Method and system for managing operation and maintenance data of central air conditioning equipment

Abstract

The invention provides an operation and maintenance data management method and system for central air-conditioning equipment, and is applied to the technical field of air-conditioning operation and maintenance data management. A first operation parameter set and a to-be-verified second operation parameter of the central air-conditioning equipment are obtained, and environment state parameters of the position where a sensor is located are combined; and calculating a theoretical reference value by using an equipment thermodynamic equilibrium model, and judging whether the sensor has measurement drift or not according to whether the deviation value and the environment state parameters meet preset conditions or not. And once the measurement drift is determined, replacing the second operation parameter with the theoretical reference value to serve as an equipment state evaluation basis, and outputting equipment fault early warning information. Therefore, the method has the advantages that the sensor measurement drift can be effectively identified, misjudgment and misoperation are avoided, and stable operation of equipment is guaranteed.

Description

Technical Field

[0001] This application relates to the field of air conditioning operation and maintenance data management technology, and in particular to a method and system for central air conditioning equipment operation and maintenance data management. Background Technology

[0002] In industrial production environments, central air conditioning equipment needs to precisely control temperature and humidity and ensure stable operation. Typically, operation and maintenance data management methods are deployed to collect data such as refrigerant pressure, temperature, and compressor current in real time to achieve monitoring, early warning, and energy efficiency optimization.

[0003] However, in high-temperature reaction environments, if the pressure sensor is located close to a heat source, when the local ambient temperature continues to rise and exceeds the sensor's design range, the physical characteristics of the sensor's internal sensitive element will change, resulting in a systematic measurement deviation: the output pressure will remain higher than the actual value, and the deviation will increase with the increase of temperature.

[0004] The existing data cleaning logic primarily targets anomalies such as random noise and instantaneous spikes, failing to identify slow, steady deviations and treating them as normal data for analysis. The fault diagnosis rule base frequently misjudges high data levels as indicating excessive refrigerant charge, issuing false warnings and causing alarm fatigue among maintenance personnel. Inexperienced operators might then incorrectly remove refrigerant, leading to insufficient refrigerant in the system.

[0005] Because the sensor output remained too high, the actual pressure drop was masked, and the system displayed normal pressure, failing to trigger any warnings. Meanwhile, insufficient refrigerant reduced cooling efficiency, causing the compressor to operate at high loads for extended periods, exacerbating wear and overheating risks, and potentially leading to premature failure. Furthermore, the maintenance data management methods consistently failed to identify the true fault, leaving the equipment in a sub-optimal state without any effective alarms.

[0006] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0007] In view of the shortcomings of the prior art, this application provides a central air conditioning equipment operation and maintenance data management method and system, which has the advantages of effectively identifying sensor measurement drift, avoiding misjudgment and misoperation, and ensuring stable operation of the equipment.

[0008] A first aspect is a method for managing operation and maintenance data of central air conditioning equipment, the method comprising the following steps: S1: Obtain a first set of operating parameters for the central air conditioning equipment, and obtain a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second operating parameters; S2: Obtain the environmental state parameters of the sensor's location; S3: Based on the first set of operating parameters, a preset equipment thermodynamic balance model is used to calculate the theoretical reference value corresponding to the second operating parameter, and the deviation value between the second operating parameter and the theoretical reference value is calculated. S4: Determine whether the deviation value meets the preset deviation characteristic conditions, and determine whether the environmental state parameters meet the preset environmental over-limit conditions; S5: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then it is determined that the sensor has experienced measurement drift. S6: If the sensor is found to have a measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault warning information is output according to the comparison result between the theoretical reference value and the preset operating threshold.

[0009] Furthermore, in step S1, the first set of operating parameters includes chilled water inlet and outlet temperatures, cooling water inlet and outlet temperatures, water pump flow rate, and compressor power, while the second operating parameter is refrigerant pressure.

[0010] Furthermore, step S2 includes: S21: Obtain local ambient temperature data at the location of the sensor through the environmental monitoring unit, or obtain operating temperature data of the heat source device adjacent to the sensor through the external control interface; the environmental state parameter is the local ambient temperature data or the operating temperature data.

[0011] Furthermore, step S3 includes: S31: Calculate the heat exchange of the condenser based on the cooling water flow rate and the temperature difference between the inlet and outlet of the cooling water; S32: Based on the heat exchange of the condenser and the power of the compressor, the theoretical saturation temperature of the refrigerant is derived by combining the principle of thermodynamic balance. S33: Determine the theoretical reference value corresponding to the refrigerant pressure based on the theoretical saturation temperature, and calculate the deviation between the refrigerant pressure and the theoretical reference value.

[0012] Furthermore, in step S4, the preset deviation characteristic conditions include the deviation value continuously exceeding a preset deviation threshold, and the trend of the deviation value's change satisfying a positive correlation with the trend of the environmental state parameter's change; the environmental exceedance condition includes the environmental state parameter exceeding a preset environmental temperature threshold; step S4 includes: S41: When the deviation value is greater than the deviation threshold within a preset time period, and the rate of change of the deviation value over time has the same sign as the rate of change of the environmental state parameter over time, it is determined that the deviation characteristic condition is met. S42: When the environmental state parameter is greater than the environmental temperature threshold, it is determined that the environmental over-limit condition is met.

[0013] Furthermore, in step S6, if it is determined that the sensor has experienced measurement drift, replacing the second operating parameter with the theoretical reference value as the basis for evaluating the status of the central air conditioning equipment includes the following steps: S61: When it is determined that the sensor has experienced measurement drift, the real-time reading of the sensor is blocked, the second operating parameter is replaced with the theoretical reference value, and fault diagnosis is performed based on the fault diagnosis rules.

[0014] Furthermore, in step S6, the output of equipment fault warning information based on the comparison result between the theoretical reference value and the preset operating threshold includes the following steps: S62: When the theoretical reference value is lower than the preset operating threshold, output a warning message for insufficient refrigerant and output a prompt message that the sensor reading is unreliable.

[0015] Furthermore, prior to step S3, the method further includes the following steps: S301: Obtain the load fluctuation characteristic value of the central air conditioning equipment, wherein the load fluctuation characteristic value is used to characterize the stability of the thermodynamic state of the central air conditioning equipment; S302: Determine whether the load fluctuation characteristic value is within the preset steady-state operating range; S303: If the load fluctuation characteristic value is within the steady-state operating range, then proceed to step S3; S304: If the load fluctuation characteristic value is not within the steady-state operating range, then the deviation threshold in the deviation characteristic condition is amplified and compensated according to the load fluctuation characteristic value, or the preset duration in the deviation characteristic condition is extended, and then step S3 is executed.

[0016] Furthermore, step S302 includes: S3021: Extract the time-domain distribution characteristics of each operating variable in the first set of operating parameters within a preset time window, and obtain the frequency command change rate of the compressor in the central air conditioning equipment; S3022: When the parameter variance in the time-domain distribution feature is less than a preset steady-state variance threshold and the frequency command change rate is less than a preset frequency conversion steady-state threshold, it is determined that the load fluctuation feature value is in the steady-state operating range; otherwise, it is determined that the load fluctuation feature value is not in the steady-state operating range. The parameter variance includes the variance of the temperature difference between the inlet and outlet of chilled water and the variance of the temperature difference between the inlet and outlet of cooling water.

[0017] Secondly, a central air conditioning equipment operation and maintenance data management system, the system being used to implement the steps in any of the methods described above, the system comprising: Parameter acquisition module: acquires a first set of operating parameters of the central air conditioning equipment, and acquires a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second set of operating parameters; Environmental monitoring module: acquires environmental state parameters of the location of the sensor; Theoretical calculation module: Based on the first set of operating parameters, it uses a preset equipment thermodynamic balance model to perform calculations to obtain the theoretical reference value corresponding to the second operating parameter, and calculates the deviation value between the second operating parameter and the theoretical reference value; Condition determination module: determines whether the deviation value meets the preset deviation characteristic conditions, and determines whether the environmental state parameters meet the preset environmental over-limit conditions; Drift determination module: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then the sensor is determined to have experienced measurement drift. Early warning output module: When it is determined that the sensor has experienced measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault early warning information is output based on the comparison result between the theoretical reference value and the preset operating threshold.

[0018] Beneficial Effects: This application proposes a central air conditioning equipment operation and maintenance data management method and system. By acquiring a first set of operating parameters and a second set of operating parameters to be verified from the central air conditioning equipment, and combining this with the environmental state parameters of the sensor's location, a theoretical reference value is calculated using the equipment's thermodynamic balance model. The system then determines whether the sensor has experienced measurement drift based on whether the deviation value and environmental state parameters meet preset conditions. Once measurement drift is determined, the theoretical reference value replaces the second operating parameter as the basis for equipment status evaluation, and equipment fault warning information is output. This method effectively identifies sensor measurement drift caused by environmental factors, avoiding systematic deviations that traditional data cleaning methods cannot identify. This prevents misjudgments and misoperations based on erroneous data, ensuring the stable operation and energy efficiency optimization of the central air conditioning equipment. Attached Figure Description

[0019] Figure 1 This is a flowchart of a central air conditioning equipment operation and maintenance data management method proposed in this application.

[0020] Figure 2 This is a structural diagram of a central air conditioning equipment operation and maintenance data management system proposed in this application.

[0021] Figure 3 This is a schematic diagram of a central air conditioning equipment operation and maintenance data management system proposed in this application.

[0022] Labeling Explanation: 201, Parameter Acquisition Module; 202, Environmental Monitoring Module; 203, Theoretical Calculation Module; 204, Condition Judgment Module; 205, Drift Judgment Module; 206, Early Warning Output Module. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and marked in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0024] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Traditional methods for managing central air conditioning equipment operation and maintenance data often fail to effectively identify sensor measurement drift caused by environmental factors. For example, if a pressure sensor in a central air conditioning system is located near a high-temperature heat source, and the local ambient temperature continues to rise beyond the sensor's design operating range, the sensor's output pressure value will consistently exceed the actual value, with the deviation increasing as the ambient temperature rises. Without addressing this issue, existing data cleaning logic often fails to effectively identify this slow, steady, and persistent measurement deviation, misinterpreting it as normal operating data. This leads to frequent misdiagnosis of false faults based on inflated data, such as overcharging of refrigerant, resulting in inaccurate warnings and alarm fatigue among maintenance personnel. More seriously, genuine refrigerant shortage faults may be masked by persistently high sensor pressure values, preventing the system from triggering effective warnings and leaving the central air conditioning equipment in a chronically unhealthy state, severely impacting its reliability and lifespan.

[0026] For this, please refer to Figure 1 This application proposes a method for managing operation and maintenance data of central air conditioning equipment, the method comprising the following steps: S1: Obtain a first set of operating parameters for the central air conditioning equipment, and obtain a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second operating parameters; S2: Obtain environmental state parameters of the sensor's location; S3: Based on the first set of operating parameters, use the preset equipment thermodynamic balance model to calculate the theoretical reference value corresponding to the second operating parameter, and calculate the deviation between the second operating parameter and the theoretical reference value; S4: Determine whether the deviation value meets the preset deviation characteristic conditions, and determine whether the environmental state parameters meet the preset environmental over-limit conditions. S5: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then it is determined that the sensor has experienced measurement drift. S6: If the sensor is found to have a measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault warning information is output based on the comparison result between the theoretical reference value and the preset operating threshold.

[0027] The working principle of this application lies in introducing a system-level physical verification mechanism. By collecting a series of other operating parameters indirectly related to the second operating parameter to be verified, a physical model based on thermodynamic balance and energy conservation is constructed. This model can calculate the theoretical reference value that the second operating parameter to be verified should possess under the current overall operating conditions of the central air conditioning equipment. This theoretical reference value originates from the overall physical laws of the central air conditioning equipment, and therefore is not affected by the influence of the local environment on individual sensors, and can serve as a benchmark for judging authenticity.

[0028] Subsequently, the second operating parameter measured in real time by the sensor is continuously compared with the calculated theoretical reference value. When a continuous and significant deviation is found between the two, and this deviation is clearly correlated with the exceeding of limits in the environmental state parameters at the sensor's location, it can be determined with high precision that the sensor has experienced measurement drift. Once drift is confirmed, the operation and maintenance data management method will immediately switch its judgment criteria, no longer trusting the distorted readings of the physical sensor, and instead using the more reliable theoretical reference value as the true basis for equipment status evaluation and fault diagnosis. In this way, even if the data from the physical sensor is deceptive, it can accurately identify masked real faults such as insufficient refrigerant and generate clear warning information containing sensor status anomalies, thereby guiding operation and maintenance personnel to perform correct operations, avoiding a chain of misjudgments and incorrect interventions, and ensuring the accuracy of the central air conditioning equipment's operational status assessment.

[0029] In a specific implementation scenario, the execution process of this method is as follows.

[0030] First, comprehensive multi-source data acquisition is conducted. This includes deploying various types of sensors to obtain the initial set of operating parameters. For example, a PT100 platinum resistance temperature sensor is used to measure the inlet and outlet temperatures of chilled water and cooling water. This type of sensor offers high accuracy and good stability, and its output signal is typically a 4 to 20 mA current signal. Electromagnetic flow meters or turbine flow meters are used to measure the flow rate of the water pump, and their output can be a pulse signal or a 4 to 20 mA signal. Hall effect current sensors combined with voltage measurements are used to indirectly calculate the real-time power consumption of the compressor. These parameters collectively form the basis for thermodynamic balance model calculations.

[0031] Simultaneously, a second operating parameter is acquired from the physical sensor to be calibrated, such as the refrigerant pressure reading measured by a piezoresistive pressure sensor. One direct approach is to deploy an additional environmental monitoring unit, such as a K-type thermocouple temperature sensor, next to the pressure sensor to be calibrated to monitor the local ambient temperature near its installation point in real time. However, in industrial production environments, it is not always suitable to install an ambient temperature sensor directly next to the sensor. Therefore, another indirect but equally effective approach is to acquire the operating temperature data of heat source equipment adjacent to the sensor, such as a high-temperature reactor, through the external control interface of an industrial control system, such as a distributed control system (DCS). This operating temperature data can serve as a strongly correlated proxy variable for the local ambient temperature. All this raw data from different sensors is transmitted to a central data processing unit via industrial fieldbuses, such as the Modbus RTU protocol, or industrial Ethernet, such as the Modbus TCP / IP protocol.

[0032] The central data processing unit can be a programmable logic controller (PLC). This unit is responsible for receiving, parsing, and storing data from various sensors, and performing preliminary preprocessing. Preprocessing includes unit conversion, such as converting the sensor's voltage or current signals into actual physical quantity units like degrees Celsius, megapascals, or kilowatts, and employing digital filtering algorithms such as median filtering or moving average filtering to remove transient random noise or spike interference from the data. It is important to emphasize that this preliminary filtering primarily targets high-frequency, short-term anomalies; it does not affect slow and systematic measurement drift caused by environmental influences.

[0033] Based on the acquired first set of operating parameters, the central data processing unit performs a series of calculations to derive the theoretical reference values ​​for the second operating parameters. Taking the calculation of the theoretical reference value for refrigerant pressure as an example, as the first step in the thermodynamic balance model of the equipment, the heat exchange of the condenser is first calculated. According to the principle of energy conservation, the heat dissipated by the condenser into the cooling water can be accurately calculated by measuring the mass flow rate of the cooling water and the temperature difference before and after it flows through the condenser. The calculation formula is: ,in It is a condenser for heat exchange. It is the mass flow rate of cooling water. It is the specific heat capacity of cooling water. and These are the outlet and inlet temperatures of the cooling water, respectively.

[0034] This thermodynamic equilibrium model is based on the physical correspondence between energy conversion within the refrigeration cycle and energy absorption by the external heat exchange medium. By measuring the cooling water flow rate and the temperature difference before and after the cooling water passes through the condenser, the total heat discharged from the condenser to the cooling water, i.e., the condenser heat transfer rate, is calculated. The condenser exchanges heat. By subtracting the compressor's input power and considering the motor's efficiency correction, the phase change enthalpy change of the refrigerant on the evaporator side can be calculated. The specific derivation process is as follows: According to the energy conservation law of the refrigeration cycle, the heat exchange of the condenser... equal to the cooling capacity of the refrigerant The sum of the effective input power of the compressor, in the known... In this case, there are ,in, This refers to the correction efficiency of the motor. This represents the input electrical power to the compressor. Furthermore, the enthalpy change of the refrigerant during the phase change on the evaporator side can be derived. for: .

[0035] Furthermore, according to the heat transfer equation of the heat exchanger, the heat transfer capacity of the condenser is... With refrigerant saturation temperature Cooling water inlet and outlet temperatures and Heat exchanger heat transfer coefficient and heat exchange area The following relationship must be satisfied: The theoretical saturation temperature of the refrigerant under the current heat load can be obtained by numerically solving this equation. .

[0036] Furthermore, by utilizing the pressure-temperature property equations of the refrigerant under saturation (such as polynomial fitting functions), the... This is converted into the corresponding theoretical saturation pressure, i.e., the theoretical reference value. : , where the function ( ) represents the physical property mapping function related to the type of refrigerant. This theoretical reference value does not change with the degradation of the electrical performance of a single sensor and is the physical criterion for determining the authenticity of measurement data.

[0037] Subsequently, the second operating parameter, namely the refrigerant pressure reading, measured in real time by the physical sensor, is continuously compared with the calculated theoretical reference value, and the deviation between the two is calculated. This deviation value is a direct quantitative indicator for determining whether the sensor is drifting.

[0038] After obtaining the deviation value and environmental state parameters, a dual-condition judgment is performed. First, it is determined whether the deviation value meets the preset deviation characteristic condition. This condition is not merely that the deviation value exceeds a fixed threshold; more importantly, the deviation value needs to exhibit a specific behavioral pattern consistent with sensor drift. Second, it is determined whether the environmental state parameters meet the preset environmental over-limit condition, that is, whether the environment in which the sensor is located has deteriorated to the point that it can cause its performance degradation.

[0039] Only when the deviation value meets the deviation characteristic condition and the environmental state parameters also meet the environmental over-limit condition can it be finally determined that the sensor has experienced measurement drift. This dual confirmation mechanism greatly improves the accuracy of diagnosis and effectively avoids misjudging other types of equipment failures or normal operating fluctuations as sensor drift.

[0040] Once sensor measurement drift is detected, the method will immediately take corrective measures. At this point, a calculated theoretical reference value will replace the unreliable physical sensor reading, serving as the basis for all subsequent status evaluations and fault diagnoses of central air conditioning equipment. For example, the theoretical reference value will be input into the existing fault diagnosis rule base and compared with various preset operating thresholds. If the comparison result shows an anomaly, such as the theoretical reference pressure value being lower than the lower limit threshold for normal refrigerant operation, a corresponding equipment fault warning message, such as insufficient refrigerant, will be output.

[0041] This warning message not only identifies the specific equipment malfunction but also includes a clear alert informing maintenance personnel which sensor has experienced measurement drift and whose current reading is unreliable. This provides maintenance personnel with a complete fault context, guiding them through proper troubleshooting and maintenance, thereby fundamentally resolving a series of cascading problems caused by distorted sensor data.

[0042] Through the above steps, the technical solution provided in this application can effectively identify and diagnose systematic and nonlinear measurement drift caused by long-term environmental over-limitation of sensors, avoiding the failure of traditional data cleaning logic and false warnings from fault diagnosis rule bases. By providing independent theoretical reference values ​​as a true reference, it can accurately reveal real faults such as insufficient refrigerant that are being masked, preventing maintenance personnel from making inappropriate interventions based on erroneous information. Ultimately, this ensures the stable and efficient operation of central air conditioning equipment under complex conditions, extends equipment lifespan, and reduces maintenance costs.

[0043] Furthermore, in step S1, the first set of operating parameters includes the inlet and outlet temperatures of chilled water, the inlet and outlet temperatures of cooling water, the water pump flow rate, and the compressor power, while the second operating parameter is the refrigerant pressure.

[0044] The inlet and outlet temperatures and flow rates of chilled water determine the evaporator's cooling capacity, while the inlet and outlet temperatures and flow rates of cooling water determine the condenser's heat dissipation. Compressor power represents the energy input into the refrigeration cycle. These core parameters collectively define the thermodynamic state of the entire central air conditioning system. Refrigerant pressure is used as the second operating parameter to be verified because it is one of the most critical indicators reflecting the normality of the refrigeration cycle, and its accuracy directly affects the reliability of the entire operation and maintenance data management method. By clearly defining these specific parameters, a clear input and verification object are provided for subsequently constructing an accurate thermodynamic balance model and performing sensor drift diagnosis, making the entire method highly operable and targeted.

[0045] Furthermore, step S2 includes: S21: Obtain local ambient temperature data at the location of the sensor through the environmental monitoring unit, or obtain operating temperature data of the heat source equipment adjacent to the sensor through the external control interface; the environmental status parameter is local ambient temperature data or operating temperature data.

[0046] In the first implementation, which involves direct measurement via an environmental monitoring unit, a separate temperature sensor, such as a fast-responding, wide-range K-type thermocouple, can be tightly mounted near the housing of the refrigerant pressure sensor to be calibrated, or on its mounting bracket. This thermocouple directly measures the air temperature surrounding the pressure sensor, providing the most accurate reflection of the thermal conditions of its operating environment.

[0047] In the second implementation, which involves indirect acquisition via an external control interface, the existing factory's automation network can be utilized, considering the challenges of adding wiring and installing sensors in some existing industrial facilities. If the primary heat source near the pressure sensor is known to be a high-temperature reactor monitored by a distributed control system (DCS), a data interface program, such as using the OPC protocol, can be developed to read the reactor's real-time operating temperature from the DCS system. Since the reactor's surface temperature is highly correlated with the surrounding air temperature, this operating temperature data can serve as a very effective proxy for environmental condition parameters.

[0048] These two methods, one being direct physical measurement and the other being system data integration, provide strong adaptability for the implementation of the method, ensuring that key information for determining whether the environment exceeds limits can be reliably obtained regardless of the field conditions.

[0049] Furthermore, step S3 includes: S31: Calculate the heat exchange of the condenser based on the cooling water flow rate and the temperature difference between the inlet and outlet of the cooling water; S32: Based on the heat exchange of the condenser and the power of the compressor, the theoretical saturation temperature of the refrigerant is derived by combining the principle of thermodynamic balance. S33: Determine the theoretical reference value corresponding to the refrigerant pressure based on the theoretical saturation temperature, and calculate the deviation between the refrigerant pressure and the theoretical reference value.

[0050] First, calculating the heat transfer of the condenser is the cornerstone of the entire thermodynamic modeling process. This is done by accurately measuring the cooling water mass flow rate and the temperature difference between the inlet and outlet of the condenser, using the heat transfer formula. This step allows for the accurate quantification of how much heat is transferred from the refrigerant to the cooling water per unit time. The accuracy of this step directly determines the reliability of subsequent derivations.

[0051] Secondly, the theoretical saturation temperature of the refrigerant is derived. In an ideal refrigeration cycle, the heat removed by the condenser consists mainly of two parts: the heat absorbed by the refrigerant in the evaporator and the heat converted from the work done by the compressor. Therefore, the heat exchange in the condenser is approximately equal to the sum of the cooling capacity and the compressor power. Using this energy balance relationship, and combining it with the physical properties of the refrigerant itself, the saturation temperature that the refrigerant should reach when undergoing a phase change in the condenser under the current energy exchange level can be calculated. This theoretical saturation temperature reflects the thermodynamic equilibrium of the central air conditioning equipment under current operating conditions and is unaffected by local sensor measurement errors.

[0052] Finally, the theoretical reference value is determined. Since there is a one-to-one, inherent physical relationship between the saturation temperature and saturation pressure of a refrigerant, this relationship can be obtained by consulting standard refrigerant property tables or using precise fitting equations. Therefore, once the theoretical saturation temperature is determined, the corresponding theoretical saturation pressure, i.e., the theoretical reference value, can be uniquely determined. This value represents the true physical value of the refrigerant pressure. Subsequently, subtracting this theoretical reference value from the actual pressure value measured by the sensor yields a deviation value that directly reflects the degree of measurement deviation by the sensor, providing direct numerical evidence for subsequent drift judgment.

[0053] Furthermore, in step S4, the preset deviation characteristic conditions include the deviation value continuously exceeding a preset deviation threshold, and the trend of the deviation value's change satisfying a positive correlation with the trend of the environmental state parameters' change; the environmental exceedance condition includes the environmental state parameters exceeding a preset environmental temperature threshold; step S4 includes: S41: When the deviation value is greater than the deviation threshold within a preset time period, and the rate of change of the deviation value over time has the same sign as the rate of change of the environmental state parameter over time, the deviation characteristic condition is determined to be met. S42: When the environmental state parameter is greater than the environmental temperature threshold, it is determined that the environmental over-limit condition is met.

[0054] First, the deviation value needs to be consistently greater than a preset deviation threshold, such as 0.05 MPa, for a preset period of time, such as 30 consecutive minutes. This requirement of consistency is to filter out transient deviations caused by normal fluctuations or instantaneous interference from the central air conditioning equipment, ensuring that the deviation being monitored is a stable and persistent systemic deviation.

[0055] Sensor drift caused by rising ambient temperature is typically positively correlated with temperature; that is, the higher the ambient temperature, the greater the deviation of the sensor reading from the true value. To capture this characteristic, the rate of change of the deviation over time (its first derivative) and environmental parameters, such as the rate of change of local ambient temperature over time, can be calculated. If these two rates of change have the same sign within the same time period—for example, if the local ambient temperature is rising while the deviation is also increasing—then a positive correlation is satisfied. This criterion greatly enhances the specificity of the diagnosis, accurately distinguishing drift caused by environmental factors from deviations caused by other reasons.

[0056] The positive correlation in the deviation characteristic condition reflects the linkage between sensor measurement error and external thermal stress. The processor extracts the pressure deviation value sequence and the ambient temperature parameter sequence through a sliding window, and performs first-order difference operations on the two sequences to obtain their respective trends over time. If the difference results of the deviation values ​​and the difference results of the ambient temperature are highly consistent in numerical sign, they are determined to be positively correlated. This means that as the ambient temperature increases, the zero-point drift generated by the sensitive thin film or signal conditioning circuit inside the sensor also increases. This trend determination logic effectively eliminates pressure anomalies caused by actual refrigerant leakage or occasional failures of electronic components, ensuring that the diagnostic conclusion points to a systematic drift caused by excessive external environmental limits.

[0057] Meanwhile, the determination of environmental exceedance conditions is relatively straightforward: when the real-time monitored environmental parameters, such as the local ambient temperature, exceed the ambient temperature threshold set for the sensor (e.g., the sensor manufacturer's specified long-term operating temperature limit of 50 degrees Celsius), the environmental exceedance condition is deemed met. This threshold provides a clear boundary for determining whether the sensor is operating in an unhealthy stress environment.

[0058] Furthermore, in step S6, if it is determined that the sensor has experienced measurement drift, replacing the second operating parameter with the theoretical reference value as the basis for evaluating the status of the central air conditioning equipment includes the following steps: S61: When it is determined that the sensor has experienced measurement drift, the real-time reading of the sensor is blocked, the second operating parameter is replaced with the theoretical reference value, and fault diagnosis is performed based on the fault diagnosis rules.

[0059] This process ensures that immediate action can be taken to prevent further spread and impact of erroneous information upon discovering an unreliable data source. To shield the sensor's real-time readings, a status flag can be set for the sensor in the data management program, for example, is_drifting = TRUE. All downstream applications or diagnostic modules that need to access this sensor data will check this flag before reading the data. If the flag is true, the program will bypass the sensor's physical input channel and instead retrieve data from a memory address storing a theoretical reference value.

[0060] Next, this verified and reliable theoretical reference value is input into the existing fault diagnosis rule base as a new second operating parameter. This rule base contains multiple fault diagnosis rules. For example, one rule states that if the refrigerant pressure is below 0.8 MPa, it is considered insufficient refrigerant. In the event of sensor drift, even if the distorted reading shows 1.0 MPa, the central air conditioning system will use the calculated theoretical reference value, such as 0.75 MPa, for the judgment. In this way, the central air conditioning system can accurately trigger the diagnosis of insufficient refrigerant based on the actual physical state, thus avoiding the problem of real faults being masked by sensor drift and ensuring the accuracy and effectiveness of fault diagnosis.

[0061] Furthermore, in step S6, based on the comparison result between the theoretical reference value and the preset operating threshold, the output of equipment fault warning information includes the following steps: S62: When the theoretical reference value is lower than the preset operating threshold, output a warning message of insufficient refrigerant and a prompt message that the sensor reading is unreliable.

[0062] This method of generating early warning information reflects a high degree of responsibility and clear guidance for maintenance personnel. When the central air conditioning system determines that the refrigerant pressure is too low based on theoretical reference values, the early warning window that pops up on the human-machine interface, or the early warning SMS sent to the maintenance personnel's mobile phone, will contain two core parts. The first part is a clear fault diagnosis conclusion, such as insufficient refrigerant, please check immediately. The second part is key contextual information and explanation of the cause, such as pressure sensor PS-001 has experienced measurement drift due to long-term local environmental overheating, the current reading is unreliable, and the central air conditioning system has switched to theoretical reference values ​​for judgment.

[0063] Such comprehensive early warning information is far more valuable than a single fault alarm. It directly informs maintenance personnel that the problem is indeed due to insufficient refrigerant, while also explaining why the central air conditioning system might have previously issued false alarms or failed to issue any alarms—the root cause being sensor drift. This not only prevents maintenance personnel from being confused by normal sensor readings and potentially making erroneous reverse operations such as removing refrigerant, but also directly points to another object requiring maintenance: the malfunctioning sensor. This clear and comprehensive information delivery greatly improves the accuracy and guidance of the early warning, ensuring the efficiency and correctness of maintenance work.

[0064] Furthermore, prior to step S3, the method also includes the following steps: S301: Obtain the load fluctuation characteristic value of the central air conditioning equipment. The load fluctuation characteristic value is used to characterize the stability of the thermodynamic state of the central air conditioning equipment. S302: Determine whether the load fluctuation characteristic value is within the preset steady-state operating range; S303: If the load fluctuation characteristic value is within the steady-state operating range, then proceed to step S3; S304: If the load fluctuation characteristic value is not in the steady-state operating range, then the deviation threshold in the deviation characteristic condition is amplified and compensated according to the load fluctuation characteristic value, or the preset duration in the deviation characteristic condition is extended, and then step S3 is executed.

[0065] The rationale behind this improvement is that the aforementioned thermodynamic balance model is most accurate when the central air conditioning equipment is operating at a relatively stable speed. When the equipment load changes drastically, such as when production lines are simultaneously turned on or off, the compressor frequency and water pump flow rate of the central air conditioning system will adjust rapidly. The central air conditioning system is in a dynamic transition process, and at this time, the parameters have not yet reached a new thermodynamic equilibrium. If theoretical reference values ​​are forcibly calculated and compared under such unsteady conditions, the deviation values ​​may fluctuate within the normal range due to the transient errors of the model itself, thus leading to misjudgments of sensor drift.

[0066] Therefore, this improved scheme first assesses the stability of the central air conditioning system by acquiring load fluctuation characteristic values. If the central air conditioning system is determined to be in a steady-state operating range, it indicates that the thermodynamic model is applicable, and the subsequent calculations and drift diagnosis process are executed normally. Conversely, if the central air conditioning system is determined to be in a non-steady-state operating range, an adaptive fault-tolerant mechanism is activated. This mechanism can dynamically adjust the triggering conditions for drift diagnosis; for example, temporarily increasing the deviation threshold for determining whether the deviation is significant by 50%, or extending the preset duration requiring the deviation to persist from 30 minutes to 60 minutes. In this way, the central air conditioning system is given sufficient time to weather the transient process and reach a new equilibrium, effectively tolerating normal parameter fluctuations under non-steady-state conditions, avoiding misjudging these normal fluctuations as sensor drift, thereby significantly improving the robustness of drift diagnosis under complex operating conditions and reducing the false alarm rate.

[0067] The load fluctuation characteristic value is a quantitative indicator for evaluating the stability of central air conditioning operation. By collecting inlet and outlet water temperature difference data on the chilled water and cooling water sides, the variance of these parameters within a preset observation period is calculated to measure the severity of thermodynamic cycle fluctuations. Simultaneously, the frequency of compressor frequency command changes is monitored. When the variance of each temperature difference parameter is below the set fluctuation threshold and the compressor frequency remains constant, the equipment is determined to be in a steady-state operating range of energy exchange balance. Performing thermodynamic calculations within this range yields the most accurate theoretical reference values. However, performing calculations in the non-steady-state range requires the introduction of dynamic compensation logic to reduce the interference of transient errors on drift determination.

[0068] Furthermore, step S302 includes: S3021: Extract the time-domain distribution characteristics of each operating variable in the first set of operating parameters within a preset time window, and obtain the frequency command change rate of the compressor in the central air conditioning equipment; S3022: When the variance of the parameters in the time domain distribution characteristics is less than the preset steady-state variance threshold and the frequency command change rate is less than the preset frequency conversion steady-state threshold, the load fluctuation characteristic value is determined to be in the steady-state operating range; otherwise, the load fluctuation characteristic value is determined not to be in the steady-state operating range. The parameter variances include the variance of the temperature difference between the inlet and outlet of chilled water and the variance of the temperature difference between the inlet and outlet of cooling water.

[0069] This assessment method comprehensively and quantitatively evaluates the operational stability of equipment through multi-dimensional data analysis. First, it extracts the time-domain distribution characteristics of key thermodynamic parameters over a period of time, such as 5 minutes. The variance of these parameters reflects the dispersion or volatility of the data. The variances of the chilled water inlet / outlet temperature difference and the cooling water inlet / outlet temperature difference are calculated. If both variances are less than their respective preset steady-state variance thresholds, it indicates that the heat exchange process of the central air conditioning system is stable. Furthermore, since the chilled water inlet / outlet temperature difference and the cooling water inlet / outlet temperature difference directly reflect the heat exchange stability of the refrigeration cycle and are most sensitive to load changes, only these two temperature differences from the first set of operating parameters are selected as the core characterization parameters for load fluctuation characteristics. Changes in pump flow rate and compressor power are indirectly reflected in temperature difference changes and are therefore not used as independent assessment indicators.

[0070] Secondly, for modern central air conditioning systems using variable frequency compressors, the compressor's operating frequency directly reflects its load level. By obtaining the compressor's frequency command change rate per unit time, if this rate of change is less than a preset variable frequency steady-state threshold, for example, a change of no more than 0.1 Hz per second, it indicates that the compressor's output is stable and the central air conditioning system load has not changed significantly.

[0071] Ultimately, only when both of the above conditions are met—namely, sufficiently small fluctuations in thermodynamic parameters and sufficiently stable compressor load output—can the equipment be determined to be in a steady-state operating range. This dual criterion, combining the thermodynamic response of the central air conditioning system with changes in control commands, can very accurately identify the operating status of the equipment, providing a reliable basis for subsequent decisions on whether to perform drift diagnosis and whether dynamic threshold compensation is needed.

[0072] Please refer to Figure 2 , Figure 3 This application also provides a central air conditioning equipment operation and maintenance data management system, which is used to implement the steps in any of the above methods, and the system includes: Parameter acquisition module 201: Acquires a first set of operating parameters of the central air conditioning equipment and acquires a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second operating parameters; Environmental monitoring module 202: Acquires environmental state parameters at the location of the sensor; Theoretical calculation module 203: Based on the first set of operating parameters, it uses a preset equipment thermodynamic balance model to perform calculations to obtain the theoretical reference value corresponding to the second operating parameter, and calculates the deviation value between the second operating parameter and the theoretical reference value; Condition determination module 204: Determines whether the deviation value meets the preset deviation characteristic conditions, and determines whether the environmental state parameters meet the preset environmental over-limit conditions; Drift determination module 205: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then the sensor is determined to have experienced measurement drift. Early warning output module 206: When it is determined that the sensor has experienced measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault early warning information is output based on the comparison result between the theoretical reference value and the preset operating threshold.

[0073] Specifically, the parameter acquisition module 201 is configured to collect various operational data of the central air conditioning equipment in real time. The first set of operational parameters may include multiple operational variables that have a thermodynamic relationship with the second operational parameter to be verified, such as chilled water inlet and outlet temperatures, cooling water inlet and outlet temperatures, water pump flow rate, and compressor power. The second operational parameter is typically sensor readings that need to be verified, such as refrigerant pressure. The parameter acquisition module 201 can interface with the central air conditioning equipment's control system, data acquisition system (SCADA), or directly with various sensors to ensure the timeliness and accuracy of the data.

[0074] The environmental monitoring module 202 is configured to acquire environmental state parameters of the location of the sensor to be calibrated. These environmental state parameters can refer to local ambient temperature data, acquired through an independent environmental monitoring unit deployed near the sensor; or they can refer to the operating temperature data of a heat source device adjacent to the sensor, acquired through an external control interface. The purpose is to assess the potential impact of environmental factors on sensor readings, providing an environmental basis for subsequent drift determination.

[0075] The theoretical calculation module 203 is configured to perform calculations based on a first set of operating parameters provided by the parameter acquisition module, using a preset equipment thermodynamic balance model. This model allows the derivation of theoretical reference values ​​corresponding to the second operating parameter. For example, when the second operating parameter is refrigerant pressure, the theoretical calculation module can calculate the condenser heat exchange based on the cooling water flow rate and the temperature difference between the inlet and outlet cooling water. Then, based on the condenser heat exchange and compressor power, and combined with the thermodynamic balance principle, it derives the theoretical saturation temperature of the refrigerant, thereby determining the theoretical reference value corresponding to the refrigerant pressure. Subsequently, the module calculates the deviation between the actually measured second operating parameter and the theoretical reference value.

[0076] The condition determination module 204 is configured to comprehensively judge the deviation value obtained by the theoretical calculation module and the environmental state parameters acquired by the environmental monitoring module. Preset deviation characteristic conditions may include the deviation value continuously exceeding a preset deviation threshold, and the trend of the deviation value's change being positively correlated with the trend of the environmental state parameters' change. Preset environmental exceedance conditions may include environmental state parameters exceeding a preset environmental temperature threshold. The condition determination module 204 will determine whether the deviation value and environmental state parameters meet the corresponding characteristics based on these preset conditions.

[0077] The drift determination module 205 is configured to make a final sensor measurement drift determination based on the judgment result of the condition determination module. If the deviation value meets the preset deviation characteristic condition and the environmental state parameters meet the preset environmental over-limit condition, the drift determination module 205 will determine that the sensor has experienced measurement drift.

[0078] The early warning output module 206 is configured to take corresponding measures when the drift determination module determines that the sensor has experienced measurement drift. Specifically, this module replaces the unreliable second operating parameter with a theoretical reference value as the basis for evaluating the status of the central air conditioning equipment, thereby ensuring that subsequent equipment diagnosis and operational decisions are based on accurate data. Furthermore, the early warning output module 206 also outputs equipment fault early warning information based on the comparison between the theoretical reference value and a preset operating threshold. For example, when the theoretical reference value is lower than the preset operating threshold, it outputs a refrigerant shortage warning and simultaneously outputs a sensor reading unreliable indication.

[0079] Through the above technical solutions, the central air conditioning equipment operation and maintenance data management system of this application can realize automated and intelligent management of central air conditioning equipment operation data, significantly improving the accuracy and real-time performance of sensor measurement drift detection. The system, through modular design, integrates complex data acquisition, thermodynamic calculation, multi-condition judgment, and early warning output functions, greatly reducing the need for manual intervention and improving operation and maintenance efficiency. Especially when sensor measurement drift occurs, the system can promptly replace unreliable sensor readings with theoretical reference values, ensuring the accuracy of equipment status evaluation and effectively avoiding misjudgments and potential equipment operation risks caused by sensor failures. Furthermore, the system can output specific equipment fault early warning information based on the comparison results between theoretical reference values ​​and preset operating thresholds, providing precise decision support for operation and maintenance personnel, thereby ensuring the stable and efficient operation of central air conditioning equipment, extending equipment lifespan, and reducing operation and maintenance costs.

[0080] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for managing operation and maintenance data of central air conditioning equipment, characterized in that, The method includes the following steps: S1: Obtain a first set of operating parameters for the central air conditioning equipment, and obtain a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second operating parameters; S2: Obtain the environmental state parameters of the sensor's location; S3: Based on the first set of operating parameters, a preset equipment thermodynamic balance model is used to calculate the theoretical reference value corresponding to the second operating parameter, and the deviation value between the second operating parameter and the theoretical reference value is calculated. S4: Determine whether the deviation value meets the preset deviation characteristic conditions, and determine whether the environmental state parameters meet the preset environmental over-limit conditions; S5: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then it is determined that the sensor has experienced measurement drift. S6: If the sensor is found to have a measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault warning information is output according to the comparison result between the theoretical reference value and the preset operating threshold.

2. The method for managing operation and maintenance data of central air conditioning equipment according to claim 1, characterized in that, In step S1, the first set of operating parameters includes chilled water inlet and outlet temperatures, cooling water inlet and outlet temperatures, water pump flow rate, and compressor power, and the second operating parameter is refrigerant pressure.

3. The method for managing operation and maintenance data of central air conditioning equipment according to claim 2, characterized in that, Step S2 includes: S21: Obtain local ambient temperature data at the location of the sensor through the environmental monitoring unit, or obtain operating temperature data of the heat source device adjacent to the sensor through the external control interface; the environmental state parameter is the local ambient temperature data or the operating temperature data.

4. The method for managing operation and maintenance data of central air conditioning equipment according to claim 2, characterized in that, Step S3 includes: S31: Calculate the heat exchange of the condenser based on the cooling water flow rate and the temperature difference between the inlet and outlet of the cooling water; S32: Based on the heat exchange of the condenser and the power of the compressor, the theoretical saturation temperature of the refrigerant is derived by combining the principle of thermodynamic balance. S33: Determine the theoretical reference value corresponding to the refrigerant pressure based on the theoretical saturation temperature, and calculate the deviation between the refrigerant pressure and the theoretical reference value.

5. The method for managing operation and maintenance data of central air conditioning equipment according to claim 1, characterized in that, In step S4, the preset deviation characteristic conditions include: the deviation value continuously exceeds a preset deviation threshold, and the trend of the deviation value's change satisfies a positive correlation with the trend of the environmental state parameter's change; the environmental exceedance condition includes the environmental state parameter exceeding a preset environmental temperature threshold; step S4 includes: S41: When the deviation value is greater than the deviation threshold within a preset time period, and the rate of change of the deviation value over time has the same sign as the rate of change of the environmental state parameter over time, it is determined that the deviation characteristic condition is met. S42: When the environmental state parameter is greater than the environmental temperature threshold, it is determined that the environmental over-limit condition is met.

6. The method for managing operation and maintenance data of central air conditioning equipment according to claim 1, characterized in that, In step S6, if it is determined that the sensor has experienced measurement drift, replacing the second operating parameter with the theoretical reference value as the basis for evaluating the status of the central air conditioning equipment includes the following steps: S61: When it is determined that the sensor has experienced measurement drift, the real-time reading of the sensor is blocked, the second operating parameter is replaced with the theoretical reference value, and fault diagnosis is performed based on the fault diagnosis rules.

7. The method for managing operation and maintenance data of central air conditioning equipment according to claim 1, characterized in that, In step S6, the output of equipment fault warning information based on the comparison result between the theoretical reference value and the preset operating threshold includes the following steps: S62: When the theoretical reference value is lower than the preset operating threshold, output a warning message for insufficient refrigerant and output a prompt message that the sensor reading is unreliable.

8. The method for managing operation and maintenance data of central air conditioning equipment according to claim 1, characterized in that, Prior to step S3, the method further includes the following steps: S301: Obtain the load fluctuation characteristic value of the central air conditioning equipment, wherein the load fluctuation characteristic value is used to characterize the stability of the thermodynamic state of the central air conditioning equipment; S302: Determine whether the load fluctuation characteristic value is within the preset steady-state operating range; S303: If the load fluctuation characteristic value is within the steady-state operating range, then proceed to step S3; S304: If the load fluctuation characteristic value is not within the steady-state operating range, then the deviation threshold in the deviation characteristic condition is amplified and compensated according to the load fluctuation characteristic value, or the preset duration in the deviation characteristic condition is extended, and then step S3 is executed.

9. A method for managing operation and maintenance data of central air conditioning equipment according to claim 8, characterized in that, Step S302 includes: S3021: Extract the time-domain distribution characteristics of each operating variable in the first set of operating parameters within a preset time window, and obtain the frequency command change rate of the compressor in the central air conditioning equipment; S3022: When the parameter variance in the time-domain distribution feature is less than a preset steady-state variance threshold and the frequency command change rate is less than a preset frequency conversion steady-state threshold, it is determined that the load fluctuation feature value is in the steady-state operating range; otherwise, it is determined that the load fluctuation feature value is not in the steady-state operating range. The parameter variance includes the variance of the temperature difference between the inlet and outlet of chilled water and the variance of the temperature difference between the inlet and outlet of cooling water.

10. A central air conditioning equipment operation and maintenance data management system, characterized in that, The system is used to implement the steps of the method according to any one of claims 1-9, the system comprising: Parameter acquisition module: acquires a first set of operating parameters of the central air conditioning equipment, and acquires a second set of operating parameters to be verified by sensors, wherein the first set of operating parameters includes multiple operating variables that have a thermodynamic relationship with the second set of operating parameters; Environmental monitoring module: acquires environmental state parameters of the location of the sensor; Theoretical calculation module: Based on the first set of operating parameters, it uses a preset equipment thermodynamic balance model to perform calculations to obtain the theoretical reference value corresponding to the second operating parameter, and calculates the deviation value between the second operating parameter and the theoretical reference value; Condition determination module: determines whether the deviation value meets the preset deviation characteristic conditions, and determines whether the environmental state parameters meet the preset environmental over-limit conditions; Drift determination module: If the deviation value meets the deviation characteristic condition and the environmental state parameter meets the environmental over-limit condition, then the sensor is determined to have experienced measurement drift. Early warning output module: When it is determined that the sensor has experienced measurement drift, the theoretical reference value is used to replace the second operating parameter as the basis for evaluating the status of the central air conditioning equipment, and the equipment fault early warning information is output based on the comparison result between the theoretical reference value and the preset operating threshold.

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