to claim 2 is characterized in that: For the molten salt energy storage system in the rated power generation working mode, the heat supply of the molten salt energy storage system is increased by opening the steam inlet valve of the molten salt energy storage system to improve the power generation output.

6. The molten salt energy storage frequency modulation control method of the heating unit according to claim 5, characterized in that: For the molten salt energy storage system in the rated power generation working mode, when there is a deep load reduction instruction, the molten salt energy storage system is adjusted by calling the boiler coordination control module to meet the power supply demand. The content of calling the boiler-machine coordination control module for adjustment includes reducing one or both of the boiler fuel amount and the feed water amount.

7. The molten salt energy storage frequency modulation control method of the heating unit according to claim 2 is characterized in that: For the molten salt energy storage system in the central power generation working mode, the load is increased or decreased or the output power of the unit is changed by changing the steam intake of the molten salt energy storage system to meet the power supply demand; Among them, the unit output power is regulated by the primary frequency regulation control module.

8. The molten salt energy storage frequency modulation control method of the heating unit according to claim 7, characterized in that: If the molten salt energy storage system cannot meet the external heat supply in the central power generation working mode by changing the unit output power through the primary frequency regulation control module, the machine-boiler coordination module is called to meet the external power supply demand by increasing the boiler output.

9. The molten salt energy storage frequency modulation control method of the heating unit according to claim 8, characterized in that: The primary frequency regulation control module is provided with a primary frequency regulation control instruction, which includes, when the grid frequency changes, adjusting the steam inlet valve of the molten salt energy storage system to change the steam inlet amount of the molten salt system, and redetermining the boiler output according to the heating pressure parameters on the premise of meeting the primary frequency regulation requirements of the unit.

10. The molten salt energy storage frequency modulation control method of a heating unit according to claim 2, characterized in that: When the operating mode of the molten salt energy storage system changes, the steam intake amount of the molten salt energy storage system is determined by re-determining the operating mode.

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