Power adjusting method based on buffer pool compressed air energy storage and energy storage system

Abstract

The invention provides a power regulation method based on buffer pool compressed air energy storage and an energy storage system, and belongs to the field of power grid dispatching. A comprehensive energy management and power control system receives a real-time power dispatching instruction sent by a power grid dispatching center; the energy storage capacity of the energy storage system and the allowable power change range of the energy storage system are fed back to a power grid dispatching center, so that the power grid dispatching center can conveniently plan and dispatch the compressed air energy storage system, and meanwhile, the comprehensive energy management and power control system receives a signal of a sensor of an air storage chamber of the compressed air energy storage system; and calculating the energy storage capacity of the compressed air energy storage system and the fluctuation power adjustment available power consumption and the frequency modulation available power consumption corresponding to the water level of the buffer pool. The comprehensive energy management and power control system sends a peak regulation power instruction to the compressed air energy storage power control system, and sends a power instruction and a frequency modulation function enable signal to the water pump power control system and the water turbine power control system. The method can provide frequency modulation response for the power grid and stabilize new energy output fluctuation.

Description

Technical Field

[0001] The present invention belongs to the field of electric energy storage systems, and in particular relates to a power regulation method and an energy storage system based on compressed air energy storage in a buffer water tank. Background Art

[0002] The constant pressure compressed air energy storage system maintains the constant air pressure in the air storage chamber through the hydraulic pressure generated by the height difference of the water column, improves the working efficiency of the compressor and the expander, improves the circulation efficiency of the energy storage system, and replaces the water and air in the air storage chamber. The volume of the discharged air is filled with water, and the compressed air entering the air storage chamber discharges the water, which improves the utilization rate of the air storage chamber. The constant pressure compressed air energy storage system will be the key development direction of the compressed air energy storage system in the future. Chinese patent application CN202210226000.8 proposes a tunnel inclined shaft heat storage isobaric compressed air hybrid energy storage system, in which the air storage chamber is built deep underground. In order to achieve high energy storage density, it is necessary to meet the large height difference between the upper reservoir and the air storage reservoir, and maintain high-pressure compressed air through high water head. Building an upper reservoir on the ground and a gas storage reservoir underground can solve the need for high water head. However, the excavation of deep underground space faces a series of safety and cost issues such as uncertain and unstable geological structure and uncertain aquifer excavation cost, which requires further technical development.

[0003] In view of this, Chinese patent application CN202123066536.8 proposes an isobaric compressed air energy storage system relying on natural conditions. However, if you choose to build an upper reservoir on the mountain, you need to ensure that the capacity of the upper reservoir is equivalent to the capacity of the air storage chamber. It is difficult to meet both the high head and the large capacity of the upper reservoir site selection conditions. Even if such conditions are met, the development of pumped storage will generally be given priority.

[0004] In addition, with the continuous increase in the proportion of new energy, the demand for smoothing the fluctuation of new energy output and grid frequency regulation is gradually increasing. However, the energy storage and release of the compressed air energy storage system are realized through compressors and expanders. Frequent changes in operating conditions and power operation endanger the stability of the system and increase the possibility of surge. If the operation deviates from the rated operating conditions, the cycle efficiency of the compressed air energy storage system will be greatly reduced. Therefore, the compressed air energy storage system is suitable for operating under rated operating conditions and nearby ranges, and is not suitable for frequent changes in operating conditions and flexible power adjustment operation modes. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a power regulation method and energy storage system based on compressed air energy storage in a buffer water tank; the integrated energy management and power control system receives instructions from the power grid dispatching center, controls the compressor, expander, water pump, and turbine in the system, and the compressor and expander work at rated conditions and the adjacent high-efficiency range, and only undertake the peak-shaving function, and do not provide a flexible power regulation function for smoothing the output fluctuations of new energy and the frequency modulation of the power grid, thereby avoiding the problems of reduced stability and reduced cycle efficiency; within the allowable range of the water level in the buffer water tank, the water pump and the turbine serve as flexible power regulation power sources to smooth the output fluctuations of new energy and respond to the power demand of the frequency modulation of the power grid. The buffer water tank is located at a higher altitude, or is realized by compressed air auxiliary pressurization in the pressure regulating chamber. The volume of the buffer water tank is smaller than the volume of the air storage chamber, and the water required for the air storage chamber is stored in another reservoir.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A power regulation method based on compressed air energy storage in a buffer water tank, a compressed air energy storage system is constructed based on compressed air energy storage in a buffer water tank, the energy storage system comprises a first compressor, an expander, a water pump and a turbine system, a buffer water tank, a water reservoir, and an air storage chamber; the buffer water tank is connected to the air storage chamber, the buffer water tank and the water reservoir are connected, and a water pump and a turbine system are arranged between the buffer water tank and the water reservoir; the air storage chamber is connected to the first compressor; the air storage chamber stores compressed air and water at the same time, the compressed air is located at the upper part of the air storage chamber, and the water is located at the bottom of the air storage chamber, and is communicated with the water in the buffer water tank through a pipeline; the air storage chamber is connected to the expander; the buffer water tank is arranged at a high place to maintain the water pressure, thereby maintaining the pressure of the air storage chamber; the water reservoir is built at a low place, and the height of the water reservoir is lower than the buffer water tank;

[0008] The integrated energy management and power control system is used to receive real-time power instructions from the power grid dispatching center, and to feed back the stored energy of the compressed air energy storage system and the power variation range allowed by the compressed air energy storage system to the power grid dispatching center, so as to facilitate planning and dispatching by the power grid dispatching center. At the same time, the integrated energy management and power control system receives the signal of the sensor of the air storage chamber of the compressed air energy storage system and the signal of the water level sensor of the buffer water tank, obtains the pressure and water level of the air storage chamber and the water level of the buffer water tank, calculates the stored energy of the compressed air energy storage system and the fluctuating power regulation available power and frequency modulation available power corresponding to the water level of the buffer water tank; the integrated energy management and power control system is connected to the compressed air energy storage power control system, the water pump power control system and the turbine power control system, sends peak shaving instructions to the compressed air energy storage power control system, sends power instructions to the water pump power control system and the turbine power control system, and sends frequency modulation function enable signals to the water pump power control system and the turbine power control system, so as to realize power regulation.

[0009] Preferably, the compressed air energy storage power control system is connected to the first motor of the first compressor, the compressor guide vanes, and the expander motor and expander guide vanes, and controls the energy storage and power generation power of the energy storage system by controlling the first motor and the compressor guide vanes.

[0010] Preferably, the turbine power control system controls the water flow by controlling the guide vanes of the mixed flow turbine or the nozzles of the impulse turbine, and controls the power of the pump turbine by controlling the working condition of the motor; the pump power control system and the turbine power control system receive the grid frequency, and automatically adjust the pump power and the turbine power according to the changes in the grid frequency to modulate the grid frequency.

[0011] Preferably, the operating conditions of the water pump and turbine system are controlled by the water level of the buffer tank and the response power required by the power grid. The buffer tank has an upper water level limit, a lower water level limit and a water level center line. The water level of the buffer tank is controlled by the water pump and turbine system to be close to the water level center line. When the water level exceeds the upper water level line, the water volume and power generation of the turbine are increased, and the water volume and energy consumption of the pump are reduced, so that the water in the buffer tank enters the reservoir and the water level of the buffer tank is lowered; when the water level is lower than the lower water level line, the water volume and power generation of the turbine are reduced, and the water volume and energy consumption of the pump are increased, so that the water in the reservoir enters the buffer tank, the water level of the buffer tank is increased, and the water level of the buffer tank is controlled at the water level center line; the water level in the buffer tank is controlled at the water level center line, and the dynamic power required by the power grid is flexibly responded to by adjusting the power of the water pump and the turbine.

[0012] Preferably, during the energy storage process of the compressed air energy storage system, the first compressor compresses the external air into the air storage chamber, and the same volume of water enters the buffer water tank, and the water in the buffer water tank enters the reservoir; during the power generation process, the compressed air is expanded to the atmosphere through the expander, and the expander drives the first generator to generate electricity. At the same time, the same volume of water enters the air storage chamber through the buffer water tank.

[0013] Preferably, the water pump and turbine system includes a first pump-turbine and a second pump-turbine, and is respectively connected to a second motor and a third motor, both of which operate in a rotating standby state, and water circulates between the second pump-turbine and the first pump-turbine to control the net inflow or outflow of water between the buffer tank and the reservoir, thereby providing flexible power response to the power grid.

[0014] The present invention also provides an energy storage system based on compressed air energy storage in a buffer water tank, the energy storage system is a compressed air energy storage system, including a first compressor, an expander, a water pump and a turbine system, a buffer water tank, a water reservoir, and an air storage chamber; the buffer water tank is connected to the air storage chamber, the buffer water tank and the water reservoir are connected, and a water pump and a turbine system are arranged between the buffer water tank and the water reservoir; the air storage chamber stores compressed air and water at the same time, the compressed air is located at the upper part of the air storage chamber, and the water is located at the bottom of the air storage chamber, which is communicated with the water in the buffer water tank through a pipeline; the air storage chamber is connected to the expander; the buffer water tank is arranged at a high place to maintain the water pressure, so as to keep the storage The pressure of the air chamber; the water reservoir is built at a low place, and the height of the water reservoir is lower than the buffer water tank; when storing energy, the first compressor injects air into the air storage chamber, and the water in the air storage chamber is injected into the buffer water tank through the pipeline connected to the buffer water tank, and flows to the water pump and turbine system through the buffer water tank, and drives the turbine in the water pump and turbine system to generate electricity, and then enters the water reservoir; in this process, the water head between the buffer water tank and the air storage chamber is a constant pressure maintained by the air storage chamber; when releasing energy, the water pump in the water pump and turbine system pumps the water of the water reservoir to the buffer water tank, and injects it into the air storage chamber through the connecting pipeline, and discharges the air from the air storage chamber to drive the expander to do work.

[0015] Preferably, the water pump and turbine system includes a first pump-turbine and a second pump-turbine, and are respectively connected to a second motor and a third motor. When the compressed air energy storage system is not working, the second pump-turbine works in a water pump mode and the first pump-turbine works in a water turbine mode, and both work in a rotating standby state; or a flexible power response is performed to the power grid. When the power required by the power grid is 0, water circulates between the second pump-turbine and the first pump-turbine, and the water is pumped into the second pump-turbine and then pressed into the first pump-turbine to generate electricity. The third motor works in a motor condition, and the second motor works in a generator condition. While the water is self-circulating in the second pump-turbine and the first pump-turbine, a portion of the water is transferred from the buffer tank to the reservoir to generate electricity, thereby compensating for energy loss and making the generating power of the second motor the same as the electric power of the third motor.

[0016] Preferably, the water pump and turbine system is composed of a plurality of impulse turbines and mixed flow pump turbines, and the electric generator is connected to the mixed flow pump turbine; when the water pumping amount of the mixed flow pump turbine is higher than the water generating amount of the impulse turbine, water enters the buffer tank from the reservoir, the power of the electric generator is higher than the power of the second generator, and the water pump and turbine system consumes power from the power grid; conversely, when the water generating amount of the impulse turbine is higher than the water pumping amount of the mixed flow pump turbine, water enters the reservoir from the buffer tank, the power of the second generator is higher than the power of the electric generator, and the water pump and turbine system composed of the impulse turbine and the mixed flow pump turbine sends power to the power grid.

[0017] Preferably, the water pump and turbine system is a water pump turbine, which is connected to the reservoir and the buffer tank through a pipeline.

[0018] Preferably, when the height difference between the buffer water tank and the air storage chamber is lower than the water head required to maintain the rated constant pressure of the air storage chamber, the buffer water tank is made into a closed pressure regulating chamber, the air pressure in the pressure regulating chamber is maintained by a compressor, and the constant pressure of the air storage chamber is maintained by both air pressure and water pressure.

[0019] Preferably, the low place is flat land, low hills or gentle slopes.

[0020] Preferably, if the capacity of the buffer water tank is large, the power of the water pump and the turbine can be decoupled from the power of the expander and the compressor and used to provide higher flexibility.

[0021] Preferably, the compressed air for maintaining the pressure in the pressure regulating chamber can be provided by a set of independent air compressors, or can be taken from the compressor in the compressed air energy storage subsystem.

[0022] Beneficial effects:

[0023] (1) The output of renewable energy is highly volatile. The power grid not only needs the peak-shaving function of energy storage, but also needs a flexible energy storage power source to smooth out the fluctuation of renewable energy output and provide frequency regulation services for the power grid. Compressors and expanders are not suitable for frequent power changes and operating conditions. Water pumps and turbines are used to pump and release water between the upper buffer tank and the lower reservoir to achieve flexible power regulation, smooth out the fluctuation of renewable energy output, and provide frequency regulation services for the power grid. At the same time, the upper reservoir maintains the internal air pressure of the gas storage chamber stable, and the water level needs to fluctuate within an acceptable range. The power and energy output limits of the flexible power source are controlled by the integrated energy management and power control system. Compressors and expanders respond to peak-shaving needs, and water pumps and turbines provide flexible power regulation to achieve peak-shaving, frequency regulation, and smooth out the fluctuation of renewable energy output, supporting the operation of the power grid.

[0024] Even if the compressed air energy storage system is not in the operating condition of energy storage or power generation, the water pump and turbine can work in the rotating standby state. Water enters the turbine from the water pump. The flow difference between the water pump and the turbine corresponds to the net inflow / outflow of the upper and lower reservoirs, which corresponds to the power absorbed / released from the power grid respectively. It can provide frequency regulation response for the power grid and smooth out the fluctuations of new energy output. The power responds quickly and can pass through zero.

[0025] (2) The compressed air energy storage system based on water pressure has the advantages of high circulation efficiency and large energy storage capacity. In order to achieve high energy storage density, it is necessary to meet the large height difference between the upper reservoir and the gas storage reservoir, and maintain high-pressure compressed air through high water head. Building an upper reservoir on the ground and building a gas storage reservoir underground can solve the need for high water head. However, the excavation of deep underground space faces a series of safety and cost issues such as uncertain and unstable geological structure, aquifers, and uncertain excavation costs, which require further technical development. If you choose to build an upper reservoir on the mountain, you need to ensure that the capacity of the upper reservoir is equivalent to that of the gas storage chamber. It is difficult to meet both the high water head and the large-capacity upper reservoir site selection conditions. Even if such conditions are met, the development of pumped storage will generally be prioritized. This invention decouples the volume of the upper reservoir from the volume of the gas storage chamber by setting up a buffer pool on the mountain. The buffer pool is only responsible for providing high water head and maintaining the pressure of the gas storage chamber, and does not need to be equivalent to the volume of the gas storage chamber. Another reservoir is built on flat land, low hills or gentle slopes. The height of the reservoir is lower than the buffer pool. It is connected to the buffer pool through a pump turbine to provide water that matches the volume of the air storage chamber and provides water for the air storage chamber. There are many geographical sites that meet such conditions, and they will not conflict with the site selection of pumped storage. A large number of pumped water and compressed air hybrid energy storage systems based on buffer pools can be built.

[0026] (3) Compressors and expanders are most efficient at rated or specified operating conditions. Deviating from this operating range will significantly reduce cycle efficiency, lose electricity, and increase operating costs. Frequent power changes will also reduce efficiency and lose electricity. In addition, when the flow rate drops to a certain level, there is a risk of surge, which affects the life and reliability of the unit. Therefore, compressors and expanders are not suitable for frequency regulation and tracking and responding to fluctuations in renewable energy output. There is a height difference between the buffer tank and the reservoir, which are connected by a pump / turbine. The pump and turbine are suitable for wide power range fluctuations, and are used to track and respond to fluctuations in renewable energy output, as well as quickly respond to grid frequency regulation requirements. Therefore, the buffer tank provides dynamic power response and frequency regulation functions while maintaining the pressure in the air storage chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of an energy storage system based on compressed air energy storage in a buffer water tank according to an embodiment of the present invention;

[0028] FIG2 is a schematic diagram of a system using multiple Francis pump turbines according to an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of a system using a mixed flow pump turbine and an impulse turbine according to an embodiment of the present invention;

[0030] FIG4 is a schematic diagram of a system using a pressure buffer tank according to an embodiment of the present invention;

[0031] FIG5 is a flow chart of a power regulation method based on compressed air energy storage in a buffer tank according to an embodiment of the present invention.

[0032] Among them, the figure markings are: 101 is a buffer water tank, 102 is a water reservoir, 103 is an air storage chamber, 104 is a first pipeline, 105 is a second pipeline, 106 is a third pipeline, 107 is a pump-turbine, 108 is a first motor, 109 is a first compressor, 110 is a first motor, 111 is an expander, 112 is a first generator, 113 is a first control valve, 114 is a second control valve, 115 is a third control valve, 116 is a fourth control valve, 201 is a first pump-turbine, 202 is a second pump-turbine, 203 is a second motor, 204 is a third motor, 301 is an impulse turbine, 302 is a mixed flow pump-turbine, 303 is a second generator, 304 is an electric generator, 305 is a water outlet, 401 is a closed pressure regulating chamber, 402 is a second motor, and 403 is a second compressor. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] like Figure 1 As shown, the energy storage system based on compressed air energy storage in a buffer tank according to an embodiment of the present invention includes a buffer tank 101, a reservoir 102, an air storage chamber 103, a first pipeline 104, a second pipeline 105, a third pipeline 106, a pump turbine 107, a first motor 108, a first compressor 109, a first motor 110, an expander 111, a first generator 112, a first control valve 113, a second control valve 114, a third control valve 115, and a fourth control valve 116.

[0035] The buffer water tank 101 is connected to the air storage chamber 103 through a first pipe 104, and the buffer water tank 101 and the water reservoir 102 are connected through a second pipe 105, a third pipe 106 and a pump turbine 107, and a first motor 108 is connected to the pump turbine 107. The air storage chamber 103 stores compressed air and water at the same time, the compressed air is located at the upper part of the air storage chamber 103, and the water is located at the bottom of the air storage chamber 103, which is connected to the water in the buffer water tank 101 through the first pipe 104. The buffer water tank 101 is higher than the air storage chamber 103, and the corresponding water column height maintains the pressure of the compressed air in the air storage chamber 103.

[0036] During the energy storage process, the first control valve 113, the second control valve 114, and the fourth control valve 116 are opened, and the third control valve 115 is closed. The first motor 110 drives the first compressor 109 to compress the external air into the air storage chamber 103, and the same volume of water enters the buffer tank 101 through the first pipe 104. Since the volume of the buffer tank 101 is limited, it is impossible to completely receive the water discharged from all the air storage chambers 103. Therefore, when the air storage chamber 103 presses water into the buffer tank 101, the buffer tank 101 is also buffered. The water in the buffer tank 101 enters the reservoir 102 through the second pipe 105, the pump turbine 107, and the third pipe 106. The height of the reservoir 102 is lower than the buffer tank 101. The pump turbine 107 drives the first motor 108 to generate electricity and feed it back to the power grid. During the power generation process, the first control valve 113, the second control valve 114, and the fourth control valve 116 are opened, and the third control valve 115 is closed. The compressed air in the air storage chamber 103 is expanded to the atmosphere through the expander 111, and the expander 111 drives the first generator 112 to generate electricity. At the same time, the same volume of water enters the air storage chamber 103 through the buffer tank 101 to fill the space in the air storage chamber 103 after the air has expanded. Since the water in the buffer tank 101 is not enough to replenish the huge volume of the air storage chamber 103, the water reservoir 102 continuously replenishes the buffer tank 101 with water while the water in the buffer tank 101 enters the air storage chamber 103. At this time, the pump-turbine 107 works in the water pump working condition, and the first motor 108 drives the pump-turbine 107 to pump water from the reservoir 102 into the buffer tank 101.

[0037] Under the operating conditions of energy storage and power generation, the first compressor 109 and the expander 111 respectively operate under rated conditions or specified conditions, with poor power regulation capabilities, and are unable to perform primary or secondary frequency modulation on the power grid or smooth out the volatility of new energy power. However, the pump-turbine 107 has better flexible power regulation characteristics, and while ensuring that the water level in the buffer tank 101 is within the allowable upper and lower limits, the pump-turbine 107 can respond to the dynamic power demand of the power grid. In addition, the system can also operate in a buffer tank short-circuit mode, with the first control valve 113 and the second control valve 114 closed, and the third control valve 115 and the fourth control valve 116 opened. When storing energy, the air in the atmosphere is pressed into the air storage chamber 103 through the first compressor 109, and the same volume of water in the air storage chamber 103 is pressed into 102 through the pump turbine 107 to maintain the pressure of the air storage chamber 103 unchanged. The pump turbine 107 operates in the turbine mode to provide part of the pressure for the air storage chamber 103. In addition, the water column corresponding to the height difference between the reservoir 102 and the air storage chamber 103 provides part of the pressure. During power generation, the compressed air in the air storage chamber 103 is expanded into the atmosphere through the expander 111, and the water pump turbine 107 works in the water pump mode, pressing an equal volume of water from the water reservoir 102 into the air storage chamber 103. The pressure in the air storage chamber 103 is the water column pressure corresponding to the height difference between the water reservoir 102 and the air storage chamber 103 plus the pressure generated by the water pump turbine 107.

[0038] like Figure 2As shown, the energy storage system based on compressed air energy storage in a buffer tank of another embodiment of the present invention replaces a pump-turbine 107 with a first pump-turbine 201 and a second pump-turbine 202, and connects a second motor 203 and a third motor 204 respectively. When the compressed air energy storage system is not working, the second pump-turbine 202 works in a water pump mode, and the first pump-turbine 201 works in a turbine mode. Both work in a rotating standby state, and can also perform flexible power response to the power grid. When the power required by the power grid is 0, water circulates between the second pump-turbine 202 and the first pump-turbine 201, and water is pumped into the second pump-turbine 202 from the third pipeline 106, and then is compressed into the first pump-turbine 20 1 power generation, the third motor 204 works in the motor working condition, and the second motor 203 works in the generator working condition. Since there is energy loss in the first pump-turbine 201, the second pump-turbine 202, the second motor 203, and the third motor 204, therefore, while the water is self-circulating in the third pipeline 106, the second pump-turbine 202, and the first pump-turbine 201, a part of the water can be passed from the buffer tank 101 through the second pipeline 105 into the reservoir 102 to generate electricity, so as to supplement the energy loss, so that the power generation power of the second motor 203 is the same as the electric power of the third motor 204. In addition, the power grid can also be allowed to compensate for this part of the energy loss. The system works in the rotating standby state, providing the power grid with the ability to flexibly adjust power. When the frequency of the power grid changes, or the output of new energy fluctuates, the system needs to respond to the demand for dynamic power of the power grid. When the amount of water pumped by the second pump-turbine 202 is greater than the amount of water passing through the first pump-turbine 201, the water in the reservoir 102 is pumped to the buffer tank 101, and the electric power consumed by the third motor 204 in the motor state is greater than the power generated by the second motor 203 in the generator state. At this time, the system as a whole obtains electric energy from the power grid; on the contrary, the amount of water generated by the first pump-turbine 201 is greater than the amount of water pumped by the second pump-turbine 202, and water enters the reservoir 102 from the buffer tank 101. The power generation of the second motor 203 is greater than the power consumption of the third motor 204, and the system as a whole outputs electric energy to the power grid. The first pump-turbine 201 and the second pump-turbine 202 work in the turbine and pump modes respectively, and do not need to switch between the pump and turbine modes. They can quickly change power or cross zero points, which is suitable for real-time tracking and smoothing the fluctuation of new energy output, or participating in power grid frequency modulation. When the compressed air energy storage system is working, when the compressed air energy storage system stores energy, water enters the buffer water tank 101 from the air storage chamber 103, and then enters the reservoir 102; when generating electricity, water enters the buffer water tank 101 from the reservoir 102, and then enters the air storage chamber 103.At this time, the first pump-turbine 201 and the second pump-turbine 202 can also be kept in working state. While maintaining the allowable water level fluctuation range in the buffer tank 101, the working power of the pump and the turbine can be dynamically adjusted, and the water exchange rate in the buffer tank 101 and the reservoir 102 can be adjusted to achieve the purpose of flexible power response.

[0039] like Figure 3 As shown, the water pump and turbine system of the system can be composed of a plurality of impulse turbines 301 and mixed flow pump turbines 302. Figure 1 The first pump turbine 201 and the mixed flow pump turbine 302 are replaced Figure 1 The second pump-turbine 202, the second generator 303 is connected to the impulse turbine 301, the electric generator 304 is connected to the mixed flow pump-turbine 302, and the water outlet 305 of the impulse turbine 301 can be higher than the water surface of the reservoir 102, so that the impulse turbine 301 works in a jet water and air environment. When the water volume pumped by the mixed flow pump turbine 302 is higher than the water volume generated by the impulse turbine 301, water enters the buffer tank 101 from the reservoir 102, the power of the electric generator 304 is greater than the power of the second generator 303, and the pump and turbine system consumes power from the power grid. Conversely, when the water volume generated by the impulse turbine 301 is higher than the water volume pumped by the mixed flow pump turbine 302, water enters the buffer tank 101 from the reservoir 102, the power of the second generator 303 is greater than the power of the electric generator 304, and the pump and turbine system composed of the impulse turbine 301 and the mixed flow pump turbine 302 sends power to the power grid.

[0040] like Figure 4As shown, when the height difference between the buffer water tank 101 and the air storage chamber 103 is lower than the water head required to maintain the rated constant pressure of the air storage chamber 103, the buffer water tank 101 can be made into a closed pressure regulating chamber, the air pressure of the pressure regulating chamber is maintained by a compressor, and the constant pressure of the air storage chamber 103 is maintained by air pressure and water pressure. The closed pressure regulating chamber 401 can be formed by a pressure vessel or a rock cave excavated in the hard rock layer on the mountain, and the inner surface is lined and sealed. The compressed air in the closed pressure regulating chamber 401 can simulate the water head of the buffer water tank, so that the altitude of the construction location of the buffer water tank can be greatly reduced. At the same time, the purpose of the closed pressure regulating chamber 401 is to maintain the pressure of the air storage chamber 103, and the volume does not need to be too large, and the construction cost is controllable. Considering that the compressed air in the closed pressure regulating chamber 401 gradually dissolves in water over time, the compressed air will gradually decrease. The compressed air that maintains the pressure of the closed pressure regulating chamber 401 can be provided by a set of independent air compressors, or it can be shared with the compressor in the compressed air energy storage process. The second motor 402 drives the second compressor 403 to inject compressed air into the closed pressure regulating chamber 401 to maintain the pressure and water volume of the compressed air in the closed pressure regulating chamber 401 .

[0041] like Figure 5 As shown, the power regulation method based on compressed gas energy storage in a buffer water tank of the embodiment of the present invention includes: using an integrated energy management and power control system to respond to the power and power requirements of the power grid, and controlling the energy storage system at the same time, and the integrated energy management and power control system is arranged in the central control and dispatching center of the energy storage system. The integrated energy management and power control system receives the real-time power command of the power grid sent by the power grid dispatching center, and feeds back the stored energy of the energy storage system and the power variation range of the stored energy of the energy storage system to the power grid dispatching center, so as to facilitate the planning and dispatching of the power grid dispatching center. At the same time, the integrated energy management and power control system receives the signal of the sensor of the gas storage chamber 103 of the energy storage system, and the signal of the water level sensor of the buffer water tank 101, obtains the pressure and water level of the gas storage chamber 103 and the water level information of the buffer water tank 101, and calculates the fluctuating power regulation available power and frequency modulation available power corresponding to the stored energy of the energy storage system and the water level of the buffer water tank 101.

[0042] The integrated energy management and power control system is connected to the compressed air energy storage power control system, the water pump power control system and the water turbine power control system, sends a peak load instruction to the compressed air energy storage power control system, sends a power instruction to the water pump power control system and the water turbine power control system, and sends a frequency modulation function enable signal to the water pump power control system and the water turbine power control system. The compressed air energy storage power control system controls the first generator 112 and the first motor 110, the water pump power control system controls the water pump turbine 107, the first water pump turbine 201, the second water pump turbine 202, and the mixed flow water pump turbine 302, and the water turbine power control system controls the water pump turbine 107, the first water pump turbine 201, the second water pump turbine 202, the impulse turbine 301, and the mixed flow water pump turbine 302. The compressed air energy storage power control system is connected to the motor of the first compressor 109, i.e., the first motor 110, the compressor guide vanes (i.e., Figure 5 The compressor is connected to the motor and guide vanes in the compressor, and the expander motor and expander guide vanes (i.e. Figure 5 The expander is connected to the motor and guide vanes), and the power of energy storage and power generation of the energy storage system is controlled by controlling the first motor 110 and the compressor guide vanes. The water pump power control system is connected to the water pump guide vanes and the water pump is connected to the motor to control the water pump power. The turbine power control system controls the water flow by controlling the guide vanes of the mixed flow turbine, i.e., the water pump turbine 107, the first water pump turbine 201, the second water pump turbine 202, and the mixed flow water pump turbine 302, or the injection needle of the impulse turbine 301, and controls the power of the water pump turbine 107, the first water pump turbine 201, and the impulse turbine 301 by controlling the working conditions of the first motor 108, the second motor 203, and the second generator 303 (i.e. Figure 5 The pump power control system and the turbine power control system receive the grid frequency, and automatically adjust the pump power and the turbine power according to the change of the grid frequency to modulate the grid frequency. When the pump and the turbine are the same unit, that is, the energy storage system uses the pump-turbine 107, when working in the pump state, the pump-turbine 107 is controlled by the pump power control system, and when working in the turbine state, the pump-turbine 107 is controlled by the turbine power control system.

[0043] The working conditions of the pump and turbine system are controlled by the water level of the buffer tank 101 and the response power required by the power grid. The buffer tank 101 has an upper water level limit, a lower water level limit and a water level center line. The water level of the buffer tank 101 is controlled by the pump and turbine system to be close to the water level center line. When the water level exceeds the upper water level line, the turbine water volume and power generation are increased, the pump water volume and energy consumption are reduced, and the water in the buffer tank 101 enters the reservoir 102, thereby lowering the water level of the buffer tank 101; when the water level is lower than the lower water level line, the turbine water volume and power generation are reduced, the pump water volume and energy consumption are increased, the water in the reservoir 102 enters the buffer tank 101, and the water level of the buffer tank 101 is increased. The control target is to control the water level in the buffer tank 101 at the water level center line. The water level in the buffer tank 101 is controlled at the water level center line. By adjusting the power of the pump and turbine system, the dynamic power required by the power grid can be flexibly responded to. When the pump flow is greater than the turbine flow, the pump power is greater than the turbine power, the water level in the buffer tank 101 moves upward, the total power of the pump and turbine is positive power, and electric energy is obtained from the power grid; when the turbine flow is greater than the pump flow, the turbine power is greater than the pump power, the water level in the buffer tank 101 moves downward, the total power of the pump and turbine is negative power, and electric energy is fed back to the power grid. The upward and downward movement of the water level in the buffer tank 101 corresponds to the total energy consumption and power generation of the pump and turbine system, respectively, and adjusts the dynamic power output of the system. The frequency modulation power command corresponding to the power grid frequency signal and the power fluctuation command received by the pump power control system and the turbine power control system are superimposed, and while maintaining the water level of the buffer tank 101, the flexible power demand of the power grid is responded to. When the water level in the buffer tank 101 is between the upper and lower limits of the water level, the integrated energy management and power control system sends a frequency modulation function enable signal to the pump power control system and the turbine power control system, and the pump power control system and the turbine power control system perform frequency modulation response according to the power grid frequency. When the water level in the buffer tank 101 exceeds the upper limit of the water level, the water level can only decrease but not increase, that is, the turbine water volume is greater than the pump water volume, and the power grid frequency can only be adjusted upward, and an upward frequency modulation enable signal is sent to the pump power control system and the turbine power control system, and the turbine power control system can only increase power, and the pump power control system can only reduce power, thereby providing upward frequency modulation for the power grid. When the water level in the buffer tank 101 is lower than the lower limit of the water level, the water level can only increase but not decrease, that is, the turbine water volume is less than the pump water volume, and the power grid frequency can only be adjusted downward, and a downward frequency modulation enable signal is sent to the pump power control system and the turbine power control system, and the turbine power control system can only reduce power, and the pump power control system can only increase power, thereby providing downward frequency modulation for the power grid.

[0044] The air storage chamber 103 stores compressed air and water at the same time. During the energy storage process, the compressor compresses the outside air into the air storage chamber, and the same volume of water enters the buffer tank 101 through the first pipe 104. Since the volume of the buffer tank 101 is limited, the water in the buffer tank 101 enters the reservoir 102. During the power generation process, the compressed air expands to the atmosphere through the expander 111, and the expander 111 drives the first generator 112 to generate electricity. At the same time, the same volume of water enters the air storage chamber 103 through the buffer tank 101. Since the water in the buffer tank 101 is not enough to replenish the huge volume of the air storage chamber 103, the reservoir 102 continuously replenishes the buffer tank 101 with water.

[0045] By replacing a pump-turbine 107 with a first pump-turbine 201 and a second pump-turbine 202, and connecting a second motor 203 and a third motor 204 respectively, both of which operate in a rotating standby state, water circulates between the second pump-turbine 202 and the first pump-turbine 201, and the net inflow / net outflow of water between the buffer tank 101 and the reservoir 102 is controlled, so that flexible power response can be performed on the power grid.

Claims

1. A power regulation method based on compressed air energy storage in a buffer tank, characterized in that: A compressed air energy storage system is constructed based on compressed air energy storage in a buffer water tank, and the energy storage system includes a first compressor, an expander, a water pump and a turbine system, a buffer water tank, a water reservoir, and an air storage chamber; the buffer water tank is connected to the air storage chamber, the buffer water tank and the water reservoir are connected, and a water pump and a turbine system are arranged between the buffer water tank and the water reservoir; the air storage chamber is connected to the first compressor; the air storage chamber stores compressed air and water at the same time, the compressed air is located at the upper part of the air storage chamber, and the water is located at the bottom of the air storage chamber, and is connected to the water in the buffer water tank through a pipeline; the air storage chamber is connected to the expander; the buffer water tank is arranged at a high place to maintain the water pressure, thereby maintaining the pressure of the air storage chamber; the water reservoir is built at a low place, and the height of the water reservoir is lower than the buffer water tank; The integrated energy management and power control system is used to receive real-time power instructions from the power grid dispatching center, and to feed back the stored energy of the compressed air energy storage system and the power variation range allowed by the compressed air energy storage system to the power grid dispatching center, so as to facilitate planning and dispatching by the power grid dispatching center. At the same time, the integrated energy management and power control system receives the signal of the sensor of the air storage chamber of the compressed air energy storage system and the signal of the water level sensor of the buffer water tank, obtains the pressure and water level of the air storage chamber and the water level of the buffer water tank, calculates the stored energy of the compressed air energy storage system and the fluctuating power regulation available power and frequency modulation available power corresponding to the water level of the buffer water tank; the integrated energy management and power control system is connected to the compressed air energy storage power control system, the water pump power control system and the turbine power control system, sends peak shaving instructions to the compressed air energy storage power control system, sends power instructions to the water pump power control system and the turbine power control system, and sends frequency modulation function enable signals to the water pump power control system and the turbine power control system, so as to realize power regulation.

2. A power regulation method based on compressed air energy storage in a buffer water tank according to claim 1, characterized in that: The first compressor is used to compress external air into the air storage chamber; the compressed air energy storage power control system is connected to the first motor of the first compressor, the compressor guide vane, and the expander motor and expander guide vane, and controls the energy storage power and power generation power of the compressed air energy storage system by controlling the first motor and the compressor guide vane.

3. A power regulation method based on compressed air energy storage in a buffer water tank according to claim 1, characterized in that: The turbine power control system controls the water flow by controlling the guide vanes of the mixed flow turbine or the nozzles of the impulse turbine, and controls the power of the pump turbine by controlling the working condition of the motor; the pump power control system and the turbine power control system receive the grid frequency, and automatically adjust the pump power and the turbine power according to the change of the grid frequency to modulate the grid frequency.

4. A power regulation method based on compressed air energy storage in a buffer water tank according to claim 3, characterized in that: The operating conditions of the pump and turbine system are controlled by the water level of the buffer tank and the response power required by the power grid. The buffer tank has an upper water level limit, a lower water level limit and a water level center line. The water level of the buffer tank is controlled by the pump and turbine system to be at the water level center line. When the water level exceeds the upper water level line, the turbine water volume and power generation are increased, the pump water volume and energy consumption are reduced, the water in the buffer tank enters the reservoir, and the water level of the buffer tank is lowered; when the water level is lower than the lower water level line, the turbine water volume and power generation are reduced, the pump water volume and energy consumption are increased, the water in the reservoir enters the buffer tank, the water level of the buffer tank is increased, and the water level in the buffer tank is controlled at the water level center line; after the water level in the buffer tank is controlled at the water level center line, the dynamic power required by the power grid is flexibly responded to by adjusting the power of the pump and turbine.

5. A power regulation method based on compressed air energy storage in a buffer water tank according to claim 4, characterized in that: During the energy storage process of the compressed air energy storage system, the first compressor compresses the external air into the air storage chamber, and the same volume of water enters the buffer tank, and the water in the buffer tank enters the reservoir; during the power generation process, the compressed air expands to the atmosphere through the expander, and the expander drives the first generator to generate electricity. At the same time, the same volume of water enters the air storage chamber through the buffer tank.

6. A power regulation method based on compressed gas energy storage in a buffer water tank according to claim 3, characterized in that: The water pump and turbine system includes a first pump-turbine and a second pump-turbine, and are respectively connected to a second motor and a third motor. The first pump-turbine and the second pump-turbine operate in a rotating standby state, so that water circulates between the second pump-turbine and the first pump-turbine, thereby controlling the net inflow or net outflow of water between the buffer tank and the reservoir, and performing flexible power response to the power grid.

7. An energy storage system based on compressed air energy storage in a buffer tank, characterized in that: The energy storage system is a compressed air energy storage system, including a first compressor, an expander, a water pump and a turbine system, a buffer water tank, a water reservoir, and an air storage chamber; the buffer water tank is connected to the air storage chamber, the buffer water tank is connected to the water reservoir, and a water pump and a turbine system are arranged between the buffer water tank and the water reservoir; the air storage chamber stores compressed air and water at the same time, the compressed air is located at the upper part of the air storage chamber, and the water is located at the bottom of the air storage chamber, and is communicated with the water in the buffer water tank through a pipeline; the air storage chamber is connected to the first compressor; the air storage chamber is connected to the expander; the buffer water tank is arranged at a high place to maintain the water pressure, thereby maintaining the pressure of the air storage chamber; The water reservoir is built at a low place, and the height of the water reservoir is lower than the buffer water tank; when storing energy, the first compressor injects air into the air storage chamber, and the water in the air storage chamber is injected into the buffer water tank through the pipeline connected to the buffer water tank, and flows to the water pump and turbine system through the buffer water tank, and drives the turbine in the water pump and turbine system to generate electricity, and then enters the water reservoir; in this process, the water head between the buffer water tank and the air storage chamber is a constant pressure maintained by the air storage chamber; when releasing energy, the water pump in the water pump and turbine system pumps the water of the water reservoir to the buffer water tank, and injects it into the air storage chamber through the connecting pipeline, and discharges the air from the air storage chamber to drive the expander to do work.

8. The energy storage system based on compressed air energy storage in a buffer water tank according to claim 7, characterized in that: The water pump and turbine system includes a first pump-turbine and a second pump-turbine, and are respectively connected to a second motor and a third motor. When the compressed air energy storage system is not working, the second pump-turbine works in a water pump mode, the first pump-turbine works in a turbine mode, and the first pump-turbine and the second pump-turbine work in a rotating standby state; or a flexible power response is performed to the power grid. When the power required by the power grid is 0, water circulates between the second pump-turbine and the first pump-turbine, the water is pumped into the second pump-turbine, and then pressed into the first pump-turbine to generate electricity, the third motor works in a motor condition, and the second motor works in a generator condition; while the water is self-circulating in the second pump-turbine and the first pump-turbine, a portion of the water is transferred from the buffer tank to the reservoir for power generation to compensate for energy loss, so that the power generation power of the second motor is the same as the electric power of the third motor.

9. The energy storage system based on compressed air energy storage in a buffer water tank according to claim 7, characterized in that: The water pump and turbine system is composed of a plurality of impulse turbines and mixed flow pump turbines, and the electric generator is connected to the mixed flow pump turbine; when the water pumping amount of the mixed flow pump turbine is higher than the water generating amount of the impulse turbine, water enters the buffer tank from the reservoir, the power of the electric generator is higher than the power of the second generator, and the water pump and turbine system consumes the power of the power grid; conversely, when the water generating amount of the impulse turbine is higher than the water pumping amount of the mixed flow pump turbine, water enters the reservoir from the buffer tank, the power of the second generator is higher than the power of the electric generator, and the water pump and turbine system composed of the impulse turbine and the mixed flow pump turbine sends power to the power grid.

10. The energy storage system based on compressed air energy storage in a buffer water tank according to claim 7, characterized in that: The water pump and water turbine system is a water pump water turbine, which is connected to the water reservoir and the buffer tank through pipelines.

11. An energy storage system based on compressed air energy storage in a buffer water tank according to any one of claims 7 to 10, characterized in that: When the height difference between the buffer water tank and the air storage chamber is lower than the water head required to maintain the rated constant pressure of the air storage chamber, the buffer water tank is made into a closed pressure regulating chamber, the air pressure in the pressure regulating chamber is maintained by the second compressor, and the constant pressure of the air storage chamber is maintained by the air pressure and water pressure.

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