Compressor anti-surge control method for frequency converter without power feedback

Abstract

The invention relates to the technical field of mechanical control, in particular to a compressor anti-surge control method with a frequency converter free of power feedback, the surge of a compressor is reversely controlled by utilizing the phenomenon that the fluctuation change of motor current is large when the compressor surges, and firstly, the variable quantity delta I of the motor current per second is monitored; comparing the monitored current variation delta I with 1 / 10 of the rated current of the motor; if the monitored variable quantity delta I is larger than 1 / 10 of the rated current of the motor, an anti-surge valve is opened according to a preset rule until delta I is smaller than or equal to 1 / 10 of the rated current of the motor; if the monitored variable quantity delta I is smaller than or equal to 1 / 10 of the rated current of the motor, the current opening degree of the anti-surge valve is kept; and the steps are repeated until the anti-surge valve stops acting, so that the technical problem that a compressor surge control method in the prior art is difficult to be universally suitable for all MVR systems or frequency converter types due to dependence on a shaft power feedback function of a specific frequency converter is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical control, and particularly to a compressor anti-surge control method without power feedback of a frequency converter. Background Art

[0002] With the continuous progress of global industrialization, the MVR (Mechanical Vapor Recompression) steam compression system has been widely used in many fields such as petroleum, chemical industry, pharmaceuticals, sewage treatment, and seawater desalination due to its characteristics of high efficiency and energy conservation. This system heats up and pressurizes the low-temperature steam through the high-speed rotation of the compressor rotor, increases its enthalpy value, and then makes the steam enter the heat exchanger for re-condensation, thereby fully exploiting and utilizing the potential of the steam and achieving efficient energy utilization.

[0003] As the core component of the MVR system, the stable operation of the compressor is crucial for the performance of the entire system. And the stable operation of the compressor highly depends on effectively avoiding the occurrence of surge. Surge is a phenomenon caused by too small inlet flow of the compressor, resulting in the pressure in the pipe network being higher than the discharge pressure of the compressor, and then causing gas backflow and large-amplitude airflow pulsation. Specifically, it is manifested as the compressor emitting a whistling sound, the rotor vibration intensifying, and the current fluctuation increasing. Surge, as an inherent characteristic of the compressor, has great harmfulness and is one of the main reasons for compressor damage. Therefore, effectively avoiding surge is of great significance for extending the service life of the compressor.

[0004] Currently, the main method to avoid surge is to monitor the flow rate at the inlet of the compressor or the rotor shaft power to judge the stability of the compression system and whether it is in the surge area. However, in the MVR system, if there is no compressor inlet flow monitoring device or the monitoring device operates inaccurately, the entire anti-surge control system will be seriously affected. To address this problem, most compressors on the market adopt a method of feedbacking whether the compressor is in the surge state through the change of shaft power. But this method requires the frequency converter to have a built-in shaft power feedback function, and in actual applications, not all frequency converters have this function, thus limiting the general applicability of this method.

[0005] In summary, the compressor surge control methods in the prior art are difficult to be generally applicable to all MVR systems or frequency converter types due to relying on the shaft power feedback function of specific frequency converters. Summary of the Invention

[0006] The purpose of the present invention is to provide a compressor anti-surge control method without power feedback of a frequency converter, aiming to solve the technical problem that the compressor surge control methods in the prior art are difficult to be generally applicable to all MVR systems or frequency converter types due to relying on the shaft power feedback function of specific frequency converters.

[0007] To achieve the above object, a compressor anti-surge control method without power feedback for a frequency converter according to the present invention includes the following steps: First, monitor the change amount ΔI of the motor current per second; Compare the monitored current change amount ΔI with 1 / 10 of the rated current of the motor; If the monitored change amount ΔI is greater than 1 / 10 of the rated current of the motor, open the anti-surge valve according to a preset rule until ΔI is less than or equal to 1 / 10 of the rated current of the motor; When the monitored change amount ΔI is less than or equal to 1 / 10 of the rated current of the motor, maintain the current opening of the anti-surge valve; Repeat the above steps until the anti-surge valve stops operating.

[0008] Among them, when the monitored change amount ΔI is greater than 1 / 10 of the rated current of the motor, the preset rule for opening the anti-surge valve is: after receiving an electrical signal, the opening of the anti-surge valve increases by one degree per second.

[0009] Among them, when the opening of the anti-surge valve increases, when part of the outlet air flow returns to the inlet through the anti-surge valve, the air flow at both ends of the compressor is stabilized, so the current fluctuation decreases, and the anti-surge valve will not increase the opening anymore, completing the entire anti-surge procedure.

[0010] Among them, before executing the control method, initialize the control parameters, including the rated current of the motor, the maximum opening of the anti-surge valve, and the opening speed.

[0011] Among them, when executing the compressor anti-surge control, monitor the operating state of the system in real time. When a fault is detected, immediately perform fault diagnosis and location, and take corresponding measures for processing.

[0012] Among them, when monitoring the operating state of the system, use a fault diagnosis algorithm based on model prediction, signal processing analysis, or data-driven learning for monitoring and diagnosis.

[0013] Among them, when the system is running, record the operating data of the system (such as current change amount, anti-surge valve opening, compressor outlet pressure, etc.), and analyze and process these data.

[0014] Among them, based on the real-time recorded operating data of the system, and combined with fuzzy control algorithm, neural network control algorithm, adaptive control algorithm, or reinforcement learning algorithm, dynamically adjust the anti-surge control strategy.

[0015] For a compressor anti-surge control method without power feedback for a frequency converter according to the present invention, the most important phenomena when the compressor surges include current fluctuations: the current of the variable-frequency compressor directly reflects the work done by the compressor rotor. Due to the repeated fluctuation of the air flow in the compressor, the current will show periodic severe fluctuations with a large amplitude.

[0016] The present invention utilizes the phenomenon that the motor current fluctuates greatly when the compressor surges, and controls the compressor surge reversely, eliminating the need to detect the flow rate in the inlet and outlet pipelines of the compressor and the condition that the frequency converter requires feedback power. Due to different motor brands or design values, the characteristic curves of the motor at constant torque are also different. Generally, when the compressor is operating normally, the amplitude of the current in a single cycle does not exceed 1 / 10 of the rated current of the motor (changed according to the on-site situation). However, when the fluctuation amount of the flow rate exceeds this value, it indicates that the compressor is in an abnormal state, and the electric signal control directly opens the anti-surge valve until the current change value ΔI does not exceed 1 / 10 times the rated current of the motor, and then the anti-surge valve stops operating.

[0017] Specifically, after receiving the electric signal, the opening of the anti-surge valve increases by one degree per second. When part of the outlet air flow returns to the inlet through the anti-surge valve, the air flow at both ends of the compressor is stabilized, and then the current fluctuation will decrease, and the opening of the anti-surge valve will no longer increase. That is, the entire anti-surge program is completed.

[0018] In this way, the technical problem in the prior art that the compressor surge control method is difficult to be generally applicable to all MVR systems or frequency converter types due to relying on the shaft power feedback function of a specific frequency converter is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a flowchart of the compressor anti-surge control method without power feedback of the frequency converter of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will describe the embodiments of the present invention in detail. The examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0022] Please refer to Figure 1 , Figure 1 It is a flowchart of the compressor anti-surge control method without power feedback of the frequency converter of the present invention.

[0023] The present invention provides a compressor anti-surge control method without power feedback of the frequency converter, including the following steps: S1. First, monitor the change in motor current per second, ΔI; For this specific embodiment, before executing the control method, initialize the control parameters, including the rated current of the motor, the maximum opening of the anti-surge valve, and the opening speed.

[0024] S2. Compare the monitored current change ΔI with 1 / 10 of the rated current of the motor; S3. If the monitored change ΔI is greater than 1 / 10 of the rated current of the motor, open the anti-surge valve according to the preset rule until ΔI is less than or equal to 1 / 10 of the rated current of the motor; For this specific embodiment, when the monitored change ΔI is greater than 1 / 10 of the rated current of the motor, the preset rule for opening the anti-surge valve is: after the anti-surge valve opening receives an electrical signal, the opening increases by one degree per second.

[0025] When the opening of the anti-surge valve increases, when part of the outlet air flow returns to the inlet through the anti-surge valve, the air flow at both ends of the compressor is stabilized, so the current fluctuation decreases, and the anti-surge valve will not increase the opening anymore, completing the entire anti-surge procedure.

[0026] S4. When the monitored change ΔI is less than or equal to 1 / 10 of the rated current of the motor, maintain the current opening of the anti-surge valve; S5. Repeat the above steps until the anti-surge valve stops operating.

[0027] For this specific embodiment, when performing the anti-surge control of the compressor, monitor the operating state of the system in real time. When a fault is detected, immediately perform fault diagnosis and location, and take corresponding measures for processing.

[0028] In the process of performing the anti-surge control of the compressor, monitoring the operating state of the system in real time plays a crucial role. This link is the key to ensuring the safe and efficient operation of the compressor. Once any abnormal or fault signal of the monitoring system is detected, the fault diagnosis and location program will be immediately started.

[0029] The fault diagnosis process is not only rapid but also accurate. It can use advanced analysis techniques and historical data comparison to quickly identify the type, cause, and specific location of the fault. In this way, it provides a strong basis for subsequent fault handling, enabling maintenance personnel to quickly locate the problem and reduce the troubleshooting time.

[0030] Once a fault is detected, the system will immediately take corresponding measures for processing. This includes automatically adjusting control parameters, switching to standby equipment, or sending an alarm to notify the maintenance personnel, etc. By quickly responding and processing, it can effectively prevent the fault from further expanding and avoid more serious damage to the compressor, such as equipment damage, production interruption, or even safety accidents.

[0031] In this way, the real-time monitoring and processing mechanism not only improves the system's response speed and processing efficiency, but also greatly enhances the system's reliability and security.

[0032] When monitoring the system operation status, a fault diagnosis algorithm based on model prediction, signal processing analysis, or data-driven learning is used for monitoring and diagnosis.

[0033] Through a fault diagnosis algorithm based on model prediction, signal processing analysis, or data-driven learning, a comprehensive monitoring and diagnosis of the system operation status is carried out.

[0034] The model prediction algorithm predicts the future state of the system by constructing a mathematical model of the system and compares it with the actual operation state. Once a difference is found, the fault source can be quickly locked. The signal processing analysis algorithm carefully analyzes various signals generated during the system operation, such as vibration, sound, temperature, etc., extracts fault characteristics from them, and provides strong evidence for fault diagnosis. The data-driven learning algorithm relies on a large amount of historical data and, through machine learning methods, discovers the internal laws of the system operation, thereby achieving accurate prediction and diagnosis of faults.

[0035] During the system operation, record the system operation data (such as current change amount, anti-surge valve opening, compressor outlet pressure, etc.), and analyze and process these data.

[0036] During the system operation, record key operation data such as current change amount, anti-surge valve opening, compressor outlet pressure, etc., and analyze and process these data, which can provide strong data support for anti-surge control. Through in-depth analysis of these data, the internal laws of the system operation can be revealed, providing a basis for optimizing control strategies. At the same time, these data can also be used for fault troubleshooting and performance evaluation, improving the maintainability and usability of the system.

[0037] Moreover, based on the real-time recorded system operation data, combined with fuzzy control algorithm, neural network control algorithm, adaptive control algorithm, or reinforcement learning algorithm, the anti-surge control strategy is dynamically adjusted.

[0038] The present invention combines intelligent control algorithms such as fuzzy control algorithm, neural network control algorithm, adaptive control algorithm, or reinforcement learning algorithm, and dynamically adjusts the anti-surge control strategy according to the real-time recorded system operation data, which can make the control system more flexible and intelligent. These algorithms can automatically adjust control parameters and strategies according to the real-time operation state of the system and changes in the external environment, so that the compressor always maintains the best working state. This dynamic adjustment mechanism not only improves the stability and adaptability of the system, but also optimizes the operation efficiency of the compressor, reducing energy consumption and costs.

[0039] Using a compressor surge prevention control method without power feedback of the present invention, the main phenomena when the compressor surges include current fluctuations: The current of the variable frequency compressor directly reflects the work done by the compressor rotor. Due to the repeated fluctuations of the air flow in the compressor, the current will show periodic severe fluctuations with a large amplitude.

[0040] The present invention utilizes the phenomenon of large changes in the motor current fluctuations generated when the compressor surges to reversely control the compressor surge, eliminating the need to detect the flow rate in the inlet and outlet pipelines of the compressor and the condition of the frequency converter having feedback power. Due to different motor brands or design values, the characteristic curves of the motor at constant torque are also different. Generally, when the compressor is operating normally, the amplitude of a single cycle of the current will not exceed 1 / 10 of the rated current of the motor (changed according to the on-site situation). However, when the fluctuation amount of the flow rate exceeds this value, it means that the compressor is in an abnormal state, and the electric signal control directly opens the anti-surge valve until the current change value ΔI does not exceed 1 / 10 times the rated current of the motor, and then the anti-surge valve stops operating.

[0041] Specifically, after receiving the electric signal, the opening of the anti-surge valve increases by one degree per second. When part of the outlet air flow returns to the inlet through the anti-surge valve, the air flow at both ends of the compressor is stabilized, and then the current fluctuations will decrease, and the opening of the anti-surge valve will no longer increase. That is, the entire anti-surge program is completed.

[0042] In this way, it solves the technical problem that the compressor surge prevention control method in the prior art is difficult to be generally applicable to all MVR systems or frequency converter types due to relying on the shaft power feedback function of a specific frequency converter.

[0043] The compressor surge prevention control method of the present invention innovatively realizes an anti-surge control strategy that does not rely on the shaft power feedback function of a specific frequency converter by real-time monitoring the change amount ΔI of the motor current per second and making a fine comparison with 1 / 10 of the rated current of the motor; The beneficial effects are as follows: 1. The general applicability is significantly enhanced: This method completely gets rid of the dependence on the shaft power feedback function of a specific frequency converter in the prior art, enabling it to be widely applicable to various MVR systems or different types of frequency converters. Regardless of the system configuration, it can effectively implement anti-surge control, greatly expanding the application scope and flexibility of the technology.

[0044] 2. The response speed is fast: Through real-time and high-precision monitoring of the motor current change, this method can almost instantly identify the potential risk of surge. Once the monitored current change exceeds the preset threshold, the anti-surge valve will be immediately opened or adjusted according to the preset rules, effectively curbing the occurrence of surge. This rapid response mechanism significantly improves the stability and reliability of the system.

[0045] 3. High control precision: This method uses 1 / 10 of the motor rated current as the precise control threshold. Through careful comparison and judgment, it ensures that the opening adjustment of the anti-surge valve is neither excessive nor insufficient. This high-precision control method optimizes the operation efficiency of the compressor, reduces unnecessary energy loss, and improves the overall performance of the system.

[0046] 4. The overall system safety is improved: Through real-time monitoring and precise adjustment, this method can effectively prevent serious consequences such as equipment damage and production interruption caused by compressor surge. It not only protects the safety of the compressor body but also ensures the stable operation of the entire production process, greatly reducing the maintenance cost and production loss, and enhancing the overall safety of the system.

[0047] 5. Easy to implement and maintain, reducing operation and maintenance costs: This method is based on the monitoring and control of the current change. The implementation process is simple and clear, without the need for complex transformation or upgrade of the existing system. At the same time, since it does not rely on specific functions or equipment, it is also more convenient and fast to maintain. This not only reduces the initial investment cost of the system but also reduces the subsequent operation and maintenance costs, making this method have significant advantages in terms of economy.

[0048] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A compressor anti-surge control method without inverter power feedback, characterized in that: The steps include: First, monitor the change in motor current ΔI per second; Compare the monitored current change ΔI with 1 / 10 of the motor rated current; If the monitored change ΔI is greater than 1 / 10 of the rated current of the motor, the anti-surge valve is opened according to the preset rule until ΔI is less than or equal to 1 / 10 of the rated current of the motor; If the monitored change ΔI is less than or equal to 1 / 10 of the rated current of the motor, the current opening of the anti-surge valve is maintained; Repeat the above steps until the anti-surge valve stops moving.

2. The compressor anti-surge control method without inverter power feedback as claimed in claim 1, characterized in that: When the monitored change ΔI is greater than 1 / 10 of the rated current of the motor, the preset rule for opening the anti-surge valve is: after the anti-surge valve opening receives the electrical signal, the opening amount increases by one degree per second.

3. The compressor anti-surge control method without inverter power feedback as claimed in claim 2, characterized in that: When the opening of the anti-surge valve increases, part of the outlet air flow returns to the inlet through the anti-surge valve, stabilizing the air flow at the front and rear ends of the compressor. The current fluctuation decreases, and the anti-surge valve will no longer increase its opening, completing the entire anti-surge procedure.

4. The compressor anti-surge control method without inverter power feedback as claimed in claim 3, characterized in that: Before executing the control method, the control parameters are initialized and set, including the rated current of the motor, the maximum opening degree of the anti-surge valve, and the opening speed.

5. The compressor anti-surge control method without inverter power feedback as claimed in claim 4, characterized in that: When executing compressor anti-surge control, the system's operating status is monitored in real time. When a fault is detected, the fault is diagnosed and located immediately, and appropriate measures are taken to deal with it.

6. The compressor anti-surge control method without inverter power feedback as claimed in claim 5, characterized in that: When monitoring the system operating status, fault diagnosis algorithms based on model prediction, signal processing analysis or data-driven learning are used for monitoring and diagnosis.

7. The compressor anti-surge control method without inverter power feedback as claimed in claim 6, characterized in that: When the system is running, the system operation data is recorded, and the data is analyzed and processed.

8. The compressor anti-surge control method without inverter power feedback as claimed in claim 7, characterized in that: Based on the real-time recorded system operation data, the anti-surge control strategy is dynamically adjusted in combination with fuzzy control algorithm, neural network control algorithm, adaptive control algorithm or reinforcement learning algorithm.

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