A surge control method for air compressors

Abstract

This invention discloses a method for anti-surge control of a compressor, comprising the following steps: S1. Obtaining the amplitude limit and rate of change limit of the pulsating pressure at the compressor inlet; S2. Real-time acquisition of the pulsating pressure signal at the compressor inlet, and calculating the measured amplitude and measured rate of change of the pulsating pressure signal according to a preset sampling period; S3. Comparing the measured amplitude with the amplitude limit, and comparing the measured rate of change with the rate of change limit; S4. Triggering an automatic anti-surge protection mechanism when the measured amplitude and measured rate of change exceed the limits; S5. After triggering the automatic anti-surge protection mechanism, controlling the compressor exhaust valve to open wider at a preset angle to reduce compressor surge. This invention effectively avoids the shortcomings of single-parameter monitoring by real-time monitoring of the amplitude and rate of change of the compressor inlet pulsating pressure, and triggering a protection mechanism when both exceed preset limits. It has the advantages of improving the accuracy of surge judgment, reducing false triggering and response delay.

Description

Technical Field

[0001] This application relates to fluid machinery control technology, and more specifically, to an anti-surge control method for compressors. Background Technology

[0002] As a core component of turbine engines, gas turbines, and industrial compression systems, the compressor's operational stability has a decisive impact on the performance and reliability of the entire power system. Under off-design conditions, such as low-speed operation, high back pressure environments, or sudden flow changes, the airflow inside the compressor is prone to separation, leading to surge. Surge manifests as periodic and severe pressure and flow oscillations, not only causing a sharp decline in compressor efficiency but also potentially inducing serious faults such as high-cycle blade fatigue and high-temperature gas backflow, and even causing structural damage to equipment and complete system shutdown, posing a significant threat to industrial production safety. Therefore, anti-surge control technology has always been a crucial aspect of compressor aerodynamic design and operation management.

[0003] Traditional surge control methods primarily rely on a single-parameter monitoring mechanism with a fixed threshold. A typical approach is to set a preset upper limit for the compressor inlet pressure amplitude, triggering a protective action when the measured value exceeds this limit. However, this method has significant drawbacks in practical applications: Firstly, relying solely on amplitude judgment is highly susceptible to sensor noise, environmental interference, or transient operating condition fluctuations. For example, random noise may cause the system to falsely trigger unnecessary protective actions, leading to production interruptions. Secondly, in the initial stage of surge, the pressure amplitude may not yet have reached the threshold, but the pressure change rate has already shown an abnormally increasing trend. Single-parameter monitoring cannot capture this crucial dynamic characteristic, resulting in system response delays and further exacerbating the surge. Furthermore, some existing technologies employ complex mathematical models (such as compressor characteristic curve fitting) to predict surge boundaries, but their calculation process is cumbersome, lacks real-time performance, and places stringent requirements on sensor accuracy and operating condition adaptability, making them difficult to implement effectively in multi-stage compressors or scenarios with frequent changes in operating conditions.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] The purpose of this application is to provide an anti-surge control method for compressors, which has the advantages of improving the accuracy of surge detection, reducing false triggering and response delay.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] A surge control method for compressors includes the following steps:

[0008] S1. Obtain the amplitude limit and rate of change limit of the pulsating pressure at the compressor inlet;

[0009] S2. Real-time acquisition of the pulsating pressure signal at the compressor inlet, and calculation of the measured amplitude and measured rate of change of the pulsating pressure signal according to the preset sampling period;

[0010] S3. Compare the measured amplitude with the amplitude limit, and compare the measured rate of change with the rate of change limit;

[0011] S4. When the measured amplitude exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, the compressor is determined to have entered a surge state, triggering the automatic anti-surge protection mechanism;

[0012] S5. After the automatic anti-surge protection mechanism is triggered, the compressor's exhaust valve is opened to a preset angle to reduce compressor surge.

[0013] Furthermore, in step S2, the sampling period includes a monitoring sampling period and a calculation sampling period;

[0014] Among them, the minimum sampling period is used to collect the pulsating pressure signal at the compressor inlet through the anti-surge sensor; the calculation sampling period is used to obtain data from the collected pulsating pressure signal and calculate the measured amplitude and measured rate of change.

[0015] Furthermore, in step S2, the measured amplitude is calculated as follows:

[0016] Sampling is performed in units of the aforementioned calculation sampling period, with 10 consecutive sampling periods;

[0017] The difference between the maximum and minimum values ​​in the data within the 10 calculation sampling periods is calculated using the following formula. This difference is used as the measured amplitude, and the measured amplitude display is updated every 100ms.

[0018] A=max(sample_buffer)-min(sample_buffer)

[0019] Where A is the measured amplitude of the pulsating pressure at the compressor inlet, max(sample_buffer) is the maximum value in the data within the calculation sampling period, and min(sample_buffer) is the minimum value in the data within the calculation sampling period.

[0020] Furthermore, in step S2, the measured rate of change is calculated as follows:

[0021] Sampling is performed in units of one calculation sampling period, and the rate of change of the pulsating pressure parameter is calculated using the following formula;

[0022] R = abs(P_current - P_prev) / 0.01

[0023] Where R is the rate of change of the pulsating pressure parameter, P_current is the current pulsating pressure at the compressor inlet, and P_prev is the pulsating pressure at the compressor inlet in the previous calculation sampling period.

[0024] Furthermore, the automatic anti-surge protection mechanism is implemented through a PLC controller;

[0025] The PLC controller is electrically connected to the anti-surge sensor that monitors the pulsating pressure signal at the compressor inlet and the exhaust valve that controls the compressor exhaust.

[0026] When the PLC controller determines that the measured amplitude of the pulsating pressure signal collected by the anti-surge sensor exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, it controls the compressor's exhaust valve to open wider at a preset angle, thereby reducing the compressor's surge.

[0027] Furthermore, the anti-surge control method is applicable to anti-surge protection for single-stage or multi-stage compressors.

[0028] In summary, the present invention has the following beneficial effects:

[0029] By monitoring the amplitude and rate of change of the compressor inlet pulsating pressure in real time, and triggering a protection mechanism when both exceed preset limits, the shortcomings of single parameter monitoring are effectively avoided. This has the advantages of improving the accuracy of surge judgment, reducing false triggering and response delay. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the anti-surge control method for air compressors described in this invention.

[0031] Figure 2 This is a flowchart of the anti-surge control method for air compressors described in this invention. Detailed Implementation

[0032] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to the figures and specific embodiments.

[0033] like Figure 1 and Figure 2 As shown, the present invention proposes an anti-surge control method for compressors, comprising the following steps:

[0034] S1. Obtain the amplitude limit and rate of change limit of the pulsating pressure at the compressor inlet;

[0035] S2. Real-time acquisition of the pulsating pressure signal at the compressor inlet, and calculation of the measured amplitude and measured rate of change of the pulsating pressure signal according to the preset sampling period;

[0036] S3. Compare the measured amplitude with the amplitude limit, and compare the measured rate of change with the rate of change limit;

[0037] S4. When the measured amplitude exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, the compressor is determined to have entered a surge state, triggering the automatic anti-surge protection mechanism; S5. After the automatic anti-surge protection mechanism is triggered, the compressor's exhaust valve is controlled to open at a preset angle to prevent the compressor from surging.

[0038] For ease of understanding, the following explains some key terms in this embodiment:

[0039] The pulsating pressure at the compressor inlet refers to the dynamic pressure fluctuations detected at the compressor inlet. These fluctuations are an important basis for judging the operational stability of the compressor.

[0040] The amplitude limit is a pre-set threshold for the intensity of pulsating pressure fluctuations at the compressor inlet, used to indicate whether the pressure fluctuations have reached a level that may trigger surge.

[0041] The rate of change limit is a pre-set threshold for the rate at which the compressor inlet pulsating pressure changes over time. It is used to indicate whether the pressure change trend is abnormal and may indicate the occurrence of surge.

[0042] Surge refers to a severe airflow oscillation phenomenon that occurs in a compressor under non-design conditions. It is characterized by periodic and large fluctuations in flow rate and pressure, which threatens the performance and lifespan of the compressor.

[0043] Automatic surge protection mechanism refers to an automated control strategy or system designed to detect compressor surge and take measures to remove it from the surge state.

[0044] An exhaust valve is an actuator installed on the compressor exhaust pipe. By adjusting its opening degree, the operating point of the compressor can be changed, thereby suppressing or eliminating surge.

[0045] In one implementation, the amplitude and rate of change limits of the pulsating pressure at the compressor inlet are acquired. These limits can be manually entered by the operator based on experience or historical data and fixed in the control system. Alternatively, these limits can be predetermined for a specific compressor model and operating condition through offline simulation or experimental testing and stored as fixed parameters.

[0046] Furthermore, the pulsating pressure signal at the compressor inlet is acquired in real time, and the measured amplitude and measured rate of change of the pulsating pressure signal are calculated according to a preset sampling period. A single, fixed sampling period can be used for data acquisition and subsequent calculations. For example, a uniform sampling period can be set, within which pressure signal acquisition and parameter calculations are completed. The measured amplitude can be obtained by simply recording the absolute value of the pressure difference between the current sampling point and the previous sampling point within each sampling period, and taking the maximum value over a period of time as the amplitude. The measured rate of change can be obtained by calculating the difference between the pressure value at the current sampling point and the pressure value at the previous sampling point, and dividing by the sampling time interval.

[0047] Therefore, the measured amplitude is compared with the amplitude limit, and the measured rate of change is compared with the rate of change limit. This comparison process can be implemented by the logic circuit or software program inside the control unit to determine whether the measured parameters exceed the preset safety range. Specifically, when the measured amplitude exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, the compressor is determined to have entered a surge state, and the automatic anti-surge protection mechanism is triggered.

[0048] In a preferred embodiment, after the automatic anti-surge protection mechanism is triggered, the compressor's exhaust valve is controlled to open to a preset angle, thus relieving compressor surge. The exhaust valve control can be achieved by a simple relay or switching circuit, which directly drives the valve actuator to open to the preset position upon receiving a trigger signal. Alternatively, a general-purpose microcontroller can receive the signal and output a fixed voltage or current signal to drive the valve.

[0049] This application achieves dynamic judgment by combining the amplitude and rate of change of the compressor inlet pulsating pressure, effectively overcoming the limitations of traditional single-parameter judgment, which is susceptible to interference and suffers from response delay. This method can more accurately identify the initial characteristics of surge, avoid false triggering and missed judgment, and achieve rapid response. By controlling the exhaust valve to open at a preset angle, the compressor quickly deflates, thereby ensuring stable operation of the compressor under complex conditions and improving system reliability.

[0050] In some of the solutions described above in this application, the pulsating pressure signal at the compressor inlet is acquired in real time and the measured amplitude and measured rate of change are calculated. However, in this process, if the sampling period is set to a single or unoptimized value, the acquired signal may be affected by high-frequency noise interference, the calculation efficiency may be low, and the dynamic response may be delayed, thereby affecting the accuracy and timeliness of the surge state judgment.

[0051] In this regard, this application further proposes that in the above-mentioned anti-surge control method for compressors, in step S2, the sampling period includes a monitoring sampling period and a calculation sampling period; wherein, the minimum monitoring sampling period is 1ms, which is used to collect the pulsating pressure signal at the compressor inlet through the anti-surge sensor; the calculation sampling period is 10ms, which is used to obtain data from the collected pulsating pressure signal and calculate the measured amplitude and the measured rate of change.

[0052] Specifically, the sampling period refers to the interval at which sampling is performed during the continuous signal digitization process. It directly determines the frequency and accuracy of signal acquisition, thus affecting the ability to capture dynamic changes and the real-time performance of data processing. In this application, to optimize this process, the sampling period is subdivided into a monitoring sampling period and a calculation sampling period. The monitoring sampling period is specifically used for the anti-surge sensor to acquire raw signals. Its function is to ensure that the rapid changes in compressor inlet pulsating pressure can be captured at high frequency and with high precision, providing sufficient density of raw data for subsequent analysis. For example, this monitoring sampling period can be implemented using a high-speed data acquisition card (DAQ card) in conjunction with the anti-surge sensor. The DAQ card has high sampling rate and high-precision analog-to-digital conversion capabilities; alternatively, it can be implemented using an embedded system or FPGA (Field Programmable Gate Array), which directly controls the sensor's data reading and timestamp recording through hardware logic to ensure millisecond-level accurate sampling. The calculation sampling period is used to extract a subset from the acquired raw data and perform subsequent calculations, such as the calculation of measured amplitude and measured rate of change. Its function is to reduce the computational load, avoid unnecessary redundant calculations, and improve the overall response efficiency of the system while ensuring data validity. For example, the calculation sampling period can be implemented on a PLC controller or industrial PC via a software timer or task scheduler, reading data from the buffer at fixed intervals for calculation.

[0053] Furthermore, this application sets the minimum monitoring sampling period to 1ms. A 1ms sampling period means acquiring 1000 data points per second, which is sufficient for capturing high-frequency components and rapid transient changes in the compressor inlet pulsating pressure signal. This effectively avoids signal distortion and information loss, providing high-resolution raw data for accurate surge detection. Simultaneously, the calculation sampling period is set to 10ms. A 10ms calculation sampling period means performing 100 calculations per second. Compared to the 1ms monitoring sampling period, this significantly reduces computational resource consumption while maintaining a certain level of real-time performance. This allows the system sufficient time for data processing, calculation of measured amplitude and rate of change, and execution of control logic, thus achieving a balance between real-time performance and computational efficiency.

[0054] Through the above technical solution, this application effectively solves the problems of noise interference and response delay in the sampling process by distinguishing between the monitoring sampling period and the calculation sampling period and optimizing their specific parameters, thereby improving the real-time performance and reliability of surge detection. Specifically, a minimum monitoring sampling period of 1ms is set for high-frequency acquisition to ensure rapid capture of pulsating pressure signal changes at the compressor inlet, reducing signal loss and noise impact. Simultaneously, a calculation sampling period of 10ms is used for data acquisition and calculation. Based on the acquired signals, amplitude and rate of change are processed, reducing the calculation frequency to optimize resource utilization and avoid inefficiency and error accumulation caused by continuous high-frequency calculations. This segmented design allows monitoring and calculation to perform their respective functions: the monitoring stage focuses on real-time signal capture to enhance dynamic response, while the calculation stage focuses on data processing to improve the stability of surge parameter generation, thus collaboratively achieving efficient and accurate anti-surge control. Therefore, this scheme can provide more accurate and timely basic data for calculating the measured amplitude and measured rate of change of the pulsating pressure signal at the compressor inlet, thereby improving the accuracy of compressor surge condition determination and the response speed of the anti-surge protection mechanism, and effectively ensuring the stable operation of the compressor.

[0055] In some of the embodiments described above in this application, a method for calculating the sampling period is proposed to calculate the measured amplitude. However, in its implementation, the lack of a specific calculation method may lead to inaccurate amplitude calculation, susceptibility to noise interference, and insufficient update frequency, which may affect the timely judgment of surge state.

[0056] In this regard, this application further proposes that the measured amplitude be calculated in step S2 as follows:

[0057] Sampling is performed in units of calculation sampling period, and 10 consecutive periods are sampled; the difference between the maximum and minimum values ​​in the data within these 10 calculation sampling periods is calculated using the following formula, and this difference is used as the measured amplitude, and the measured amplitude display is updated every 100ms;

[0058] A = max(sample_buffer) - min(sample_buffer), where A is the measured amplitude of the pulsating pressure at the compressor inlet, max(sample_buffer) is the maximum value in the data within the calculation sampling period, and min(sample_buffer) is the minimum value in the data within the calculation sampling period.

[0059] Specifically, sampling is performed in units of calculation sampling periods, with 10 consecutive periods to ensure the regularity and stability of data acquisition, while reducing the interference of transient noise by acquiring continuous data sequences. For example, an anti-surge sensor can trigger a data read at the beginning of each calculation sampling period, storing the data of 10 consecutive calculation sampling periods in a buffer; alternatively, the control system can set a timer to interrupt the data acquisition operation every calculation sampling period and maintain a circular queue containing the data of the 10 most recent sampling points.

[0060] Based on this, the difference between the maximum and minimum values ​​in the data within the 10 calculation sampling periods is calculated using the formula A = max(sample_buffer) - min(sample_buffer), and this difference is used as the measured amplitude. This calculation method directly reflects the actual fluctuation range of the pulsating pressure, avoiding the problem of using average values ​​to potentially mask extreme values, thereby improving the accuracy of amplitude measurement. In specific implementation, after obtaining the data from the 10 calculation sampling periods, a software algorithm can be used to traverse the dataset, find the maximum and minimum values, and then calculate the difference between them; alternatively, a dedicated signal processing module or digital signal processor (DSP) chip can be used to quickly calculate the maximum and minimum values ​​within a specified data window through hardware acceleration and then perform the difference calculation.

[0061] Furthermore, this application specifies that the measured amplitude display should be updated every 100ms to ensure regular refresh of amplitude information, which helps to capture changes in surge state in a timely manner. This can be achieved by setting an independent timer that triggers an amplitude update operation every 100ms, writing the latest calculated measured amplitude to the display register or communication interface; or, in the main control loop, a counter or timestamp can be used to determine whether the 100ms update interval has been reached, and if so, the amplitude update logic is executed.

[0062] The above technical solution involves continuous sampling in units of a calculation sampling period, and determining the measured amplitude based on the difference between the maximum and minimum values ​​of data within 10 consecutive periods. This effectively filters out instantaneous noise interference and more accurately reflects the actual fluctuation range of the compressor inlet pulsating pressure. Simultaneously, the measured amplitude is updated every 100ms, ensuring timely updates of amplitude information and enabling the anti-surge control system to quickly respond to changes in compressor operating conditions. This precise and high-frequency amplitude calculation method significantly improves the accuracy and real-time performance of surge detection, providing a reliable data foundation for timely triggering of the automatic anti-surge protection mechanism, effectively avoiding misjudgments or omissions, and ensuring the stable operation of the compressor.

[0063] In some of the solutions described above in this application, a method for calculating the rate of change of pulsating pressure is proposed to monitor the dynamics of compressor inlet pressure in real time. However, in its implementation, the calculation method may lack a specific definition, resulting in inaccurate quantification of the rate of change, susceptibility to transient noise interference or response delay, thereby affecting the accuracy and timeliness of surge judgment.

[0064] In response, this application further proposes that in step S2, the measured rate of change is calculated as follows: sampling is performed in units of one calculation sampling period, and the rate of change of the pulsating pressure parameter is calculated using the following formula: R=abs(P_current-P_prev) / 0.01, where R is the rate of change of the pulsating pressure parameter, P_current is the current pulsating pressure at the compressor inlet, and P_prev is the pulsating pressure at the compressor inlet in the previous calculation sampling period.

[0065] Specifically, sampling is performed in units of one calculation sampling period, which is a preset time interval for data processing and calculation. For example, in some of the embodiments described above, the calculation sampling period is 10ms. Sampling in units of a single calculation sampling period means that within each fixed time interval, the system acquires one or a set of data points for subsequent rate of change calculations. For example, the system can be configured to acquire the latest pulsating pressure data point from the anti-surge sensor at the beginning of each calculation sampling period and use it as the current sampled value. This sampling method ensures the fixity and consistency of data sampling, provides a stable time reference for subsequent rate of change calculations, and avoids calculation errors introduced by fluctuations in the sampling frequency.

[0066] Based on this, the rate of change of the pulsating pressure parameter is calculated using the formula R = abs(P_current - P_prev) / 0.01. This formula defines the specific calculation method for the rate of change of pulsating pressure R. It uses the absolute difference between the current pulsating pressure P_current and the pulsating pressure P_prev in the previous calculation sampling period, and then divides it by a fixed time interval of 0.01 seconds (i.e., a calculation sampling period of 10 ms), thereby quantifying the magnitude of the change in pulsating pressure per unit time. For example, at the end of each calculation sampling period, the control system reads the pulsating pressure value at the current moment as P_current, and obtains the pulsating pressure value from the historical data storage of the previous calculation sampling period as P_prev, and then directly applies the formula R = abs(P_current - P_prev) / 0.01 for calculation. To improve the robustness of the calculation, the average or median of the pulsating pressure data collected in the current and previous calculation sampling periods can also be used when calculating P_current and P_prev, respectively, and then substituted into the formula for calculation. Here, R is the calculated value, representing the degree of change of the compressor inlet pulsating pressure per unit time. Its magnitude directly reflects the severity and speed of pressure fluctuations and can be directly compared with the preset rate of change limit as one of the bases for determining whether the compressor has entered a surge state. P_current refers to the pulsating pressure value of the compressor inlet obtained from the anti-surge sensor within the current calculation sampling period. It is the latest data point used for real-time rate of change calculation. For example, P_current can be the instantaneous pressure value output by the anti-surge sensor at the end of the current calculation sampling period, directly reflecting the pressure state at that moment. P_prev refers to the pulsating pressure value of the compressor inlet obtained from the anti-surge sensor within the previous calculation sampling period immediately adjacent to the current calculation sampling period. It is compared with P_current to determine historical data points of pressure change. For example, P_prev can be the instantaneous pressure value at the end of the previous calculation sampling period read from the historical data storage module. This direct differential calculation method can quickly and in real time reflect the instantaneous change trend of pulsating pressure, and by taking the absolute value, the rate of change can uniformly represent the severity of pressure rise or fall, providing key dynamic parameters for early warning of surge.

[0067] The above technical solution clearly defines sampling as a unit of one calculation sampling period (e.g., 10ms), which ensures a fixed time interval for data acquisition and effectively avoids calculation errors and transient noise interference caused by unstable sampling frequency.

[0068] Meanwhile, the formula R=abs(P_current- P_prev) / 0.01 is used to directly calculate the absolute difference between the current pulsating pressure and the pulsating pressure of the previous sampling period, and then divide it by a fixed time interval (0.01 seconds), achieving real-time and efficient quantification of the dynamic changes in compressor inlet pulsating pressure. This method based on a fixed sampling period and direct differential calculation significantly simplifies the algorithm complexity and improves computational efficiency, enabling the system to capture the drastic pressure changes at the initial stage of surge more quickly and accurately. Compared to methods that rely solely on amplitude judgment or complex model prediction, this scheme effectively reduces the risk of misjudgment and missed judgment, significantly improving the response speed and reliability of anti-surge control. Therefore, when the compressor enters a surge state, it can trigger the automatic anti-surge protection mechanism more promptly, controlling the compressor's exhaust valve to open at a preset angle, achieving rapid surge relief, effectively protecting the compressor, and ensuring its stable operation.

[0069] In some of the solutions mentioned above in this application, an automatic anti-surge protection mechanism is proposed to trigger anti-surge protection. However, in this process, the use of traditional dedicated controllers results in high costs, poor real-time performance, and difficulty in widespread adoption in industrial scenarios.

[0070] To address this, this application further proposes an implementation method for an automatic anti-surge protection mechanism, which is implemented through a PLC controller. A PLC controller, or Programmable Logic Controller, is a digital electronic system designed and developed specifically for industrial applications. Its main functions are to receive signals from input devices such as sensors, perform logical operations, sequential control, timing, counting, and arithmetic operations through internally stored programs, and output control signals to actuators such as valves and motors. PLC controllers have advantages such as high reliability, strong anti-interference capability, flexible programming, and ease of maintenance and expansion, and are widely used in various industrial automation control fields.

[0071] The implementation methods of PLC controllers can include, but are not limited to: Siemens S7 series PLCs, Rockwell Automation's Allen-Bradley ControlLogix series PLCs, and Mitsubishi Electric's Q series PLCs.

[0072] The PLC controller is electrically connected to an anti-surge sensor that monitors the pulsating pressure signal at the compressor inlet and an exhaust valve that controls the compressor's exhaust. Electrical connection refers to establishing an electrical path via wires or wireless communication to transmit signals or electrical energy. In this application, the electrical connection between the PLC controller, the anti-surge sensor, and the exhaust valve aims to ensure that the pulsating pressure signal collected by the sensor can be transmitted to the PLC controller for processing in real time and accurately, while ensuring that the control commands issued by the PLC controller can be quickly and reliably transmitted to the exhaust valve to achieve precise adjustment of the compressor's exhaust volume. This electrical connection can take various forms, such as hard-wired connection via analog input / output modules, switch signal connection via digital input / output modules, or data communication connection via fieldbus protocols such as industrial Ethernet (e.g., Profinet, EtherNet / IP) or serial communication (e.g., Modbus RTU). The anti-surge sensor is a key component for real-time monitoring of the compressor inlet pulsating pressure. Its function is to convert the airflow pressure fluctuations at the compressor inlet into electrical signals that can be recognized by the electronic control system. The sensor needs to possess high sensitivity, fast response, and the ability to operate stably in harsh industrial environments to accurately capture the subtle pressure pulsations that precede surge. Anti-surge sensors can be implemented in ways including, but not limited to: piezoelectric pressure sensors, which use the piezoelectric effect to convert pressure changes into electrical signals; MEMS (Micro-Electro-Mechanical Systems) pressure sensors, which are small, fast-responding, and highly accurate; and strain gauge-based pressure sensors, which reflect pressure changes by measuring the deformation of the pressure-bearing component. The exhaust valve, an actuator used to regulate the compressor's exhaust flow, plays a crucial role in anti-surge control. When the compressor enters a surge state, opening the exhaust valve can quickly release the internal pressure of the compressor, increase the airflow channel area, thereby changing the compressor's operating point and pulling it out of the surge region, achieving anti-surge control. Exhaust valves can be implemented in ways including, but not limited to: pneumatic butterfly valves, which use compressed air to drive the actuator to control the valve's opening; electric ball valves, which use a motor to drive the valve's rotation and opening; and hydraulic regulating valves, which use a hydraulic system to provide power to precisely control the valve's opening.

[0073] When the PLC controller determines that the measured amplitude and measured rate of change of the pulsating pressure signal collected by the anti-surge sensor exceed the amplitude limit and rate of change limit respectively, it controls the compressor's exhaust valve to open wider by a preset angle, thus preventing the compressor from surging. The determination process refers to the PLC controller comparing and analyzing the measured amplitude and rate of change data received from the anti-surge sensor with the preset amplitude and rate of change limits according to a preset logic program. This process is the core of the anti-surge control strategy, determining when the anti-surge protection mechanism is triggered. The PLC controller uses its internal comparison instructions and logic operation instructions to evaluate the compressor's operating status in real time to identify the presence of surge risk. Controlling the compressor's exhaust valve to open wider by a preset angle means that after determining that the compressor has entered a surge state, the PLC controller sends a specific control command to the exhaust valve, causing its actuator to adjust the valve opening to a preset angle. This preset angle was determined through system debugging and optimization, aiming to ensure an effective reduction in the compressor's internal pressure in the shortest possible time, allowing the compressor to quickly escape surge conditions, while avoiding new instability caused by excessively large or small valve openings. This control action can be achieved in ways including, but not limited to: the PLC directly driving the valve positioner via an analog output module to precisely control the valve opening; or the PLC controlling the solenoid valve via a digital output module, which in turn drives a pneumatic or hydraulic actuator to quickly bring the valve to the preset opening.

[0074] Through the above technical solution, this application employs a PLC controller to implement an automatic anti-surge protection mechanism. Leveraging the widespread use and high reliability of PLCs in industrial control, it effectively reduces system deployment costs and enhances stability under varying operating conditions, thus overcoming the high cost and low adaptability of traditional dedicated controllers. The direct electrical connection between the PLC controller and the anti-surge sensor and exhaust valve establishes a direct link for real-time data acquisition and control, ensuring immediate transmission of sensor signals and rapid execution of valve actions, significantly improving the system's dynamic response capability and preventing surge deterioration caused by control delays. Furthermore, when the PLC controller combines measured amplitude and measured rate of change parameters for comprehensive judgment, it improves the accuracy and robustness of surge state identification, effectively reducing the risk of false triggering caused by noise or transient interference. By controlling the exhaust valve to open at a preset angle, the stability and predictability of valve action are achieved, enabling the compressor to quickly exit the surge state and preventing secondary oscillations caused by improper valve adjustment, thereby ensuring the stable operation of the compressor.

[0075] In some of the embodiments described above in this application, an anti-surge control method is proposed to monitor and respond to compressor surge conditions in real time. However, in this process, the method may only be designed for single-stage compressors. When applied to multi-stage compressors, due to the complex flow characteristics and operating condition changes of multi-stage compressors, the anti-surge protection mechanism may not respond accurately or be adaptable enough, and may not be able to effectively handle the surge risk unique to multi-stage compressors.

[0076] In this regard, this application further proposes that the anti-surge control method is applicable to anti-surge protection of single-stage compressors or multi-stage compressors.

[0077] Specifically, a single-stage compressor typically refers to a compressor containing only one compression stage (i.e., a set of moving and stationary blades). Its structure is relatively simple, and the airflow path and pressure changes are relatively direct. Its surge characteristics are usually manifested as a systemic periodic oscillation of the airflow under specific flow rates and pressure ratios. The anti-surge control method of this application acquires the amplitude limit and rate of change limit of the pulsating pressure at the compressor inlet, collects the pulsating pressure signal at the compressor inlet in real time, and calculates the measured amplitude and measured rate of change of the pulsating pressure signal according to a preset sampling period. Then, the measured amplitude is compared with the amplitude limit, and the measured rate of change is compared with the rate of change limit. When the measured amplitude exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, the compressor is determined to have entered a surge state, triggering an automatic anti-surge protection mechanism. This mechanism controls the compressor's exhaust valve to open wider at a preset angle, causing the compressor to deflate. This method can effectively identify the precursors or initial surge of a single-stage compressor and trigger protective actions in a timely manner.

[0078] Multistage compressors consist of multiple compression stages connected in series to achieve higher pressure ratios. Their internal airflow is complex, with interactions between stages, leading to surge phenomena that can manifest as overall surge, localized interstage surge, or rotating stall. Furthermore, their surge boundaries and dynamic response characteristics are more complex. The anti-surge control method presented in this application, through its dynamic monitoring and rapid response capabilities of pulsating pressure signals, can adapt to the complex surge modes that may occur in multistage compressors under different operating conditions. For example, this method can be deployed at the inlet of the multistage compressor to macroscopically monitor the stability of the overall airflow; or, where conditions permit, by placing sensors between different stages, more refined monitoring of localized surge can be achieved, thereby ensuring reliable anti-surge protection even under complex operating conditions of multistage compressors. This applicability means that the design of this anti-surge control method is not limited to a specific compressor type but has universal applicability. By analyzing the general characteristics (amplitude and rate of change) of compressor inlet pulsating pressure, this method can effectively identify and respond to any surge phenomenon that manifests as abnormal fluctuations in pulsating pressure at the inlet, regardless of whether the compressor is single-stage or multi-stage. This design avoids the need for extensive customized development for different compressor types, reducing implementation costs and complexity.

[0079] The following example will provide a more detailed explanation of the above technical solution:

[0080] In an industrial production environment, the stability of a multi-stage compressor during operation is affected by fluctuations in flow rate and pressure. To effectively prevent and control compressor surge, this embodiment employs an anti-surge control method.

[0081] Before the system is put into operation, the amplitude limit and rate of change limit of the compressor inlet pulsating pressure are preset according to the compressor's design characteristics and safe operating boundaries. For example, the amplitude limit is set to 5 kPa and the rate of change limit is set to 10 kPa / s. These limits are stored in the PLC controller electrically connected to the compressor control system.

[0082] During compressor operation, an anti-surge sensor monitors the pulsating pressure signal at the compressor inlet in real time. This sensor continuously acquires raw pulsating pressure data with a minimum sampling period of 1ms, ensuring high-resolution pressure change information. The PLC controller then extracts and processes this raw data with a calculation sampling period of 10ms.

[0083] Specifically, to calculate the measured amplitude, the PLC controller continuously collects data for 10 cycles at a 10ms sampling period, i.e., acquiring data within a 100ms time window. Then, the difference between the maximum and minimum values ​​of the pulsating pressure within this 100ms is calculated using the formula A = max(sample_buffer) - min(sample_buffer), and this difference is taken as the current measured amplitude. This measured amplitude is updated every 100ms, ensuring timely reflection of pressure fluctuation amplitude. Compared to traditional methods that rely solely on fixed thresholds, this dynamic amplitude calculation method more accurately reflects the intensity of pressure fluctuations under current operating conditions, reducing misjudgments caused by transient noise or non-surge conditions.

[0084] Meanwhile, to calculate the measured rate of change, the PLC controller acquires the current pulsating pressure P_current at the compressor inlet and the pulsating pressure P_prev in the previous sampling period in real time, using a 10ms sampling cycle. Then, the rate of change of the pulsating pressure parameter is calculated using the formula R=abs(P_current- P_prev) / 0.01. This method of calculating the rate of change based on the pressure difference within a short period can quickly capture the trend of compressor inlet pressure changes, providing crucial information for early warning of surge. Compared to the longer sampling periods or sliding window calculation methods used in existing technologies, this method significantly improves the dynamic response speed, enabling the system to identify early surge characteristics earlier and avoiding the problem that response delays may exacerbate surge.

[0085] The PLC controller continuously compares the measured amplitude calculated in real time with the preset amplitude limit, and also compares the measured rate of change with the preset rate of change limit. When the PLC controller detects that the measured amplitude exceeds the amplitude limit of 5 kPa and the measured rate of change simultaneously exceeds the rate of change limit of 10 kPa / s, it determines that the compressor has entered a surge state. This combined judgment mechanism overcomes the limitations of traditional single-parameter judgment, which is easily affected by noise interference or transient operating conditions, and improves the accuracy and reliability of surge judgment.

[0086] Once the compressor is detected to be in a surge state, the PLC controller immediately triggers the automatic anti-surge protection mechanism. This PLC controller controls the compressor's exhaust valve via an electrical connection. After the protection mechanism is triggered, the PLC controller sends a command to the exhaust valve, causing it to rapidly open by a preset angle (e.g., a rapid 20-degree increase). This rapid opening of the exhaust valve effectively reduces the compressor outlet pressure, changes the compressor's operating point, and thus allows the compressor to quickly exit the surge state, avoiding potential damage to the compressor blades and the entire system caused by surge. This direct and rapid valve control strategy, compared to the potentially single or slow-responding valve actions in existing technologies, can more effectively achieve rapid surge de-surge.

[0087] Using the above method, the multi-stage compressor can achieve efficient and reliable anti-surge protection under complex operating conditions, ensuring the stable operation of the system. This method effectively solves the problems of false triggering, missed judgment, response delay, large computational load, and poor real-time performance existing in the prior art by optimizing the parameter monitoring mechanism, improving the dynamic response speed, and simplifying the control logic.

[0088] In this document, the terms "upper," "lower," "front," "back," "left," "right," "top," "bottom," "inner," "outer," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used for the clarity of expressing the technical solution and for the convenience of description, and therefore should not be construed as limiting the present invention.

[0089] In this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0090] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for anti-surge control of a compressor, characterized in that, Includes the following steps: S1. Obtain the amplitude limit and rate of change limit of the pulsating pressure at the compressor inlet; S2. Real-time acquisition of the pulsating pressure signal at the compressor inlet, and calculation of the measured amplitude and measured rate of change of the pulsating pressure signal according to the preset sampling period; S3. Compare the measured amplitude with the amplitude limit, and compare the measured rate of change with the rate of change limit; S4. When the measured amplitude exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, the compressor is determined to have entered a surge state, triggering the automatic anti-surge protection mechanism; S5. After the automatic anti-surge protection mechanism is triggered, the compressor's exhaust valve is opened to a preset angle to reduce compressor surge.

2. The anti-surge control method for a compressor according to claim 1, characterized in that, In step S2, the sampling period includes the monitoring sampling period and the calculation sampling period; Among them, the minimum sampling period is used to collect the pulsating pressure signal at the compressor inlet through the anti-surge sensor; the calculation sampling period is used to obtain data from the collected pulsating pressure signal and calculate the measured amplitude and measured rate of change.

3. The anti-surge control method for a compressor according to claim 2, characterized in that, In step S2, the measured amplitude is calculated as follows: Sampling is performed in units of the aforementioned calculation sampling period, with 10 consecutive sampling periods; The difference between the maximum and minimum values ​​in the data within the 10 calculation sampling periods is calculated using the following formula. This difference is used as the measured amplitude, and the measured amplitude display is updated every 100ms. A=max(sample_buffer)-min(sample_buffer) Where A is the measured amplitude of the pulsating pressure at the compressor inlet, max(sample_buffer) is the maximum value in the data within the calculation sampling period, and min(sample_buffer) is the minimum value in the data within the calculation sampling period.

4. The anti-surge control method for a compressor according to claim 2, characterized in that, In step S2, the measured rate of change is calculated as follows: Sampling is performed in units of one calculation sampling period, and the rate of change of the pulsating pressure parameter is calculated using the following formula; R = abs(P_current - P_prev) / 0.01 Where R is the rate of change of the pulsating pressure parameter, P_current is the current pulsating pressure at the compressor inlet, and P_prev is the pulsating pressure at the compressor inlet in the previous calculation sampling period.

5. The anti-surge control method for a compressor according to claim 1, characterized in that, The automatic anti-surge protection mechanism is implemented through a PLC controller; The PLC controller is electrically connected to the anti-surge sensor that monitors the pulsating pressure signal at the compressor inlet and the exhaust valve that controls the compressor exhaust. When the PLC controller determines that the measured amplitude of the pulsating pressure signal collected by the anti-surge sensor exceeds the amplitude limit and the measured rate of change exceeds the rate of change limit, it controls the compressor's exhaust valve to open wider at a preset angle, thereby reducing the compressor's surge.

6. The anti-surge control method for a compressor according to claim 1, characterized in that, The anti-surge control method is applicable to anti-surge protection of single-stage or multi-stage compressors.

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