Hydraulic compressed air energy storage-thermal power pipe network operation system and method

Abstract

Disclosed in the present invention are a hydraulic compressed air energy storage-thermal power pipe network operation system and method. The system comprises a compressed air energy storage system, a battery charging and swapping system, a distributed photovoltaic power generation system, a power distribution network system, wherein the compressed air energy storage system, the battery charging and swapping system and the distributed photovoltaic power generation system are connected to the power distribution network system. The system and method can avoid adverse effects of a surge in a charging load of an electric vehicle and photovoltaic grid connection on the voltage stability, transient stability and frequency stability of a power distribution network system.

Description

A hydraulic compressed air energy storage-heating pipe network operation system and method Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a hydraulic compressed air energy storage-thermal pipe network operation system and method. Background Art

[0002] The explosive growth of electric vehicles has increased grid load. The simultaneous charging of electric vehicles exacerbates regional grid peak-to-valley variations, posing new challenges to grid regulation. Considering that renewable energy sources such as photovoltaics will gradually become the primary power source in the future, the lack of output from distributed photovoltaics at night, coupled with the surge in electric vehicle charging loads, will significantly challenge evening peak power balance and the safe and stable operation of the system. The grid-connected operation of distributed photovoltaics and electric vehicles will significantly impact the voltage, transient, and frequency stability of the distribution network, becoming a key challenge in the construction of new power systems.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a hydraulic compressed air energy storage-thermal pipe network operation system and method. The system and method can avoid the adverse effects of the surge in electric vehicle charging load and photovoltaic grid connection on the voltage stability, transient stability and frequency stability of the distribution network system.

[0005] To achieve the above-mentioned objectives, the present invention discloses a hydraulic compressed air energy storage-thermal pipeline operation system, which includes a compressed air energy storage system, a charging and swapping system, a distributed photovoltaic power generation system and a distribution network system. The compressed air energy storage system, the charging and swapping system and the distributed photovoltaic power generation system are connected to the distribution network system.

[0006] The present invention discloses a method for operating a hydraulic compressed air energy storage-heating network, comprising the following steps:

[0007] During the off-peak period at night, the compressed air energy storage system and the charging and swapping system absorb the off-peak electricity of the distribution network system and convert the electrical energy into air pressure energy and battery energy of electric vehicles;

[0008] During the parity electricity period, peak electricity period and peak period, the compressed air energy storage system and distributed photovoltaic system generate electricity to charge the electric vehicles of the charging and swapping system or release electricity to the distribution network system. The charging and swapping system allows electric vehicles to replace batteries at any time.

[0009] In the compressed air energy storage system, from 11 p.m. to 7 a.m. the next day, the electric energy output by the distribution network system is used to drive the energy storage pump to pump water from the water tank into the thermal pipe. The gas in the thermal pipe is compressed and the electrical energy is converted into air pressure energy and stored.

[0010] In the compressed air energy storage system, from 7 a.m. to 8 a.m. the next day, the water in the thermal pipe enters the water tank through the turbine. During this process, the turbine continuously discharges and releases electrical energy to the distribution network system.

[0011] In the compressed air energy storage system, from 8 a.m. to 11:30 a.m. the next day, the water in the thermal pipe enters the water tank through the turbine. During this process, the turbine continuously discharges, releasing electrical energy to the distribution network system. The distributed photovoltaic system outputs electrical energy, releasing electrical energy to the distribution network system.

[0012] In the compressed air energy storage system, from 11:30 to 18:30 the next day, the electric energy output by the distributed photovoltaic system and the distribution network system is used to drive the energy storage pump to pump water from the water tank into the thermal pipe. The gas in the thermal pipe is compressed and the electrical energy is converted into air pressure energy and stored.

[0013] In the compressed air energy storage system, from 18:30 to 23:00 the next day, the water in the thermal pipe enters the water tank through the turbine. During this process, the turbine continuously discharges and supplies power to the distribution network system.

[0014] The present invention has the following beneficial effects:

[0015] During specific operation, the hydraulic compressed air energy storage-thermal pipe network operation system and method described in the present invention are rationally planned according to the characteristics of distributed photovoltaic power generation and electric vehicles. During the low-power phase at night, the compressed air energy storage system and the charging and battery swapping system absorb the off-peak electricity of the distribution network system. At other times, the compressed air energy storage system and the distributed photovoltaic system are used to generate electricity to supply power to the electric vehicles of the charging and battery swapping system and the distribution network system, so as to avoid the adverse effects of the surge in electric vehicle charging load and the adverse effects on the voltage stability, transient stability and frequency stability of the distribution network system after the photovoltaic grid is connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural diagram of a hydraulic compressed air energy storage system;

[0017] Figure 2 is a schematic diagram of the hydraulic compressed air energy storage-heating network operation system;

[0018] FIG3 is a flow chart of the method of the present invention.

[0019] Among them, 1 is the thermal pipe, 2 is the buffer tank, 3 is the liquid level gauge, 4 is the first pressure gauge, 5 is the second pressure gauge, 6 is the first electric valve, 7 is the second electric valve, 8 is the third electric valve, 9 is the fourth electric valve, 10 is the first flow meter, 11 is the second flow meter, 12 is the soft connection head, 13 is the energy storage pump, 14 is the electric motor, 15 is the turbine, 16 is the generator, 17 is the plug, 18 is the water tank, 19 is the host computer, and 20 is the integrated control cabinet. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0021] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0022] 1 , the compressed air energy storage system of the present invention includes a thermal pipeline 1, a buffer tank 2, a liquid level gauge 3, a first pressure gauge 4, a second pressure gauge 5, a first electric valve 6, a second electric valve 7, a third electric valve 8, a fourth electric valve 9, a first flow meter 10, a second flow meter 11, a flexible connector 12, an energy storage pump 13, a motor 14, a turbine 15, a generator 16, a plug 17, a water tank 18, a host computer 19, and an integrated control cabinet 20.

[0023] One end of the thermal pipe 1 is provided with a plug 17, and the other end of the thermal pipe 1 is connected to the buffer tank 2, which is connected to the water tank 18 via the first electric valve 6, the first flow meter 10 and the turbine 15; the buffer tank 2 is connected to the water tank 18 via the second electric valve 7; the buffer tank 2 is connected to the water tank 18 via the first pressure gauge 4, the third electric valve 8, the soft connection reducer 12, the energy storage pump 13, the second pressure gauge 5, the second flow meter 11 and the fourth electric valve 9, and a liquid level gauge 3 is provided on the buffer tank 2.

[0024] The host computer 19 is connected to the integrated control cabinet 20 , and the integrated control cabinet 20 is connected to the motor 14 , the generator 16 , the first electric valve 6 , the second electric valve 7 , the third electric valve 8 , the fourth electric valve 9 , the liquid level meter 3 , the first pressure gauge 4 and the second pressure gauge 5 .

[0025] Before energy storage, a certain amount of gas space is retained in thermal pipe 1, and pressurized nitrogen gas is injected into the pipe to establish an initial pressure. Based on previous theoretical research, the system's energy density is maximized when the ratio of the initial gas volume to the water volume is between 0.5 and 0.6.

[0026] During the energy storage process, the motor 14 absorbs photovoltaic or grid off-peak electricity to drive the energy storage pump 13, pressurizing the water in the water tank 18 and injecting it into the thermal pipe 1. The gas volume in the thermal pipe 1 decreases and the air pressure continues to increase. When the air pressure in the thermal pipe 1 reaches 1.0 MPa, energy storage is stopped (lower than the design pressure level of the thermal pipe 1 of 1.6 MPa), and the electrical energy is converted into air pressure energy and stored in the thermal pipe 1. To avoid air corrosion to the pipeline, nitrogen is used as the gas medium.

[0027] During power generation, first electric valve 6 is opened, causing the gas in thermal pipe 1 to expand. The high-pressure water drives turbine 15, driving generator 16 to generate electricity, converting the air's pressure energy into electrical energy, which is then released to the power grid or other power-consuming facilities within the industrial park. As the volume of gas in thermal pipe 1 increases and the air pressure gradually decreases, the volume of water in thermal pipe 1 gradually decreases, and the liquid level in water tank 18 gradually rises. The power generation process ends when the air pressure in thermal pipe 1 drops to a set value or the liquid level in water tank 18 reaches a set value.

[0028] Referring to Figure 2, the hydraulic compressed air energy storage-thermal pipeline operation system includes a compressed air energy storage system, a charging and swapping system, a distributed photovoltaic power generation system and a distribution network system. The compressed air energy storage system, the charging and swapping system and the distributed photovoltaic power generation system are connected to the distribution network system.

[0029] The hydraulic compressed air energy storage-heating network operation method of the present invention comprises the following steps:

[0030] During the off-peak electricity period at night (8 hours), the compressed air energy storage system and charging and swapping system absorb the off-peak electricity of the distribution network and convert the electrical energy into air pressure energy and battery energy of electric vehicles.

[0031] During the parity electricity period, peak electricity period and peak period, the compressed air energy storage system and distributed photovoltaic system generate electricity to charge the electric vehicles of the charging and swapping system or release electricity to the power grid. The charging and swapping system allows electric vehicles to replace batteries at any time.

[0032] Referring to Figure 3, the working process of the compressed air energy storage system is as follows:

[0033] 8 hours of water pumping during valley period + 3.5 hours of power generation during peak period for the grid + 1 hour of power generation during flat period for the grid + 8 hours of solar flat period water pumping for energy storage + 4.5 hours of power generation during evening peak period for the grid

[0034] 8 hours of pumping during valley period and 8 hours of pumping during valley period (6 hours of photovoltaic power generation and 2 hours of energy storage during valley period): From 11:00 PM to 7:00 AM the next day (8 hours in duration), during the photovoltaic power generation period, the motor 14 drives the energy storage pump 13 to pump water from the water tank 18 into the thermal pipe 1. The gas in the thermal pipe 1 is compressed, and the pressure gradually rises from 0.4 MPa to 1 MPa. The electrical energy is converted into air pressure energy and stored.

[0035] The company supplies power to the grid for 3.5 hours during peak hours, 1 hour during flat hours, and 4.5 hours during evening peak hours, all of which enable power generation within 4.5 hours.

[0036] This method allows for two charges and two discharges; the parameters of the energy storage pump 13 remain unchanged. The flow rate of the energy storage pump 13 is 0.35 cubic meters per second, the weighted average head of the energy storage pump 13 is 0.75 MPa, the power of the energy storage pump 13 is 300 kW, and the stored energy is 2400 kWh, resulting in 4800 kWh of energy after two charges.

[0037] The two discharges are assumed to last 4.5 hours. The morning peak is only 3.5 hours, which is less than the designed 4.5 hours. Therefore, the one-hour morning flat period is considered as generating time. The maximum head of turbine 15 is 1.0 MPa, the rated head of turbine 15 is 0.7 MPa, the weighted average flow rate of turbine 15 is 0.19 cubic meters per second, and the weighted average flow rate of turbine 15 is 0.67 cubic meters per second. The power of generator 16 is 371 kW, the efficiency of generator 16 is 0.92, the power of turbine 15 is 402 kW, and the total power generation is 3392 kWh.

[0038] Under this method, there is no investment in charging and swapping facilities, and accordingly there is no income from charging and swapping facilities.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A hydraulic compressed air energy storage-heating pipe network operation system, characterized in that: It includes a compressed air energy storage system, a charging and swapping system, a distributed photovoltaic power generation system and a distribution network system. The compressed air energy storage system, the charging and swapping system and the distributed photovoltaic power generation system are connected to the distribution network system, and adopts an operating mode of 8 hours of valley pumping + 3.5 hours of peak power generation for the grid + 1 hour of flat power generation for the grid + 8 hours of photovoltaic pumping energy storage + 4.5 hours of evening peak power generation for the grid.

2. A method for operating a hydraulic compressed air energy storage-heating network, characterized in that: The hydraulic compressed air energy storage-heating pipe network operation system according to claim 1 comprises the following steps: During the off-peak period at night, the compressed air energy storage system and the charging and swapping system absorb the off-peak electricity of the distribution network system and convert the electrical energy into air pressure energy and battery energy of electric vehicles; During the parity electricity period, peak electricity period and peak period, the compressed air energy storage system and distributed photovoltaic system generate electricity to charge the electric vehicles of the charging and swapping system or release electricity to the distribution network system. The charging and swapping system allows electric vehicles to replace batteries at any time.

3. The hydraulic compressed air energy storage-heating network operation method according to claim 2, characterized in that: In the compressed air energy storage system, from 11 p.m. to 7 a.m. the next day, the electric energy output by the distribution network system is used to drive the energy storage pump (13) to pump water from the water storage tank (18) into the thermal pipe (1). The gas in the thermal pipe (1) is compressed, and the electric energy is converted into air pressure energy and stored.

4. The hydraulic compressed air energy storage-heating network operation method according to claim 2, characterized in that: In the compressed air energy storage system, from 7 o'clock to 8 o'clock the next day, the water in the thermal pipe (1) enters the water storage tank (18) through the turbine (15). During this process, the turbine (15) continuously discharges and releases electric energy to the distribution network system.

5. The hydraulic compressed air energy storage-heating network operation method according to claim 2, characterized in that: In the compressed air energy storage system, from 8:00 to 11:30 the next day, the water in the thermal pipe (1) enters the water storage tank (18) through the turbine (15). During this process, the turbine (15) continuously discharges electricity, releasing electrical energy to the distribution network system. The electrical energy output by the distributed photovoltaic system also releases electrical energy to the distribution network system.

6. The hydraulic compressed air energy storage-heating network operation method according to claim 2, characterized in that: In the compressed air energy storage system, from 11:30 to 18:30 the next day, the electric energy output by the distributed photovoltaic system and the distribution network system is used, and the motor (14) drives the energy storage pump (13) to pump water from the water storage tank (18) into the thermal pipe (1). The gas in the thermal pipe (1) is compressed, and the electric energy is converted into air pressure energy and stored.

7. The hydraulic compressed air energy storage-heating network operation method according to claim 2, characterized in that: In the compressed air energy storage system, from 18:30 to 23:00 the next day, the water in the thermal pipe (1) enters the water storage tank (18) through the turbine (15). During this process, the turbine (15) continuously discharges to supply power to the distribution network system.

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