A flexible power generation system combining solar power, coal storage, and energy storage, and its operation method.

Abstract

This invention discloses a flexible solar-coal-storage complementary power generation system and its operation method. The system includes a coal-fired thermal power generation system and a solar-coupled thermal storage system comprising a solar collector, an oil-water heat exchanger, an oil-salt heat exchanger, a steam-molten salt heat exchanger, a brine heat exchanger group, a cold salt tank, and a hot salt tank. Simultaneous storage of solar energy and reheat steam heat is achieved through the oil-water and steam-molten salt heat exchangers. The impact of insufficient sunlight on the unit is compensated for by adjusting the water flow rate heated by the brine heat exchanger group and coordinating with the rotation speed of the hot molten salt, while simultaneously increasing the load ramp-up rate. Flexible solar energy storage is achieved when sunlight is sufficient by adjusting the molten salt flow rate entering the oil-salt heat exchanger, maintaining system stability. The load ramp-down rate is increased by adjusting the reheat steam regulating valve and coordinating with the feedwater regulating valve. Energy cascade utilization is achieved by adjusting the No. 1, No. 2, and No. 3 steam-water regulating valves. This invention enables flexible coupling of solar, coal, and storage, improving the system's efficient and flexible operation capabilities.

Description

Technical Field

[0001] This invention relates to the field of multi-energy complementary power generation technology, specifically to a flexible power generation system and operation method that combines solar power, coal, and energy storage. Background Technology

[0002] In recent years, with the gradual increase in the proportion of wind and photovoltaic power generation in my country, large-scale grid connection of photovoltaic and wind power has exacerbated the fluctuations in grid voltage and frequency, leading to difficulties in the absorption of renewable energy power generation in my country. This requires coal-fired power generation and solar thermal power generation to improve their flexibility, enabling them to efficiently utilize solar energy when solar energy fluctuates and the grid has frequent peak-shaving and frequency regulation needs, meeting the grid's load-changing and low-load operation requirements, and maintaining efficient and flexible operation. Existing solar and coal-fired power generation technologies are insufficient to maintain efficient solar energy utilization under fluctuating light conditions, and coal-fired power generating units struggle to efficiently couple solar energy and quickly respond to grid peak-shaving and frequency regulation needs under different light intensities. There is currently no reasonable solution to meet the performance requirements of efficient and flexible operation of solar thermal power generation coupled with coal-fired power generation systems. The problems that need to be solved include: 1) When the power grid has a rapid and large demand for peak regulation, solar thermal power generation is limited by meteorological conditions and coal-fired units are affected by the minimum stable combustion load of the boiler. Neither can meet the requirements of rapid load change and low load operation. It is necessary to seek a solar-coal coupling scheme with more efficient and flexible operation potential and increase thermal energy storage devices to improve system flexibility.

[0003] 2) It is necessary to solve the problem of control difficulties in solar and coal-fired power generation systems when both illumination conditions and power output requirements change. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a flexible power generation system and operation method that integrates solar power generation and solar thermal power generation. This system achieves flexible coupling between coal-fired power generation and solar thermal power generation. By utilizing a thermal storage device, it can store heat from both solar collectors and reheat steam, quickly offsetting the impact of changes in sunlight conditions on the operational stability of the coal-fired thermal power generation system. This achieves decoupling of the boiler and turbine, enabling the flexible power generation system to rapidly and significantly change loads under different sunlight conditions, smoothly cope with varying solar radiation conditions, and simultaneously reduce coal consumption and improve economic efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A flexible power generation system combining solar power, coal, and energy storage includes a coal-fired thermal power generation system and a solar-coupled thermal energy storage system: wherein, The coal-fired thermal power generation system includes a boiler 1, a high-pressure turbine cylinder 2, a low-pressure turbine cylinder 3, a condenser 4, a condensate pump 5, a low-pressure heater 6, a deaerator 7, a feedwater pump 8, and a high-pressure heater 9 connected in sequence. The superheated steam outlet of the boiler 1 is connected to the inlet of the high-pressure turbine cylinder 2; the water inlet of the boiler 1 is connected to the water outlet of the high-pressure heater 9; the steam outlet of the high-pressure turbine cylinder 2 is connected to the reheat steam inlet of the boiler 1 via a pipeline, and the extraction steam outlet of the high-pressure turbine cylinder 2 is connected to the steam inlet of the high-pressure heater 9 via a pipeline; the reheat steam outlet of the boiler 1... The steam outlet is connected to the steam inlet of the intermediate and low-pressure cylinder 3 of the steam turbine; the first-stage extraction steam outlet of the intermediate and low-pressure cylinder 3 of the steam turbine is connected to the steam inlet of the deaerator 7 through a pipeline, and the second-stage extraction steam outlet is connected to the steam inlet of the low-pressure heater 6 through a pipeline; the water outlet of the deaerator 7 is connected to the high-pressure heater 9 through the feedwater pump 8; the steam outlet of the intermediate and low-pressure cylinder 3 of the steam turbine is connected to the steam inlet of the condenser 4; the water outlet of the condenser 4 is connected to the water inlet of the low-pressure heater 6 through the condensate pump 5; the water outlet of the low-pressure heater 6 is connected to the water inlet of the deaerator 7. The solar-coupled thermal storage system includes a solar collector 11, an oil-water heat exchanger 12, and an oil-salt heat exchanger 13 connected in sequence; it also includes a steam-molten salt heat exchanger 14, a hot molten salt tank 15, a hot salt pump 16, a brine heat exchanger group 17, a cold molten salt tank 18, and a cold salt pump 19 connected in sequence; the water inlet of the oil-water heat exchanger 12 is connected to the outlet of the feedwater pump 8 through a feedwater regulating valve 10, and the water outlet is connected to the feedwater inlet of the boiler 1 through a pipeline; the steam inlet of the steam-molten salt heat exchanger 14 is connected to the reheat steam outlet of the boiler 1 through a reheat steam regulating valve 20, and the water outlet is connected to the steam inlet of the high-pressure heater 9 through a No. 1 pipeline. The steam-water regulating valve 24 is connected to the water medium outlet, which is also connected to the steam inlet of the deaerator 7 via the second steam-water regulating valve 25. The water medium outlet is also connected to the steam inlet of the low-pressure heater 6 via the third steam-water regulating valve 26. The water medium inlet of the brine heat exchanger group 17 is connected to the water medium pipeline of the coal-fired thermal power generation system, and the water medium outlet is connected to the water medium pipeline of the coal-fired thermal power generation system with a temperature higher than that of the water medium inlet. The molten salt outlet of the cold molten salt tank 18 is connected to the molten salt inlet of the oil-salt heat exchanger 13 via the cold salt pump 19, and the molten salt outlet of the oil-salt heat exchanger 13 is connected to the molten salt inlet of the steam molten salt heat exchanger 14 via a pipeline.

[0006] The brine heat exchanger group 17 includes a No. 1 brine heat exchanger 171, a No. 2 brine heat exchanger 172, and a No. 3 brine heat exchanger 173. The molten salt inlet of the No. 1 brine heat exchanger 171 is connected to the hot molten salt tank 15 via a hot salt pump 16, and its molten salt outlet is connected to the molten salt inlet of the No. 2 brine heat exchanger 172 via a pipeline. Its working fluid inlet is connected to the working fluid outlet of the high-pressure heater 9 via a feedwater regulating valve 21, and its working fluid outlet is connected to the feedwater inlet of the boiler 1 via a pipeline. The No. 2 brine heat exchanger 172... The molten salt outlet of the No. 3 brine heat exchanger 173 is connected to the molten salt inlet of the No. 3 brine heat exchanger 173 via a pipeline. The water working medium inlet is connected to the water working medium outlet of the feedwater pump 8 via the feedwater regulating valve 22. The water working medium outlet is connected to the feedwater inlet of the boiler 1 via a pipeline. The molten salt outlet of the No. 3 brine heat exchanger 173 is connected to the molten salt inlet of the cold molten salt tank 18 via a pipeline. The water working medium inlet is connected to the water working medium outlet of the condensate pump 5 via the feedwater regulating valve 23. The water working medium outlet is connected to the water working medium inlet of the deaerator 7 via a pipeline.

[0007] The working temperature of the molten salt is 100℃~575℃.

[0008] The heat transfer oil operates at a temperature of 180℃ to 390℃.

[0009] The solar collector 11 is composed of multiple solar collector tubes 111 connected in series and then in parallel.

[0010] The above-mentioned operation method of a flexible power generation system with complementary solar power and coal storage involves increasing the opening of the reheat steam regulating valve 20 when the coal-fired thermal power generation system needs to rapidly reduce load or operate at low load. The flow rate of molten salt entering the oil-salt heat exchanger 13 and the steam-molten salt heat exchanger 14 is regulated by adjusting the speed of the cold salt pump 19. The flow rates of steam entering the high-pressure heater 9, the deaerator 7, and the low-pressure heater 6 are regulated by adjusting the openings of the No. 1 steam-water regulating valve 24, the No. 2 steam-water regulating valve 25, and the No. 3 steam-water regulating valve 26, respectively. The goal is to ensure that the steam flow rate entering the low-pressure cylinder 3 of the turbine meets the requirements of the rate of change of electrical load and low-load operation while maintaining high efficiency, allowing the system to meet the requirements of rapid and efficient load reduction. When the coal-fired thermal power generation system needs to rapidly increase load, the opening of the feedwater regulating valve 10 is increased, the speed of the hot salt pump 16 is increased, and the feedwater regulating valves 21 and 26 are adjusted sequentially. The opening and closing of valve 22 and feedwater regulating valve 23 are adjusted with the following objectives: the load increase rate is matched with the flow rate and heat release rate of the feedwater in the brine heat exchanger group 17, allowing the coal-fired unit to quickly and efficiently increase its load. When the solar radiation intensity is high, feedwater regulating valve 10 is adjusted to increase the feedwater flow into the oil-water heat exchanger 12. When all the feedwater at the outlet of the deaerator 7 is heated by the oil-water heat exchanger 12 and the outlet water temperature of the oil-water heat exchanger 12 is higher than the outlet water temperature of the high-pressure heater 9, the speed of the cold brine pump 19 is adjusted to regulate the molten salt flow into the oil-salt heat exchanger 13. The adjustment objective is to keep the outlet water temperature of the oil-water heat exchanger 12 the same as the outlet water temperature of the high-pressure heater 9, meeting the inlet water temperature requirements of the boiler 1. When the light intensity is insufficient, the valve openings of feedwater regulating valve 10, feedwater regulating valve 21, and feedwater regulating valve 22 are adjusted with the objective of keeping the water temperature entering the boiler 1 constant, maintaining stable system operation.

[0011] Compared with the prior art, the present invention has the following advantages: (1) This invention achieves flexible storage of residual solar energy by adding an oil-salt heat exchanger and a cold molten salt tank and a hot molten salt tank connected in series with the oil-water heat exchanger, and achieves stable output power by adjusting the feedwater regulating valve to match the flow rate of the cold salt pump and adjusting the output power disturbance caused by rapid changes in sunlight.

[0012] (2) By increasing heat storage, the present invention can simultaneously store excess heat from solar energy and reheat steam, maintain stable combustion of the boiler, and achieve rapid load change rate and low load operation.

[0013] (3) By adjusting the valve opening of No. 1 steam-water regulating valve, No. 2 steam-water regulating valve and No. 3 steam-water regulating valve, No. 1 water supply regulating valve, No. 2 water supply regulating valve and No. 3 water supply regulating valve, as well as the flow rate of cold salt pump and hot salt pump, the present invention completes the matching of the power and temperature of the system power generation change rate, the heat storage process and the heat release process, realizes the energy cascade utilization, and enables the system to operate efficiently and flexibly. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the flexible power generation system that combines solar power, coal storage, and energy storage according to the present invention. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 As shown, this invention discloses a flexible power generation system that combines solar power and coal storage, comprising a coal-fired thermal power generation system and a solar-coupled thermal storage system. The coal-fired thermal power generation system includes, in sequence, a boiler 1, a high-pressure turbine cylinder 2, a low-pressure turbine cylinder 3, a condenser 4, a condensate pump 5, a low-pressure heater 6, a deaerator 7, a feedwater pump 8, and a high-pressure heater 9. The superheated steam outlet of the boiler 1 is connected to the inlet of the high-pressure turbine cylinder 2. The water inlet of the boiler 1 is connected to the water outlet of the high-pressure heater 9. The steam outlet of the high-pressure turbine cylinder 2 is connected to the reheat steam inlet of the boiler 1 via a pipeline, and the extraction steam outlet of the high-pressure turbine cylinder 2 is connected to the high-pressure heater 9. The steam inlet of boiler 9 is connected via a pipeline; the reheat steam outlet of boiler 1 is connected to the steam inlet of the intermediate and low-pressure cylinder 3 of the turbine; the first-stage extraction steam outlet of the intermediate and low-pressure cylinder 3 of the turbine is connected to the steam inlet of deaerator 7 via a pipeline, and the second-stage extraction steam outlet is connected to the steam inlet of low-pressure heater 6 via a pipeline; the water outlet of deaerator 7 is connected to high-pressure heater 9 via feedwater pump 8; the steam outlet of intermediate and low-pressure cylinder 3 of the turbine is connected to the steam inlet of condenser 4; the water outlet of condenser 4 is connected to the water inlet of low-pressure heater 6 via condensate pump 5; the water outlet of low-pressure heater 6 is connected to the water inlet of deaerator 7. The solar-coupled thermal storage system includes a solar collector 11, an oil-water heat exchanger 12, and an oil-salt heat exchanger 13 connected in sequence; it also includes a steam-molten salt heat exchanger 14, a hot molten salt tank 15, a hot salt pump 16, a brine heat exchanger group 17, a cold molten salt tank 18, and a cold salt pump 19 connected in sequence. The water inlet of the oil-water heat exchanger 12 is connected to the outlet of the feedwater pump 8 via a feedwater regulating valve 10, and the water outlet is connected to the feedwater inlet of the boiler 1 via a pipeline. The steam inlet of the steam-molten salt heat exchanger 14 is connected to the reheat steam outlet of the boiler 1 via a reheat steam regulating valve 20, the water outlet is connected to the steam inlet of the high-pressure heater 9 via a first steam-water regulating valve 24, the water outlet is also connected to the steam inlet of the deaerator 7 via a second steam-water regulating valve 25, and the water outlet is also connected to the steam inlet of the low-pressure heater 6 via a third steam-water regulating valve 25. Water regulating valve 26 is connected; the molten salt outlet of steam molten salt heat exchanger 14 is connected to the inlet of hot molten salt tank 15 through a pipeline, the outlet of hot molten salt tank 15 is connected to the molten salt inlet of brine heat exchanger group 17 through hot salt pump 16, the molten salt outlet of brine heat exchanger group 17 is connected to the molten salt inlet of cold molten salt tank 18 through a pipeline, the molten salt outlet of cold molten salt tank 18 is connected to the molten salt inlet of oil-salt heat exchanger 13 through cold salt pump 19, the molten salt outlet of oil-salt heat exchanger 13 is connected to the molten salt inlet of steam molten salt heat exchanger 14 through a pipeline; the water working medium inlet of brine heat exchanger group 17 is connected to the water working medium pipeline of coal-fired thermal power generation system, and the water working medium outlet is connected to the water working medium pipeline of coal-fired thermal power generation system with a temperature higher than that of the water working medium inlet; solar collector 11 is used to heat the heat transfer oil in oil-water heat exchanger 12 and oil-salt heat exchanger 13.

[0017] In a preferred embodiment of the present invention, the brine heat exchanger group 17 includes a No. 1 brine heat exchanger 171, a No. 2 brine heat exchanger 172, and a No. 3 brine heat exchanger 173, corresponding to the high-pressure heater 9, the deaerator 7, and the low-pressure heater 6. The molten salt inlet of the No. 1 brine heat exchanger 171 is connected to the hot molten salt tank 15 via a hot salt pump 16, and the molten salt outlet is connected to the molten salt inlet of the No. 2 brine heat exchanger 172 via a pipeline. The working fluid inlet is connected to the working fluid outlet of the high-pressure heater 9 via a feedwater regulating valve 21, and the working fluid outlet is connected to the feedwater inlet of the boiler 1 via a... The pipelines are connected; the molten salt outlet of the No. 2 brine heat exchanger 172 is connected to the molten salt inlet of the No. 3 brine heat exchanger 173 through a pipeline, the water working medium inlet is connected to the water working medium outlet of the feedwater pump 8 through the feedwater regulating valve 22, and the water working medium outlet is connected to the feedwater inlet of the boiler 1 through a pipeline; the molten salt outlet of the No. 3 brine heat exchanger 173 is connected to the molten salt inlet of the cold molten salt tank 18 through a pipeline, the water working medium inlet is connected to the water working medium outlet of the condensate pump 5 through the feedwater regulating valve 23, and the water working medium outlet is connected to the water working medium inlet of the deaerator 7 through a pipeline.

[0018] As a preferred embodiment of the present invention, the working temperature of the molten salt is 100℃~575℃, which meets the working temperature requirements for heating the molten salt by heat transfer oil and reheat steam. At the same time, the wide working temperature range of the molten salt is beneficial for efficient utilization and storage of solar energy and reheat steam thermal energy.

[0019] In a preferred embodiment of the present invention, the working temperature of the heat transfer oil in the oil-water heat exchanger 12 and the oil-salt heat exchanger 13 is 180℃~390℃, which can ensure that the working temperature of the heat transfer oil meets the requirements for safe heating of feed water and heating of molten salt.

[0020] As a preferred embodiment of the present invention, the solar collector 11 is composed of multiple solar collector tubes 111 connected in series and then in parallel, which is beneficial for the solar energy to heat the heat transfer oil in stages and for the heat transfer oil to fully absorb the solar energy.

[0021] like Figure 1 As shown, the operation method of the flexible power generation system of the present invention, which is a combination of solar power and coal storage, involves increasing the opening of the reheat steam regulating valve 20 when the coal-fired thermal power generation system needs to rapidly reduce load or operate at low load. The flow rate of molten salt entering the oil-salt heat exchanger 13 and the steam-molten salt heat exchanger 14 is adjusted by regulating the speed of the cold salt pump 19. The flow rates of steam entering the high-pressure heater 9, the deaerator 7, and the low-pressure heater 6 are adjusted by regulating the openings of the No. 1 steam-water regulating valve 24, the No. 2 steam-water regulating valve 25, and the No. 3 steam-water regulating valve 26, respectively. The goal is to ensure that the steam flow rate entering the low-pressure cylinder 3 of the turbine meets the requirements of the rate of change of electrical load and low-load operation while maintaining high efficiency, allowing the system to meet the requirements of rapid and efficient load reduction. When the coal-fired thermal power generation system needs to rapidly increase load, the opening of the feedwater regulating valve 10 is increased, the speed of the hot salt pump 16 is increased, and the feedwater regulating valves 21 and 26 are adjusted sequentially. The opening and closing of throttle valve 22 and feedwater regulating valve 23 are adjusted with the following objectives: the load increase rate is matched with the flow rate and heat release rate of the feedwater to the brine heat exchanger group 17, allowing the coal-fired unit to quickly and efficiently increase its load. When the solar radiation intensity is high, feedwater regulating valve 10 is adjusted to increase the feedwater flow into the oil-water heat exchanger 12. When all the feedwater at the outlet of deaerator 7 is heated by the oil-water heat exchanger 12 and the outlet water temperature of the oil-water heat exchanger 12 is higher than the outlet water temperature of the high-pressure heater 9, the speed of the cold brine pump 19 is adjusted to regulate the molten salt flow into the oil-salt heat exchanger 13. The adjustment objective is to keep the outlet water temperature of the heated water in the oil-water heat exchanger 12 the same as the outlet water temperature of the high-pressure heater 9, meeting the inlet water temperature requirements of boiler 1. When the light intensity is insufficient, the valve openings of feedwater regulating valve 10, feedwater regulating valve 21, and feedwater regulating valve 22 are adjusted with the objective of keeping the water temperature entering boiler 1 constant, maintaining stable system operation.

[0022] This invention employs a solar-coupled thermal storage system and a coal-fired thermal power generation system to achieve cascaded energy utilization. By storing solar energy and internal heat from the coal-fired generator unit, the solar-coupled thermal storage system can increase the load-changing rate of the coal-fired thermal power generation system under different load change rate requirements, achieving efficient and flexible operation. Simultaneously, it safely and effectively utilizes solar energy under varying illumination conditions, reducing the impact of solar energy fluctuations on the power generation capacity of the coal-fired thermal power generation system. When the coal-fired thermal power generation system needs to reduce load, the opening of the reheat steam regulating valve is adjusted, and excess steam is transferred through a steam-molten salt heat exchanger. Heat is stored in a molten salt tank, efficiently improving the system's load-reducing capacity. When the coal-fired thermal power generation system needs to increase its load, heat is quickly input into the system by adjusting the feedwater regulating valve and the steam-water regulating valve, in conjunction with the speed of the molten salt pump, rapidly meeting the system's load-increasing rate requirements. When sunlight is sufficient, the heat transfer oil uses the remaining energy after heating the feedwater to heat the molten salt, which is then stored through an oil-salt heat exchanger. When sunlight is insufficient, the brine heat exchanger group is also used to heat the feedwater, achieving efficient utilization of solar energy, reducing coal consumption in the coal-fired thermal power generation system, and improving the operating economy of the system. This invention can solve the problems of insufficient economic efficiency and flexibility in the operation of solar energy and coal-fired units.

Claims

1. A flexible power generation system that combines solar power, coal storage, and solar energy, characterized in that: This includes coal-fired thermal power generation systems and solar-coupled thermal storage systems: among which, The coal-fired thermal power generation system includes a boiler (1), a high-pressure cylinder of a steam turbine (2), a medium- and low-pressure cylinder of a steam turbine (3), a condenser (4), a condensate pump (5), a low-pressure heater (6), a deaerator (7), a feedwater pump (8), and a high-pressure heater (9) connected in sequence; the superheated steam outlet of the boiler (1) is connected to the inlet of the high-pressure cylinder of the steam turbine (2); the water inlet of the boiler (1) is connected to the water outlet of the high-pressure heater (9); the steam outlet of the high-pressure cylinder of the steam turbine (2) is connected to the reheat steam inlet of the boiler (1) through a pipeline, and the extraction steam outlet of the high-pressure cylinder of the steam turbine (2) is connected to the steam inlet of the high-pressure heater (9) through a pipeline; the boiler (1) The reheat steam outlet is connected to the steam inlet of the low-pressure cylinder (3) of the turbine; the first stage extraction steam outlet of the low-pressure cylinder (3) of the turbine is connected to the steam inlet of the deaerator (7) through a pipeline, and the second stage extraction steam outlet is connected to the steam inlet of the low-pressure heater (6) through a pipeline; the water outlet of the deaerator (7) is connected to the high-pressure heater (9) through the feed water pump (8); the steam outlet of the low-pressure cylinder (3) of the turbine is connected to the steam inlet of the condenser (4); the water outlet of the condenser (4) is connected to the water inlet of the low-pressure heater (6) through the condensate pump (5); the water outlet of the low-pressure heater (6) is connected to the water inlet of the deaerator (7); The solar-coupled thermal storage system includes a solar collector (11), an oil-water heat exchanger (12), and an oil-salt heat exchanger (13) connected in sequence; it also includes a steam molten salt heat exchanger (14), a hot molten salt tank (15), a hot salt pump (16), a brine heat exchanger group (17), a cold molten salt tank (18), and a cold salt pump (19) connected in sequence; the water inlet of the oil-water heat exchanger (12) is connected to the outlet of the feedwater pump (8) through a feedwater regulating valve (10), and the water outlet is connected to the feedwater inlet of the boiler (1) through a pipeline; the steam inlet of the steam molten salt heat exchanger (14) is connected to the reheat steam outlet of the boiler (1) through a reheat steam regulating valve (20), and the water outlet is connected to the steam outlet of the high-pressure heater (9). The inlet is connected to the No. 1 steam-water regulating valve (24), and the water outlet is also connected to the steam inlet of the deaerator (7) through the No. 2 steam-water regulating valve (25). The water outlet is also connected to the steam inlet of the low-pressure heater (6) through the No. 3 steam-water regulating valve (26). The water inlet of the brine heat exchanger group (17) is connected to the water pipeline of the coal-fired thermal power generation system, and the water outlet is connected to the water pipeline of the coal-fired thermal power generation system with a temperature higher than that of the water inlet. The molten salt outlet of the cold molten salt tank (18) is connected to the molten salt inlet of the oil-salt heat exchanger (13) through the cold salt pump (19), and the molten salt outlet of the oil-salt heat exchanger (13) is connected to the molten salt inlet of the steam molten salt heat exchanger (14) through a pipeline.

2. The flexible power generation system with complementary photovoltaic, coal, and energy storage as described in claim 1, characterized in that: The brine heat exchanger group (17) includes a No. 1 brine heat exchanger (171), a No. 2 brine heat exchanger (172), and a No. 3 brine heat exchanger (173). The molten salt inlet of the No. 1 brine heat exchanger (171) is connected to the hot molten salt tank (15) via a hot salt pump (16), and the molten salt outlet is connected to the molten salt inlet of the No. 2 brine heat exchanger (172) via a pipeline. The water medium inlet is connected to the water medium outlet of the high-pressure heater (9) via a feedwater regulating valve (21), and the water medium outlet is connected to the feedwater inlet of the boiler (1) via a pipeline. The No. 2 brine heat exchanger (171) The molten salt outlet of 2) is connected to the molten salt inlet of the No. 3 brine heat exchanger (173) through a pipeline. The water working medium inlet is connected to the water working medium outlet of the feed water pump (8) through the No. 2 feed water regulating valve (22). The water working medium outlet is connected to the feed water inlet of the boiler (1) through a pipeline. The molten salt outlet of the No. 3 brine heat exchanger (173) is connected to the molten salt inlet of the cold molten salt tank (18) through a pipeline. The water working medium inlet is connected to the water working medium outlet of the condensate pump (5) through the No. 3 feed water regulating valve (23). The water working medium outlet is connected to the water working medium inlet of the deaerator (7) through a pipeline.

3. The flexible power generation system with complementary photovoltaic, coal, and energy storage as described in claim 1, characterized in that: The working temperature of molten salt is 100℃~575℃.

4. The flexible power generation system with complementary photovoltaic, coal, and energy storage as described in claim 1, characterized in that: The working temperature of the heat transfer oil in the oil-water heat exchanger (12) and the oil-salt heat exchanger (13) is 180℃~390℃.

5. A flexible power generation system that combines solar power, coal storage, and solar energy according to claim 1, characterized in that: The solar collector (11) is composed of multiple solar collector tubes (111) connected in series and then in parallel.

6. The operation method of a flexible power generation system with complementary photovoltaic, coal and energy storage as described in any one of claims 1 to 5, wherein when the coal-fired thermal power generation system needs to rapidly reduce load or operate at low load, the opening of the reheat steam regulating valve (20) is increased, and the flow rate of molten salt entering the oil-salt heat exchanger (13) and the steam-molten salt heat exchanger (14) is regulated by adjusting the speed of the cold salt pump (19), and the flow rate of molten salt entering the high-pressure heater is regulated by adjusting the opening of the No. 1 steam-water regulating valve (24), the No. 2 steam-water regulating valve (25), and the No. 3 steam-water regulating valve (26), respectively. 9) The steam flow rate, the steam flow rate entering the deaerator (7), and the steam flow rate entering the low-pressure heater (6) are adjusted. The adjustment goal is to adjust the steam flow rate entering the low-pressure cylinder (3) of the turbine to meet the requirements of the change rate of the electric load and the low-load operation, and to ensure high efficiency. The system can meet the requirements of rapid and efficient load reduction. When the coal-fired thermal power generation system needs to rapidly increase the load, the opening of the feedwater regulating valve (10) is increased, the speed of the hot salt pump (16) is increased, and the feedwater regulating valve No. 1 (21) and feedwater regulating valve No. 2 (21) are adjusted in sequence. The opening and closing of the regulating valve (22) and the valve opening of the feedwater regulating valve (23) are adjusted with the following objectives: the load increase rate is matched with the flow rate and heat release rate of the feedwater of the brine heat exchanger group (17), so that the coal-fired unit can quickly and efficiently increase the load; when the solar radiation intensity is high, the feedwater regulating valve (10) is adjusted to increase the feedwater flow rate into the oil-water heat exchanger (12); when all the feedwater at the outlet of the deaerator (7) is heated by the oil-water heat exchanger (12) and the outlet water working fluid temperature of the oil-water heat exchanger (12) is higher than the outlet water temperature of the high-pressure heater (9). When the cold salt pump (19) speed is adjusted, the flow rate of molten salt entering the oil-salt heat exchanger (13) is regulated. The goal of the adjustment is to keep the outlet water working medium temperature of the oil-water heat exchanger (12) the same as the outlet water working medium temperature of the high-pressure heater (9) to meet the water working medium inlet temperature requirements of the boiler (1). When the light intensity is insufficient, the valve opening of the feed water regulating valve (10), feed water regulating valve No. 1 (21), and feed water regulating valve No. 2 (22) is adjusted. The goal of the adjustment is to keep the water temperature entering the boiler (1) unchanged and maintain the stable operation of the system.

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