Distributed photovoltaic power generation and air compression linkage system and control method

Abstract

The invention relates to a distributed photovoltaic power generation and air compression linkage system and a control method. The system comprises a distributed photovoltaic power generation subsystem, an air compression subsystem and a control unit. The distributed photovoltaic power generation subsystem comprises a photovoltaic power generation unit and an uncontrollable load unit; the compressed air subsystem comprises a compressed air system control unit and a plurality of air compressors; the control unit monitors the active power PP of load electricity utilization and the photovoltaic power generation power PPV of the photovoltaic power generation unit in real time, is connected with the compressed air system control unit, monitors the operation state of an air compressor in real time, obtains the air pressure Ba of a compressed air pipeline and the air suction pressure Bb of the air compressor, and sends the air pressure Bb to the compressed air system control unit. And performing linkage control on the distributed photovoltaic power generation subsystem and the compressed air subsystem. Compared with the prior art, the method has the advantages that photovoltaic benefit maximization is achieved through linkage control, the unloading time of a compressed air system is shortened, and the power utilization cost of an enterprise is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed photovoltaic system optimization, and in particular to a distributed photovoltaic power generation and compressed air linkage system and a control method. Background Art

[0002] Most of the distributed photovoltaic power generation systems built by industrial enterprises are independently operated systems. However, there are generally production breaks within enterprises due to lunch breaks, holiday rotations, maintenance, etc. At this time, the enterprise's production electricity load is relatively low. Once it overlaps with the photovoltaic power generation period, it is very easy to cause the photovoltaic power generation to have surplus power connected to the grid or be abandoned, which cannot maximize the reduction of energy costs for the enterprise. Enterprises generally have compressed air systems due to production needs. Generally, they are equipped with multiple air compressors, which are divided into common and standby, and independently controlled. During the production breaks, there is also a low load / unloading operation state, no compressed air is generated, and the equipment idles, resulting in a waste of electricity.

[0003] After searching, China's invention patent application publication number CN117220338A discloses a renewable energy power generation and air energy storage distributed power generation system for distributed power generation. With the help of this system, low-cost energy conversion and energy storage power generation can be achieved. Its technical solution: includes photovoltaic power generation equipment and wind power generation equipment, wherein the photovoltaic power generation equipment and wind power generation equipment are respectively connected to DC / DC and DC / DC through circuits, and the direct current obtained by the photovoltaic power generation equipment and the wind power generation equipment are converted into a unified voltage, and then converted into alternating current through DC / AC; the alternating current obtained by the DC / AC is used for power-consuming equipment, and the surplus power is used to charge the energy storage battery and the air compressor for air compression. The present invention can absorb abandoned electricity, meet the combined supply of heat, electricity and water, and has strong flexibility in multi-mode switching. The existing patent application has the problem of not disclosing how to control the surplus power in linkage with the compressed air system.

[0004] How to maximize the benefits of photovoltaic power generation while reducing the unloading time of the compressed air system to reduce the company's electricity costs has become a technical problem that needs to be solved. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a distributed photovoltaic power generation and compressed air linkage system and control method.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, a distributed photovoltaic power generation and compressed air linkage system is provided, the system comprising a distributed photovoltaic power generation subsystem and a compressed air subsystem; the distributed photovoltaic power generation subsystem comprises a photovoltaic power generation unit and an uncontrollable load unit; the compressed air subsystem comprises a compressed air system control unit and a plurality of air compressors; the system is characterized in that it comprises a control unit respectively connected to the distributed photovoltaic power generation subsystem and the compressed air subsystem;

[0008] The control unit monitors the load active power P in real time P and the photovoltaic power generation power P of the photovoltaic power generation unit PV The control unit is connected to the compressed air system control unit to monitor the operating status of the air compressor in real time and obtain the air pressure B of the compressed air pipeline. a and air compressor suction pressure B b , to carry out linkage control of the distributed photovoltaic power generation subsystem and the compressed air subsystem.

[0009] Preferably, the control unit has the rated power of the built-in air compressor, and the corresponding relationship between the electric valve and the energy storage electric valve corresponding to each air compressor.

[0010] Preferably, the control unit calculates the maximum allowable compression ratio ε through a built-in compression ratio and power relationship function. max The compression ratio ε is set set The power difference.

[0011] Preferably, the system further comprises a display setting unit for setting parameters to the control unit, wherein the parameters include:

[0012] Start power threshold P set , where P set >0;

[0013] Restoration power threshold P set2 , and P set <P set2 ;

[0014] And a first delay time t1 and a second delay time t2 of the control unit.

[0015] Preferably, the compressed air system control unit includes an energy storage tank for storing compressed air generated by the air compressor according to the command of the control unit.

[0016] More preferably, the compressed air system control unit further comprises an air inlet valve and an air supply valve disposed at both ends of the energy storage tank;

[0017] The air inlet valve and the air supply valve are connected to the control unit;

[0018] The control unit obtains the states of the intake valve and the supply valve, and sends control commands to the intake valve and the supply valve.

[0019] Preferably, the compressed air system control unit comprises an electric valve and an energy storage electric valve of a compressed air pipeline respectively connected to the control unit;

[0020] The control unit obtains the states of the electric valve and the energy storage electric valve, and issues control commands to the electric valve and the energy storage electric valve.

[0021] According to another aspect of the present invention, a method for controlling the linkage of distributed photovoltaic power generation and compressed air is provided, the method comprising three stages in sequence, corresponding to the sub-methods of state setting, absorption control and recovery control respectively;

[0022] The state setting sub-method includes the following steps:

[0023] Step S1: The control unit monitors the operating status of each air compressor, obtains the current operating time and operating status of each air compressor, and selects and sets the air compressors in each operating status according to the operating status, wherein the operating status includes the operating, standby and fault status; the control unit sets the rated power corresponding to the air compressor in the standby state according to the rated power of each built-in air compressor;

[0024] Step S2: The control unit monitors the opening and closing states of each electric valve and the energy storage electric valve, controls the electric valve corresponding to the air compressor in the standby state and the energy storage electric valve to be in a closed state and set, controls the electric valve corresponding to the air compressor in the running state to be in a closed state and set, and controls the electric valve corresponding to the air compressor in the fault state and the energy storage electric valve to be in a closed state and set;

[0025] Step S3: The control unit monitors the compressed air pipeline pressure B a juxtaposition;

[0026] Step S4: The control unit monitors the air compressor suction pressure B b and place.

[0027] Preferably, the control sub-method comprises the following steps:

[0028] Step S5: The control unit obtains the photovoltaic power generation power P PV and load active power P P ;

[0029] Step S6: Determine whether the photovoltaic power generation power P PV >0, if no, then wait; if yes, then execute step S7;

[0030] Step S7: Calculate and determine whether P P -P PV ≥P setIf yes, then wait; if no, then execute step S8;

[0031] Step S8: Calculate the load to be regulated △P1=P set -(P P -P PV ), get the compression ratio ε set at the current moment set , calculate the maximum allowable compression ratio ε through the built-in compression ratio and power relationship function max The compression ratio ε is set set The power difference △P2;

[0032] Step S9: Compare △P1 and △P2. If △P1≤△P2, adjust the air compressor air supply compression ratio to the maximum allowable compression ratio ε. max , and enter step S10; if △P1>△P2, adjust the air compressor air supply compression ratio to the maximum allowable compression ratio ε max , and calculate the power difference △P3 = △P1-△P2, and calculate the rated power of the air compressor in the standby state, and get the number of air compressors that are greater than or equal to and closest to △P3 P ai is the rated power of the aith standby air compressor, and the corresponding standby air compressor is turned on, and the corresponding energy storage electric valve and intake valve are opened; if the sum of the rated powers of the standby air compressors is less than △P3, that is Then all the air compressors in standby state are turned on and the corresponding energy storage electric valves and air intake valves are opened, and the process goes to step S10;

[0033] Step S10: If P P -P PV ≥P set , then go to step S11; otherwise return to step S9;

[0034] Step S11: After the first delay time t1, determine if P P -P PV ≥P set2 , then enter the recovery control phase; otherwise, return to step S10.

[0035] More preferably, the recovery control sub-method comprises the following steps:

[0036] Step S12: Restore the compression ratio to the set supply pressure compression ratio ε set , judge if P P -P PV <P set , then return to step S5; otherwise, execute step S13;

[0037] Step S13: If P P -P PV ≥P set2, then execute step S14; otherwise, return to step S11;

[0038] Step S14: After the second delay time t2, if P P -P PV ≥P set2 , then exit the consumption control stage and return to the daily control logic of the compressed air subsystem; otherwise, return to step S12.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1) The present invention monitors the power generation power of the photovoltaic power generation unit and the total active power of the load, as well as the operating status and air pressure of the air compressor in real time. Under the condition of ensuring the safety of the compressed air system's gas supply, it increases the photovoltaic power consumption by regulating the compressed air subsystem's gas supply pressure and the energy storage tank, and performs linkage control on the distributed photovoltaic power generation subsystem and the compressed air subsystem, thereby reducing the waste caused by unloading the compressed air subsystem during production intervals, and at the same time improving the utilization efficiency of photovoltaics, reducing the impact on the large power grid and the enterprise's electricity costs.

[0041] 2) The present invention transforms the compressed air system control unit, adds an energy storage gas tank, an air intake valve and an air supply valve, an electric valve of the compressed air pipeline and an energy storage electric valve, obtains their status in real time, and issues control commands according to specific circumstances to achieve linkage control of the distributed photovoltaic power generation subsystem and the compressed air subsystem.

[0042] 3) In the absorption control stage, the present invention adopts a staged multi-step control strategy to gradually absorb the surplus photovoltaic power, including increasing the compression ratio to the maximum compression ratio, increasing the compression ratio to the maximum compression ratio and starting some standby air compressors and opening the corresponding energy storage electric valves and intake valves, starting all some standby air compressors and opening the corresponding energy storage electric valves and intake valves, so as to achieve stable absorption of surplus photovoltaic power and ensure the safe energy storage of the compressed air subsystem.

[0043] 4) The overall transformation cost of the linkage system of the present invention is low, and the structure is simple and reliable. For example, on the basis of the original compressed air system control unit, the compressed air pipeline is transformed, and energy storage tanks, various electric valves, control units and electric meters are added. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of the air linkage system in the present invention;

[0045] Figure 2 It is a structural schematic diagram of the compressed air system control unit in the present invention;

[0046] Figure 3 It is a schematic diagram of the characteristic curve of compression ratio and power in the present invention;

[0047] Figure 4 It is a flow chart of the control method in the present invention;

[0048] Figure 5 It is a schematic diagram of the state setting process in the present invention;

[0049] Figure 6 It is a schematic diagram of the consumption control process in the present invention;

[0050] Figure 7 It is a schematic diagram of the recovery control flow in the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] The present embodiment relates to a distributed photovoltaic power generation and compressed air linkage system, which fully utilizes photovoltaic power generation in a low-cost manner, reduces the electricity waste of the intermittent compressed air system in the enterprise production, and fully utilizes the energy storage characteristics of the compressed air system by adjusting the operating parameters and control strategies, thereby increasing the enterprise self-use rate of distributed photovoltaic power generation, which can not only reduce power grid fluctuations, but also increase corporate profits and reduce electricity costs.

[0053] Figure 1 and Figure 2 The system block diagram of the present invention is shown, which at least includes a control unit 1, a transformer 2, an electric meter 3, a photovoltaic power generation unit 4, a compressed air system control unit 5, an uncontrollable load unit 6, a gas storage tank 7, a pressure monitoring unit 11, a display setting unit 12, and an air compressor A1-A n wait.

[0054] Figure 1 Indicates that photovoltaic power generation unit 4, compressed air system control unit 5, uncontrollable load unit 6, transformer 2, and electric meter 3 belong to the same transformer distribution circuit, and control unit 1 obtains load active power P through electric meter 3 P and the photovoltaic power generation power P of the photovoltaic power generation unit 4 PV , and connected to the compressed air system control unit 5.

[0055] The electricity generated by the photovoltaic power generation unit 4 is supplied to the compressed air system control unit 5 and the uncontrollable load unit 6 through the transformer 2 and the electric meter 3 .

[0056] Figure 2Indicates that the air compressor (A1-An) generates compressed air to the air storage tank 7, and the daily operation of the air compressor is in the compressed air system control unit 5; the control unit 1 obtains the operating status of the air compressor (A1-An), the air pressure B of the compressed air pipeline monitored by the pressure monitoring unit 11 a and air compressor suction pressure B b .

[0057] The control unit 1 is composed of a single chip microcomputer and a control program running on the single chip microcomputer, and integrates the function calculation of the relationship between compression ratio and power, such as Figure 3 .

[0058] The control unit 1 contains the rated power of the air compressors, and the corresponding relationship between the electric valves and energy storage electric valves corresponding to each air compressor.

[0059] The system also includes a display setting unit 12 for setting parameters to the control unit 1. The following settings can be performed so that the system can flexibly set parameters according to different environmental conditions:

[0060] 1) Set the starting power threshold P set , P set Represents the power threshold for starting consumption control, where P set >0; such as P set Can be set to 100kW, generally not less than 50kW;

[0061] 2) Set the recovery power threshold P set2 , P set2 Indicates the power threshold for starting recovery control, and P set <P set2 ; such as P set2 Can be set to 300kW;

[0062] 3) Set the first delay time t1 and the second delay time t2.

[0063] The system further comprises an energy storage tank 8 for storing compressed air according to the command of the control unit 1;

[0064] The system also includes electric valves (D1-Dn) and energy storage electric valves (C1-Cn) of the compressed air pipeline, and is connected to a control unit 1, which can obtain the status of the electric valves and issue control commands.

[0065] The system also includes an intake valve 9 and an air supply valve 10 of the energy storage gas tank 8, and is connected to a control unit 1. The control unit 1 can obtain the status of the intake valve 9 and the air supply valve 10, and issue control commands to the intake valve 9 and the air supply valve 10.

[0066] The compressed air system control unit 5 contains the daily operation control logic and can set the air supply pressure compression ratio ε set, compression ratio ε = B a / B b , where B a is the air pressure in the compressed air pipeline, B b It is the suction pressure of the air compressor. The suction pressure of the air compressor is generally atmospheric pressure, about 1 kg.

[0067] This embodiment also relates to a distributed photovoltaic power generation and compressed air control method, which is divided into three stages: Figure 4 , first the state is set, then the absorption control, and finally the recovery control. The specific steps are as follows:

[0068] like Figure 5 , the specific steps of status setting are as follows:

[0069] Step S1: The control unit 1 monitors the operating status of each air compressor (A1-An), obtains the current operating time and operating status of each air compressor, screens and sets the air compressors in operating, standby and fault states respectively; the control unit 1 has built-in rated power of each air compressor, and sets the rated power corresponding to the air compressor in standby state.

[0070] Step S2: The control unit 1 monitors the opening and closing status of each electric valve (D1-Dn), controls the electric valve and the energy storage electric valve corresponding to the air compressor in the standby state to be closed and set, controls the energy storage electric valve corresponding to the air compressor in the running state to be closed and set, and controls the electric valve D and the energy storage electric valve C corresponding to the air compressor in the fault state to be closed and set.

[0071] Step S3: The control unit 1 monitors the compressed air pipeline pressure B a and place.

[0072] Step S4: Control unit 1 monitors the air compressor suction pressure B b and place.

[0073] like Figure 6 , the consumption control adopts a multi-step control strategy to gradually consume the energy. The specific steps are as follows:

[0074] Step S5: Control unit 1 obtains photovoltaic power generation power P PV and load active power P P .

[0075] Step S6: Determine whether the photovoltaic power generation power P PV >0, if no, then wait; if yes, then execute step S7.

[0076] Step S7: Calculate and determine whether P P -P PV ≥P set If yes, then wait; if no, then execute step S8.

[0077] Step S8: Calculate the load to be regulated △P1=P set -(P P -P PV ), the control unit 1 obtains the compression ratio ε set at the current moment set , calculate the maximum allowable compression ratio ε through the built-in compression ratio and power relationship function max The compression ratio ε is set set The power difference △P2,

[0078] Step S9: Compare △P1 and △P2. If △P1≤△P2, the control unit 1 adjusts the air compressor air supply compression ratio to the maximum allowable compression ratio ε. max (ε max and Figure 6 Maximum air supply pressure in B max There is a corresponding conversion relationship), and enter step S10; if △P1>△P2, the control unit 1 not only adjusts the air compressor air supply compression ratio to the maximum allowable compression ratio ε max , and also calculate the power difference △P3 = △P1-△P2, and at the same time calculate the rated power of the air compressor in the standby state, and get the number of air compressors that are greater than or equal to and closest to △P3 P ai is the rated power of the air compressor in the aith standby state, and the corresponding air compressor in the standby state is turned on and the corresponding energy storage electric valve and intake valve 9 are opened; if the sum of the rated powers of the air compressors in the standby state is less than △P3, that is Then all the air compressors in standby state are turned on and the corresponding energy storage electric valves and the air intake valve 9 are opened, and the process goes to step S10;

[0079] Step S10: Control unit 1 performs calculations. If P P -P PV ≥P set , then go to step S11; if P P -P PV <P set , then return to step S9.

[0080] Step S11: Control unit 1 performs calculation after a delay of t1 minutes. If P P -P PV ≥P set2 , then execute step S12. P -P PV <P set2 , then return to step S10.

[0081] like Figure 7 , the specific steps to restore control are as follows:

[0082] Step S12: Control unit 1 restores the compression ratio to the set value ε set After the execution, if P P -P PV <P set , then return to step S5; if P P -P PV ≥P set , then execute step S13.

[0083] Step S13: Control unit 1 performs calculations. If P P -P PV ≥P set2 , then execute step S14; if P P -P PV <P set2 , then return to step S11.

[0084] Step S14: After the second delay time t2, perform calculation. If P P -P PV ≥P set2 , then exit the consumption control program and return to the daily control logic of the compressed air system; if P P -P PV <P set2 , then return to step S12.

[0085] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A distributed photovoltaic power generation and compressed air linkage system, the system comprising a distributed photovoltaic power generation subsystem and a compressed air subsystem; the distributed photovoltaic power generation subsystem comprises a photovoltaic power generation unit (4) and an uncontrollable load unit (6); the compressed air subsystem comprises a compressed air system control unit (5) and a plurality of air compressors, characterized in that: The system comprises a control unit (1) connected to a distributed photovoltaic power generation subsystem and a compressed air subsystem respectively; The control unit (1) monitors the load active power P in real time. P and the photovoltaic power generation power P of the photovoltaic power generation unit (4) PV The control unit (1) is connected to the compressed air system control unit (5) to monitor the operating status of the air compressor in real time and obtain the air pressure B of the compressed air pipeline. a and air compressor suction pressure B b , to carry out linkage control of the distributed photovoltaic power generation subsystem and the compressed air subsystem.

2. A distributed photovoltaic power generation and compressed air linkage system according to claim 1, characterized in that: The control unit (1) has the rated power of the built-in air compressor, and the corresponding relationship between the electric valve and the energy storage electric valve corresponding to each air compressor.

3. A distributed photovoltaic power generation and compressed air linkage system according to claim 1, characterized in that: The control unit (1) calculates the maximum allowable compression ratio ε through a built-in compression ratio and power relationship function. max The compression ratio ε is set set The power difference.

4. A distributed photovoltaic power generation and compressed air linkage system according to claim 1, characterized in that: The system further comprises a display setting unit (12) for setting parameters to the control unit (1), wherein the parameters include: Start power threshold P set , where P set >0; Restoration power threshold P set2 , and P set <P set2 ; And a first delay time t1 and a second delay time t2 of the control unit (1).

5. The linkage system of distributed photovoltaic power generation and compressed air according to claim 1, characterized in that: The compressed air system control unit (5) comprises an energy storage tank (8) for storing compressed air generated by the air compressor according to the command of the control unit (1).

6. A distributed photovoltaic power generation and compressed air linkage system according to claim 5, characterized in that: The compressed air system control unit (5) further comprises an air inlet valve (9) and an air supply valve (10) arranged at both ends of the energy storage gas tank (8); The air inlet valve (9) and the air supply valve (10) are connected to the control unit (1); The control unit (1) obtains the states of the air intake valve (9) and the air supply valve (10), and issues control commands to the air intake valve (9) and the air supply valve (10).

7. A distributed photovoltaic power generation and compressed air linkage system according to claim 1, characterized in that: The compressed air system control unit (5) comprises an electric valve and an energy storage electric valve of a compressed air pipeline respectively connected to the control unit (1); The control unit (1) obtains the states of the electric valve and the energy storage electric valve, and issues control commands to the electric valve and the energy storage electric valve.

8. A control method for a linkage system of distributed photovoltaic power generation and compressed air according to any one of claims 1 to 7, characterized in that: The method comprises three stages in sequence, corresponding to the sub-methods of state setting, absorption control and recovery control respectively; The state setting sub-method includes the following steps: Step S1: The control unit (1) monitors the operating status of each air compressor, obtains the current operating time and operating status of each air compressor, and selects and respectively sets the air compressors in each operating status according to the operating status, wherein the operating status includes the operating, standby and fault status; the control unit (1) sets the rated power corresponding to the air compressor in the standby state according to the rated power of each built-in air compressor; Step S2: The control unit (1) monitors the opening and closing states of each electric valve and the energy storage electric valve, controls the electric valve corresponding to the air compressor in the standby state and the energy storage electric valve to be in a closed state and set, controls the electric valve corresponding to the air compressor in the running state to be in a closed state and set, and controls the electric valve corresponding to the air compressor in the fault state and the energy storage electric valve to be in a closed state and set; Step S3: The control unit (1) monitors the compressed air pipeline pressure B a juxtaposition; Step S4: The control unit (1) monitors the air compressor suction pressure B b and place.

9. The control method according to claim 8, characterized in that: The control sub-method includes the following steps: Step S5: The control unit (1) obtains the photovoltaic power generation power P PV and load active power P P ; Step S6: Determine whether the photovoltaic power generation power P PV >0, if no, then wait; if yes, then execute step S7; Step S7: Calculate and determine whether P P -P PV ≥P set If yes, then wait; if no, then execute step S8; Step S8: Calculate the load to be regulated △P1=P set -(P P -P PV ), get the compression ratio ε set at the current moment set , calculate the maximum allowable compression ratio ε through the built-in compression ratio and power relationship function max The compression ratio ε is set set The power difference △P2; Step S9: Compare △P1 and △P2. If △P1≤△P2, adjust the air compressor air supply compression ratio to the maximum allowable compression ratio ε. max , and enter step S10; if △P1>△P2, adjust the air compressor air supply compression ratio to the maximum allowable compression ratio ε max , and calculate the power difference △P3 = △P1-△P2, and calculate the rated power of the air compressor in the standby state, and get the number of air compressors that are greater than or equal to and closest to △P3 P ai For a i The rated power of the air compressors in the standby state is calculated, and the corresponding air compressors in the standby state are turned on, and the corresponding energy storage electric valves and air intake valves (9) are opened; if the sum of the rated powers of the air compressors in the standby state is less than △P3, that is, Then all the air compressors in standby mode are turned on and the corresponding energy storage electric valves and air intake valves (9) are opened, and the process goes to step S10; Step S10: If P P -P PV ≥P set , then go to step S11; otherwise return to step S9; Step S11: After the first delay time t1, determine if P P -P PV ≥P set2 , then enter the recovery control phase; otherwise, return to step S10.

10. The control method according to claim 9, characterized in that: The recovery control sub-method includes the following steps: Step S12: Restore the compression ratio to the set supply pressure compression ratio ε set , judge if P P -P PV <P set , then return to step S5; otherwise, execute step S13; Step S13: If P P -P PV ≥P set2 , then execute step S14; otherwise, return to step S11; Step S14: After the second delay time t2, if P P -P PV ≥P set2 , then exit the consumption control stage and return to the daily control logic of the compressed air subsystem; otherwise, return to step S12.

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