Expressway service area zero-carbon energy supply system coupled with photovoltaic and RSOFC and operation method of expressway service area zero-carbon energy supply system

Abstract

The invention discloses a photovoltaic and RSOFC coupled zero-carbon energy supply system for an expressway service area and an operation method. The system comprises a photovoltaic power generation unit, an SOFC power generation unit and an SOEC hydrogen production unit. When illumination is sufficient in the daytime, the photovoltaic power generation unit is used for generating power, the SOEC hydrogen production unit is used for electrolyzing water vapor through surplus electric energy of photovoltaic power generation to generate hydrogen and oxygen and storing the hydrogen and the oxygen, the SOFC power generation unit is used for generating power through the hydrogen at night, and meanwhile released heat is used for supplying heat. The influence caused by non-uniform distribution of new energy in time and space can be effectively reduced, the traditional energy consumption is reduced, and the energy consumption cost is further reduced. The photovoltaic unit and the SOFC / SOEC unit are deeply coupled, the problem that clean heat supply, power supply and hydrogen supply of the expressway service area are difficult to cooperate can be solved, various shares can be flexibly distributed and complemented, unnecessary energy loss is reduced, power generation is more stable, and meanwhile dependence on fossil energy supply can be reduced.

Description

Technical Field

[0001] The present invention belongs to the field of energy technology such as photovoltaic power generation and RSOFC power generation system operation, and relates to a technology for integrating photovoltaic power generation with RSOFC power generation system, and in particular to a zero-carbon energy supply system for highway service areas coupled with photovoltaics and RSOFC and an operation method. Background Art

[0002] The transportation industry is the third largest source of carbon emissions after industry and construction. Improving the energy efficiency of the transportation system and reducing carbon emissions have become urgent needs. The "photovoltaic + highway" model has become one of the important paths for the green transformation of the two major industries of transportation and energy. Highway service areas are typical representatives of various types of energy consumption in the transportation industry. However, photovoltaic power generation has strong time-varying characteristics and intermittent nature, and there is a major problem of "source-grid-load" mismatch, which cannot meet the energy needs of important transportation hubs such as highway service areas. Converting excess photovoltaic power generation into easily storable forms of energy can effectively improve the flexibility and energy efficiency of the system, and is a very promising technical route for building a "zero-carbon" energy system in the transportation field.

[0003] Renewable Solid Oxide Fuel Cell (RSOFC) is a clean, efficient and flexible energy conversion device that has both power generation (SOFC) and energy storage (SOEC) functions. With reversible solid oxide fuel cells as the core component, making full use of their characteristics of both power generation and energy storage, building an integrated power generation and energy storage system, and coupling it with photovoltaic power generation can greatly improve the operational flexibility of the power generation system and improve the energy utilization efficiency of the system. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a zero-carbon energy supply system and operation method for highway service areas that couple photovoltaic power generation and RSOFC. The present invention provides a method for the operation of a zero-carbon energy supply system that integrates photovoltaic power generation and power generation and energy storage with RSOFC as the core component in highway service areas. Photovoltaic power generation and RSOFC are combined to construct a zero-carbon energy supply system that integrates power generation, heat supply and energy storage. When the power generated by photovoltaic power generation exceeds the power demand of the highway service area, the SOFC power generation unit maintains ultra-low load operation without stopping, and the SOEC hydrogen production unit operates under high load conditions. The SOEC hydrogen production unit uses excess power to electrolyze water to produce hydrogen and store hydrogen and oxygen; when the power generated by photovoltaic power generation is less than the power demand of the highway service area, the SOEC hydrogen production unit maintains ultra-low load operation without stopping, and the SOFC power generation unit operates under high load conditions, and generates electricity through hydrogen fuel to maintain the power demand of users, and uses high-temperature exhaust gas for heating.

[0005] In order to achieve the above object, the technical solution adopted by the present invention to solve the technical problem is:

[0006] A zero-carbon energy supply system for highway service areas that couples photovoltaics and RSOFC, including a photovoltaic power generation unit, a SOFC power generation unit, and a SOEC hydrogen production unit;

[0007] The photovoltaic power generation unit comprises a solar photovoltaic array 1, a DC / DC converter 2 and a first DC to AC inverter 3; wherein the solar photovoltaic array 1, the DC / DC converter 2 and the first DC to AC inverter 3 are connected in sequence through cables, and the first DC to AC inverter 3 is connected to the power grid to form a circuit loop;

[0008] The SOFC power generation unit includes a SOFC stack 4, a second DC to AC inverter 5, a combustion chamber 6, a first regenerator 7, a second regenerator 8, a third regenerator 9, a fourth regenerator 11, a first three-way mixing valve 10, a first fan 12, a second fan 14, a first water pump 13, a first oxygen storage tank 15, a first hydrogen storage tank 16, a first water storage tank 17, a first mixer 18 and a first heat exchanger 19; wherein the first water storage tank 17, the first water pump 13, and the second regenerator 8 fuel sides are connected in sequence through pipelines and the pipelines connected to the first hydrogen storage tank 16, the first fan 12, and the fourth regenerator 11 fuel sides are connected at the first three-way mixing valve 10, and then introduced into the fuel inlet end of the SOFC stack 4, and the SOFC The fuel outlet of the stack 4 is connected to the combustion chamber 6; the oxygen in the first oxygen storage tank 15 is sequentially passed through the second fan 14, the oxygen side of the third reheater 9, and the oxygen side of the first reheater 7 to the oxygen inlet of the SOFC stack 4, and the oxygen outlet of the SOFC stack 4 is connected to the combustion chamber 6. The exhaust gas at the outlet of the combustion chamber 6 is divided into two parts, one part of the exhaust gas passes through the exhaust gas side of the first reheater 7 and the exhaust gas side of the fourth reheater 11, and the other part of the exhaust gas passes through the exhaust gas side of the second reheater 8 and the exhaust gas side of the third reheater 9 in the first mixer 18 and is discharged through the high temperature side of the first heat exchanger 19; the SOFC stack 4 is connected to the second DC to AC inverter 5 through a cable, and the second DC to AC inverter 5 is connected to the power grid to form a circuit loop;

[0009] The SOEC hydrogen production unit includes an electric heater 20, a SOEC stack 21, an AC to DC inverter 22, a fifth regenerator 23, a sixth regenerator 24, a seventh regenerator 25, an eighth regenerator 26, a ninth regenerator 28, a second three-way mixing valve 27, a third fan 29, a fourth fan 31, a second water pump 30, a second oxygen storage tank 32, a third oxygen storage tank 33, a second hydrogen storage tank 34, a third hydrogen storage tank 39, a second water storage tank 35, a third water storage tank 40, a condenser 36, a steam-water separator 37 and a dryer 38; wherein the second water storage tank 35, the second water pump 30, the fuel side of the sixth regenerator 24, and the fuel side of the seventh regenerator 25 are sequentially connected by pipelines and connected to the pipeline connected by the second hydrogen storage tank 34, the third fan 29, and the fuel side of the ninth regenerator 28 at the second three-way mixing valve 27, and pass through the electric heater 20 to the SOEC stack 21 The fuel inlet end of the SOEC stack 21 passes through the tail gas side of the seventh reheater 25, the tail gas side of the eighth reheater 26, the condenser 36, the steam-water separator 37, and the dryer 38 in sequence, and is connected to the third hydrogen storage tank 39 to form a closed fuel pipeline. The water separated by the steam-water separator 37 enters the third water storage tank 40 for storage; the oxygen passes through the second oxygen storage tank 32, the fourth fan 31, the oxygen side of the eighth reheater 26, the oxygen side of the fifth reheater 23, and the electric heater 20 in sequence and enters the oxygen inlet end of the SOEC stack 21. The oxygen outlet end of the SOEC stack 21 passes through the tail gas side of the fifth reheater 23, the tail gas side of the sixth reheater 24, and the tail gas side of the ninth reheater 28 in sequence and is connected to the third oxygen storage tank 33; the SOEC stack 21 is connected to the AC to DC inverter 22 through a cable, and the AC to DC inverter 22 is connected to the power grid to form a circuit loop.

[0010] The operation method of the system is as follows: when the photovoltaic power generation unit operates normally, the solar photovoltaic array 1 converts solar energy into electrical energy, the DC / DC converter 2 converts the direct current output by the solar cell into stable direct current of different pressures, thereby realizing maximum power point tracking, and the first DC to AC inverter 3 converts the direct current into alternating current and then connects it to the power grid.

[0011] When the SOFC power generation unit is operating normally, the electric energy generated by the SOFC stack 4 is converted into AC power through the second DC to AC inverter 5 and then connected to the power grid; the second fan 14 is turned on to draw out the oxygen in the first oxygen storage tank 15, and the oxygen passes through the oxygen side of the third regenerator 9 and the oxygen side of the first regenerator 7 in turn to absorb heat, and then enters the SOFC stack 4 from the oxygen inlet end of the SOFC stack 4, and then enters the combustion chamber 6 from the oxygen outlet end of the SOFC stack 4, and the first fan 12 is turned on to draw out the hydrogen in the first hydrogen storage tank 16 and absorb heat through the fuel side of the fourth regenerator 11, and at the same time adjust the speed of the first water pump 13, take water from the first water storage tank 17 and introduce it into the second regenerator 8 fuel The material side undergoes endothermic evaporation to obtain water vapor which is then mixed with hydrogen in the first three-way mixing valve 10. The mixed gas flows into the SOFC stack 4 from the fuel inlet end to react and release electrical energy. The high-temperature exhaust gas after the reaction is passed into the combustion chamber 6 to catalytically combust the excess hydrogen in the stack to obtain an exhaust gas with a higher temperature. After the exhaust gas is discharged from the combustion chamber 6, a part of it passes through the exhaust gas side of the first reheater 7 and the exhaust gas side of the fourth reheater 11 in turn to release heat, and the other part passes through the exhaust gas side of the second reheater 8 and the exhaust gas side of the third reheater 9 in turn to release heat. The two parts of exhaust gas are mixed in the first mixer 18 and then pass through the high-temperature side of the first heat exchanger 19 for heating.

[0012] When the SOEC hydrogen production unit is operating normally, the electric energy from the power grid is converted into DC power through the AC to DC inverter 22 and then connected to the SOEC stack 21 for reaction; the fourth fan 31 is turned on to draw out the oxygen in the second oxygen storage tank 32, and enters the oxygen inlet end of the SOEC stack 21 after passing through the oxygen side of the eighth reheater 26, the oxygen side of the fifth reheater 23, and the electric heater 20. The oxygen-enriched air at the air pole outlet of the SOEC stack 21 passes through the tail gas side of the fifth reheater 23, the tail gas side of the sixth reheater 24, and the tail gas side of the ninth reheater 28 in turn to preheat the reaction gas, and the oxygen-enriched air after waste heat recovery is transported to the third oxygen storage tank 33 for storage; the third fan 29 is turned on to draw out the hydrogen in the second hydrogen storage tank 34 The fuel side is preheated through the ninth regenerator 28, and the second water pump 30 is turned on at the same time, and the speed of the second water pump 30 is adjusted. Water is taken from the second water storage tank 35 and introduced into the fuel side of the sixth regenerator 24 and the fuel side of the seventh regenerator 25 for absorbing heat, and then mixed with hydrogen in the second three-way mixing valve 27. The mixed gas passes through the electric heater 20 and flows into the SOEC stack 21 to consume external electrical energy for electrolysis. The hydrogen produced by the chemical reaction and the hydrogen input from the front end of the SOEC stack 21 are reheated by the seventh regenerator 25 and the eighth regenerator 26 for the unreacted gas, and finally enters the third hydrogen storage tank 39 for storage after passing through the condenser 36, the steam-water separator 37, and the dryer (38). The separated condensed water is stored in the third water storage tank 40.

[0013] The system operation method is as follows: when the electric energy generated by photovoltaic power generation exceeds the user's electricity demand, the SOFC power generation unit maintains ultra-low load operation without stopping, and the SOEC hydrogen production unit operates at a high load, and the excess electric energy is converted into hydrogen and stored by the SOEC hydrogen production unit; when the electric energy generated by photovoltaic power generation is less than the user's electricity demand, the SOEC hydrogen production unit maintains ultra-low load operation without stopping, and the SOFC power generation unit operates at a high load, generates electricity through hydrogen fuel to maintain the user's electricity demand, and uses high-temperature exhaust gas for heating.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1) The working fluids of the system of the present invention only include oxygen, water and hydrogen, which are completely recycled and reused without the use of fossil energy, which can effectively reduce the carbon emissions of the entire service area.

[0016] 2) The present invention deeply couples photovoltaics with SOFC / SOEC units to achieve integrated power generation, hydrogen production and heat supply, which can solve the problem of clean heating, electricity and hydrogen supply being difficult to coordinate in highway service areas. When there is excess solar power supply, SOEC is used to produce hydrogen for energy storage. When there is insufficient solar power supply, SOFC is used to generate electricity. The remaining low-quality heat energy after SOFC power generation is used for heating. By flexibly allocating the various shares, they complement each other, thereby reducing energy loss and making power generation more stable.

[0017] 3) During operation, the system adjusts the stack load by controlling the current through the AC / DC inverter, changes the relative proportion and flow rate of hydrogen and water, and controls the working fluid temperature through the electric heater to switch the operating mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the zero-carbon energy supply system in highway service areas that couples photovoltaics and RSOFC. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the purpose and specific implementation methods of the present invention, the present invention will be further described below in conjunction with the accompanying drawings.

[0020] like Figure 1 The highway service area zero-carbon energy supply system coupled with photovoltaic and RSOFC shown includes a photovoltaic power generation unit, a SOFC power generation unit, and a SOEC hydrogen production unit, wherein SOFC represents a solid oxide fuel cell and SOEC represents a solid oxide electrolysis cell.

[0021] The photovoltaic power generation unit comprises a solar photovoltaic array 1, a DC / DC converter 2 and a first DC to AC inverter 3; wherein the solar photovoltaic array 1, the DC / DC converter 2 and the first DC to AC inverter 3 are connected in sequence through cables, and the first DC to AC inverter 3 is connected to the power grid to form a circuit loop;

[0022] The SOFC power generation unit includes a SOFC stack 4, a second DC to AC inverter 5, a combustion chamber 6, a first regenerator 7, a second regenerator 8, a third regenerator 9, a fourth regenerator 11, a first three-way mixing valve 10, a first fan 12, a second fan 14, a first water pump 13, a first oxygen storage tank 15, a first hydrogen storage tank 16, a first water storage tank 17, a first mixer 18 and a first heat exchanger 19; wherein the first water storage tank 17, the first water pump 13, and the second regenerator 8 fuel sides are connected in sequence through pipelines and the pipelines connected to the first hydrogen storage tank 16, the first fan 12, and the fourth regenerator 11 fuel sides are connected at the first three-way mixing valve 10, and then introduced into the fuel inlet end of the SOFC stack 4, and the SOFC The fuel outlet of the stack 4 is connected to the combustion chamber 6; the oxygen in the first oxygen storage tank 15 is sequentially passed through the second fan 14, the oxygen side of the third reheater 9, and the oxygen side of the first reheater 7 to the oxygen inlet of the SOFC stack 4, and the oxygen outlet of the SOFC stack 4 is connected to the combustion chamber 6. The exhaust gas at the outlet of the combustion chamber 6 is divided into two parts, one part of the exhaust gas passes through the exhaust gas side of the first reheater 7 and the exhaust gas side of the fourth reheater 11, and the other part of the exhaust gas passes through the exhaust gas side of the second reheater 8 and the exhaust gas side of the third reheater 9 in the first mixer 18 and is discharged through the high temperature side of the first heat exchanger 19; the SOFC stack 4 is connected to the second DC to AC inverter 5 through a cable, and the second DC to AC inverter 5 is connected to the power grid to form a circuit loop;

[0023] The SOEC hydrogen production unit includes an electric heater 20, a SOEC stack 21, an AC to DC inverter 22, a fifth regenerator 23, a sixth regenerator 24, a seventh regenerator 25, an eighth regenerator 26, a ninth regenerator 28, a second three-way mixing valve 27, a third fan 29, a fourth fan 31, a second water pump 30, a second oxygen storage tank 32, a third oxygen storage tank 33, a second hydrogen storage tank 34, a third hydrogen storage tank 39, a second water storage tank 35, a third water storage tank 40, a condenser 36, a steam-water separator 37 and a dryer 38; wherein the second water storage tank 35, the second water pump 30, the fuel side of the sixth regenerator 24, and the fuel side of the seventh regenerator 25 are sequentially connected by pipelines and connected to the pipeline connected by the second hydrogen storage tank 34, the third fan 29, and the fuel side of the ninth regenerator 28 at the second three-way mixing valve 27, and pass through the electric heater 20 to the SOEC stack 21 The fuel inlet end of the SOEC stack 21, the fuel outlet end of the SOEC stack 21 is connected to the third hydrogen storage tank 39 after passing through the seventh reheater 25 exhaust side, the eighth reheater 26 exhaust side, the condenser 36, the steam-water separator 37, and the dryer 38 in sequence to form a closed fuel pipeline, and the water separated by the steam-water separator 37 enters the third water storage tank 40 for storage; the oxygen passes through the second oxygen storage tank 32, the fourth fan 31, the eighth reheater 26 oxygen side, the fifth reheater 23 oxygen side, and the electric heater 20 in sequence and enters the oxygen inlet end of the SOEC stack 21, and the oxygen outlet end of the SOEC stack 21 passes through the fifth reheater 23 exhaust side, the sixth reheater 24 exhaust side, and the ninth reheater 28 exhaust side in sequence to be connected to the third oxygen storage tank 33; the SOEC stack 21 is connected to the AC to DC inverter 22 through a cable, and the AC to DC inverter 22 is connected to the power grid to form a circuit loop.

[0024] The operation method of the zero-carbon energy supply system of the highway service area coupled with photovoltaic and RSOFC is that when the electricity generated by photovoltaic power generation exceeds the electricity demand of the user, the SOFC power generation unit maintains ultra-low load operation without stopping, the SOEC hydrogen production unit operates at a high load, and the excess electricity is converted into hydrogen and stored by the SOEC hydrogen production unit; when the electricity generated by photovoltaic power generation is less than the electricity demand of the user, the SOEC hydrogen production unit maintains ultra-low load operation without stopping, the SOFC power generation unit operates at a high load, generates electricity through hydrogen fuel to maintain the electricity demand of the user, and uses high-temperature exhaust gas for heating. The photovoltaic power generation unit operates normally, the solar photovoltaic array 1 converts solar energy into electricity, the DC / DC converter 2 converts the DC output of the solar cell into stable DC of different pressures, thereby realizing maximum power point tracking, and the first DC to AC inverter 3 converts the DC into AC and then connects it to the power grid. When the SOFC power generation unit is operating normally, the electric energy generated by the SOFC stack 4 is converted into AC power through the second DC to AC inverter 5 and then connected to the power grid; the second fan 14 is turned on to draw out the oxygen in the first oxygen storage tank 15, and the oxygen passes through the oxygen side of the third regenerator 9 and the oxygen side of the first regenerator 7 in turn to absorb heat, and then enters the SOFC stack 4 from the oxygen inlet end of the SOFC stack 4, and then enters the combustion chamber 6 from the oxygen outlet end of the SOFC stack 4, and the first fan 12 is turned on to draw out the hydrogen in the first hydrogen storage tank 16 and absorb heat through the fuel side of the fourth regenerator 11, and at the same time adjust the speed of the first water pump 13, take water from the first water storage tank 17 and introduce it into the second regenerator 8 fuel The material side undergoes endothermic evaporation to obtain water vapor which is then mixed with hydrogen in the first three-way mixing valve 10. The mixed gas flows into the SOFC stack 4 from the fuel inlet end to react and release electrical energy. The high-temperature exhaust gas after the reaction is passed into the combustion chamber 6 to catalytically combust the excess hydrogen in the stack to obtain an exhaust gas with a higher temperature. After the exhaust gas is discharged from the combustion chamber 6, a part of it passes through the exhaust gas side of the first reheater 7 and the exhaust gas side of the fourth reheater 11 in turn to release heat, and the other part passes through the exhaust gas side of the second reheater 8 and the exhaust gas side of the third reheater 9 in turn to release heat. The two parts of exhaust gas are mixed in the first mixer 18 and then pass through the high-temperature side of the first heat exchanger 19 for heating.When the SOEC hydrogen production unit is operating normally, the electric energy from the power grid is converted into DC power through the AC to DC inverter 22 and then connected to the SOEC stack 21 for reaction; the fourth fan 31 is turned on to draw out the oxygen in the second oxygen storage tank 32, and enters the oxygen inlet end of the SOEC stack 21 after passing through the oxygen side of the eighth reheater 26, the oxygen side of the fifth reheater 23, and the electric heater 20. The oxygen-enriched air at the air pole outlet of the SOEC stack 21 passes through the tail gas side of the fifth reheater 23, the tail gas side of the sixth reheater 24, and the tail gas side of the ninth reheater 28 in turn to preheat the reaction gas, and the oxygen-enriched air after waste heat recovery is transported to the third oxygen storage tank 33 for storage; the third fan 29 is turned on to draw out the hydrogen in the second hydrogen storage tank 34 The fuel side is preheated through the ninth regenerator 28, and the second water pump 30 is turned on at the same time, and the speed of the second water pump 30 is adjusted. Water is taken from the second water storage tank 35 and introduced into the fuel side of the sixth regenerator 24 and the fuel side of the seventh regenerator 25 for absorbing heat, and then mixed with hydrogen in the second three-way mixing valve 27. The mixed gas passes through the electric heater 20 and flows into the SOEC stack 21 to consume external electrical energy for electrolysis. The hydrogen produced by the chemical reaction and the hydrogen input from the front end of the SOEC stack 21 are reheated by the seventh regenerator 25 and the eighth regenerator 26 for the unreacted gas, and finally enters the third hydrogen storage tank 39 for storage after passing through the condenser 36, the steam-water separator 37, and the dryer (38). The separated condensed water is stored in the third water storage tank 40.

[0025] In actual operation, the photovoltaic power generation unit always keeps running. When the electricity generated by photovoltaic power generation is less than the user's electricity demand, that is, when the solar power generation is insufficient, the SOEC hydrogen production unit keeps running at ultra-low load without stopping, and the SOFC power generation unit runs at high load, generating electricity through hydrogen fuel to maintain the user's electricity demand, and using high-temperature exhaust gas for heating. At this time, the power of the second fan 14 and the first fan 12 is increased, the power of the first water pump 13 is reduced, and the first three-way mixing valve 10 is opened. The remaining H after passing through the SOFC stack is 2 After catalytic combustion in the combustion chamber, heat is supplied. When the electricity generated by photovoltaic power generation exceeds the user's electricity demand, that is, when there is excess solar power generation, the SOFC power generation unit maintains ultra-low load operation without stopping, and the SOEC hydrogen production unit operates at a high load state. The excess electricity is converted into hydrogen and stored through the SOEC hydrogen production unit. At this time, the electricity is converted into direct current through the AC to DC inverter 22 and then connected to the SOEC stack 21, reducing the power of the fourth fan 31 and the third fan 29, increasing the power of the second water pump 30, opening the second three-way mixing valve 27, and opening the electric heater 20 to control the working medium temperature to ensure the normal operation of the SOEC.

Claims

1. A zero-carbon energy supply system for highway service areas coupling photovoltaics and RSOFC, characterized in that: It includes photovoltaic power generation unit, SOFC power generation unit and SOEC hydrogen production unit; The photovoltaic power generation unit comprises a solar photovoltaic array (1), a DC / DC converter (2) and a first DC to AC inverter (3); wherein the solar photovoltaic array (1), the DC / DC converter (2) and the first DC to AC inverter (3) are connected in sequence via cables, and the first DC to AC inverter (3) is connected to a power grid to form a circuit loop; The SOFC power generation unit comprises a SOFC stack (4), a second DC to AC inverter (5), a combustion chamber (6), a first regenerator (7), a second regenerator (8), a third regenerator (9), a fourth regenerator (11), a first three-way mixing valve (10), a first fan (12), a second fan (14), a first water pump (13), a first oxygen storage tank (15), a first hydrogen storage tank (16), a first water storage tank (17), a first mixer (18) and a first heat exchanger (19); wherein the fuel sides of the first water storage tank (17), the first water pump (13) and the second regenerator (8) are connected in sequence through pipelines, and the pipelines connected to the fuel sides of the first hydrogen storage tank (16), the first fan (12) and the fourth regenerator (11) are connected at the first three-way mixing valve (10) and then lead to the fuel inlet of the SOFC stack (4). end, the fuel outlet end of the SOFC stack (4) is connected to the combustion chamber (6); the oxygen in the first oxygen storage tank (15) is sequentially passed through the second fan (14), the oxygen side of the third reheater (9), and the oxygen side of the first reheater (7) to the oxygen inlet end of the SOFC stack (4); the oxygen outlet end of the SOFC stack (4) is connected to the combustion chamber (6); the exhaust gas at the outlet of the combustion chamber (6) is divided into two parts, one part of the exhaust gas passes through the exhaust gas side of the first reheater (7) and the exhaust gas side of the fourth reheater (11) and the other part of the exhaust gas passes through the exhaust gas side of the second reheater (8) and the exhaust gas side of the third reheater (9) and is discharged through the high temperature side of the first heat exchanger (19); the SOFC stack (4) is connected to the second DC to AC inverter (5) by a cable, and the second DC to AC inverter (5) is connected to the power grid to form a circuit loop; The SOEC hydrogen production unit comprises an electric heater (20), a SOEC stack (21), an AC to DC inverter (22), a fifth regenerator (23), a sixth regenerator (24), a seventh regenerator (25), an eighth regenerator (26), a ninth regenerator (28), a second three-way mixing valve (27), a third fan (29), a fourth fan (31), a second water pump (30), a second oxygen storage tank (32), a third oxygen storage tank (33), a second hydrogen storage tank (34), and a third hydrogen storage tank (39). , a second water storage tank (35), a third water storage tank (40), a condenser (36), a steam-water separator (37) and a dryer (38); wherein the second water storage tank (35), the second water pump (30), the fuel side of the sixth regenerator (24), and the fuel side of the seventh regenerator (25) are sequentially connected through pipelines and connected to the pipeline connected by the second hydrogen storage tank (34), the third fan (29), and the fuel side of the ninth regenerator (28) at the second three-way mixing valve (27), and pass through the electric heater (20) to pass into S The fuel inlet end of the OEC stack (21) and the fuel outlet end of the SOEC stack (21) are connected to the third hydrogen storage tank (39) after passing through the tail gas side of the seventh regenerator (25), the tail gas side of the eighth regenerator (26), the condenser (36), the steam-water separator (37), and the dryer (38) in sequence to form a fuel closed pipeline. The water separated by the steam-water separator (37) enters the third water storage tank (40) for storage; the oxygen passes through the second oxygen storage tank (32), the fourth fan (31), the eighth regenerator (26) in sequence. ) oxygen side, the fifth reheater (23) oxygen side, the electric heater (20) and then enter the oxygen inlet end of the SOEC stack (21); the oxygen outlet end of the SOEC stack (21) is connected to the third oxygen storage tank (33) through the exhaust gas side of the fifth reheater (23), the exhaust gas side of the sixth reheater (24) and the exhaust gas side of the ninth reheater (28); the SOEC stack (21) is connected to the AC to DC inverter (22) through a cable, and the AC to DC inverter (22) is connected to the power grid to form a circuit loop.

2. The method for operating the system according to claim 1, characterized in that: When the photovoltaic power generation unit operates normally, the solar photovoltaic array (1) converts solar energy into electrical energy, the DC / DC converter (2) converts the direct current output by the solar cell into stable direct current of different pressures, thereby achieving maximum power point tracking, and the first direct current to alternating current inverter (3) converts the direct current into alternating current and then connects it to the power grid; When the SOFC power generation unit is operating normally, the electric energy generated by the SOFC stack (4) is converted into AC power by the second DC to AC inverter (5) and then connected to the power grid; the second fan (14) is turned on to draw out the oxygen in the first oxygen storage tank (15), and the oxygen is successively passed through the oxygen side of the third reheater (9) and the oxygen side of the first reheater (7) to absorb heat, and then enters the SOFC stack (4) from the oxygen inlet end of the SOFC stack (4), and then enters the combustion chamber (6) from the oxygen outlet end of the SOFC stack (4); the first fan (12) is turned on to draw out the hydrogen in the first hydrogen storage tank (16) and absorb heat through the fuel side of the fourth reheater (11); at the same time, the speed of the first water pump (13) is adjusted to take water from the first water storage tank (17) and introduce it into the second reheater The fuel side of the regenerator (8) absorbs heat and evaporates to obtain water vapor, which is then mixed with hydrogen in a first three-way mixing valve (10). The mixed gas flows into the SOFC stack (4) from the fuel inlet end of the SOFC stack (4) to react and release electrical energy. The high-temperature tail gas after the reaction is passed into the combustion chamber (6) to catalytically burn the excess hydrogen in the stack to obtain a higher-temperature tail gas. After the tail gas is discharged from the combustion chamber (6), a portion of the tail gas is sequentially released through the tail gas side of the first regenerator (7) and the tail gas side of the fourth regenerator (11), and the other portion is sequentially released through the tail gas side of the second regenerator (8) and the tail gas side of the third regenerator (9). The two portions of tail gas are mixed in the first mixer (18) and then passed through the high-temperature side of the first heat exchanger (19) for heat supply. When the SOEC hydrogen production unit is operating normally, the electric energy from the power grid is converted into direct current through the AC to DC inverter (22) and then connected to the SOEC stack (21) for reaction; the fourth fan (31) is turned on to draw out the oxygen in the second oxygen storage tank (32), and the oxygen inlet end of the SOEC stack (21) is entered after passing through the oxygen side of the eighth reheater (26), the oxygen side of the fifth reheater (23), and the electric heater (20); the oxygen-enriched air at the air pole outlet of the SOEC stack (21) passes through the tail gas side of the fifth reheater (23), the tail gas side of the sixth reheater (24), and the tail gas side of the ninth reheater (28) in turn to preheat the reaction gas; the oxygen-enriched air after waste heat recovery is transported to the third oxygen storage tank (33) for storage; the third fan (29) is turned on to draw out the hydrogen in the second hydrogen storage tank (34) and pass through the oxygen side of the fifth reheater (23), the tail gas side of the sixth reheater (24), and the tail gas side of the ninth reheater (28) The fuel side is preheated through the ninth regenerator (28), and the second water pump (30) is turned on at the same time. The speed of the second water pump (30) is adjusted, and water is taken from the second water storage tank (35) and introduced into the fuel side of the sixth regenerator (24) and the fuel side of the seventh regenerator (25) for heat absorption, and then mixed with hydrogen in the second three-way mixing valve (27). The mixed gas passes through the electric heater (20) and flows into the SOEC stack (21) to absorb external electrical energy for electrolysis. The hydrogen generated by the chemical reaction and the hydrogen input from the front end of the SOEC stack (21) are reheated by the seventh regenerator (25) and the eighth regenerator (26) to reheat the unreacted gas, and finally enter the third hydrogen storage tank (39) for storage after passing through the condenser (36), the steam-water separator (37), and the dryer (38). The separated condensed water is stored in the third water storage tank (40).

3. The operating method according to claim 2, characterized in that: When the electricity generated by photovoltaic power generation exceeds the user's electricity demand, the SOFC power generation unit maintains ultra-low load operation without stopping, and the SOEC hydrogen production unit operates at a high load, and the excess electricity is converted into hydrogen and stored through the SOEC hydrogen production unit; when the electricity generated by photovoltaic power generation is less than the user's electricity demand, the SOEC hydrogen production unit maintains ultra-low load operation without stopping, and the SOFC power generation unit operates at a high load, generating electricity through hydrogen fuel to maintain the user's electricity demand, and using high-temperature exhaust gas for heating.

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