Multi-stage frequency conversion vortex machine unit control method

Abstract

The invention relates to the technical field of air compressors, in particular to a multi-group frequency conversion vortex unit control system. S1, a user presses a power-on button; s2, judging whether the vortex unit has a fault or not; s3, troubleshooting and solving the fault problem; s4, whether the single vortex machine in the unit breaks down or not is judged; s5, cancelling the joint control of the fault single machine; s6, the fault single machine is solved and eliminated, and the actual accumulated operation time of the single machine is restored; s7, adding joint control to each single machine; s8, judging whether the exhaust pressure of the output end is higher than the shutdown pressure or not; s9, judging the accumulative running time of each single machine which is not in the running state; s10, enabling each single machine to enter an operation mode; s11, the number of the started vortex machines in the unit is judged; s12, controlling the MPC through an intelligent core algorithm; s13, whether the tail end exhaust pressure is larger than the set shutdown pressure or not is judged; s14, comparing the operation time of each single machine; and S15, a standby mode. The control method has the advantage of timely and accurately controlling the vortex machine.

Description

Technical Field

[0001] The present invention relates to the technical field of air compressors, and in particular to a control system for multiple groups of variable frequency scroll units. Background Art

[0002] As energy consumption and environmental protection issues become increasingly severe, high-efficiency, energy-saving oil-free scroll machine systems have become an inevitable trend in the development of the industry. Large scroll compressors are a type of volumetric compression compressor. The compression components consist of a moving scroll and a static scroll, including many structural features that allow the gas to flow through the compressor housing in a bypass manner to reduce entrained oil.

[0003] In the existing technology, most factories use three separate scroll compressors for starting. However, due to the starting characteristics of the motor, the existing variable frequency control system has problems of low control accuracy and slow response speed when multiple groups of scroll compressors work together.

[0004] Based on this, the present invention designs a control system for multiple groups of variable frequency scroll units to solve the above problems. Summary of the invention

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a control system for multiple groups of variable frequency scroll units, comprising the following steps: S1, the user presses the power button; S2, determines whether the scroll unit has a fault, if so, proceeds to step S3; if not, jumps to step S4; S3, troubleshoots and solves the fault; S4, determines whether the single scroll machine in the unit has a fault, jumps to step S7 for the single machine without a fault; the single machine with a fault enters step S5; S5, cancels the joint control of the faulty single machine, and gives the faulty single machine a maximum operating time; S6, solves the single machine that has a fault and restores the actual cumulative operating time of the single machine; S7, each single machine joins the joint control, and obtains the cumulative operating time of each single machine in turn; S8, determines the exhaust pressure at the output end Whether the force is higher than the shutdown pressure, if so, jump to step S15, if not, enter step S9; S9, judge the cumulative running time of each unit that is not in the running state, if it is the smallest, enter step S10; if not, enter step S15; S10, each unit enters the running mode and adopts PID speed regulation; S11, judge the number of scroll machines in the unit, if less than 2, enter step S10; if greater than or equal to 2, enter S12; S12, control MPC through the intelligent core algorithm; S13, judge whether the terminal exhaust pressure is greater than the set shutdown pressure, if so, enter S14, if not, enter S12 for prediction and judgment; S14, compare the running time of each unit; S15, standby mode.

[0006] Preferably, in S3, the exhaust fault, temperature fault and emergency stop fault of the unit are checked.

[0007] Preferably, in S6, the communication fault and inverter fault of the single machine are checked.

[0008] Preferably, the PID formula in S10 is specifically: u(k)=(Kp*e(k)2)*e(k)+Ki*T*∑e(i)+(Kd / T)*[Pv(k)–Pv(k-1)].

[0009] Preferably, the specific formula of the core algorithm in S12 is: [\min_{u(t),u(t+1),...,u(t+N_p-1)}\sum_{k=t}^{t+N_p-1}||y(k|t)-r(k)||^2_{Q}+||u(k|t)||^2_{R}].

[0010] Preferably, it also includes S16, a load balancing strategy, when there are multiple machines turned on in the unit and the load rate is very low, entering S14.

[0011] Preferably, in the PID formula, when e(k)≥5, kp=100; when 1≥e(k)≤5, kp=50; when 0.2≥e(k)1, kp=5.

[0012] In summary, this application has the following beneficial technical effects:

[0013] 1. The main difference between the variable frequency scroll machine and the industrial frequency scroll machine lies in their driving mode and energy efficiency control. The variable frequency scroll machine adjusts the speed of the motor through the inverter, while the industrial frequency scroll machine is directly connected to a fixed frequency power supply and cannot adjust the speed.

[0014] 2. Higher energy efficiency: The variable frequency scroll machine can adjust the output power and speed according to actual needs, which means that energy consumption can be greatly reduced under partial load and the energy efficiency ratio of the overall system can be improved.

[0015] 3. Higher control accuracy: Frequency conversion technology enables the equipment to control output more accurately and achieve fine adjustment of parameters such as pressure and flow, which is especially important for industrial applications that require precise control.

[0016] 4. Stronger adaptability: The variable frequency scroll machine can respond quickly to load changes and is suitable for application scenarios that require frequent output adjustments or face irregular load changes.

[0017] 5. Reduced maintenance costs: Through intelligent monitoring and preventive maintenance reminders, sudden failures are reduced, equipment life is extended, external load changes are quickly responded to, indoor environment comfort is maintained, and a convenient user interaction experience is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] Figure 1 Schematic diagram of the overall logic of the control system in this embodiment. DETAILED DESCRIPTION

[0020] 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 only 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 are within the scope of protection of the present invention.

[0021] The following is combined with Figure 1 This application is described in further detail.

[0022] A control system for multiple groups of variable frequency scroll units includes the following steps:

[0023] S1, the user presses the power button;

[0024] S2, determine whether the scroll unit has a fault, if so, go to step S3; if not, jump to step S4;

[0025] S3, troubleshoot and solve the faults, mainly troubleshoot and solve the exhaust faults, temperature faults and emergency stop faults of the unit, and enter S4 after repair;

[0026] S4, respectively determine whether the single scroll machine in the unit is faulty, if there is no fault in the single scroll machine, jump to step S7; if there is a fault in the single scroll machine, go to step S5;

[0027] S5, cancel the joint control of the faulty single machine, give the faulty single machine the maximum running time, and enter S6 after repair;

[0028] S6, troubleshoot the faulty single machine and restore the actual accumulated running time of the single machine, mainly troubleshoot the communication fault and inverter fault of the single machine, and enter S7 after repair and troubleshooting;

[0029] S7, each single machine joins the joint control, and obtains the accumulated running time of each single machine in turn;

[0030] S8, judging whether the exhaust pressure at the output end of the unit is higher than the shutdown pressure, if so, jumping to step S15, if not, entering step S9;

[0031] S9, determine the accumulated running time of each stand-alone machine that is not in running state, if it is the smallest, go to step S10; if it is not the smallest, go to step S15;

[0032] S10, each single machine enters the running mode, adopts PID speed regulation, and enters S11 after the speed regulation is normal;

[0033] S11, judging the number of scroll machines in operation in the unit, if it is less than 2, proceeding to step S10; if it is greater than or equal to 2, proceeding to S12;

[0034] S12, control MPC through intelligent core algorithm;

[0035] S13, determine whether the terminal exhaust pressure is greater than the set shutdown pressure, if so, proceed to S14, if not, proceed to S12 for prediction and judgment;

[0036] S14, comparing the running time of each single machine;

[0037] S15, standby mode;

[0038] S16, balanced load strategy, after controlling MPC through the intelligent core algorithm of S12, it also enters S16. When there are multiple machines turned on in the unit and the load rate (current operating frequency / set rated frequency) is very low, it enters S14.

[0039] The PID formula in S10 is specifically: u(k)=(Kp*e(k)2)*e(k)+Ki*T*∑e(i)+(Kd / T)*[Pv(k)–Pv(k-1)], Kp is taken according to the actual deviation: when e(k)≥5, kp=100; when 1≥e(k)≤5, kp=50; when 0.2≥e(k)1, kp=5, wherein the performance of each component in the formula is shown in Table 1.

[0040]

[0041] The specific formula of the core algorithm in S12 is: [\min_{u(t),u(t+1),...,u(t+N_p-1)}\sum_{k=t}^{t+N_p-1}||y(k|t)-r(k)||^2_{Q}+||u(k|t)||^2_{R}]

[0042] Where (u(k|t)) is the control input predicted at time (t) for the future time (k); (y(k|t)) is the system output predicted at time (t) for the future time (k); (r(k)) is the reference trajectory or set point; (N_p) is the length of the predicted horizon; (Q) and (R) are weighting matrices corresponding to the penalty terms for the output error and control input, respectively; (||.||^2) represents the square of the Euclidean norm, which is used to measure the size of the error or control input.

[0043] The implementation principle of this embodiment is as follows: output a control signal to the variable frequency drive according to a preset control logic; adopt an advanced PID algorithm combined with model predictive control (MPC) to dynamically adjust the working state of each group of scroll compressors according to real-time collected environmental parameters (such as indoor and outdoor temperature and humidity, load change rate, etc.) and historical operation data to achieve rapid response and high efficiency energy saving; load balancing strategy: automatically evaluate the working efficiency and remaining life of each compressor through an algorithm, reasonably distribute the load, avoid long-term high-load operation of a single device, extend the overall service life of the system and maintain efficient operation; fault self-diagnosis and fault-tolerant mechanism: integrated fault detection module, can monitor the operating state of the compressor in real time, once an abnormality is found, immediately start the standby unit or adjust the working mode of other units to ensure uninterrupted and stable operation of the system, so as to control the scroll machine in a timely and accurate manner;

[0044] This embodiment also has the following advantages:

[0045] 1. The main difference between the variable frequency scroll machine and the industrial frequency scroll machine lies in their driving mode and energy efficiency control. The variable frequency scroll machine adjusts the speed of the motor through the inverter;

[0046] 2. Higher energy efficiency: The variable frequency scroll machine can adjust the output power and speed according to actual needs, which means that energy consumption can be greatly reduced under partial load and the energy efficiency ratio of the overall system can be improved.

[0047] 3. Higher control accuracy: Frequency conversion technology enables the equipment to control output more accurately and achieve fine adjustment of parameters such as pressure and flow, which is especially important for industrial applications that require precise control.

[0048] 4. Stronger adaptability: The variable frequency scroll machine can respond quickly to load changes and is suitable for application scenarios that require frequent output adjustments or face irregular load changes.

[0049] 5. Reduced maintenance costs: Through intelligent monitoring and preventive maintenance reminders, sudden failures are reduced, equipment life is extended, external load changes are quickly responded to, indoor environment comfort is maintained, and a convenient user interaction experience is provided.

[0050] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control system for multiple variable frequency scroll units, characterized in that: The method comprises the following steps: S1, the user presses the power button; S2, judging whether the scroll unit has a fault, if so, proceeding to step S3; if not, jumping to step S4; S3, troubleshooting and solving the fault; S4, judging whether the scroll unit in the unit has a fault, and if there is no fault, jumping to step S7; if there is a fault, the unit enters step S5; S5, canceling the joint control of the faulty unit, giving the faulty unit a maximum running time; S6, solving and eliminating the faulty unit and restoring the actual accumulated running time of the unit; S7, each single machine joins the joint control, and the cumulative running time of each single machine is obtained in turn; S8, judge whether the exhaust pressure at the output end is higher than the shutdown pressure, if so, jump to step S15, if not, enter step S9; S9, judge the cumulative running time of each single machine that is not in operation, if it is the smallest, enter step S10; if not, enter step S15; S10, each single machine enters the operation mode and adopts PID speed regulation; S11, judge the number of scroll machines in the unit, if less than 2, enter step S10; if greater than or equal to 2, enter S12; S12, control MPC through the intelligent core algorithm; S13, judge whether the terminal exhaust pressure is greater than the set shutdown pressure, if so, enter S14, if not, enter S12 for prediction and judgment; S14, compare the running time of each single machine; S15, standby mode.

2. A control system for multiple variable frequency scroll units according to claim 1, characterized in that: In S3, the exhaust fault, temperature fault and emergency stop fault of the unit are checked.

3. A control system for multiple variable frequency scroll units according to claim 2, characterized in that: In S6, the communication faults and inverter faults of a single machine are checked.

4. A control system for multiple variable frequency scroll units according to claim 1, characterized in that: The specific PID formula in S10 is: u(k)=(Kp*e(k)2)*e(k)+Ki*T*∑e(i)+(Kd / T)*[Pv(k)–Pv(k-1)].

5. A control system for multiple variable frequency scroll units according to claim 1, characterized in that: The specific formula of the core algorithm in S12 is: [\min_{u(t),u(t+1),...,u(t+N_p-1)}\sum_{k=t}^{t+N_p-1}||y(k|t)-r(k)||^2_{Q}+||u(k|t)||^2_{R}].

6. A control system for multiple variable frequency scroll units according to claim 1, characterized in that: It also includes S16 and load balancing strategy. When there are multiple machines turned on in the unit and the load rate is very low, it enters S14.

7. A control system for multiple variable frequency scroll units according to claim 4, characterized in that: In the PID formula, when e(k)≥5, kp=100; when 1≥e(k)≤5, kp=50; when 0.2≥e(k)1, kp=5.

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