A precise control system for constant pressure water return flow rate of a spherical tank in a compressed air energy storage power station

Abstract

This invention discloses a precise control system for constant-pressure water return flow in spherical tanks of a compressed air energy storage power station, belonging to the field of energy storage technology. It includes independent constant-pressure water return branches corresponding to each spherical tank and a central control unit. Each independent constant-pressure water return branch is equipped with a constant-pressure water return on / off valve, a flow detection device, and a constant-pressure water return regulating valve. The central control unit has a calculation module that calculates the theoretical total drainage volume based on the initial liquid level during tank transfer. It can compare the cumulative return flow with the theoretical total drainage volume in real time, adjust the regulating valve opening in a closed loop, and interlock the valve to close when the flow rate reaches the target. This invention can adapt to parameter changes under different operating conditions and during tank transfer periods, improve the accuracy of return flow control, stabilize the operating pressure of the spherical tanks, enhance the safety and stability of the energy storage system, extend the service life of the spherical tanks, and reduce system operating losses.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station. Background Technology

[0002] Compressed air energy storage, as a core component of new energy storage, is an important technological means to improve the regulation capability of power systems and has already laid the foundation for large-scale commercial application. With the technological iteration of the industry, compressed air energy storage power plants have placed higher demands on the level of automation and regulation stability. As the core of heat exchange and storage, the pressure control of the spherical tank is the core factor restricting the automation level and system stability of the power plant's heat exchange and storage system. Improving the control accuracy of the flow rate of the constant pressure outlet pipeline of the spherical tank can directly improve the stability and automation level of the heat exchange and storage system.

[0003] Compressed air energy storage power stations using water as the heat exchange medium are equipped with pressurized water tanks, employing a water-pressure-controlled and nitrogen-pressure-stabilized operation mode. To reduce tank costs and floor space, the heat exchange system is typically configured with a shared hot and cold water spherical tank, storing high-temperature and low-temperature water alternately (low-temperature water temperature range 50-80℃, high-temperature water temperature range 200-240℃). However, during heat exchange operation, significant temperature differences between high and low temperatures occur under different operating conditions and at different tank transfer times, causing real-time changes in the density and volume of the medium within the spherical tank. This results in frequent pressure fluctuations in the tank and makes accurate control of the return water flow rate impossible. Traditional control methods often employ simple PID regulation, which cannot adapt to parameter changes caused by operating conditions and temperature differences. This easily leads to problems such as constant-pressure water overshoot and large pressure fluctuations in the spherical tank, affecting not only the safety and stability of the system but also shortening the lifespan of the spherical tank and increasing operating losses in the constant-pressure system. Summary of the Invention

[0004] To address the technical problems of low return water flow control accuracy, large pressure fluctuations in the spherical tank during tank transfer in existing compressed air energy storage power stations, and inability to adapt to multiple operating conditions, this invention provides a precise control system for the constant pressure return water flow of spherical tanks in compressed air energy storage power stations. This system can accurately calculate the theoretical drainage volume based on the initial liquid level during tank transfer, and achieve precise control of the return water flow by using a closed-loop control mechanism that compares the measured flow rate with the theoretical value in real time. This stabilizes the operating pressure of the spherical tank, improves system safety and energy efficiency, and extends the service life of the spherical tank.

[0005] The technical solution adopted in the present invention, a precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station, is as follows: A precise control system for constant pressure water return flow of spherical tanks in a compressed air energy storage power station includes independent constant pressure water return branches corresponding to each spherical tank in the energy storage power station, and a central control unit connected to each independent constant pressure water return branch. Each independent constant pressure water return branch is sequentially equipped with a constant pressure water return switch valve, a flow detection device, and a constant pressure water return regulating valve along the return water direction. The central control unit is pre-loaded with a calculation module that calculates the theoretical total drainage volume based on the initial liquid level parameters of the spherical tank during the tank reversal process. During the tank reversal operation, the central control unit collects real-time operating parameters of the spherical tanks, calculates the theoretical total drainage volume of the corresponding tank reversal process through the calculation module, compares the cumulative return water flow collected by the flow detection device with the theoretical total drainage volume in real time, adjusts the opening of the constant pressure water return regulating valve in a closed loop based on the comparison result, and interlocks and closes the constant pressure water return switch valve and constant pressure water return regulating valve of the corresponding independent constant pressure water return branch when the cumulative return water flow reaches the theoretical total drainage volume.

[0006] A further improvement of the technical solution of the present invention is that: the inlet end of the independent constant pressure return water branch is connected to the constant pressure water outlet at the bottom of the corresponding spherical tank, and the outlet end of the independent constant pressure return water branch is connected to the constant pressure return water main of the power station; each spherical tank is equipped with a pressure detection device for collecting real-time pressure inside the tank and a liquid level detection device for collecting real-time liquid level inside the tank, and both the pressure detection device and the liquid level detection device are signal connected to the central control unit.

[0007] A further improvement to the technical solution of this invention lies in the fact that the theoretical total drainage volume calculation formula of the calculation module is: Q≥ρ×[V n +V n+1 -η×V 总 ]-m0 Where Q is the theoretical total drainage volume; ρ is the density of the cold liquid water inside the spherical tank; V n V is the volume of the medium inside the outlet ball tank at the initial moment of tank switching; n+1 V represents the volume of the medium inside the inlet spherical tank at the initial moment of the transfer; η is the preset ratio of the initial cold water volume to the total incoming water volume in the inlet spherical tank; 总 is the total volume of a single spherical tank; m0 is the mass of the medium corresponding to the initial liquid level in the inlet spherical tank.

[0008] A further improvement to the technical solution of the present invention is that the medium volume V inside the water outlet spherical tank... n With the medium volume V in the inlet spherical tank n+1 All values ​​are calculated based on the radius of the corresponding spherical tank and the real-time liquid level at the initial moment of tank tipping. The calculation formula is as follows: Where R is the radius of the spherical tank and H is the real-time liquid level of the spherical tank at the initial moment of tank transfer.

[0009] A further improvement of the technical solution of the present invention is that: the central control unit is preset with valve opening interlock logic, and the opening conditions of the constant pressure return water switch valve and the constant pressure return water regulating valve are: the real-time liquid level of the corresponding spherical tank is greater than the preset lower limit of the liquid level; the interlock opening conditions are: the low temperature water outlet shut-off valve of the corresponding spherical tank is opened to the correct position, the high temperature water inlet shut-off valve of the adjacent inlet spherical tank is opened to the correct position, and the real-time pressure of the corresponding spherical tank is greater than the preset upper limit of the pressure.

[0010] A further improvement of the technical solution of the present invention is that: the central control unit is preset with valve association interlock protection logic, and the interlock closing condition of the constant pressure return water switch valve and the constant pressure return water regulating valve also includes: the real-time liquid level of the corresponding spherical tank is ≤ the preset liquid level protection value.

[0011] A further improvement of the technical solution of the present invention is that: the central control unit adjusts the opening of the constant pressure return water regulating valve according to the difference between the cumulative return water flow and the theoretical total drainage: when the difference between the cumulative return water flow and the theoretical total drainage increases, the opening of the constant pressure return water regulating valve is reduced; when the difference decreases, the opening of the constant pressure return water regulating valve is increased, thereby realizing continuous and precise adjustment of the return water flow.

[0012] A further improvement of the technical solution of the present invention is that the operating states of each independent constant pressure return water branch are independent of each other, and the central control unit can control the independent constant pressure return water branch corresponding to a single spherical tank individually without matching the operating states of the other spherical tanks.

[0013] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: This invention adopts a configuration where each spherical tank corresponds to a single independent constant pressure return water branch. Each branch is controlled independently without waiting for the global status to be unified. It can adapt to the control requirements of different tank transfer periods and different operating conditions, greatly improving the system's operational flexibility.

[0014] This invention is based on the accurate calculation of the theoretical total drainage volume at the initial liquid level of the tank. By comparing the measured cumulative flow with the theoretical value in real time, the valve opening is adjusted in a closed loop. This breaks through the control limitations of traditional PID regulation, can adapt to the changes in medium density and volume caused by temperature differences, improves the control accuracy of return water flow, avoids overshoot of constant pressure water, and stabilizes the operating pressure of the spherical tank.

[0015] This invention sets up multiple interlock protection logics, combining pressure, liquid level, flow rate and other multi-dimensional parameters to achieve interlock control of valves. This not only ensures accurate control of flow rate during the tank transfer process, but also improves the safety of system operation, extends the service life of the spherical tank, reduces operating losses of the constant pressure system, and improves the overall energy efficiency of the power plant. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the overall structure of a precise control system for constant pressure water return flow in a spherical tank of a compressed air energy storage power station according to the present invention. Figure 2 This is a schematic diagram of the independent constant pressure return water branch structure of a spherical tank constant pressure return water flow precision control system for a compressed air energy storage power station according to the present invention. Figure 3 This is a flow control logic block diagram of a precise control system for constant pressure water return flow in a spherical tank of a compressed air energy storage power station, according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention. Example

[0018] This embodiment takes the case of transferring water from spherical tank N to spherical tank N+1 in a compressed air energy storage power station as an example: The precise control system for constant pressure water return flow of the compressed air energy storage power station's spherical tanks in this embodiment includes an independent constant pressure water return branch corresponding to each spherical tank in the power station, and a central control unit that is signal-connected to each independent constant pressure water return branch. Specifically, spherical tank N is equipped with an Nth independent constant pressure water return branch, and spherical tank N+1 is equipped with an N+1th independent constant pressure water return branch. Each branch has the same structure, and along the return water direction, it is sequentially equipped with a constant pressure water return on / off valve, an electromagnetic flowmeter, and a pneumatic constant pressure water return regulating valve. The inlet end of the branch is connected to the constant pressure water outlet at the bottom of the corresponding spherical tank, and the outlet end is connected to the main constant pressure water return pipe of the power station.

[0019] Each spherical tank is equipped with a pressure sensor with an accuracy of ±0.075% and a level sensor with an accuracy of ±1%, which are used to collect the real-time pressure and real-time level inside the tank, respectively. The electromagnetic flow meter is installed on the main pipeline of the independent constant pressure return water branch to collect the instantaneous flow rate and cumulative flow rate of the return water. The pressure sensor, level sensor, electromagnetic flow meter, constant pressure return water switch valve, and constant pressure return water regulating valve are all connected to the central control unit.

[0020] The central control unit has a pre-set interlocking logic between the calculation module and the valves. The formula for calculating the theoretical total drainage volume of the calculation module is as follows: Q≥ρ×[V n +V n+1 -η×V 总 ]-m0 In this embodiment, ρ is the density of cold liquid water, taken as 985 kg / m³. 3η is the preset ratio of the initial cold water volume to the total incoming water volume in the inlet spherical tank, taken as 79.66%; Vtotal is the total volume of a single spherical tank, taken as 2960.44 m³; m0 is the mass of the medium corresponding to the initial liquid level in inlet spherical tank N+1, taken as 43740.5 kg; V n V is the volume of the medium at the initial moment of the inversion of the N-type effluent spherical tank. n+1 The volume of the medium at the initial moment of the inlet spherical tank N+1 being transferred is calculated using the following formula: R is the radius of the spherical tank, and H is the real-time liquid level value at the initial moment of the tank being tilted.

[0021] Valve interlocking logic includes: Opening condition: Real-time liquid level of the corresponding spherical tank > 2%; Interlock opening conditions: The low temperature water outlet shut-off valve of the corresponding spherical tank is in place, the high temperature water inlet shut-off valve of the adjacent inlet spherical tank is in place, and the real-time pressure of the corresponding spherical tank is >2.65MPa (G). Interlocking conditions: The cumulative return water flow of the corresponding spherical tank is greater than or equal to the theoretical total discharge, or the real-time liquid level of the corresponding spherical tank is less than or equal to 1.7%.

[0022] The working principle of this embodiment is as follows: Initial state determination of tank transfer: The central control unit collects the valve status and tank parameters, confirms that the low temperature water outlet shut-off valve of tank N is open, the high temperature water inlet shut-off valve of tank N+1 is open, and the real-time liquid level of tank N is >2%, which meets the opening conditions, and determines that the tank transfer process is started.

[0023] Valve interlock opening: When the central control unit detects that the real-time pressure of tank N is >2.65MPa(G), meeting the interlock opening condition, the interlock opens the constant pressure return water switch valve and constant pressure return water regulating valve of the independent constant pressure return water branch of tank N, starting the constant pressure water return discharge; at the same time, the initial liquid level H of tank N is recorded. n The initial liquid level H of spherical tank N+1 n+1 .

[0024] Theoretical total drainage calculation: The central control unit, through its computing module, calculates based on H... n H n+1 Calculate V n With V n+1 Substituting the values ​​into the theoretical total drainage calculation formula, we obtain the theoretical total drainage of tank N during this tank transfer process.

[0025] Flow closed-loop regulation: The central control unit receives the cumulative return water flow collected by the electromagnetic flow meter in real time, compares the cumulative return water flow with the theoretical total discharge in real time, and adjusts the opening of the constant pressure return water regulating valve according to the difference: when the difference between the cumulative return water flow and the theoretical total discharge increases, the opening of the constant pressure return water regulating valve is closed to reduce the return water flow; when the difference decreases, the opening of the constant pressure return water regulating valve is opened to increase the return water flow, thereby achieving continuous and precise regulation of the return water flow and maintaining the pressure stability of the N-type spherical tank.

[0026] Valve interlock closure: When the central control unit collects the cumulative return water flow rate ≥ the theoretical total drainage, or the real-time liquid level of tank N ≤ 1.7%, the constant pressure return water switch valve and constant pressure return water regulating valve of independent constant pressure return water branch N will be immediately interlocked and closed, ending the constant pressure water return water control process of this tank transfer.

[0027] In the above embodiments, a precise control system for the constant pressure water return flow of a spherical tank in a compressed air energy storage power station is provided. This invention employs a configuration where each spherical tank corresponds to a single independent constant pressure water return branch. Each branch is controlled independently, eliminating the need to wait for global state unification. This system can adapt to control requirements during different tank transfer periods and under different operating conditions, significantly improving system operational flexibility. Based on the initial liquid level during tank transfer, this invention accurately calculates the theoretical total drainage volume. By comparing the measured cumulative flow with the theoretical value in real time, the valve opening is adjusted in a closed loop, overcoming the limitations of traditional PID control. This system can adapt to changes in medium density and volume caused by temperature differences, improving the accuracy of return water flow control, avoiding constant pressure water overshoot, and stabilizing the operating pressure of the spherical tank. This invention sets up multiple interlocking protection logics, combining pressure, liquid level, and flow rate parameters to achieve interlocking control of the valves. This ensures precise flow control during the tank transfer process, improves system operational safety, extends the service life of the spherical tank, reduces operating losses in the constant pressure system, and improves the overall energy efficiency of the power station.

[0028] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A precise control system for constant pressure water return flow rate of a spherical tank in a compressed air energy storage power station, characterized in that: The system includes independent constant-pressure return water branches corresponding to each spherical tank in the energy storage power station, and a central control unit connected to each independent constant-pressure return water branch via signal. Each independent constant-pressure return water branch is equipped with a constant-pressure return water switch valve, a flow detection device, and a constant-pressure return water regulating valve in sequence along the return water direction. The central control unit is pre-loaded with a calculation module that calculates the theoretical total drainage volume based on the initial liquid level parameters of the spherical tank during the tank reversal process. Under the tank reversal condition, the central control unit collects the real-time operating parameters of the spherical tank, calculates the theoretical total drainage volume of the corresponding tank reversal process through the calculation module, compares the cumulative return water flow collected by the flow detection device with the theoretical total drainage volume in real time, adjusts the opening of the constant-pressure return water regulating valve in a closed loop according to the comparison result, and interlocks and closes the constant-pressure return water switch valve and constant-pressure return water regulating valve of the corresponding independent constant-pressure return water branch when the cumulative return water flow reaches the theoretical total drainage volume.

2. The precise control system for constant pressure water return flow rate of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The inlet of the independent constant pressure return water branch is connected to the constant pressure water outlet at the bottom of the corresponding spherical tank, and the outlet of the independent constant pressure return water branch is connected to the constant pressure return water main of the power station; each spherical tank is equipped with a pressure detection device for collecting real-time pressure inside the tank and a liquid level detection device for collecting real-time liquid level inside the tank, and both the pressure detection device and the liquid level detection device are signal connected to the central control unit.

3. The precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The formula for calculating the theoretical total drainage volume of the calculation module is as follows: Q≥ρ×[V n +V n+1 -η×V 总 ]-m0 Where Q is the theoretical total drainage volume; ρ is the density of the cold liquid water inside the spherical tank; V n V is the volume of the medium inside the outlet ball tank at the initial moment of tank switching; n+1 V represents the volume of the medium inside the inlet spherical tank at the initial moment of the transfer; η is the preset ratio of the initial cold water volume to the total incoming water volume in the inlet spherical tank; 总 is the total volume of a single spherical tank; m0 is the mass of the medium corresponding to the initial liquid level in the inlet spherical tank.

4. The precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station according to claim 3, characterized in that: The medium volume V in the outlet ball tank n With the medium volume V in the inlet spherical tank n+1 All values ​​are calculated based on the radius of the corresponding spherical tank and the real-time liquid level at the initial moment of tank tipping. The calculation formula is as follows: Where R is the radius of the spherical tank and H is the real-time liquid level of the spherical tank at the initial moment of tank transfer.

5. The precise control system for constant pressure water return flow rate of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The central control unit is preset with valve opening interlock logic. The opening conditions for the constant pressure return water switch valve and the constant pressure return water regulating valve are: the real-time liquid level of the corresponding spherical tank is greater than the preset lower limit of the liquid level; the interlock opening conditions are: the low temperature water outlet shut-off valve of the corresponding spherical tank is fully open, the high temperature water inlet shut-off valve of the adjacent inlet spherical tank is fully open, and the real-time pressure of the corresponding spherical tank is greater than the preset upper limit of the pressure.

6. The precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The central control unit is preset with valve interlock protection logic. The interlock closing condition of the constant pressure return water switch valve and the constant pressure return water regulating valve also includes: the real-time liquid level of the corresponding spherical tank is ≤ the preset liquid level protection value.

7. The precise control system for constant pressure water return flow rate of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The central control unit adjusts the opening of the constant pressure return water regulating valve based on the difference between the cumulative return water flow and the theoretical total drainage: when the difference between the cumulative return water flow and the theoretical total drainage increases, the opening of the constant pressure return water regulating valve is reduced; when the difference decreases, the opening of the constant pressure return water regulating valve is increased, thereby achieving continuous and precise adjustment of the return water flow.

8. The precise control system for constant pressure water return flow of a spherical tank in a compressed air energy storage power station according to claim 1, characterized in that: The operating states of each independent constant pressure return water branch are independent of each other. The central control unit can control the independent constant pressure return water branch corresponding to a single spherical tank individually without matching the operating states of the other spherical tanks.

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