High-energy-efficiency joint control method and system for air compression station

Abstract

The invention discloses a high-energy-efficiency joint control method and system for an air compression station. The method comprises the following steps that working condition data of all screw air compressors in the air compression station under different exhaust pressures are stored in a database of a controller; the controller records the post-processing equipment pressure difference of each screw air compressor; according to the pressure difference of the post-processing equipment, the controller calculates the actual exhaust pressure required by each screw air compressor; whether each screw air compressor is in a fault state or not is monitored in real time, and if yes, the screw air compressors in the fault state are excluded from the control queue; the screw air compressor with the highest priority is firstly started, and the operation number of the screw air compressors is dynamically adjusted according to the pressure of the header pipe after ts seconds; the pipe network flow demand range is calculated under the steady-state working condition, total power consumption minimization serves as a target function, and under the set constraint condition, the controller determines the optimal operation scheme through an enumeration algorithm traversing the screw air compressor combination. According to the invention, efficient joint control of the screw air compressor can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressed air, and in particular relates to a high-energy-efficiency joint control method and system for an air compressor station. Background Art

[0002] Compressed air plays a vital role in the industrial sector. Not only is it one of the three major driving forces in industrial production, second only to electricity, it is also widely used in equipment manufacturing, automotive, metallurgy, electricity, electronics, medical, textile, and other industries. Despite its high energy consumption, compressed air's importance in the industrial sector cannot be ignored. To reduce energy consumption and improve efficiency, a series of measures are necessary, including optimizing system design, implementing advanced energy-saving technologies, and improving equipment efficiency.

[0003] Screw air compressors have become the first choice in many industrial applications due to their advantages such as high efficiency and energy saving, stable operation, low maintenance cost, strong adaptability and strong continuous air supply capacity, providing users with feasible compressed air solutions.

[0004] In practical applications, air compression stations provide compressed air to users within a stable pressure range. Due to fluctuations in user gas consumption, air compression stations are typically equipped with multiple screw compressors of varying specifications to accommodate these fluctuations. Traditional control methods involve setting a start / stop pressure band for each compressor, allowing each compressor to start, stop, and load / unload within a wide pressure band. Alternatively, an automatic control system employs a sequential start / stop method, assigning different priorities to each compressor to achieve stable pressure control.

[0005] Since the actual operating conditions and rated operating conditions of screw air compressors are not always the same, and the models and cumulative operating hours of the air compressors in the same air compression station are also different, the performance curves of the air compressors are also different. Relying solely on the above control methods cannot ensure that the screw air compressors in the air compression station can achieve efficient operation.

[0006] Therefore, how to improve the operating efficiency of the air compressor station is one of the technical problems that technical personnel in this field urgently need to solve. Summary of the Invention

[0007] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a high-energy-efficiency joint control method and system for an air compressor station, thereby effectively improving the operating efficiency of the air compressor station.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a high-efficiency joint control method for an air compressor station, comprising the following steps:

[0010] S1. The controller database stores the operating condition data of each screw air compressor in the air compression station at different exhaust pressures, wherein the operating condition data includes the flow rate and power of each screw air compressor at different speeds under different exhaust pressures; the screw air compressor includes a variable frequency screw air compressor and a power frequency screw air compressor;

[0011] S2. The controller records the pressure difference of the post-processing equipment of each screw air compressor. The post-processing equipment pressure difference is the difference between the exhaust pressure of the screw air compressor after entering the post-processing equipment and then entering the compressed air pipeline network and the pipeline pressure;

[0012] S3. Based on the pipe network set pressure and the pressure difference of the post-processing equipment corresponding to each screw air compressor, the controller calculates the actual exhaust pressure required by each screw air compressor, sets the actual exhaust pressure of each variable frequency screw air compressor as the set pressure of each variable frequency screw air compressor, and sets the loading and unloading pressure band of each power frequency screw air compressor according to the actual required exhaust pressure;

[0013] S4. Real-time monitoring of each screw air compressor to see if it is in a faulty state. If so, the screw air compressor in the faulty state is excluded from the control queue;

[0014] S5. The controller starts the screw air compressor according to the input start and stop sequence, starting the screw air compressor with the highest priority first. s After a few seconds, the number of screw air compressors in operation is dynamically adjusted according to the main pipe pressure;

[0015] S6. Calculate the pipeline network flow demand range under steady-state conditions, with minimizing total power consumption as the objective function. Under set constraints, the controller determines the optimal operating plan by traversing the screw air compressor combination through an enumeration algorithm.

[0016] As a preferred technical solution, in step S1, if the controller does not store the flow and power values of a variable frequency screw air compressor at a certain exhaust pressure and a specific load rate, the flow and power values are obtained by linear fitting based on the adjacent known load rates, powers, and flow rates at the exhaust pressure.

[0017] As a preferred technical solution, the linear fitting is specifically as follows:

[0018] For variable frequency screw air compressors, under a known exhaust pressure, the load rate η1 corresponds to a flow rate q1 and a power p1, and the load rate η2 corresponds to a flow rate q2 and a power p2. The value of the load rate n is between 0 and 1.

[0019] Load rate η x The flow rate = (η x -η1)*(q2-q1) / (η2-η1), where η1<η x <η2;

[0020] Load rate η x Power = (η x -η1)*(p2-p1) / (η2-η1), where η1<η x <η2;

[0021] For a power frequency screw air compressor, under a known exhaust pressure, the corresponding flow rate during loading is q l , the power is p l ; The corresponding flow rate during unloading is 0 and the power is p ul ; When the machine is stopped, the flow rate and power are both 0. In the following formula, η is the load rate, and n is 1 or 0.

[0022] The flow rate of the industrial frequency screw air compressor = q l *η;

[0023] Power of industrial frequency screw air compressor = (p l -p ul )*η+p ul .

[0024] As a preferred technical solution, step S1 further includes the following steps:

[0025] Set an attenuation ratio b for the screw air compressor, and correct the flow parameters according to the attenuation coefficient b and the accumulated running time.

[0026] As a preferred technical solution, in step S3, the start and stop sequence of each air compressor and the main pipe loading pressure setting value p are recorded in the controller. ls , unloading pressure setting value p uls , loading and unloading delay value t s , flow adjustment range q m .

[0027] As a preferred technical solution, step S4 is specifically as follows: the controller reads the pipeline set pressure, pipeline actual pressure, pipeline flow, operating status, fault status, motor speed, actual exhaust pressure, and set pressure information of each screw air compressor in real time through the field bus; the controller determines the fault status of each screw air compressor based on the read information and excludes the screw air compressor in a faulty state from the control queue.

[0028] As a preferred technical solution, step S5 is specifically as follows:

[0029] S51, if the main pipe pressure is lower than the loading pressure setting value p ls , the system adds the air compressor with the highest priority according to the start and stop order of the air compressors;

[0030] S52, if the main pipe pressure is at the loading pressure setting value p ls and unloading pressure setting value puls During this time, the system does not move and enters a steady state;

[0031] S53, if the main pipe pressure is higher than the unloading pressure setting value p uls The system unloads the air compressor with the lowest priority among the currently running air compressors according to the start and stop order of the air compressors.

[0032] As a preferred technical solution, step S6 is specifically as follows:

[0033] S61, the controller reads the current pipe network flow Q t and the pipe network pressure F, calculate the upper limit value Q of the flow constraint max =Q t +q m and the lower limit Q of the flow constraint min =Q t +Q m ;

[0034] S62. If there are n screw air compressors in the system, the power of each screw air compressor at the pressure is P(x1), P(x2)…P(x n ), the flow rates are Q(x1), Q(x2)…Q(x n ), x is the load rate, and the following objective function is obtained:

[0035] P total =P(x1)+P(x2)+…P(x n );

[0036] S63, the controller performs cyclic calculations on all the screw air compressors and load rate combinations by enumeration, and calculates the load rates x1, x2, ... x of each screw air compressor that meets the constraints. n , so that the total power of the equipment Ptotal is minimized.

[0037] As a preferred technical solution, in step 6, the constraints are as follows:

[0038] Traffic Constraint: Q min ≤Q(x1)+Q(x2)+…Q(x n )≤Q max ;

[0039] Decision variable range: variable frequency screw air compressor 0≤x≤1, industrial frequency screw air compressor x∈{0,1}.

[0040] In the second aspect, the present invention provides a high-energy-efficiency joint control system for an air compressor station, which is applied to the high-energy-efficiency joint control method for an air compressor station, and is characterized in that it includes a controller, multiple screw air compressors, multiple post-processing equipment, and a pipe network pressure sensor and a pipe network flow meter arranged on the compressed air pipe network; the controller is connected to the multiple screw air compressors through a first field bus on the one hand, and is connected to the pipe network pressure sensor and the pipe network flow meter through a second field bus on the other hand.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] The present invention builds a closed-loop control system by real-time monitoring of pipeline pressure, flow and equipment status, achieves optimal load distribution of air compressor units under steady-state conditions, and quickly responds to demand changes through a dynamic pressure compensation mechanism under transient conditions. It avoids the hysteresis effect of traditional PID control and overcomes the defect that the single control mode of variable frequency speed regulation cannot adapt to multiple types of air compressor units. In particular, by incorporating the pressure difference of the post-processing equipment into the pressure parameter correction system, the pressure loss caused by equipment such as filters and dryers is effectively compensated, so that the system pressure setting value is always close to the actual gas demand. Compared with the control method with a fixed pressure threshold, the ineffective operation time of the air compressor can be reduced. In addition, an enumeration algorithm is used to exhaust the feasible solution space, and the unit combination scheme with the best energy efficiency is screened out under the premise of ensuring flow balance, which solves the technical bottleneck that traditional optimization algorithms are prone to falling into local optimality. The overall technical solution significantly improves the comprehensive energy efficiency of the air compressor station system through the organic integration of data-driven, dynamic matching, and multi-objective optimization, while reducing the frequency of equipment start-up and shutdown, and significantly extending the service life of key components. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0044] Figure 1 The relationship between the speed and shaft power of the same screw compressor at different pressures

[0045] Figure 2 The relationship between the speed and flow of the same screw compressor at different pressures

[0046] Figure 3 The relationship between flow rate and shaft power of the same screw compressor at different pressures

[0047] Figure 4 It is a structural diagram of the control system of the present invention;

[0048] Figure 5 is a flow chart of the control method of the present invention;

[0049] Figure 6 This is an operation flow chart of the present invention according to priority and main pipe pressure;

[0050] Figure 7 It is a flow chart of the actual operation of the controller after the system of the present invention is stabilized. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0052] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0053] like Figure 1-Figure 3 The figure below shows the speed, flow rate, and power of a typical screw air compressor at different exhaust pressures. In actual applications, screw air compressors are divided into two types: power frequency and variable frequency. The power frequency type has only two states: full load and unloaded. When fully loaded, it reaches 100% flow and power, while when unloaded, it is 40% power and does not generate any flow. The variable frequency type can be adjusted steplessly between 40% and 100% load.

[0054] like Figure 4 As shown, a high-efficiency joint control system for an air compression station in this embodiment includes a controller, multiple screw air compressors, multiple post-processing equipment, and a pipe network pressure sensor and a pipe network flow meter arranged on the compressed air pipe network; each screw air compressor corresponds to a group of post-processing equipment, and the post-processing equipment includes a dryer and a filter; the controller is connected to multiple screw air compressors through a first field bus (field bus 1) on the one hand, and is connected to the pipe network pressure sensor and the pipe network flow meter through a second field bus (field bus 2) on the other hand. The controller connects each screw air compressor to the pipe network pressure sensor and the pipe network flow meter through the field bus to monitor the data and status of each screw air compressor, as well as the pressure and flow of the pipe network. The controller can control the start and stop, loading and unloading of each air compressor, as well as the maximum speed of the variable frequency screw air compressor.

[0055] In actual applications, an air compression station will use multiple screw air compressors with different flow rates. Multiple screw air compressors will eventually be connected to the same compressed air network and operate under the same exhaust pressure. In order to achieve efficient operation of multiple screw air compressors, Figure 5 As shown, the joint control method is as follows:

[0056] S1. The controller database stores the operating data of each screw air compressor in the air compression station at different exhaust pressures, wherein the operating data includes the flow rate and power of each screw air compressor at different speeds under different exhaust pressures.

[0057] It is understood that the screw compressors described include variable frequency screw compressors and industrial frequency screw compressors. The motor of the variable frequency screw compressor is controlled by a frequency converter, and its speed can be dynamically adjusted according to gas demand. The output volume varies with the speed, and stable pressure is maintained by continuously adjusting the speed, eliminating the need for frequent loading and unloading. The motor of the industrial frequency screw compressor directly drives the screw main unit at a fixed speed, with a constant output volume. The pressure is adjusted by loading / unloading (loading and unloading control): when the set pressure is reached, the compressor is unloaded and idling, and reloaded after the pressure drops.

[0058] Furthermore, step S1 is specifically as follows:

[0059] The controller's database stores operating data for each screw compressor in the station at different exhaust pressures, including flow and power at various speeds and exhaust pressures. If the controller doesn't store the flow and power values for a specific variable-frequency screw compressor at a specific load factor, a linear fit can be used to determine the values using adjacent known load factors, powers, and flow rates at that exhaust pressure.

[0060] Furthermore, the fitting method is as follows:

[0061] For a variable frequency screw air compressor, under a known exhaust pressure, the load rate η1 corresponds to a flow rate q1 and a power p1, the load rate η2 corresponds to a flow rate q2 and a power p2, and the value of the load rate n is between 0 and 1.

[0062] Load rate η x (η1<η x <η2) flow rate = (η x -η1)*(q2-q1) / (η2-η1);

[0063] Load rate η x (η1<η x <η2)=(η x -η1)*(p2-p1) / (η2-η1).

[0064] For industrial frequency screw air compressors, there are only three states: loading, unloading, and shutdown. Under a known exhaust pressure, the corresponding flow rate during loading is q l , power is p l ; The corresponding flow rate during unloading is 0 and the power is p ul ;When the machine is shut down, the flow rate and power are both 0. In the following formula, η is the load rate and n is 1 or 0.

[0065] The flow rate of the industrial frequency screw air compressor = q l *η;

[0066] Power of industrial frequency screw air compressor = (p l -p ul )*η+p ul .

[0067] Furthermore, since the flow rate of a screw air compressor will decay due to wear and tear over time, a decay ratio b can be set for the screw air compressor. The flow rate decreases by b% for every 1000 hours of cumulative operating time of the screw air compressor. For example, if a screw air compressor has a cumulative operating time of h hours and an initial full-load flow rate of q, then its current actual flow rate q' = q*(1-b*h / 1000).

[0068] S2. If the screw air compressor first enters the post-processing equipment and then enters the compressed air network (such as Figure 4 ), since the pressure loss of each post-processing equipment is inconsistent, it is also necessary to enter the difference between the exhaust pressure of each screw air compressor and the pipe network pressure (hereinafter referred to as post-processing pressure difference) p dp1 、p dp2 …p dpn .

[0069] S3. Based on the pipe network set pressure and the pressure difference of the post-processing equipment corresponding to each screw air compressor, the controller calculates the actual exhaust pressure required by each screw air compressor, and sets the actual exhaust pressure of each variable frequency screw air compressor as the set pressure of each screw air compressor through the field communication bus, and sets the loading and unloading pressure band of each industrial frequency screw air compressor according to the actual required exhaust pressure.

[0070] Furthermore, the controller needs to record the start and stop sequence of each air compressor and the main pipe loading pressure setting value p ls , unloading pressure setting value p uls , loading and unloading delay value t s , flow adjustment range q m .

[0071] S4. Real-time monitoring of each screw air compressor to see if it is in a faulty state. If so, the screw air compressor in the faulty state is excluded from the control queue;

[0072] Furthermore, step S4 is specifically as follows:

[0073] The controller reads the network set pressure, actual pressure, flow rate, operating status, fault status, motor speed, actual exhaust pressure, set pressure and other information of each screw air compressor in real time through the field bus; the controller determines the fault status of each screw air compressor and excludes the screw air compressor in the fault state from the control queue.

[0074] S5, system starts, the controller starts the air compressor according to the recorded start and stop sequence, starts the air compressor with the highest priority first, and after ts seconds, performs the following actions according to the main pipe pressure, such as Figure 6 As shown:

[0075] S51, if the main pipe pressure is lower than the loading pressure setting value p ls , the system adds the air compressor with the highest priority according to the start and stop order of the air compressors;

[0076] S52, if the main pipe pressure is at the loading pressure setting value p ls and unloading pressure setting value p uls During this time, the system does not move and enters a steady state;

[0077] S53, if the main pipe pressure is higher than the unloading pressure setting value p uls The system unloads the air compressor with the lowest priority among the currently running air compressors according to the start and stop order of the air compressors.

[0078] S6. After ts seconds after the system enters the stable operation state, the controller performs the following steps according to the actual operation situation, such as Figure 7 As shown:

[0079] S61, the controller reads the current pipe network flow Q t and the pipe network pressure F, calculate the upper limit value Q of the flow constraint max =Q t +q m and the lower limit Q of the flow constraint min =Q t +Q m ;

[0080] S62. If there are n screw air compressors in the system, the power of each screw air compressor at the pressure is P(x1), P(x2)…P(x n ), the flow rates are Q(x1), Q(x2)…Q(x n ), x is the load rate, and the following objective function is obtained:

[0081] P total =P(x1)+P(x2)+…P(x n );

[0082] Constraints:

[0083] (1) Traffic Constraint: Q min ≤Q(x1)+Q(x2)+…Q(x n )≤Q max ;

[0084] (2) Decision variable range: 0≤x≤1 for variable frequency machine, x∈{0,1} for industrial frequency machine;

[0085] S63, the controller performs cyclic calculations on all combinations of startup and load rates by enumeration, and calculates the load rates x1, x2, ...x of each screw air compressor that meets the constraints. n , so that the total power of the equipment Ptotal is minimized.

[0086] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0087] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high energy efficiency joint control method for an air compressor station, characterized in that: The steps include: S1. The controller database stores the operating condition data of each screw air compressor in the air compression station at different exhaust pressures, wherein the operating condition data includes the flow rate and power of each screw air compressor at different speeds under different exhaust pressures; the screw air compressor includes a variable frequency screw air compressor and a power frequency screw air compressor; S2. The controller records the pressure difference of the post-processing equipment of each screw air compressor. The post-processing equipment pressure difference is the difference between the exhaust pressure of the screw air compressor after entering the post-processing equipment and then entering the compressed air pipeline network and the pipeline pressure; S3. Based on the pipe network set pressure and the pressure difference of the post-processing equipment corresponding to each screw air compressor, the controller calculates the actual exhaust pressure required by each screw air compressor, sets the actual exhaust pressure of each variable frequency screw air compressor as the set pressure of each variable frequency screw air compressor, and sets the loading and unloading pressure band of each power frequency screw air compressor according to the actual required exhaust pressure; S4. Real-time monitoring of each screw air compressor to see if it is in a faulty state. If so, the screw air compressor in the faulty state is excluded from the control queue; S5. The controller starts the screw air compressor according to the input start and stop sequence, starting the screw air compressor with the highest priority first. s After a few seconds, the number of screw air compressors in operation is dynamically adjusted according to the main pipe pressure; S6. Calculate the pipeline network flow demand range under steady-state conditions, with minimizing total power consumption as the objective function. Under set constraints, the controller determines the optimal operating plan by traversing the screw air compressor combination through an enumeration algorithm.

2. The high energy efficiency joint control method of the air compressor station according to claim 1 is characterized in that: In step S1, if the controller does not store the flow and power values of a variable frequency screw air compressor at a certain exhaust pressure and a specific load rate, the flow and power values are obtained by linear fitting based on the adjacent known load rates, powers, and flow rates at the exhaust pressure.

3. The high energy efficiency joint control method of the air compressor station according to claim 2 is characterized in that: The linear fitting is specifically: For variable frequency screw air compressors, under a known exhaust pressure, the load rate η1 corresponds to a flow rate q1 and a power p1, and the load rate η2 corresponds to a flow rate q2 and a power p2. The value of the load rate n is between 0 and 1. Load rate η x The flow rate = (η x -η1)*(q2-q1) / (η2-η1), where η1<η x <η2; Load rate η x Power = (η x -η1)*(p2-p1) / (η2-η1), where η1<η x <η2; For a power frequency screw air compressor, under a known exhaust pressure, the corresponding flow rate during loading is q l , power is p l ; The corresponding flow rate during unloading is 0 and the power is p ul ; When the machine is stopped, the flow rate and power are both 0. In the following formula, η is the load rate, and n is 1 or 0. The flow rate of the industrial frequency screw air compressor = q l *η; Power of industrial frequency screw air compressor = (p l -p ul )*η+p ul .

4. The high energy efficiency joint control method of an air compressor station according to claim 2, characterized in that: Step S1 further includes the following steps: Set an attenuation ratio b for the screw air compressor, and correct the flow parameters according to the attenuation coefficient b and the accumulated running time.

5. The high energy efficiency joint control method of an air compressor station according to claim 1, characterized in that: In step S3, the start and stop sequence of each air compressor and the main pipe loading pressure setting value p are entered into the controller. ls , unloading pressure setting value p uls , loading and unloading delay value t s , flow adjustment range q m .

6. The high energy efficiency joint control method of an air compressor station according to claim 1, characterized in that: The specific steps of step S4 are as follows: the controller reads the network set pressure, actual network pressure, network flow, operating status, fault status, motor speed, actual exhaust pressure, and set pressure information of each screw air compressor in real time through the field bus; the controller determines the fault status of each screw air compressor based on the read information, and excludes the screw air compressor in the fault state from the control queue.

7. The high energy efficiency joint control method of an air compressor station according to claim 1, characterized in that: Step S5 is specifically as follows: S51, if the main pipe pressure is lower than the loading pressure setting value p ls , the system adds the air compressor with the highest priority according to the start and stop order of the air compressors; S52, if the main pipe pressure is at the loading pressure setting value p ls and unloading pressure setting value p uls During this time, the system does not move and enters a steady state; S53, if the main pipe pressure is higher than the unloading pressure setting value p uls The system unloads the air compressor with the lowest priority among the currently running air compressors according to the start and stop order of the air compressors.

8. The high energy efficiency joint control method of an air compressor station according to claim 1, characterized in that: Step S6 is specifically as follows: S61, the controller reads the current pipe network flow Q t and the pipe network pressure F, calculate the upper limit value Q of the flow constraint max =Q t +q m and the lower limit Q of the flow constraint min =Q t +Q m ; S62. If there are n screw air compressors in the system, the power of each screw air compressor at the pressure is P(x1), P(x2)…P(x n ), the flow rates are Q(x1), Q(x2)…Q(x n ), x is the load rate, and the following objective function is obtained: P total =P(x1)+P(x2)+…P(x n ); S63, the controller performs cyclic calculations on all the screw air compressors and load rate combinations by enumeration, and calculates the load rates x1, x2, ... x of each screw air compressor that meets the constraints. n , so that the total power of the equipment Ptotal is minimized.

9. The high energy efficiency joint control method for an air compressor station according to claim 8, characterized in that: In step 6, the constraints are as follows: Traffic Constraint: Q min ≤Q(x1)+Q(x2)+…Q(x n )≤Q max ; Decision variable range: variable frequency screw air compressor 0≤x≤1, industrial frequency screw air compressor x∈{0,1}.

10. A high energy efficiency joint control system for an air compressor station, characterized in that: The high-efficiency joint control method of an air compressor station as described in any one of claims 1 to 9 is characterized in that it includes a controller, multiple screw air compressors, multiple post-processing equipment, and a pipe network pressure sensor and a pipe network flow meter arranged on the compressed air pipe network; the controller is connected to the multiple screw air compressors through a first field bus on the one hand, and is connected to the pipe network pressure sensor and the pipe network flow meter through a second field bus on the other hand.

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