Method for scaling up compressor operational availability

Abstract

The invention relates to a method and system for controlling a compressor system to enhance efficiency and longevity through dynamic setpoint adjustments based on real-time monitoring and predictive modeling. It involves a control unit and at least one compressor providing compressed air. The method monitors process variables, estimates them using a compressor model, and derives a health score to determine an operating range. Internal setpoints are dynamically adjusted to compensate for degradation, while limiting setpoint ranges ensure safe operation. External setpoints remain unchanged unless necessary. If safe operation cannot be guaranteed, the system activates protective measures and generates alerts. When internal adjustments are insufficient to meet external setpoints safely, the control unit may issue warnings or, as a last resort, modify external setpoints.

Description

[0001] METHOD FOR SCALING UP COMPRESSOR OPERATIONAL AVAILABILITY

[0002] Technical Field of the Present Invention

[0003]

[0001] The present invention relates to the field of compressor systems , specifically to methods for enhancing the operational availability of compressors used in general compressor systems .

[0004] Background of the Present Invention

[0005]

[0002] Air compressors are used in various industries , such as automotive, manufacturing, construction, and more . They are essential for powering tools and equipment, making them an integral part of any industrial process . Depending on the required pressure, the desired application, a desired result, and other preconditions , one can choose from a variety of compressor technologies , such as an axial compressor versus a centrifugal compressor, as well as an oil-free versus an oil-lubricated compressor . However, air compressors may have limitations that can negatively impact their efficiency, energy consumption, and productivity . Fortunately, with the rise of smart technologies , air compressors are being revolutionized, offering improved performance, sustainability, and cost-effectiveness .

[0006]

[0003] In most industrial environments and / or the medical sector, high compressor availability is expected without having tocompromise on performance . However, like most mechanical machines , some form of degradation will inevitably occur over time due to, among other things , the presence of rotating parts , contamination in the ambient air around the machine, large temperature differences , the loss of oil and other internal or external influences that may prevent and / or deteriorate the proper functioning of the compressor . Traditional maintenance practices often fall short due to technical and economic constraints , resulting in unintended compressor downtime . There is a need for a method that can proactively increase compressor availability by managing its operational parameters more ef fectively .

[0007]

[0004] T radi tionally, air compressor maintenance is performed on a fixed schedule, which can result in unnecessary downtime and wasted resources . With smart technologies , maintenance can be performed based on the compressor ' s actual condition .

[0008]

[0005] Predictive maintenance can save time and money by reducing the need for frequent maintenance checks . It can also prevent unexpected equipment failures , which can lead to costly repairs and downtime . Furthermore, predictive maintenance can increase the lifespan of the air compressor, reducing the need for replacements and lowering costs .

[0009]

[0006] A solution to avoid an unintentional and premature failure is to schedule technical maintenance in a timely and regular manner . This is commonly known as preventive maintenance . Necessary actions can then be taken, such as lubrication of mechanical parts , replacement of oil in the refrigerant cooling circuit, andreplacement of critical parts . However, as is known by the professional , such preventive maintenance is not always done in a timely manner due to a variety of both technical and economic reasons , such as lack of spare parts or staf f shortages . The compressor will then be kept in operation, whether intentionally or not, even though there is a risk of such failure .

[0010]

[0007] Configuring every installation in the most efficient way is not a straightforward task . There is a large variety of these systems that make improving the optimization of the systems difficult for humans . Multiple compressors may be connected in a compressed air system to supply compressed air to the same distribution network . These compressors could be of several types , sizes , and ages , which could cause an unequal load and system inefficiencies . There is a large variety of pneumatic networks that can be divided into various categories according to their structure, size, layout, and capacity . Customers may have several requirements for the system in terms of energy ef ficiency and demand requirements .

[0011]

[0008] To handle the large variety of systems in which a compressor can be configured, there is a plurality of parameters available .

[0012]

[0009] These parameters may be technical , such as power, pressure ratio and / or start-up time . Other parameters may include economic parameters , such as investment and / or maintenance costs , or even environmental requirements , such as energy-efficiency and / or noise levels during operation . Taking all these parameters into accountand correcting for the different system layouts is difficult in practice .

[0013]

[0010] In the present invention, a method for determining and controlling the operating margin of a compressor system is described . The method comprises iteratively performing the following steps : measuring one or more process quantities indicative of the instantaneous operation of the compressor; estimating a set of process quantities based on measured process quantities and / or on the internal setpoints and / or the external setpoints of the compressor using a model that comprises a heat transfer characteristic between the compressor and its cooling circuit, where the heat transfer characteristic incorporates a degradation parameter; matching the estimated process quantities to the measured process quantities by adj usting the degradation parameter; determining the operating margin based on the degradation parameter and the internal setpoints of the compressor; and executing the related task if the degradation parameter exceeds a predefined soft or hard limit, thereby restricting the operating range to ensure safe operation when required .

[0014]

[0011] The step of measuring is understood to be retrieving the value ( s ) of a quantity obtained from one or more observations , recordings , or samplings at a specific physical location by means of suitable instruments , such as sensors for expressing an observed quantity in a number with a relevant unit that can be compared with other values of the same quantity .

[0012] The step of estimating is understood to be the determination of a value of a quantity based on measured process quantities and / or set points , using a scienti fic model representative of a technical process and / or apparatus with as input the measured process quantities and / or set points , and as output the value that needs to be determined and is therefore estimated, based on one or more calculations .

[0015]

[0013] The step of matching is understood to have a set of parameters within a set of equations iteratively converge to a set of certain optimal values , such that the difference between the model and the measurements is minimal . The step of matching is therefore done based on one or more calculations . Also, iteratively performing the steps means that the steps are performed repeatedly .

[0016]

[0014] In a first step, process quantities are measured that are indicative of the instantaneous operation of the compressor system. In an embodiment of the invention, these process quantities are an ambient temperature, cooling temperature, compressor temperature, electrical current, speed, inlet pressure, outlet pressure , ambient pressure, humidity, and / or flow rate . Furthermore, note that this list is non-exhaus five and that other process parameters , representative of the compressor operation, can also be measured . On the other hand, it should also be noted that not all process quantities are measured, but some of them.

[0017]

[0015] In the present invention, the process quantities are variables or factors that can be measured, some of which can also be controlled to influence the operation and performance of the compressor system. These variables are critical for maintainingoptimal function, and ensuring safety of the system. They include both external setpoints , which are directly related to the application requirements , and internal setpoints , which are related to the compressor' s internal operations and safety limits . External and internal setpoints are defined relative to what is considered internal or external from the perspective of the master controller of the compressor or compressor system.

[0018]

[0016] In a second step, these one or more process quantities of the compressor are estimated . This estimation is made based on one or more measured process quantities and / or setpoints of the compressor that serve as input to a scientific model of the compressor, wherein the output of the model are the estimated process quantities .

[0019]

[0017] It should further be noted that the first and second steps can be performed in parallel and simultaneously . The used term ' first ' and ' second ' therefore serves to distinguish between the different steps but does not indicate a specific chronology and / or hierarchy between the two steps . On the other hand, it must, of course, be understood that estimating process quantities based on other measured process quantities does imply that this measurement is carried out prior to the estimate .

[0020]

[0018] The model representative of the machine is a scientific model such as a physical or multi-physical model comprising a set of differential equations and / or empirical relations describing the different physical parts of the machine and their dependence on each other by means of one or more common variables .

[0019] In an embodiment of the present invention, one or more process quantities are estimated based on a model comprising a heat transfer characteristic between the compressor and the cooling circuit, wherein this heat transfer characteristic comprises a degradation parameter .

[0021]

[0020] Further in the present invention, a method for dynamically adj usting internal setpoints to ensure continued safe and efficient performance in the face of component degradation is introduced .

[0022]

[0021] The present invention comprises a setpoint shifting process that adj usts internal setpoints dynamically based on real-time conditions and the determined degradation parameter ( s ) . By shifting internal setpoints like fan speed, and oil inj ection pressure , the system can temporarily adapt to changing operational demands under degrading conditions without compromising safety .

[0023]

[0022] The system continuously monitors the health of the compressor using sensor data and a compressor model . The health score reflects the condition, degradation, and ageing of the compressor or its components .

[0024]

[0023] By quantifying degradation and its impact on performance, the system can proactively manage and mitigate the effects of wear and contamination . This allows for timely interventions before critical failures occur .

[0024] The system adapts internal setpoints based on real-time conditions , such as ambient temperature, load demands and degradation parameters . For example, it adj usts the fan speed to prevent overheating when the cooling circuit is partially clogged.

[0025]

[0025] The present invention takes into account multi-dimensional ambient conditions ( temperature, humidity, inlet pressure ) and adj usts operation accordingly, optimizing performance under various environmental factors .

[0026]

[0026] When external setpoints cannot be reached without risking safety, the system temporarily shifts internal setpoints to maintain safe operation and to allow to reach the required external setpoints . This may involve the fan motor running at higher speeds , which can increase its temperature and ageing rate, but keeps the compressor operating safely .

[0027]

[0027] The system raises warnings when setpoint shifting is applied, informing operators about the potentially increased risk of component ageing . This ensures that any trade-of fs are made consciously and managed appropriately .

[0028]

[0028] By continuously monitoring the health and degradation of components , the system enables predictive maintenance . Maintenance actions are scheduled based on the actual condition of the compressor, reducing unnecessary downtime and extending component life .

[0029] The system' s ability to adapt to degradation and contamination levels allows for more optimal and cost-ef ficient scheduling of overhauls , ensuring they are performed only when necessary, and avoiding premature interventions .

[0029]

[0030] The system ensures that the compressor operates within safe limits at all times by dynamically adj usting internal setpoints and operating ranges based on real-time health scores and environmental conditions .

[0030]

[0031] In case of signi ficant degradation or failure to reach external setpoints , the system implements fallback mechanisms to maintain safe operation, for instance, by temporarily increasing cooling efforts .

[0031]

[0032] T raditional compressor systems operate with fixed and / or a predetermined range of internal setpoints and a predetermined external setpoint range . In other words , the setpoints are maintained regardless of the compressor' s health condition .

[0032]

[0033] Regular maintenance schedules are established to inspect and clean components , replace worn parts , and ensure the compressor operates within safe limits . Preventive maintenance can be effective but often leads to unnecessary downtime and costs .

[0033]

[0034] Advanced compressors are equipped with sensors to monitor various parameters such as temperature, pressure, humidity andvibration . Data from these sensors are used to assess the health of the compressor and identify potential issues before they lead to failures .

[0034]

[0035] Some compressor systems include redundant components , such as additional cooling fans or backup compressors , to ensure continued operation if a primary component fails or becomes inefficient .

[0035]

[0036] In case of component failure or degradation, the system can automatically switch to backup components to maintain operation . This approach increases system reliability but also adds complexity and cost .

[0036]

[0037] The attempts made in the state of the art to alleviate the problems associated with optimized performance of a compressed air system are described in the following patents .

[0037]

[0038] United States Appl . No . US2021172436 discloses a compressor or pump, including at least one compressor or pump element for pressuri zed supply of a fluid to a network of consumers of such pressuri zed fluid; a motor coupled with the compressor or pump element . The compressor or pump is equipped with a control having a basic control for the nominal regulation of one or more control parameters (Q, pw) as a function of a desired, set working point of the compressor within the nominal set working range of the compressor or pump, set during design . The control is further provided with an additional control function for static or dynamic adj ustment of the working range limit values . The nominal control range of one or more control parameters is adj usted as a function of the actual working conditions of the compressor or pump that deviate from the nominal working conditions .

[0039] US2005165581 discloses a method for protecting an electric motor of a motor driven consumer equipped with a controller for controlling the capacity or the power of the consumer, comprises the following steps : the determination of the thermal condition of the motor by direct measurement on the motor ; and the limitation of the maximum capacity or the maximum power of the consumer as a function of the aforementioned determined thermal condition .

[0038]

[0040] US2017130982 relates to methods , devices , and systems for an inferential sensor for internal heat exchanger . One device includes a memory, and a processor configured to execute executable instructions stored in the memory to receive a number of measured process quantities of a heat exchanger, including a number of measured inlet process quantities and a number of measured outlet process quantities , predict, using a dynamic differential model including the number of measured inlet process quantities , internal parameters of the heat exchanger and a number of outlet process quantities of the heat exchanger, compare the number of measured outlet process quantities with the number of predicted outlet process quantities , and update, based on the comparison, the internal parameters of the heat exchanger .

[0039]

[0041] The state-of-the-art methods provide a range of solutions to manage compressor degradation and cooling circuit contamination . However, there is a need for more adaptive, real-time approaches that can dynamically adj ust operating parameters based on the actual condition of the compressor, ensuring safe and efficient operation without excessive maintenance or downtime . The proposed invention addresses these gaps by introducing a comprehensivesystem that continuously monitors and adj usts internal setpoints to optimize compressor performance under varying conditions .

[0040]

[0042] The present invention maximizes efficiency by dynamically adj usting internal setpoints and operating ranges , the compressor system operates more efficiently under varying degrading conditions , reducing energy consumption and improving overall performance in the long term.

[0041]

[0043] Predictive and condition-based maintenance reduces the frequency and cost of maintenance activities , while optimized overhaul intervals ensure timely and effective interventions .

[0042]

[0044] The system temporarily maintains safe and reliable operation even under degraded conditions , preventing unexpected failures and ensuring continuous service to the customer .

[0043]

[0045] By integrating these innovative mechanisms , the present invention offers a comprehensive solution that maintains and / or maximizes system efficiency even under degrading conditions , prolongs the operation of the machine, continues satisfying the flow demand even with a compressor that has degraded components and subsystems , and provides reliable performance in a wide range of operating conditions .

[0044]

[0046] Traditional compressor systems operate within fixed setpoint ranges that are determined at the time of manufacture . Over time, components degrade, and the cooling circuit can become contaminated, leading to inefficient operation and potentialoverheating . The present invention addresses these issues by dynamically adj usting internal setpoints based on real-time measurements and model predictions .

[0045] Objects of the Present Invention

[0046]

[0047] One of the obj ectives of this invention is to provide a way to manage a compressor system optimally and efficiently .

[0047]

[0048] The obj ect of the present invention is to adj ust the internal setpoints dynamically based on real-time operational conditions , ensuring the compressor runs at optimal efficiency .

[0048]

[0049] Another obj ect of the present invention is to handle situations where the compressor ' s cooling circuit is degraded or contaminated, ensuring that the compressor can still operate safely by dynamically adj usting fan speed and other internal setpoints . To integrate real-time data and compressor models to predict and respond to operational challenges proactively, enhancing system resilience and reducing the risk of shutdowns .

[0049]

[0050] Another obj ect of the present invention is to reduce the amount of time a technician needs to optimize maintenance planning and delivery for an entire fleet of compressor systems .

[0051] Another obj ect of the present invention is to adapt the compressor ' s internal setpoints based on changing environmental and load conditions to maintain ef ficient performance .

[0050]

[0052] Another obj ect of the present invention is continuously monitoring the health of the compressor and its components , providing a real-time health score that reflects their condition and degradation .

[0051]

[0053] Another obj ect of the present invention is implementing a mechanism that limits operating ranges when degradation reaches levels that threaten safe operation, ensuring the compressor can continue to operate within safe limits . Also, providing warnings when internal setpoint shi fting is applied, ensuring that operators are informed of potential safety concerns .

[0052]

[0054] Another obj ect of the present invention is to enable predictive maintenance scheduling based on the actual condition and health of the compressor, reducing unnecessary maintenance activities and downtime, determining the optimal intervals for overhauls based on degradation data and health scores , ensuring maintenance actions are timely and necessary .

[0053]

[0055] Another obj ect of the present invention is to ensure that external setpoints , in an embodiment of the invention; motor speed and outlet pressure, are maintained under all circumstances to prevent operational disruptions for the customer ' s applications . To implement fallback mechanisms that maintain safe operation even when external setpoints cannot be reached, safeguarding the customer ' s applications , and ensuring continuous service .

[0056] Another obj ect of the present invention is to adapt to various ambient conditions ( temperature, humidity, inlet pressure ) and multi-dimensional operating ranges ( speed, outlet pressure ) to optimize performance across a wide range of environments . To allow for temporary adj ustments in the design range of components , such as increasing fan speed, to compensate for degraded conditions and maintain compressor performance .

[0054]

[0057] By achieving these obj ects , the present invention provides a robust and intelligent system that not only optimi zes the efficiency and lifespan of compressor systems but also enhances their safety, reliability, and adaptability to varying operational conditions .

[0055] of the Present Invention

[0056]

[0058] The present invention shows an advanced control system for compressors that dynamically optimizes efficiency, prolongs the time until the next overhaul , and ensures reliable performance . Central to this innovation are two key components : the setpoint shifting block and the limiting setpoint ranges block .

[0057]

[0059] The present invention relates to a comprehensive health scoring system that monitors the condition and aging of the compressor and its components . This system guides maintenance and operational adj ustments by providing a degradation assessment andissuing warnings when necessary . The adaptive control feature modifies operational parameters based on real-time data, ensuring optimal performance and predictive maintenance .

[0058]

[0060] As used herein, the terms ' compressor speed ' and 'motor speed ' may be used interchangeably, unless otherwise specified . In many implementations , the compressor is directly coupled to the motor, resulting in the same rotational speed for both . However, in cases where a transmission mechanism such as a gearbox, belt drive, or variable-speed drive is employed, the compressor speed may differ from the motor speed . Even in such cases , there is a direct proportional relationship between the motor speed and the compressor speed . Unless the distinction is relevant to the context, references to either term should be understood to encompass both possibilities .

[0059] res of the Present Invention

[0060]

[0061] Accompanying drawings are given solely for the purpose of exemplifying a method for scaling up compressor operational availability, whose advantages over prior art were outlined above and will be explained in brief hereinafter .

[0061]

[0062] The drawings are not meant to delimit the scope of protection as identified in the claims nor should they be referred to alone in an effort to interpret the scope identified in said claimsY1

[0062] without recourse to the technical disclosure in the description of the present invention .

[0063]

[0063] Figure 1 is a block diagram displaying functional blocks of a compressor system according to the present invention .

[0064]

[0064] Figure 2 is a graph plotting compressor speed on the X-axis and ambient temperature on the Y-axis . The graph illustrates the operational limits of the system under normal conditions and in a degraded state according to the present invention .

[0065]

[0065] Figure 3 expands on the information presented in Figure 2 by adding a third axis representing outlet pressure according to the present invention .

[0066]

[0066] Figure 4 is a chart plotting motor speed on the X-axis and temperature on the Y-axis including several lines representing different conditions of the oil according to an embodiment of the invention .

[0067]

[0067] Figure 5 shows the effect of cooler clogging on the relationship between fan speed and motor speed, illustrating how the system dynamically adj usts operating limits and internal setpoints to maintain safe operation as clogging progresses from 60% to 80% according to an embodiment of the invention .Detailed

[0068]

[0069] of the Present Invention

[0070]

[0068] Fig . 1 illustrates a block diagram of a control system designed to dynamically optimize the operation of a compressor by adj usting internal setpoints and / or limiting operating ranges based on realtime health assessments . A controller, which manages the overall operation of the compressor . Said controller accepts external setpoints from the user, operator or external systems and sets values for internal setpoints , both of which are chosen to uphold the customers air consumption requirements in the best possible way . These external setpoints are crucial for maintaining the operational pressure of the network, and potentially the air flow to the network- or cooling water outflow delivered by the compressor system and ensuring the customer ' s applications run smoothly . In an embodiment of the invention, said controller controls the outlet pressure to meet the external setpoint based on a PID regulation . The figure 1 illustrates a comprehensive control system where each component interacts to dynamically manage and optimi ze the operation of the compressor . The integration of real-time health assessments , setpoint adj ustments , and operating range limitations ensures efficient and safe operation, adapting to varying conditions .

[0071]

[0069] In the present invention, the setpoint shifting block is essential to dynamically adj ust internal setpoints to optimize compressor performance while ensuring safety . Internal setpoints include parameters that can be varied within certain limits , such as fan speed, and oil inj ection pressure . These parameters normally operate within standard design limits , as determined by the internal setpoint generator block, but can temporarily be adj ustedto maintain system performance without risking immediate additional degradation or wear . The setpoint shi fting block receives input from the internal setpoint generator and suggests new setpoints based on current operating conditions and health scores . These adj usted setpoints are then used by the controller to control the compressor .

[0072]

[0070] Internal setpoints are the parameters within a compressor system that the setpoint shifting block adj usts autonomously to fine-tune and optimize the system' s performance . These setpoints are determined based on the system' s internal logic, real-time sensor data, and the overall operational state of the equipment . They serve as intermediary targets that the control system uses to ensure smooth and efficient operation, without requiring direct input from the operator or external entities .

[0073]

[0071] Internal setpoints can be changed frequently by the control algorithm to adapt to varying operational conditions , such as changes in temperature or pressure . The control unit monitors these conditions and modifies internal setpoints in real-time .

[0074]

[0072] Internal setpoints often play a role in fine-tuning the performance of specific components or subsystems to meet the larger goals defined by external setpoints . Examples of internal setpoints are : fan speed, motor or internal cooling rates that can be adj usted to manage thermal conditions within the compressor, valve positions , etc .

[0075]

[0073] In a standalone compressor unit, the compressor speed might be considered an internal setpoint because it is controlled by thecontrol algorithm to regulate the outlet pressure, which is often the primary performance criterion specified by the customer . The compressor speed may be adapted to balance the flow demand by the customer with flow supply from the compressor at the pressure desired by the customer . In this context, the setpoint shifting block adj usts internal setpoints to maintain the desired outlet pressure as accurately as possible . In a system with multiple compressors operating in parallel , the speed of each individual compressor can be treated alternatively as an external setpoint .

[0076]

[0074] External setpoints represent the parameters that are defined and set by the user, operator, or external systems . These setpoints specify the overall performance targets or desired outcomes for the compressor system. The control unit ' s main goal is to achieve and maintain these external setpoints by adj usting the internal setpoints accordingly .

[0077]

[0075] External setpoints are typically established by the customer or operator and are based on the speci fic requirements for the application . They reflect the desired performance metrics such as the target pressure, allowed variation of the target pressure, temperature, or air flow rate .

[0078]

[0076] These setpoints are generally less flexible than internal setpoints because they represent fixed performance targets that the system must meet to satisfy the operational requirements . The control unit strives to achieve these targets while managing the internal setpoints to deal with variations in system conditions .

[0077] A common example of an external setpoint in industrial applications is the specified air pressure required by pneumatic tools or other machinery . The compressor system adj usts its internal operations to consistently maintain the specified pressure , ensuring that downstream processes function smoothly .

[0079]

[0078] The distinction between internal and external setpoints is not always fixed and can vary depending on the specific configuration of the compressor system. The context in which the system operates determines which parameters are treated as internal or external .

[0080]

[0079] In a system with one or multiple compressors operating in parallel or in series where standalone compressors are controlled by their controllers , individual compressor speeds , inter-stage pressures , and cooling rates are usually considered internal setpoints because the setpoint shifting block manipulates these to balance the load and maintain system efficiency . The compressor outlet pressures or airflow resulting in overall system output pressure or total airflow delivered to the end user would be considered external setpoints , as these are dictated by the customer' s requirements .

[0081]

[0080] In a system with multiple compressors operating in parallel or in series where individual compressors are controlled by a central controller, individual compressor speeds , internal fan speeds , outlet pressures , or compressor bypass valve positions might be considered internal with respect to the local and central controller of the multiple compressors . They are adj usted by the central controller or local controllers to optimize performance ofthe multiple compressors operating in parallel or in series and protect the multiple compressors from wear . The overall system output pressure or total airflow delivered to the end user would be considered external setpoints , as these are dictated by the customer' s requirements .

[0082]

[0081] When the compressor system operates , the external setpoints are tried to be met by shifting internal setpoints . I f the system detects degradation or a risk of operating outside safe conditions , it dynamically adj usts internal setpoints to keep the system stable while striving to achieve the external targets . However, if the internal adj ustments are not sufficient to meet the external setpoints in a safe way, the control unit may issue alerts or warnings , and as a last resort, modify the external setpoints .

[0083]

[0082] A health scoring system analyzes the sensor data in conj unction with a compressor model to assess the current health and condition of the compressor and its components . This score reflects the current state of the compressor, indicating levels of degradation and potential risks . The health scoring system informs the setpoint shifting and limiting setpoint ranges blocks , allowing for real-time adj ustments to maintain optimal performance and safety .

[0084]

[0083] The health scoring system also facilitates predictive maintenance . By assessing the condition of the compressor and its components , the system can predict when maintenance will be required, allowing for timely interventions that prevent unexpected breakdowns and extend the life of the compressor .

[0084] The compressor model , a mathematical representation of the compressor, predicts its behavior under various operating conditions and aids in generating accurate health scores by simulating dif ferent scenarios based on current sensor data . The system employs a network of sensors to collect real-time data on various operational parameters , including temperature, pressure, speed, and more . This data is fed into the compressor model , which simulates the compressor' s behavior and predicts future conditions , including potentially harmful operating conditions given the generated health score . Based on these predictions and current health scores , whenever potentially harmful operating conditions may arise, the system dynamically adj usts internal setpoints and operating ranges .

[0085]

[0085] The limiting setpoint ranges block adj usts itself according to the allowable operating ranges of the compressor based on the health score . When degradation reaches a certain level , the operating range is reduced to ensure safe operation . Inputs to the limiting setpoint ranges block include component-specific degradation information . Degradation over time, represented as degradation ( t) , is monitored for specific components , guiding the adj ustments made by the limiting setpoint ranges block .

[0086]

[0086] The f irst action taken by the limiting setpoint ranges block when degradation is detected is to decide a new range of allowed internal setpoints . The internal setpoint generator creates new internal setpoints within the range of internal setpoints . Then, the setpoint shifting block implements internal setpoint shifting . This process involves dynamically adj usting the internal setpoints of the compressor, such as temperature thresholds or fan speeds , to compensate for the identified degradation . The setpointshifting block utilizes real-time data and the health score to make these adj ustments . Internal setpoint shifting is prioritized over external setpoint shifting as it allows the system to meet the external setpoints by temporarily stepping outside the original design constraints of some internal setpoints , guaranteeing uptime of the system.

[0087]

[0087] However, if internal point shifting alone is insufficient to maintain safe and ef ficient operation, the system then considers adj usting external setpoints as a later step . External setpoint shifting involves modi fying the broader operational parameters , such as pressure settings or flow rates , to further reduce strain on the compressor components . This step is taken when the degradation is too significant for internal adj ustments alone to mitigate the risks , ensuring that the compressor continues to operate even under deteriorating conditions . By sequentially applying these strategies— starting with internal adj ustments and escalating to external modifications only when necessary— the system maximizes efficiency, prolongs the time until the next overhaul , and ensures reliable performance .

[0088]

[0088] The setpoints are continuously monitored and adj usted by the setpoint shifting block and the limiting setpoint ranges block . By dynamically controlling internal setpoints , the system can maintain optimal performance even as components degrade over time . Adj ustments of internal setpoints help to prevent unsafe operating conditions , ensure that external setpoints are met, and manage the aging of internal components . For instance, increasing the fan speed may help cool down the compressor below the safety threshold when it contains a degrading component and there is a high ambient temperature, albeit at the cost of faster fan motor aging .

[0089] In an embodiment of the invention, a warning system monitors if the external setpoints cannot be reached despite of adj usted internal setpoints . I f the external setpoint is not achieved, it triggers a warning, indicating a potential risk of accelerated aging for certain components and of the customer requirement not being met under all possible circumstances . This risk is communicated to the controller and relevant blocks to ensure that temporary measures do not cause long-term damage . In an embodiment of the invention, the user could decide to start a back-up compressor as a result of said communication .

[0089]

[0090] Additionally in another embodiment of the invention, the warning system is designed to notify the user, operator or external system whenever internal setpoint shifting occurs . I f the system initiates internal adj ustments to compensate for degradation or other operational concerns , the warning system tracks these changes and evaluates the potential impact on the compressor ' s components . Specifically, it assesses the risk of accelerated aging for less critical components , which may experience increased strain due to the shifted setpoints . The warning system then generates an alert that details the specific internal adj ustments made and highlights the associated risks , particularly the potential for accelerated wear on non-essential components .

[0090]

[0091] This warning serves as a crucial feedback mechanism, allowing the user to make informed decisions about further adj ustments or maintenance actions . By providing real-time information about the consequences of internal setpoint shifts , the system ensures that temporary measures do not inadvertently lead to long-term damage .The integrated approach of monitoring both internal and external adj ustments , combined with a robust warning system, ensures that the compressor operates within safe limits while balancing performance and component health .

[0091]

[0092] According to the invention, an effective setpoint domain represents the actual range of setpoints within which the compressor can safely operate . This domain is dynamic, changing based on real-time conditions and health assessments .

[0092]

[0093] Figure 2 is a two-dimensional plot with ambient temperature on the y-axis and compressor speed on the x-axis . It illustrates the operational range limits of the compressor under both normal and degraded conditions . The solid rectangle defines the normal operating range where the compressor can function without any issues . However, as the compressor degrades due to factors such as wear and tear or contamination, the safe operational range reduces . This reduction is depicted by the slanted line inside the rectangle, which shows the new, more restricted operating range under degraded conditions . The area above the slanted line represents the range that can no longer be safely utilized due to the degradation . This figure emphasizes the dynamic nature of the operational range , which needs to be adj usted based on the realtime health status of the compressor to ensure continued operation . For example, the compressor model allows to simulate the temperature of the oil given degradation within the operational range limits . I f the simulated oil temperature is above the limit, the range can be limited based on the simulation so that the outlet temperature is lower than the limit .

[0094] According to the present invention, a soft limit is a threshold set for a process quantity that, when exceeded, indicates a warning or a potential issue that might not immediately compromise the system' s operation but can lead to accelerated degradation or reduced lifespan of components if maintained for an extended period . Soft limits are typically associated with internal setpoints and allow for some degree of flexibility in operations to maintain the external setpoints .

[0093]

[0095] Soft limits on internal setpoints allow for temporary deviations that might cause increased wear but do not immediately j eopardi ze the system. For example , a soft limit on motor winding temperature might permit short-term operation at higher temperatures to maintain the required compressor speed, but prolonged operation beyond this limit would accelerate insulation aging .

[0094]

[0096] According to the present invention, a hard limit is a strict threshold set for a process quantity that, when exceeded, poses a significant risk to the system' s safe operation and requires immediate corrective action to prevent damage or failure . Hard limits are often associated with thresholds on certain critical process quantities that must not be surpassed to ensure the system' s safety and reliability .

[0095]

[0097] Hard limits on certain critical process quantities represent absolute maximum values that cannot be exceeded without risking severe damage . For instance , the maximum allowable oil temperature is a hard limit, beyond which the compressor must be shut down to prevent catastrophic failure .

[0098] Hard limits on external setpoints ensure that the compressor operates within safe boundaries set by the user . For instance, if the required outlet pressure exceeds a hard limit due to system constraints , the compressor will reduce or cease operation to prevent over-pressurization and potential damage .

[0096]

[0099] When a hard limit is exceeded in the present invention, it triggers an immediate and decisive reaction to protect the system.

[0097]

[0100] In an embodiment of the invention, the system will either shut down the compressor or significantly reduce its load to prevent any further increase in the process quantity that has exceeded the hard limit . This is to avoid catastrophic failure or damage to the compressor and associated components .

[0098]

[0101] In another embodiment of the invention, an immediate alert is generated and communicated to the operators , maintenance personnel , or control systems . This alert includes details about the speci fic hard limit that was exceeded and the current status of the compressor .

[0099]

[0102] In another embodiment of the invention, the compressor system will be prevented from restarting or returning to normal operation until the issue causing the hard limit breach is resolved and the system is verified to be safe for operation . This includes checks and confirmations from maintenance personnel when necessary .

[0103] Figure 3 is a three-dimensional representation of the operational range limits , adding another dimension to the previous figure . Here, the axes are ambient temperature ( y-axis ) , compressor speed (x-axis ) , and outlet pressure ( z-axis ) . The solid cuboid represents the normal operational range of the compressor when it is in good condition . Similar to Figure 2 , the degraded condition of the compressor leads to a reduced operational range, which is shown as a smaller, irregularly shaped surface inside the cuboid . This surface, defined by the inner boundaries , represents the new range limits under degraded conditions . The shape of this degraded range is influenced by the interplay between ambient temperature, speed, and outlet pressure, demonstrating that degradation affects the compressor ' s performance in a multidimensional manner . This figure illustrates how complex the limitations become when multiple factors are considered and highlights the need for continuous monitoring and adj ustment of operational parameters to maintain safe and efficient compressor performance .

[0100]

[0104] Fig . 4 demonstrates how the compressor ' s operational range is adj usted based on degradation and oil temperature to ensure safe operation when the cooler is clogged by, for example 86% , according to an embodiment of the invention . According to an embodiment of the invention, the dynamic adj ustment of the compressor ' s operational range is based on real-time assessments of degradation and ambient conditions . By continuously adapting the speed limits , the system ensures that the compressor continues to operate within the specified temperature limits , even as it ages or faces varying environmental conditions . For instance, to ensure safe continued operation, the controller may limit the maximum speed to 3100 rpm.

[0105] The graph in the figure represents the relationship between the motor speed (on the horizontal axis ) and the oil temperature (on the vertical axis ) under different conditions . Also, it shows the predetermined ambient and shutdown oil temperatures .

[0101]

[0106] The healthy oil temperature line represents the oil temperature over the entire speed range ( from 1500 rpm to 3600 rpm) for a healthy compressor operating in 35 °C ambient air . The oil temperature stays below the predefined hard limit of 70 °C across the entire speed range, indicating that it is safe to operate the compressor at any speed within this range under these conditions .

[0102]

[0107] The clogged oil temperature line represents the computed oil temperature for a compressor with a cooling circuit that is clogged by 86% , also operating in 35 °C ambient air . For this degraded compressor, the oil temperature exceeds the 70 °C limit at speeds above 3100 rpm. Therefore, to ensure continued operation, the controller limits the maximum speed to 3100 rpm, if internal setpoint shi fting did not ensure a continuing operation . This prevents the oil temperature from exceeding the safe threshold, even though it reduces the available speed range .

[0103]

[0108] Additionally, the graph demonstrates how the operational range can change with varying ambient temperatures . For example, if the ambient temperature drops in the evening or at night, the compressor can operate at higher speeds without exceeding the oil temperature limit . This flexibility allows the compressor to adapt to changing conditions while maintaining safe operation .

[0109] Figure 5 illustrates an example of the effect of cooler clogging on the operating limits and internal setpoint adj ustments in the compressor system. The figure consists of three graphs showing the relationship between fan speed and motor speed as the degree of cooler clogging increases . The compressor system dynamically adj usts its operating range based on internal and external setpoints to maintain safe operating conditions .

[0104]

[0110] In the first graph a) , the cooler is assumed to be in normal working condition, without significant clogging . The fan speed and motor speed maintain a healthy relationship within the safe operating domain . The system operates under normal setpoints , and the upper fan speed limit is represented by the dashed line labeled " fan speed limit . " This limit ensures that the compressor remains within safe operating margins , preventing overheating or other operational issues . This limit also ensures that the fan is operating at maximum efficiency with the minimal wear of the fan .

[0105]

[0111] In the second graph b) , representing a 60% clogged cooler, the fan speed limit has been temporarily raised, as indicated by the dashed line labeled "Temporary fan speed limit . " This adj ustment is controlled by the system' s internal setpoints , which are shifted to account for the decreased cooling capacity of the system. As the cooler becomes clogged, the heat transfer ef ficiency decreases , requiring the system to compensate by increasing fan speed to maintain safe oil temperatures at the highest motor speeds . The solid black line depicts the adj usted relationship between fan and motor speed, while the dotted boundary indicates the zero operating margin; below this boundary, the oil temperature would become too high for safe operation .

[0112] In the third graph c) , the cooler clogging has worsened to 80% . The system' s operating range has been further reduced, as represented by the narrowing of the safe operating domain and the inaccessible motor speed range indicated . The temporary fan speed limit has been adj usted once again to compensate for the reduced cooling efficiency . However, as the clogging becomes more severe, the system is reaching the limits of its internal adj ustments . The boundary labeled " zero operating margin" is critical ; exceeding this boundary results in conditions where the system cannot guarantee safe operation, potentially leading to overheating or other failures .

[0106]

[0113] The 1 imiting setpoint ranges block, dynamically adj usts the fan speed limits based on the degree of cooler clogging . Initially, internal setpoint shifting occurs to compensate for the degradation in cooling efficiency . I f the clogging progresses , and internal adj ustments are no longer suf ficient, external setpoints , such as motor speed limits , may need to be adj usted to protect the system from further damage . The system' s health scoring unit continuously monitors degradation levels , such as cooler clogging, and communicates this information to the setpoint shifting block and limiting setpoint ranges block . The fan speed is automatically adj usted to maintain operation within the safe domain, but i f the clogging becomes excessive, as depicted in the final graph, the compressor system may need to take protective actions , such as reducing motor speed or even shutting down, to prevent unsafe conditions .

[0114] The invention pertains to a method for controlling a compressor system comprising a control unit and at least one compressor configured to provide compressed air .

[0107]

[0115] In an embodiment of the invention, a controller is gathering process quantities by monitoring the compressor system. Process quantities comprise temperature, pressure, and motor speed, which provide real-time data on the operational status of the compressor .

[0108]

[0116] In another embodiment of the invention, the gathered data is used to estimate at least one process quantity based on internal setpoints and at least one external setpoint of the compressor using a compressor model . This model incorporates the physical and operational characteristics of the compressor, allowing for accurate estimation of process quantities under different conditions .

[0109]

[0117] In another embodiment of the invention, from the gathered data and the compressor model , a health score is derived . This health score is indicative of the condition, degradation, or aging of the compressor system or its components . The health score provides a quantitative measure of the compressor ' s health, facilitating proactive maintenance and operational adj ustments .

[0110]

[0118] In another embodiment of the invention, based on the health score, the control unit determines an operating range . The setpoints are dynamically adj usted using a setpoint shifting block to compensate for degradation . The setpoint shifting block modifies internal setpoints , such as fan speed, to maintain optimal performance .

[0119] In a further embodiment of the invention, when safe operation cannot be guaranteed the operating range is reduced, by the limiting setpoint ranges block . This block ensures that the compressor operates within safe limits by excluding parts of the operational range where process quantities exceed predefined safe limits .

[0111]

[0120] In a further embodiment of the invention, the control unit maintains external setpoints , such as outlet pressure and motor speed, which are critical for the compressor ' s interaction with external systems . While these external setpoints are maintained, internal setpoints are adj usted to optimize performance and safety .

[0112]

[0121] In a further embodiment of the invention, soft limits are thresholds that, when exceeded, allow for temporary adj ustments and increased aging of components to maintain performance . Hard limits , on the other hand, trigger immediate protective actions such as shutting down the compressor system to prevent damage or unsafe conditions .

[0113]

[0122] In another embodiment of the invention, when a soft or hard limit is exceeded, the system generates an alert detailing the specific limit breached . This alerting mechanism ensures that operators are informed of potential issues and can take corrective action promptly . In cases where a hard limit is exceeded, the system may prevent the compressor from restarting until the condition causing the breach is resolved and verified to be safe .

[0123] In another embodiment of the invention, when a soft limit is exceeded, a cooling system is activated to reduce the temperature of the compressor components . The setpoint shifting block may also adapt fan speed limits based on actual ambient conditions and the current health score .

[0114]

[0124] In another embodiment of the invention, to enhance the accuracy and efficiency of the control process , the compressor model may incorporate a lookup table or a machine learning regression model or a physical model trained on historical data of compressor operation . These tools enable the system to predict and respond to various operational scenarios more effectively .

[0115]

[0125] In another embodiment of the invention, the health scoring unit continuously monitors sensor data to update the health score in real-time . This continuous monitoring allows the system to respond dynamically to changes in the compressor ' s condition and operating environment .

[0116]

[0126] In another embodiment of the invention, the limiting setpoint ranges block dynamically adj usts the permissible range of internal setpoints based on detected degradation levels . This dynamic adj ustment ensures that the compressor operates safely throughout its lifespan .

[0117]

[0127] In another embodiment of the invention, the compressor model can simulate the compressor ' s performance under various conditions , providing valuable insights into how different factors affect the compressor ' s operation . This simulation capability supports proactive maintenance and optimization strategies .

Claims

Claims1 . - A method for controlling a compressor system comprising at least one control unit and at least one compressor configured to provide compressed air, said method comprising the steps of :gathering process quantities by monitoring said compressor system,estimating at least one process quantity based on internal setpoints and at least one external setpoint of the compressor using a compressor model ;- deriving a health score from the gathered data and the compressor model ,- determining an operating range based on the setpoints of the compressor,characterized in that;- dynamically adj usting the internal setpoints using a setpoint shifting block to compensate for degradation,- maintaining external setpoints , while allowing adj ustment of internal setpoints .2 . - The method for controlling a compressor system of claim 1 , wherein the operating range is reduced using a limiting setpoint ranges block when safe operation cannot be guaranteed .3 . - The method for controlling a compressor system of claim 1 , wherein the internal set points are adj usted when a soft limit is exceeded .4 . - The method for controlling a compressor system of claim 1 , wherein the external set points are modified when a hard limit is exceeded .5 . - The method for controlling a compressor system of claim 1 , wherein the immediate protective action upon exceeding a hard limit includes shutting down the compressor system.

6. - The method for controlling a compressor system of claim 3 or claim 4 , wherein generating an alert when a soft or hard limit is exceeded, detailing the specific limit breached .7 . - The method for controlling a compressor system of claim 1 , in a system with multiple compressors operating in parallel , whereby the speed of each individual compressor is defined as the external setpoint .8 . - The method for controlling a compressor system of claim 1 , wherein a condition indication is representative of the condition, degradation, or aging of the compressor system or its components based on the health score .

9. - The method for controlling a compressor system of claim 1 , wherein the model used for estimating the process quantities includes a lookup table or a machine learning regression model ora physical model trained on historical data of compressor operation .10 . - The method for controlling a compressor system of claim 1 , wherein adj usting the internal set points includes activating a cooling system to reduce the temperature of the compressor components .11 . - The method for controlling a compressor system of claim 5 , wherein the compressor system is prevented from restarting until the condition causing the hard limit breach is resolved and verified to be safe .12 . - The method for controlling a compressor system of claim 1 , wherein adj usting the internal set points includes adapting the fan speed limits of the compressor system based on the actual ambient conditions and the current condition indication .13 . - The method for controlling a compressor system of claim 1 , wherein the limiting setpoint ranges block dynamically adj usts the range of permissible internal setpoints based on the degradation levels detected by the health scoring unit .14 . - The method for controlling a compressor system of claim 1 , wherein the setpoint shifting block attempts to restore the original setpoint range by temporarily allowing increased aging of the components to maintain the external setpoint .15 . - The method for controlling a compressor system of claim 1 , wherein the health scoring unit continuously monitors sensor data to update the health score in real-time .

16. - The method for controlling a compressor system of claim 1 , wherein the limiting setpoint ranges block excludes parts of the operational range where process quantities exceed predefined safe limits .17 . - The method for controlling a compressor system of claim 1 , wherein the setpoint shifting block adj usts setpoints based on ambient conditions , comprising ambient temperature and humidity .18 . - The method for controlling a compressor system of claim 1 , wherein the compressor model simulates the compressor' s performance under various conditions to provide model outputs .

19. - A compressor system comprising :- at least one compressor configured to provide compressed air; - at least one control unit configured to gather process quantities by monitoring said compressor system;- a compressor model configured to estimate at least one process quantity based on internal setpoints and at least one external setpoint of the compressor;- a health scoring unit configured to derive a health score from the gathered data and the compressor model ;- a setpoint shifting block configured to dynamically adj ust the internal setpoints to compensate for degradation;wherein the control unit maintains external setpoints while allowing the adj ustment of internal setpoints .20 . - The compressor system of claim 19, wherein the limit setpoint ranges block is configured to determine an operating range based on the setpoints of the compressor and reduce the operating range when safe operation cannot be guaranteed .21 . - The compressor system of claim 19, wherein the control unit is configured to execute an immediate protective action, including shutting down the compressor system, upon exceeding a hard limit .22 . - The compressor system of claim 19, further comprising an alerting unit configured to generate an alert when a soft or hard limit is exceeded, detailing the specific limit breached .23 . - The compressor system of claim 19, wherein the health scoring unit provides a condition indication representative of the condition, degradation, or aging of the compressor system or its components based on the health score .24 . - The compressor system of claim 19, wherein the compressor model includes a lookup table or a machine learning regression model or a physical model trained on historical data of compressor operation .25 . - The compressor system of claim 19, further comprising a cooling system, wherein the setpoint shifting block adj usts the internal setpoints by activating the cooling system to reduce the temperature of the compressor components .

26. - The compressor system of claim 22 , wherein the control unit prevents the compressor system from restarting until the condition causing the hard limit breach is resolved and verified to be safe .27 . - The compressor system of claim 19, wherein the setpoint shifting block adapts the fan speed limits of the compressor system based on the actual ambient conditions and the current condition indication .28 . - The compressor system of claim 19, wherein the limiting setpoint ranges block dynamically adj usts the range of permissible internal setpoints based on the degradation levels detected by the health scoring unit .

29. - The compressor system of claim 19, wherein the setpoint shifting block attempts to restore the original setpoint range by temporarily allowing increased aging of the components to maintain the external setpoint .30 . - The compres sor system of claim 19 , wherein the health scoring unit continuously monitors sensor data to update the health score in real- time .31 . - The compres sor system of claim 19 , wherein the limiting setpoint ranges block exclude s parts of the operational range where proces s quantitie s exceed prede fined safe l imits .32 . - The compres sor system of claim 19 , wherein the setpoint shi fting block adj usts setpoints based on ambient conditions , including ambient temperature and humidity .

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