Cascade phase change energy storage system combined with thermal power unit

Abstract

Embodiments of this disclosure provide a cascade phase change energy storage system for a combined thermal power unit, comprising: a generator system and an energy storage system. The generator system includes: a boiler, a steam turbine, a cooling tower, and a regenerator system. The water circulation of the generator system flows along the direction of the boiler, steam turbine, cooling tower, regenerator system, and boiler. The energy storage system includes a cascade thermal storage tank and an air heat exchange system. The temperature of the cascade thermal storage tank gradually decreases from bottom to top. The air heat exchange system includes a heat storage side and a heat release side. The heat storage side uses a renewable green electricity-driven electric heater as a heat source, and the heat release side uses compressed and heated air to drive a gas turbine. The high-temperature waste heat assists the regenerator system of the generator system in heating the feedwater. In the event of boiler abandonment, the high-temperature waste heat will replace the boiler for evaporation and superheating, ensuring the steam supply to the steam turbine, enabling the steam turbine to operate normally, and thus ensuring the normal power generation of the generator system.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the field of energy storage technology, specifically relating to a cascade phase change energy storage system for combined thermal power units. Background Technology

[0002] With increasing energy demand and stricter environmental standards, existing energy utilization methods face two major challenges: efficiency and the environment. Thermal power generation, as one of the main methods of electricity production, typically requires boilers to provide steam. However, as the service life of boilers gradually decreases, they struggle to meet the steam demands of steam turbines. Therefore, there is an urgent need for a system that can address the steam requirements of thermal power generation. Summary of the Invention

[0003] The embodiments disclosed herein are intended to at least address one of the technical problems existing in the prior art, and to provide a cascade phase change energy storage system for combined thermal power units.

[0004] Embodiments of this disclosure provide a cascade phase change energy storage system for a combined thermal power unit, the cascade phase change energy storage system for the combined thermal power unit comprising:

[0005] A generator system, comprising: a boiler, a steam turbine, a cooling tower, and a regenerator system, wherein water circulation in the generator system flows along the direction of the boiler, the steam turbine, the cooling tower, the regenerator system, and the boiler;

[0006] An energy storage system comprising a cascaded thermal storage tank and an air heat exchange system, wherein the hot end outlet of the cascaded thermal storage tank is connected to the hot end inlet of the air heat exchange system, and the air heat exchange system is configured to vaporize water output from the regenerator system and deliver it to the inlet of the turbine; and / or to vaporize water output from the cooling tower and deliver it to the inlet of the turbine.

[0007] In some embodiments of this disclosure, the air heat exchange system includes:

[0008] The high-temperature heat exchanger has its hot-end outlet connected to the hot-end inlet of the cascaded heat storage tank, its cold-end inlet connected to the outlet of the cooling tower, and its cold-end outlet connected to the inlet of the steam turbine.

[0009] In some embodiments of this disclosure, the air heat exchange system includes:

[0010] The high-temperature heat exchanger has its hot-end outlet connected to the hot-end inlet of the cascaded heat storage tank, its cold-end inlet connected to the outlet of the regenerator system, and its cold-end outlet connected to the inlet of the steam turbine.

[0011] In some embodiments of this disclosure, the air heat exchange system includes:

[0012] A low-temperature heat exchanger, wherein the cold end outlet of the high-temperature heat exchanger is connected to the hot end inlet of the low-temperature heat exchanger, the cold end outlet of the low-temperature heat exchanger is connected to the atmosphere, the cold end inlet of the low-temperature heat exchanger is connected to the outlet of the cooling tower, and the hot end outlet of the low-temperature heat exchanger is connected to the inlet of the boiler.

[0013] In some embodiments of this disclosure, the power generation system further includes a gas turbine, the hot end outlet of the cascade thermal storage tank is connected to the inlet of the gas turbine, and the outlet of the gas turbine is connected to the hot end inlet of the high-temperature heat exchanger.

[0014] In some embodiments of this disclosure, the power generation system further includes a generator connected to the gas turbine and a steam turbine.

[0015] In some embodiments of this disclosure, the steam extraction outlet of the steam turbine is connected to the hot end inlet of the regenerator system, and the cold end outlet of the regenerator system is connected to the inlet of the boiler.

[0016] In some embodiments of this disclosure, the energy storage system further includes a thermal storage system, which includes: a thermal storage blower, an ultra-high temperature electric heater, and a renewable energy device. The outlet of the thermal storage blower is connected to the inlet of the ultra-high temperature electric heater, the outlet of the ultra-high temperature electric heater is connected to the hot end inlet of the cascade thermal storage tank, and the renewable energy device is connected to the ultra-high temperature electric heater.

[0017] In some embodiments of this disclosure, the thermal storage system further includes a thermal storage heat exchanger, the hot end inlet of which is connected to the cold end outlet of the cascade thermal storage tank.

[0018] In some embodiments of this disclosure, the air heat exchange system further includes a heat-releasing blower and an air compressor. The inlet of the heat-releasing blower is connected to air, the outlet of the heat-releasing blower is connected to the inlet of the air compressor, and the outlet of the air compressor is connected to the cold end inlet of the cascade heat storage tank.

[0019] The cascade phase change energy storage system of the combined thermal power unit disclosed herein can transfer the heat energy of the cascade heat storage tank to the water circulation of the generator system through the air heat exchange system of the energy storage system, thereby providing an additional branch for the generator system to supply steam. When the boiler of the generator system cannot normally supply steam to the turbine, the energy storage system can vaporize the water output from the cooling tower and / or the water output from the regenerator system, and then transport the vaporized steam to the inlet of the turbine to ensure the steam supply of the turbine, so that the turbine can operate normally, thereby ensuring the normal power generation of the generator system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a cascade phase change energy storage system for a combined thermal power unit according to an embodiment of this disclosure (boiler operating normally);

[0021] Figure 2 for Figure 1 The diagram shows the structure of a cascade phase change energy storage system for a combined thermal power unit (the boiler is not in operation).

[0022] The labels in the attached diagram are as follows:

[0023] 100. Cascade phase change energy storage system for combined thermal power units;

[0024] 10. Generator system; 11. Boiler; 12. Steam turbine; 13. Cooling tower; 14. Regenerator system; 15. Generator; 16. Gas turbine;

[0025] 20. Energy storage system; 21. Cascade energy storage tank; 22. Air heat exchange system; 221. High-temperature heat exchanger; 222. Low-temperature heat exchanger; 223. Heat release fan; 224. Air compressor; 23. Thermal storage system; 231. Thermal storage fan; 232. Ultra-high temperature electric heater; 233. Renewable energy equipment; 234. Thermal storage heat exchanger;

[0026] L1, First low-temperature branch; L2, Second low-temperature branch; H1, First high-temperature branch; H2, Second high-temperature branch. Detailed Implementation

[0027] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0028] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0029] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0030] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0031] like Figure 1As shown, embodiments of this disclosure provide a cascade phase change energy storage system 100 for a combined thermal power unit. The cascade phase change energy storage system 100 for a combined thermal power unit includes a generator system 10 and an energy storage system 20. Specifically, the generator system 10 includes a boiler 11, a steam turbine 12, a cooling tower 13, and a regenerator system 14. The water circulation of the generator system flows along the direction of the boiler 11, the steam turbine 12, the cooling tower 13, the regenerator system 14, and the boiler 11. The energy storage system 20 includes a cascade thermal storage tank and an air heat exchange system 22. The hot end outlet of the cascade thermal storage tank is connected to the hot end inlet of the air heat exchange system 22. The air heat exchange system 22 is configured to vaporize water output from the regenerator system 14 and deliver it to the inlet of the steam turbine 12; and / or to vaporize water output from the cooling tower 13 and deliver it to the inlet of the steam turbine 12.

[0032] The combined thermal power unit cascade phase change energy storage system 100 of this disclosure includes a generator system 10 and an energy storage system 20. The generator system 10 includes a boiler 11, a steam turbine 12, a cooling tower 13, and a regenerator system 14. Water circulation in the generator system 10 flows along the direction of the boiler 11, steam turbine 12, cooling tower 13, and regenerator system 14, changing the water's state from gaseous to liquid, and ultimately returning to the boiler 11, thus forming a water circulation. The energy storage system 20... 0 includes: a cascaded thermal storage tank and an air heat exchange system 22. The hot end outlet of the cascaded thermal storage tank is connected to the hot end inlet of the air heat exchange system 22. The air heat exchange system 22 can vaporize the water output from the regenerator system 14 and transport the vaporized water vapor to the inlet of the turbine 12 to provide energy for the turbine 12 to do work. Or / and the air heat exchange system 22 can vaporize the water output from the cooling tower 13 and transport the vaporized water vapor to the inlet of the turbine 12 to provide energy for the turbine 12 to do work. The cascade phase change energy storage system 100 of the combined thermal power unit in this embodiment can transfer the heat energy of the cascade heat storage tank to the water circulation of the generator system 10 through the air heat exchange system 22 of the energy storage system 20, so as to provide another branch for the generator system 10 to supply steam. When the boiler 11 of the generator system 10 cannot supply steam to the turbine 12 normally, the energy storage system 20 can vaporize the water output from the cooling tower 13 and / or the water output from the regenerator system 14, and then transport the vaporized steam to the inlet of the turbine 12 to ensure the steam supply of the turbine 12, so that the turbine 12 can operate normally, thereby ensuring the normal power generation of the generator system 10.

[0033] In some embodiments of this disclosure, such as Figure 1As shown, the air heat exchange system 22 includes: a high-temperature heat exchanger 221; the hot-end outlet of the cascade heat storage tank is connected to the hot-end inlet of the high-temperature heat exchanger 221; the cold-end inlet of the high-temperature heat exchanger 221 is connected to the outlet of the regenerator system 14; and the cold-end outlet of the high-temperature heat exchanger 221 is connected to the inlet of the steam turbine 12. Specifically, the hot air from the cascade heat storage tank can be transported to the hot-end inlet of the high-temperature heat exchanger 221 through the hot-end outlet of the cascade heat storage tank. The hot air transfers part of its heat to the water circulation of the generator system 10 through the high-temperature heat exchanger 221, and the dissipated hot air is discharged through the cold-end outlet of the high-temperature heat exchanger 221. Meanwhile, the water output from the outlet of the regenerator system 14 of the generator system 10 is transported to the high-temperature heat exchanger 221 through the first high-temperature branch H1. The water absorbs the heat from the hot air output from the cascade heat storage tank, and the condensate is vaporized to form steam. Then, it is output through the hot end outlet of the high-temperature heat exchanger 221 and finally transported to the inlet of the steam turbine 12 through the second high-temperature branch H2 to provide steam for the steam turbine 12.

[0034] In some embodiments of this disclosure, the air heat exchange system 22 includes: a high-temperature heat exchanger 221; a hot-end outlet of a cascaded heat storage tank connected to the hot-end inlet of the high-temperature heat exchanger 221; a cold-end inlet of the high-temperature heat exchanger 221 connected to the outlet of the cooling tower 13 (not shown in the figure); and a cold-end outlet of the high-temperature heat exchanger 221 connected to the inlet of the steam turbine 12. Specifically, hot air from the cascaded heat storage tank can be transported to the hot-end inlet of the high-temperature heat exchanger 221 through the hot-end outlet of the cascaded heat storage tank. The hot air transfers some of its heat to the water circulation of the generator system 10 through the high-temperature heat exchanger 221, and the cooled hot air is discharged through the cold-end outlet of the high-temperature heat exchanger 221. At the same time, condensate output from the outlet of the cooling tower 13 of the generator system 10 is transported to the high-temperature heat exchanger 221. The condensate absorbs the heat from the hot air output from the cascaded heat storage tank, and the condensate is vaporized to form steam. This steam is then output through the hot-end outlet of the high-temperature heat exchanger 221 and finally enters the inlet of the steam turbine 12 to provide steam for the steam turbine 12.

[0035] In some embodiments of this disclosure, the air heat exchange system 22 includes: a low-temperature heat exchanger 222, the cold end outlet of the high-temperature heat exchanger 221 is connected to the hot end inlet of the low-temperature heat exchanger 222, the cold end outlet of the low-temperature heat exchanger 222 is in communication with the atmosphere, the cold end inlet of the low-temperature heat exchanger 222 is connected to the outlet of the cooling tower 13 through a first low-temperature branch L1, and the hot end outlet of the low-temperature heat exchanger 222 is connected to the hot end outlet of the regenerator system 14 through a second low-temperature branch L2, that is, the hot end outlet of the low-temperature heat exchanger 222 is connected to the inlet of the boiler 11 through the second low-temperature branch L2.

[0036] When boiler 11 is operating normally, the air with a certain amount of heat discharged from the cold end outlet of high-temperature heat exchanger 221 enters low-temperature heat exchanger 222 through the hot end inlet of low-temperature heat exchanger 222. The air transfers heat to the water circulation of generator system 10 through low-temperature heat exchanger 222, and after dissipating heat, it is discharged into the atmosphere through the cold end outlet of low-temperature heat exchanger 222. At the same time, the condensate from the outlet of cooling tower 13 reaches the cold end inlet of low-temperature heat exchanger 222 through the first low-temperature branch L1, and then enters low-temperature heat exchanger 222 through the cold end inlet of low-temperature heat exchanger 222. After absorbing heat from the air in low-temperature heat exchanger 222, the condensate temperature rises, and the heated water is discharged through the hot end outlet of low-temperature heat exchanger 222 into the second low-temperature branch L2, and then enters the inlet of boiler 11 through the second low-temperature branch L2.

[0037] When boiler 11 is not operating normally (such as...) Figure 2 As shown, the condensate from the outlet of cooling tower 13 reaches the cold end inlet of low-temperature heat exchanger 222 through the first low-temperature branch L1, and then enters low-temperature heat exchanger 222 through the cold end inlet of low-temperature heat exchanger 222. After absorbing heat from the air in low-temperature heat exchanger 222, the condensate temperature rises. The heated water is discharged into the second low-temperature branch L2 through the hot end outlet of low-temperature heat exchanger 222, and then enters the first high-temperature branch H1 connected to it through the second low-temperature branch L2. The heated water enters the high-temperature heat exchanger 221 through the first high-temperature branch H1 and is heated, and then is discharged to the inlet of steam turbine 12 through the second high-temperature branch H2.

[0038] In some embodiments of this disclosure, the power generation system further includes a gas turbine 16. The hot-end outlet of the cascade energy storage tank is connected to the inlet of the gas turbine 16, and the outlet of the gas turbine 16 is connected to the hot-end inlet of the high-temperature heat exchanger 221. Specifically, the hot air from the cascade energy storage tank 21 reaches the inlet of the gas turbine 16 through its hot-end outlet and enters the gas turbine 16 through the inlet to provide a gas medium for the gas turbine 16. After the hot air performs work in the gas turbine 16, it is discharged into the hot-end inlet of the high-temperature heat exchanger 221 through the outlet of the gas turbine 16, so as to utilize the residual heat of the hot air to vaporize part of the water in the water circulation of the generator system 10, thereby improving the utilization rate of the hot air.

[0039] In some embodiments of this disclosure, the power generation system further includes a generator 15, which is connected to a gas turbine 16 and a steam turbine 12. That is, the gas turbine 16 and the steam turbine 12 jointly provide mechanical energy to the generator 15. When the steam turbine 12 provides less mechanical energy to the generator 15, the gas turbine 16 can also provide a certain amount of mechanical energy to the generator 15 to ensure sufficient mechanical energy for the generator 15 to generate electricity.

[0040] In some embodiments of this disclosure, the extraction steam outlet of the steam turbine 12 is connected to the hot-end inlet of the regenerator system 14, and the cold-end outlet of the regenerator system 14 is connected to the inlet of the boiler 11. The extraction steam from the steam turbine 12 heats the condensate flowing through the regenerator system 14 to increase its temperature. Specifically, the extraction steam from the steam turbine 12 reaches the hot-end inlet of the regenerator system 14 through the extraction steam outlet of the steam turbine 12, enters the regenerator system 14 through the hot-end inlet, and transfers heat to the condensate. Part of the heat from the extraction steam is absorbed and discharged to the inlet of the boiler 11 through the cold-end outlet of the regenerator system 14. When the boiler 11 is in an abnormal operating state (e.g....), Figure 2 As shown, the water from the cold end outlet of the regenerator system 14 enters the cold end inlet of the high-temperature regenerator system 14 through the first high-temperature branch H1.

[0041] In some embodiments of this disclosure, the energy storage system 20 further includes a thermal storage system 23, which includes a thermal storage blower 231, an ultra-high temperature electric heater 232, and a renewable energy device 233. The inlet of the thermal storage blower 231 is connected to the atmosphere, the outlet of the thermal storage blower 231 is connected to the inlet of the ultra-high temperature electric heater 232, the outlet of the ultra-high temperature electric heater 232 is connected to the hot end inlet of the cascaded thermal storage tank, and the renewable energy device 233 is connected to the ultra-high temperature electric heater 232. Specifically, the thermal storage blower 231 delivers air to the ultra-high temperature electric heater 232, which heats the air. The heated air then enters the hot end inlet of the cascaded energy storage tank 21 through the outlet of the ultra-high temperature electric heater 232, thus entering the cascaded energy storage tank 21 and storing the heat in the cascaded distributed thermal storage materials. Extremely hot air enters the cascade energy storage tank 21 from the bottom, flows from bottom to top, and exits through the cold end outlet at the top of the tank. Specifically, the renewable energy device 233 can be a renewable natural energy source such as solar or wind power to improve the utilization rate of renewable energy. It should be noted that the heating temperature range of the ultra-high temperature electric heater 232 in this embodiment is 1200℃~1500℃.

[0042] From bottom to top, the phase change temperature of the thermal storage material in the tiered energy storage tank 21 gradually decreases. For example, the tiered energy storage tank 21 contains three layers of thermal storage material. The phase change temperature of the thermal storage material at the bottom is 1500℃, the phase change temperature of the thermal storage material in the middle is 1200℃, and the phase change temperature of the thermal storage material at the top is 1000℃. As hot air flows from bottom to top, the ultra-high temperature hot air first comes into contact with the thermal storage material at the bottom. The thermal storage material at the bottom undergoes a phase change at 1500℃ and stores a large amount of thermal energy in the thermal storage material at the bottom. As the hot air that has lost some heat continues to flow to the thermal storage material in the middle, the thermal storage material in the middle undergoes a phase change at 1200℃ and stores a large amount of thermal energy in the thermal storage material in the middle. The hot air that has lost a large amount of heat continues to flow to the thermal storage material at the top, the thermal storage material at the top undergoes a phase change at 1000℃ and stores a large amount of thermal energy in the thermal storage material at the top. After the hot air stores most of its heat in the tiered heat storage material, some heat remains. The hot air with the remaining heat is discharged through the cold end outlet of the tiered energy storage tank 21.

[0043] In some embodiments of this disclosure, the thermal storage system 23 further includes a thermal storage heat exchanger 234. The hot end inlet of the thermal storage heat exchanger 234 is connected to the cold end outlet of the cascade thermal storage tank. Hot air flows through the cascade energy storage tank 21 and stores most of the heat in the cascade material. The remaining heat is discharged from the hot air through the cold end outlet of the cascade energy storage tank 21 to the hot end inlet of the thermal storage heat exchanger 234, where the heat is transferred to other fluids, improving the utilization rate of thermal energy. After the heat of the hot air is absorbed, it is discharged into the atmosphere through the cold end outlet of the thermal storage heat exchanger 234.

[0044] In some embodiments of this disclosure, the air heat exchange system 22 further includes a heat-dissipating blower 223 and an air compressor 224. The inlet of the heat-dissipating blower 223 is connected to air, and the outlet of the heat-dissipating blower 223 is connected to the inlet of the air compressor 224. The outlet of the air compressor 224 is connected to the cold end inlet of the cascade energy storage tank 21. Specifically, the heat-dissipating blower 223 delivers air to the air compressor 224, which compresses the air and delivers it to the cold end inlet of the cascade energy storage tank 21. The compressed air flows from the top to the bottom of the cascade energy storage tank 21, absorbing heat from each stage of the energy storage material during the airflow process, and finally dissipating the highly heated air through the hot end outlet at the bottom of the cascade energy storage tank 21.

[0045] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A cascade phase change energy storage system for a combined heat and power unit, characterized in that, The cascade phase change energy storage system of the combined thermal power unit includes: A generator system includes a boiler, a steam turbine, a cooling tower, and a regenerator system. Water circulation in the generator system flows along the direction of the boiler, the steam turbine, the cooling tower, the regenerator system, and the boiler. The generator system also includes a gas turbine and a generator, with the gas turbine connected to the generator and the generator connected to the steam turbine. An energy storage system comprising a cascaded thermal storage tank and an air heat exchange system, wherein the hot end outlet of the cascaded thermal storage tank is connected to the inlet of the gas turbine, the outlet of the gas turbine is connected to the hot end inlet of the air heat exchange system, and the air heat exchange system is configured to vaporize water output from the regenerator system and deliver it to the inlet of the turbine; and / or to vaporize water output from the cooling tower and deliver it to the inlet of the turbine.

2. The cascading phase change thermal energy storage system of a combined heat and power plant of claim 1, wherein, The air heat exchange system includes: The high-temperature heat exchanger has its hot-end outlet connected to the hot-end inlet of the cascaded heat storage tank, its cold-end inlet connected to the outlet of the cooling tower, and its cold-end outlet connected to the inlet of the steam turbine.

3. The step phase change thermal energy storage system of a combined heat and power plant according to claim 1, characterized in that, The air heat exchange system includes: The high-temperature heat exchanger has its hot-end outlet connected to the hot-end inlet of the cascaded heat storage tank, its cold-end inlet connected to the outlet of the regenerator system, and its cold-end outlet connected to the inlet of the steam turbine.

4. The cascading phase change thermal energy storage system of a combined heat and power plant according to claim 2 or 3, characterized in that, The air heat exchange system includes: A low-temperature heat exchanger, wherein the cold end outlet of the high-temperature heat exchanger is connected to the hot end inlet of the low-temperature heat exchanger, the cold end outlet of the low-temperature heat exchanger is connected to the atmosphere, the cold end inlet of the low-temperature heat exchanger is connected to the outlet of the cooling tower, and the hot end outlet of the low-temperature heat exchanger is connected to the inlet of the boiler.

5. The cascade phase change energy storage system for combined thermal power units according to claim 1, characterized in that, The steam extraction outlet of the steam turbine is connected to the hot end inlet of the regenerator system, and the cold end outlet of the regenerator system is connected to the inlet of the boiler.

6. The cascade phase change energy storage system for combined thermal power units according to claim 1, characterized in that, The energy storage system also includes a thermal storage system, which includes: a thermal storage blower, an ultra-high temperature electric heater, and a renewable energy device. The outlet of the thermal storage blower is connected to the inlet of the ultra-high temperature electric heater, the outlet of the ultra-high temperature electric heater is connected to the hot end inlet of the cascade thermal storage tank, and the renewable energy device is connected to the ultra-high temperature electric heater.

7. The cascade phase change energy storage system for combined thermal power units according to claim 1, characterized in that, The thermal storage system also includes a thermal storage heat exchanger, the hot end inlet of which is connected to the cold end outlet of the cascade thermal storage tank.

8. The cascade phase change energy storage system for combined thermal power units according to claim 1, characterized in that, The air heat exchange system also includes a heat-releasing blower and an air compressor. The inlet of the heat-releasing blower is connected to the air, the outlet of the heat-releasing blower is connected to the inlet of the air compressor, and the outlet of the air compressor is connected to the cold end inlet of the cascade heat storage tank.

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