Multi-temperature zone coordinated refrigeration system and energy-saving control method for variable temperature cold storage

Abstract

This invention discloses a multi-temperature zone coordinated refrigeration system and energy-saving control method for variable-temperature cold storage, belonging to the field of cold storage temperature control technology. The system includes: calling a dynamic load prediction model based on the acquired initial real-time monitoring dataset to calculate the heat load change trend data for each temperature zone over a preset period; adjusting the electronic expansion valve and generating start-up control commands based on the heat load trend and the temperature and humidity requirements of the goods, starting, stopping, or switching the refrigeration unit to operate the system; activating the central oil circuit management module during system operation to monitor the compressor oil level and compare it with a preset safety threshold to generate oil circuit adjustment commands; starting the intelligent oil pump to deliver oil according to the commands, while using the evaporator outlet superheat or pressure value as a feedback signal to control the electronic expansion valve in a closed loop; and summarizing the data from the actuators and sensors and feeding it back to the central controller to form a closed loop. This invention achieves multi-temperature zone coordinated control, improving refrigeration efficiency and equipment safety, and reducing energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of cold storage temperature control technology, specifically a multi-temperature zone coordinated refrigeration system and energy-saving control method for variable temperature cold storage. Background Technology

[0002] Currently, existing variable temperature cold storage facilities suffer from several technical challenges during operation: First, the switching between high and low temperature units largely relies on manual operation or simple timing control, failing to adjust in real time according to the actual temperature requirements and load changes of each temperature zone, easily leading to energy waste or insufficient temperature control accuracy. Second, in multi-temperature zone systems, the refrigeration oil is prone to uneven distribution within the pipelines, causing wear and tear on some units due to insufficient oil, affecting equipment lifespan. Third, if refrigerant cross-flow occurs in the refrigeration systems corresponding to different temperature zones, it will disrupt the refrigerant balance of each system, resulting in a significant decrease in refrigeration efficiency and even equipment failure. While existing technologies offer some solutions addressing individual problems, such as standalone unit switching control or refrigerant recovery devices, they lack a control method that integrates high and low temperature unit switching, refrigeration oil balance, and refrigerant balance, failing to effectively improve the stability and efficiency of multi-temperature zone operation in variable temperature cold storage. Therefore, developing a method that achieves coordinated control of these three aspects has become a key requirement for the current development of variable temperature cold storage technology. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a multi-temperature zone coordinated refrigeration system and energy-saving control method for variable-temperature cold storage. Based on the acquired initial real-time monitoring dataset, a dynamic load prediction model is invoked to calculate the heat load change trend data for each temperature zone over a preset period. Combining the heat load trend with the temperature and humidity requirements of the goods, the electronic expansion valve is adjusted, and start-up control commands are generated to start, stop, or switch the refrigeration units to operate the system. During system operation, the central oil circuit management module is activated to monitor the compressor oil level and compare it with a preset safety threshold to generate oil circuit adjustment commands. The intelligent oil pump is activated according to the commands to deliver oil, while the evaporator outlet superheat or pressure value serves as a feedback signal to control the electronic expansion valve in a closed loop. Data from the actuators and sensors are aggregated and fed back to the central controller, forming a closed loop. This invention achieves coordinated control of multiple temperature zones, improving refrigeration efficiency and equipment safety while reducing energy consumption.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] Multi-temperature zone energy-saving control methods for variable-temperature cold storage include:

[0006] S1: Obtain the initial real-time monitoring dataset through the central controller; the initial real-time monitoring dataset includes the internal temperature, internal humidity, cargo attribute information, and warehouse door opening and closing status parameters of each temperature zone;

[0007] S2: Based on the initial real-time monitoring dataset, the dynamic load prediction model built into the central controller is called to calculate the heat load change trend data for each temperature zone during a preset period.

[0008] S3: Based on the heat load change trend data and the temperature and humidity requirements corresponding to the cargo attribute information, adjust the electronic expansion valve of the refrigeration circuit and generate a start-up control command. Then, start, stop or switch the refrigeration unit according to the start-up control command to put the refrigeration system into operation.

[0009] S4: During the operation of the refrigeration system, the central controller starts the central oil circuit management module to monitor the real-time oil level of the compressor in each refrigeration system to obtain an oil level monitoring dataset, and compares the real-time oil level in the oil level monitoring dataset with a preset safety threshold to generate an oil circuit adjustment command.

[0010] S5: Start the intelligent oil pump according to the oil circuit adjustment command, and transport the refrigeration oil in the oil source compressor with sufficient oil level to the oil shortage compressor through the parallel oil circuit. At the same time, the central controller uses the superheat or pressure value of the evaporator outlet of each refrigeration circuit as a feedback signal to independently close the electronic expansion valve of the corresponding refrigeration circuit.

[0011] S6: Summarize the operating data of the actuators and the monitoring data of the sensors and feed them back to the central controller; the actuators include a refrigeration unit, an electronic expansion valve, and an intelligent oil pump.

[0012] Specifically, the dynamic load prediction model is a time-series prediction model based on a long short-term memory network. Its input is historical time-series data and real-time data in the initial real-time monitoring dataset, and its output is the predicted heat load value of each temperature zone within a preset period. The heat load change trend data includes at least the predicted heat load value of each temperature zone at a preset time node and the heat load change rate calculated based on the predicted heat load value of continuous time nodes.

[0013] Specifically, the process of adjusting the electronic expansion valve of the refrigeration circuit and generating a start-up control command includes:

[0014] The central controller analyzes the heat load change trend data to obtain the predicted change direction and magnitude of the heat load within a preset period. At the same time, the central controller calls the acquired cargo attribute information and uses the preset storage temperature range in the cargo attribute information as the control target boundary.

[0015] If the analysis determines If the rate of change of heat load is greater than zero, a target storage temperature cooling control strategy will be generated. However, the temperature zone temperature after the target storage temperature cooling control strategy is implemented must not be lower than the lower limit of the control target boundary. express The predicted heat load value at any given time. This represents the predicted heat load value at time t;

[0016] If the analysis determines If the rate of change of heat load is less than zero, a target warehouse temperature rise control strategy is generated, but the temperature zone temperature after the target warehouse temperature rise control strategy is executed must not exceed the upper limit of the control target boundary.

[0017] The target warehouse temperature cooling control strategy and the target warehouse temperature heating control strategy are combined to form the target warehouse temperature control strategy.

[0018] The central controller calculates the target opening value of the electronic expansion valve based on the new target temperature value determined by the target storage temperature control strategy, combined with the current evaporator outlet superheat signal read in real time from the refrigeration circuit sensor, and sends a control signal containing the target opening value to the electronic expansion valve.

[0019] The central controller synchronously performs energy planning based on the same heat load change trend data and the determined target storage temperature control strategy. It calculates the operating combination of refrigeration units that meet the predicted heat load value within a preset time period and their optimal operating frequency, and generates start-stop commands or frequency conversion commands, which are then sent to the corresponding refrigeration units as start-up control commands.

[0020] Specifically, the steps of S4 include:

[0021] After the refrigeration system enters the operating state according to the generated start-up control command, the central controller starts the built-in central oil circuit management module; the central oil circuit management module obtains the real-time oil level through the oil level sensor installed on each compressor; the oil level sensor is a liquid level switch or a continuous oil level transmitter;

[0022] The central oil circuit management module calls the preset safety threshold and compares each real-time oil level in the oil level monitoring dataset with the preset safety threshold one by one; the preset safety threshold includes a low oil level alarm threshold and a low oil level shutdown threshold.

[0023] If the real-time oil level of the compressor is lower than the low oil level alarm threshold but higher than the low oil level shutdown threshold, an oil replenishment warning command will be generated.

[0024] If the real-time oil level of the compressor is lower than the low oil level shutdown threshold, an emergency shutdown command will be generated.

[0025] The oil replenishment warning command and the shutdown emergency command together constitute the oil circuit adjustment command.

[0026] Specifically, the steps of S5 include:

[0027] The central controller analyzes the oil circuit adjustment command to determine the compressor that is short of oil and the compressor that has oil supply.

[0028] A start command is sent to the intelligent oil pump connected to the oil source compressor, and at the same time, the corresponding solenoid valves connecting the oil source compressor and the oil shortage compressor on the parallel oil circuit are opened. A dedicated oil delivery path from the oil source compressor to the oil shortage compressor is constructed based on the parallel oil circuit. The parallel oil circuit is a common oil circuit connecting the oil tanks of all refrigeration system compressors. It is equipped with multiple solenoid valves controlled by the central controller. The oil delivery path is dynamically configured by controlling the opening and closing of different solenoid valves.

[0029] After the intelligent oil pump starts running, it delivers the refrigerant oil in the oil source compressor to the oil-deficient compressor according to the dedicated oil delivery path. The pump continues until the central oil circuit management module detects that the real-time oil level of the oil-deficient compressor has returned to the preset safe range. Then, the intelligent oil pump stops running and the corresponding solenoid valve is closed.

[0030] Specifically, the steps of S5 further include:

[0031] During the oil replenishment process, the central controller uses the superheat or pressure value at the evaporator outlet of the corresponding refrigeration circuit as the process variable for each refrigeration circuit. At the same time, it retrieves the preset target superheat or target pressure of each refrigeration circuit as the set value, calculates the deviation between the process variable and the set value, and inputs the deviation value into the PID algorithm for calculation to obtain the control quantity of the electronic expansion valve.

[0032] The control quantity of the electronic expansion valve is converted into the opening adjustment signal of the electronic expansion valve and sent to the electronic expansion valve of the corresponding refrigeration circuit.

[0033] Specifically, the central controller communicates with temperature sensors, humidity sensors, warehouse door status sensors, and cargo information identification terminals distributed in each temperature zone via an industrial bus or Internet of Things protocol, and acquires the initial real-time monitoring dataset in a periodic or event-triggered manner.

[0034] The cargo attribute information is obtained by the cargo information identification terminal; the cargo information identification terminal is an RFID reader, a QR code scanner, or a manual input terminal; the cargo attribute information includes at least the cargo type, warehousing time, preset storage temperature range, and preset storage humidity range.

[0035] The cold storage door opening and closing status parameters include the number of times the cold storage door is opened, the duration of each opening, and the opening range. The central controller's built-in algorithm calculates the instantaneous cooling loss caused by the opening of the cold storage door based on the cold storage door opening and closing status parameters, and feeds the instantaneous cooling loss as an input parameter into the dynamic load prediction model.

[0036] Specifically, the refrigeration unit uses a variable frequency compressor; the optimal operating frequency in the start-up control command is the frequency control signal sent to the corresponding variable frequency compressor.

[0037] The multi-temperature zone energy-saving control method for variable temperature cold storage also includes an emergency backup control mode: when the central controller detects abnormal sensor data or communication interruption in at least two temperature zones, it automatically switches to the preset emergency operating parameters to maintain the basic refrigeration function of each temperature zone until the fault is cleared and the normal control mode is restored.

[0038] The multi-temperature zone coordinated refrigeration system for variable temperature cold storage includes: a data sensing module, a decision-making module, a refrigeration execution module, an oil circuit management module, and a feedback and optimization module;

[0039] The data sensing module is used to acquire the initial real-time monitoring dataset;

[0040] The decision-making module is used to receive the initial real-time monitoring dataset, perform analysis, prediction, and decision-making, and generate power-on control commands.

[0041] The refrigeration execution module is used to receive power-on control commands and perform refrigeration and temperature zone adjustment actions;

[0042] The oil circuit management module is used to monitor and maintain the refrigeration oil balance of the compressor;

[0043] The feedback and optimization module is used to aggregate the operating data of the actuator and the monitoring data of the sensor, and then provide feedback.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] 1. This invention proposes a multi-temperature zone coordinated refrigeration system for variable temperature cold storage, and optimizes and improves its architecture, operation steps and processes. The system has the advantages of simple process, low investment and operating costs, and low production and working costs.

[0046] 2. This invention proposes a multi-temperature zone energy-saving control method for variable temperature cold storage. Through the logic of initial data acquisition, heat load prediction, and predictive control, it achieves precise and energy-saving multi-temperature zone refrigeration. Based on the cargo attributes and heat load change trend data, it adjusts the electronic expansion valve, starts, stops, or switches the refrigeration unit, avoiding the energy waste caused by traditional blind refrigeration. At the same time, it performs independent closed-loop control on the electronic expansion valve of each loop to ensure that different temperature zones meet the temperature and humidity requirements for cargo storage, thereby improving refrigeration quality and refrigeration efficiency.

[0047] 3. This invention proposes a multi-temperature zone energy-saving control method for variable temperature cold storage, constructing a dual insurance mechanism of equipment operation protection and global closed-loop optimization. The central oil circuit management module monitors the compressor oil level in real time and dynamically replenishes oil, effectively preventing compressor damage due to oil shortage and extending equipment life. At the same time, it summarizes the data from the actuators and sensors and feeds them back to the central controller to form a continuously optimized control closed loop, which can promptly correct operational deviations and ensure long-term stable and low-consumption operation of the system. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the multi-temperature zone energy-saving control method for variable temperature cold storage of the present invention;

[0049] Figure 2 This is a flowchart illustrating the principle of the multi-temperature zone energy-saving control method for variable temperature cold storage of the present invention.

[0050] Figure 3 This is a diagram of the multi-temperature zone coordinated refrigeration system architecture of the variable temperature cold storage of the present invention. Detailed Implementation

[0051] Example 1:

[0052] Please see Figure 1 and Figure 2 The present invention provides an embodiment of a multi-temperature zone energy-saving control method for variable temperature cold storage, comprising the following steps:

[0053] S1: Obtain the initial real-time monitoring dataset through the central controller; the initial real-time monitoring dataset includes the internal temperature, internal humidity, cargo attribute information, and warehouse door opening and closing status parameters of each temperature zone;

[0054] S2: Based on the initial real-time monitoring dataset, the dynamic load prediction model built into the central controller is called to calculate the heat load change trend data for each temperature zone during a preset period.

[0055] The dynamic load prediction model is a time-series prediction model based on a long short-term memory network. Its input is historical time-series data and real-time data in the initial real-time monitoring dataset, and its output is the predicted heat load value of each temperature zone within a preset period. The heat load change trend data includes at least the predicted heat load value of each temperature zone at a preset time node and the heat load change rate calculated based on the predicted heat load value of continuous time nodes. The long short-term memory network is prior art in this field and is not an inventive solution of this application, so it will not be described in detail here.

[0056] Furthermore, the dynamic load forecasting model adopts an online learning mechanism; by comparing the actual monitoring data fed back by S6 with its own forecast data from the previous period, it automatically calculates the forecast deviation and updates the weights of the dynamic load forecasting model online based on the forecast deviation, so as to dynamically adapt to the actual usage mode of the cold storage.

[0057] S3: Based on the heat load change trend data and the temperature and humidity requirements corresponding to the cargo attribute information, adjust the electronic expansion valve of the refrigeration circuit and generate a start-up control command. Then, start, stop or switch the refrigeration unit according to the start-up control command to put the refrigeration system into operation.

[0058] Further, starting, stopping, or switching the refrigeration unit according to the aforementioned start-up control command to put the refrigeration system into operation includes:

[0059] (1) After generating the start-up control command, the central controller parses the start-up control command to determine the specific number of the refrigeration unit to be started, stopped or switched and the corresponding operating parameter requirements. Then the central controller sends the command signal to the control module of the refrigeration unit. The command signal includes the operation type of the target refrigeration unit, i.e., start-up, stop or switch, as well as details such as the initial operating frequency after start-up and the unit connection sequence before and after switch.

[0060] (2) For a refrigeration unit that needs to be started, after the control module receives the command signal, it first performs a self-test to check whether the circuit connection, refrigerant pressure, compressor status, etc. inside the unit are normal. If the self-test passes, the control module starts the pre-processing program of the unit, such as preheating the compressor and turning on auxiliary equipment such as the condenser fan. After all the preparation parameters meet the standards, the operating frequency of the compressor is gradually increased so that the unit can smoothly transition from the standby state to the running state and output cooling capacity.

[0061] (3) For refrigeration units that need to be stopped, the control module will not immediately cut off the operation after receiving the signal. Instead, it will first reduce the operating frequency of the compressor and reduce the output of cooling capacity. At the same time, it will coordinate with the associated electronic expansion valve to gradually adjust the opening to avoid sudden changes in the pressure of the refrigeration circuit due to sudden shutdown. After the unit's operating parameters tend to stabilize, the compressor, condenser fan and other equipment will be shut down in sequence to put the unit into standby mode. The pressure, temperature and other parameters of the unit after shutdown will be continuously monitored to ensure the safety of the shutdown process.

[0062] (4) For refrigeration units that need to be switched, the central controller will plan the switching sequence. First, the target unit will be started according to the start-up steps. After the unit is running stably and the cooling output reaches the preset level, the original operating unit will be gradually shut down according to the stop steps. At the same time, during the entire switching process, the central controller will monitor the temperature change of the corresponding temperature zone in real time and compensate for the cooling fluctuation during the switching process by adjusting the opening of the electronic expansion valve to ensure that the temperature zone temperature is always maintained within the range required by the goods and achieve seamless connection between units.

[0063] (5) When all the operations corresponding to the instructions are completed, the central controller confirms through the data fed back by the sensors that each unit is in the operating state required by the instructions, and that the overall cooling capacity output of the refrigeration system can meet the current needs of each temperature zone. At this time, it is determined that the refrigeration system has entered a stable operating state.

[0064] The refrigeration unit uses a variable frequency compressor; the optimal operating frequency in the start-up control command is the frequency control signal sent to the corresponding variable frequency compressor.

[0065] S4: During the operation of the refrigeration system, the central controller starts the central oil circuit management module to monitor the real-time oil level of the compressor in each refrigeration system to obtain an oil level monitoring dataset, and compares the real-time oil level in the oil level monitoring dataset with a preset safety threshold to generate an oil circuit adjustment command.

[0066] S5: Start the intelligent oil pump according to the oil circuit adjustment command, and transport the refrigeration oil in the oil source compressor with sufficient oil level to the oil shortage compressor through the parallel oil circuit. At the same time, the central controller uses the superheat or pressure value of the evaporator outlet of each refrigeration circuit as a feedback signal to independently close the electronic expansion valve of the corresponding refrigeration circuit.

[0067] S6: Summarize the operating data of the actuators and the monitoring data of the sensors and feed them back to the central controller; the actuators include a refrigeration unit, an electronic expansion valve, and an intelligent oil pump.

[0068] Furthermore, the aggregated actuator operation data includes at least: the operating status of each refrigeration unit, real-time operating frequency, cumulative start-stop count, real-time opening of each electronic expansion valve, operating status of each intelligent oil pump, current running time, and cumulative running time; the sensor monitoring data includes at least: updated internal temperature and humidity of each temperature zone, status of each refrigeration unit door, real-time oil level of each compressor, and superheat and pressure value at the outlet of each refrigeration circuit evaporator.

[0069] Furthermore, all the data summarized in S6 is fed back to the central controller and stored in a preset historical database; the historical database provides historical time series data support for the dynamic load prediction model, which is used for the periodic rolling training and optimization of the model, so as to realize the self-learning and adaptive improvement of the system's prediction capability.

[0070] The multi-temperature zone energy-saving control method for the variable temperature cold storage also includes an emergency backup control mode: when the central controller detects abnormal sensor data or communication interruption in at least two temperature zones, it automatically switches to preset emergency operating parameters to maintain the basic refrigeration function of each temperature zone until the fault is cleared and the normal control mode is restored.

[0071] Furthermore, the emergency operating parameters are a set of fixed and conservative operating parameters pre-stored by the central controller to ensure the basic cooling function of each temperature zone when sensor data is abnormal or communication is interrupted.

[0072] Furthermore, the emergency operation parameters include: basic refrigeration equipment operation parameters, temperature zone safety critical control parameters, and equipment protection backup parameters. The basic refrigeration equipment operation parameters include preset fixed refrigeration unit start-up and shutdown combinations, fixed compressor operating frequency, and fixed electronic expansion valve opening. These parameter values ​​are set based on the historical minimum cooling capacity requirement of the cold storage to avoid insufficient cooling capacity. The temperature zone safety critical control parameters include preset emergency temperature and humidity ranges for different cargo attributes and corresponding refrigeration start-up and shutdown trigger thresholds. For example, if the temperature exceeds the emergency range by 2°C above the upper limit, the standby unit is activated; if it falls below the lower limit by 2°C, some units are shut down to prevent excessive temperature deviation from the emergency range, which could damage the cargo. The equipment protection backup parameters include preset minimum compressor oil level guarantee values, fixed intelligent oil pump oil replenishment intervals, and refrigeration circuit pressure safety thresholds to prevent equipment damage due to lack of dynamic monitoring during emergency operation.

[0073] Furthermore, the multi-temperature zone energy-saving control method for variable temperature cold storage also includes a fault diagnosis module, which generates a system maintenance prompt when it detects a continuous mismatch between the opening degree of the electronic expansion valve and the superheat feedback or an abnormal oil circuit adjustment frequency.

[0074] In summary, this invention first acquires initial real-time monitoring data such as temperature, humidity, and cargo attributes. Based on this data, a dynamic load prediction model is used to forecast the future heat load of each temperature zone, shifting control from passive response to active prediction. Then, combining the heat load forecast with the cargo's temperature and humidity requirements, the refrigeration unit and electronic expansion valve are started and adjusted to bring the refrigeration system into operation. Next, the compressor oil level is monitored during system operation, generating an oil replenishment command to ensure the safety of core equipment. The oil replenishment action is then executed, while the electronic expansion valve is fine-tuned using evaporator outlet parameters as feedback to improve refrigeration accuracy. Finally, all actuator operating data and sensor monitoring data are aggregated and transmitted back to the central controller, providing updated data for the next round of control, completing the closed loop, and achieving full-process control from startup to continuous optimization.

[0075] The electronic expansion valve that regulates the refrigeration circuit and generates start-up control commands includes:

[0076] S3.1: The central controller analyzes the heat load change trend data to obtain the predicted change direction and magnitude of the heat load within a preset period. At the same time, the central controller calls the acquired cargo attribute information and uses the preset storage temperature range in the cargo attribute information as the control target boundary.

[0077] Furthermore, the central controller analyzes the heat load change trend data to obtain the predicted change direction and magnitude of the heat load within a preset period, including:

[0078] (1) The central controller first receives the heat load change trend data output by the dynamic load prediction model. The central controller first verifies the validity of the heat load change trend data and removes obvious outliers, such as data that exceed the historical maximum heat load of the temperature zone by 1.5 times or are lower than the minimum heat load by 0.5 times. Then, it interpolates and completes the missing time node data to ensure that the data is continuous and complete in the time dimension.

[0079] (2) The central controller divides the entire cycle into multiple continuous sub-intervals according to the preset cycle length. The division of sub-intervals is determined based on the sensitivity of heat load changes. For example, if the preset cycle is 24 hours and the warehouse door is frequently opened and closed during the day and the heat load fluctuates greatly, the period from 6:00 to 22:00 during the day is divided into one sub-interval every hour, and the period from 22:00 to 6:00 the next day is divided into one sub-interval every two hours. Then, the predicted heat load values ​​at the start time, middle time and end time are extracted from each sub-interval as key data points for analyzing the direction and magnitude of change.

[0080] (3) The central controller compares the key data points of adjacent sub-intervals pairwise. First, it compares the heat load value at the end of the previous sub-interval with the heat load value at the beginning of the next sub-interval. If the heat load value of the next sub-interval is greater than that of the previous sub-interval, it is initially determined that the heat load of the period is on an upward trend. If the heat load value of the next sub-interval is less than that of the previous sub-interval, it is initially determined that the heat load is on a downward trend. If the difference between the two is within the preset fluctuation range, such as not exceeding 2% of the average heat load of the temperature zone, it is determined to be a stable trend. Then, the trend is verified by combining the heat load values ​​at the middle time and the beginning and end times of the sub-interval. For example, if the heat load value at the end of the previous sub-interval is less than the heat load value at the beginning of the next sub-interval, and the heat load value at the middle time of the next sub-interval is greater than the heat load value at the beginning time, the upward trend can be confirmed, thus avoiding misjudgment of the trend due to the deviation of a single data point.

[0081] (4) For periods that are determined to be rising or falling, the central controller first calculates the difference between key data points in adjacent sub-intervals, that is, the heat load value at the corresponding time of the next sub-interval minus the heat load value at the corresponding time of the previous sub-interval, to obtain the absolute change. Then, the absolute change is divided by the heat load value at the corresponding time of the previous sub-interval to obtain the relative change rate, which reflects the magnitude of the change. For example, the heat load value at the end of the previous sub-interval can be any value, and the heat load value at the beginning of the next sub-interval can be a larger value. If the absolute difference between the two accounts for 10% of the previous value, the change is determined to be large; if it accounts for only 3%, the change is determined to be small. At the same time, the central controller summarizes the change magnitude of all sub-intervals in the entire preset period and calculates the maximum change magnitude, minimum change magnitude and average change magnitude.

[0082] (5) The central controller integrates the heat load change direction of each sub-zone, including rising, falling, and stable, and the corresponding change amplitude, including absolute change, relative change rate, maximum change amplitude, minimum change amplitude, or average change amplitude, into a structured analytical result. The analytical result is then compared with the heat load change pattern of the same period in the history of the temperature zone. If the deviation between the current analytical result and the historical pattern is within the preset reasonable range, such as not exceeding 15%, the analytical result is confirmed to be valid. If the deviation exceeds the preset reasonable range, the central controller will retrieve the original output data of the dynamic load prediction model again and repeat the above preprocessing, interval division, trend analysis, and amplitude calculation steps to check for data processing errors until the analytical result conforms to the historical pattern, and finally form an accurate conclusion on the heat load prediction change direction and amplitude within the preset period.

[0083] If the analysis determines If the rate of change of heat load is greater than zero, a target storage temperature cooling control strategy will be generated. However, the temperature zone temperature after the target storage temperature cooling control strategy is implemented must not be lower than the lower limit of the control target boundary. express The predicted heat load value at any given time. This represents the predicted heat load value at time t;

[0084] Furthermore, the target warehouse temperature cooling control strategy refers to a set of targeted and executable refrigeration control schemes formulated by the central controller after determining that the heat load is on the rise, in order to avoid the temperature zone temperature from exceeding the preset storage temperature range of the goods and to maintain refrigeration efficiency.

[0085] Furthermore, the process of generating the target storage temperature cooling control strategy includes:

[0086] (1) The central controller first retrieves the preset storage temperature range corresponding to the temperature zone in the cargo attribute information, and uses the lower limit of the range as the safety threshold for cooling. Then, it calculates the target temperature range by combining the real-time temperature of the current temperature zone and the increase in heat load. For example, if the preset storage temperature range is zone A, the current temperature is higher than the upper limit of zone A, and the heat load change rate is large, then the target temperature range is set to a safe range close to the lower limit of zone A to ensure that the temperature after cooling meets the cargo storage requirements and leaves a buffer space to avoid excessive cooling. At the same time, the central controller will record the upper and lower limits of the target temperature range.

[0087] (2) The central controller calculates the additional cooling capacity required to achieve the target temperature range based on the difference between the predicted heat load value and the current heat load value in the heat load change trend data, combined with the inherent parameters such as the volume and insulation performance of the temperature zone. If the heat load change rate is large, it means that the cooling capacity loss is fast, so the cooling capacity increment is increased during the calculation; if the change rate is small, it is calculated according to the actual difference to avoid wasting cooling capacity.

[0088] (3) Based on the required increase in cooling capacity, the central controller analyzes the current operating status of each refrigeration unit, including the load rate of the running units, the start-up preparation status of the standby units, and the energy efficiency parameters of each unit. If the remaining cooling capacity of the existing running units can meet the demand for increased cooling capacity, then only the operating frequency of these units is adjusted to increase their output power; if the existing units cannot meet the demand, then the standby units are started in order of energy efficiency from high to low, and the unit model that matches the increase in cooling capacity is selected first to avoid large units operating at low load. At the same time, the start-up time and frequency adjustment gradient of each unit are clarified to ensure that the cooling output increases.

[0089] (4) The central controller calculates the initial opening adjustment value of the electronic expansion valve based on the target temperature range and the current evaporator outlet superheat. The greater the increase in heat load, the greater the initial opening adjustment. Then, the step-by-step adjustment rhythm of the opening is set. For example, in the early stage of cooling, it is quickly adjusted to about 80% of the target opening, and then gradually fine-tuned to the precise opening based on temperature feedback. At the same time, the sensor data of each refrigeration circuit is associated to ensure that the adjustment of multiple electronic expansion valves in the same temperature zone is synchronized, so as to avoid uneven distribution of cooling capacity.

[0090] (5) The central controller presets the time interval for temperature monitoring. When the heat load change rate is large, the interval is shortened to track the temperature change of the temperature zone in real time. If the actual temperature drops faster than expected and is close to the lower limit of the target temperature range, the frequency of the refrigeration unit is automatically reduced or the opening of the electronic expansion valve is reduced to slow down the cooling rate. If the temperature drops slower than expected, the operating frequency of the unit is increased or the valve opening is increased to accelerate the cooling process. When sudden situations such as the opening of the warehouse door cause an increase in cold energy loss, the cold energy compensation mechanism is temporarily triggered to briefly increase the unit output and maintain the cooling trend.

[0091] (6) Integrate the above target temperature range, cooling capacity increment, unit scheduling scheme, electronic expansion valve adjustment path and dynamic correction rules into a complete target warehouse temperature cooling control strategy. Then simulate the execution effect of the strategy under the current working conditions and check whether there are risks such as refrigeration unit overload or abnormal pressure. If there are risks, adjust the unit combination or adjustment parameters until the strategy meets the equipment safety operation requirements and finally form an executable target warehouse temperature cooling control strategy.

[0092] Furthermore, the central controller calculates the initial opening adjustment value of the electronic expansion valve based on the target temperature range and the current evaporator outlet superheat, including:

[0093] (1) The central controller first retrieves the reference superheat parameter corresponding to the refrigeration circuit; the reference superheat parameter is preset based on the refrigerant type, evaporator structure and temperature zone design standard, and at the same time, the corresponding target superheat is calculated according to the target temperature range;

[0094] (2) The central controller collects the temperature and pressure values ​​of the refrigerant in real time through the temperature sensor and pressure sensor installed at the evaporator outlet, and obtains the current superheat by combining the refrigerant physical property parameters;

[0095] (3) Calculate the difference between the current superheat and the target superheat to obtain the superheat deviation; if the current superheat is greater than the target superheat, it means that the refrigerant flow is insufficient and the opening of the electronic expansion valve needs to be increased; if the current superheat is less than the target superheat, it means that the refrigerant flow is too large and the opening of the electronic expansion valve needs to be reduced; if the superheat deviation is within the allowable range, there is no need to adjust the initial opening.

[0096] Furthermore, in this invention, the allowed range is set to positive and negative. .

[0097] (4) The central controller calls the pre-stored superheat deviation-opening adjustment comparison table to obtain the preliminary opening adjustment value; the superheat deviation-opening adjustment comparison table is established based on a large amount of experimental data and records the electronic expansion valve opening adjustment ratio corresponding to different superheat deviations.

[0098] (5) Correct the initial opening adjustment value according to the target temperature range to obtain the corrected initial opening adjustment value; if the target temperature range is low, increase the opening adjustment value, such as by 10%, under the same superheat deviation to speed up the refrigerant flow rate adjustment; if the target temperature range is high, reduce the opening adjustment value, such as by 10%, to avoid over-adjustment.

[0099] (6) The central controller sets the minimum and maximum safe opening of the electronic expansion valve. After the corrected initial opening adjustment value is superimposed with the current opening, if the result is lower than the minimum safe opening, it will be forcibly adjusted to the minimum safe opening; if it is higher than the maximum safe opening, it will be forcibly adjusted to the maximum safe opening to ensure that the valve operates in the safe range and avoid evaporator frosting due to insufficient opening or compressor liquid slugging due to excessive opening.

[0100] (7) After the safety range verification, the central controller determines the final initial opening adjustment value of the electronic expansion valve, and records the superheat deviation, target temperature range and correction basis corresponding to the adjustment value.

[0101] Furthermore, the calculation process for the target superheat includes:

[0102] (1) The central controller retrieves the reference superheat of the refrigeration circuit; the reference superheat is a fixed value preset based on the refrigerant type, evaporator design specifications and normal operating requirements of the temperature zone, representing the ideal superheat level for the circuit to achieve efficient heat exchange under standard operating conditions;

[0103] (2) Extract the upper and lower limits from the target temperature range to determine the temperature range that needs to be controlled. For example, if the target temperature range is a certain range, the upper and lower limits are the two endpoints of that range.

[0104] (3) The central controller calls the pre-stored temperature-superheat correlation table; the temperature-superheat correlation table is established through experimental data and records the superheat correction coefficients corresponding to different temperatures. Specifically, the lower the temperature, the smaller the superheat correction coefficient; the higher the temperature, the larger the superheat correction coefficient, so as to reflect the characteristics that a slightly smaller superheat is needed in low temperature environment to avoid evaporator frost and a slightly larger superheat is needed in high temperature environment to improve heat exchange efficiency.

[0105] (4) Multiply the reference superheat by the superheat correction coefficients corresponding to the upper and lower limits of the target temperature range respectively to obtain the target superheat upper and lower limits that match the target temperature range, thus forming the target superheat range;

[0106] (5) Compare the calculated target superheat range with the safe superheat range of the refrigeration circuit. If the target superheat range is within the safe superheat range, it is confirmed to be effective. If it exceeds the safe superheat range, the excess part is automatically corrected to the safe boundary value to ensure that the target superheat matches the temperature requirement and does not cause equipment operation risk. The safe superheat range includes the preset minimum and maximum allowable superheat.

[0107] (6) Based on the current control priority, determine the specific value from the target superheat range. If it is necessary to quickly approach the target temperature, select the superheat value with a larger bias correction coefficient; if it is necessary to operate stably, select the intermediate value and finally output the target superheat that matches the target temperature range.

[0108] Furthermore, the current calculation process for superheat includes:

[0109] (1) The central controller receives the actual temperature of the refrigerant collected by the temperature sensor installed at the outlet of the evaporator; the actual temperature of the refrigerant reflects the true temperature state of the refrigerant when it leaves the evaporator;

[0110] (2) The central controller receives the refrigerant pressure value collected by the pressure sensor at the same location, and then calls the pre-stored physical property parameter table of the refrigerant. According to the pressure value, the corresponding saturation temperature is queried. In the physical property parameter table, each refrigerant has a unique saturation temperature under a specific pressure. The saturation temperature is the critical temperature at which the refrigerant changes from liquid to gas.

[0111] (3) The difference between the actual temperature at the evaporator outlet collected by the temperature sensor and the saturation temperature obtained by the pressure value is the current superheat. For example, if the actual temperature at the evaporator outlet is any value and the saturation temperature under the corresponding pressure is another value, the difference between the two is the current superheat. This value directly reflects the degree of complete evaporation of the refrigerant in the evaporator.

[0112] If the analysis determines If the rate of change of heat load is less than zero, a target warehouse temperature rise control strategy is generated, but the temperature zone temperature after the target warehouse temperature rise control strategy is executed must not exceed the upper limit of the control target boundary.

[0113] Furthermore, the process of generating the target storage temperature rise control strategy includes:

[0114] (1) Obtain the target temperature range;

[0115] (2) The central controller calculates the amount of cooling capacity that can be reduced to achieve the target temperature range based on the difference between the predicted heat load value and the current heat load value in the heat load change trend data, combined with the insulation performance of the temperature zone, ambient temperature and other parameters. If the absolute value of the heat load change rate is large, it means that the cooling demand is decreasing rapidly, and the amount of cooling capacity that can be reduced is large; if the absolute value of the heat load change rate is small, it is calculated according to the actual difference to avoid a sudden rise in temperature due to excessive reduction in cooling capacity.

[0116] (3) Based on the amount of cooling capacity that can be reduced, the central controller analyzes the current operating status of each refrigeration unit. If the load rate of the existing operating units is low and the basic needs can still be met after reducing the cooling capacity, the operating frequency of these units will be reduced first to reduce the cooling capacity output. If the cooling capacity is reduced significantly and the frequency reduction alone cannot meet the needs, some units will be shut down in order of energy efficiency from low to high, with priority given to shutting down units with longer operating time or lower energy efficiency to avoid inefficient operation.

[0117] (4) The central controller calculates the initial opening contraction value of the electronic expansion valve based on the target temperature range and the current evaporator outlet superheat. The greater the decrease in heat load, the greater the initial opening contraction, but not lower than the preset ratio of the minimum safe opening, to prevent the evaporator from frosting due to a sudden decrease in refrigerant flow. Then, the step-by-step contraction rhythm of the opening is set. For example, in the early stage of heating, it is quickly contracted to about 80% of the target opening, and then gradually fine-tuned to the precise opening based on subsequent temperature feedback. At the same time, the sensor data of each refrigeration circuit is associated to ensure that the adjustment of multiple electronic expansion valves in the same temperature zone is synchronized, and to avoid imbalance in the distribution of cooling capacity.

[0118] (5) The central controller presets the time interval for temperature monitoring. When the heat load decreases rapidly, the interval is shortened to track the temperature change of the temperature zone in real time. If the actual temperature rises faster than expected and is close to the upper limit of the target temperature range, the operating frequency of some units will be automatically increased or the opening of the electronic expansion valve will be increased to slow down the temperature rise. If the temperature rise is slower than expected, the operating frequency of the units will be further reduced or the valve opening will be reduced to accelerate the temperature rise process. When sudden events such as a sudden drop in the external ambient temperature cause a reduction in cooling loss, the cooling fine-tuning mechanism will be temporarily triggered to temporarily reduce the unit output and maintain the temperature rise trend.

[0119] (6) Integrate the above target temperature range, the amount of cooling capacity that can be reduced, the unit load reduction or shutdown scheme, the electronic expansion valve contraction adjustment path and dynamic correction rules into a complete target warehouse temperature rise control strategy. Then simulate the execution effect of the target warehouse temperature rise control strategy under the current working conditions, check whether there are risks such as temperature exceeding the preset range or frequent unit start-up and shutdown. If there are risks, adjust the unit load reduction range or valve adjustment parameters until the strategy meets the equipment safety and temperature control accuracy requirements, and finally form an executable target warehouse temperature rise control strategy.

[0120] Furthermore, the calculation process for the initial opening contraction value includes:

[0121] (1) The central controller retrieves the pre-stored temperature and superheat correlation data according to the target temperature range and determines the target superheat range that matches the target temperature range;

[0122] (2) The central controller obtains the actual temperature of the refrigerant through the temperature sensor at the evaporator outlet, obtains the corresponding pressure value through the pressure sensor, looks up the saturation temperature at that pressure in conjunction with the refrigerant property parameter table, and then subtracts the saturation temperature from the actual temperature to obtain the current superheat. Subsequently, the current superheat is continuously collected and verified three times. If the fluctuation of the three values ​​is within the preset range, the current superheat is confirmed to be valid; if the fluctuation is too large, the backup sensor data is activated or the sensor self-test is triggered.

[0123] (3) Compare the current superheat with the target superheat range: If the current superheat is lower than the lower limit of the target superheat range, it means that the refrigerant flow is too high and the opening of the electronic expansion valve needs to be reduced; if the current superheat is within the target superheat range, no adjustment is needed; if the current superheat is higher than the upper limit of the target superheat range, it is a case where the opening needs to be increased and this reduction adjustment logic is not applicable. For cases where reduction is needed, calculate the difference between the current superheat and the lower limit of the target superheat range. The larger the difference, the more obvious the excessive flow and the larger the opening needs to be reduced.

[0124] (4) The central controller calls the pre-stored superheat deviation-opening contraction comparison table; the superheat deviation-opening contraction comparison table is established based on experimental data and records the opening contraction ratio corresponding to different superheat deviations.

[0125] (5) Correct the preliminary calculated shrinkage value according to the target temperature range to obtain the preliminary shrinkage value: If the target temperature range is high, increase the shrinkage ratio appropriately under the same deviation, such as by 5%, and reduce the cold output to meet the heating demand; if the target temperature range is low, reduce the shrinkage ratio, such as by 5%, to avoid excessive shrinkage and excessive temperature fluctuation.

[0126] (6) The central controller presets the minimum safe opening of the electronic expansion valve. After subtracting the initial contraction value from the current opening, if the difference is lower than the minimum safe opening, the initial contraction value is adjusted to the difference between the current opening and the minimum safe opening to ensure that the valve retains the basic opening and avoids evaporator frosting or refrigerant flow interruption due to insufficient opening.

[0127] (7) After the safety baseline verification, the initial opening and contraction value is obtained, and the superheat deviation, target temperature range and correction basis corresponding to the initial opening and contraction value are recorded.

[0128] S3.2: The target storage temperature cooling control strategy and the target storage temperature heating control strategy are combined to form the target storage temperature control strategy;

[0129] S3.3: The central controller calculates the target opening value of the electronic expansion valve based on the new target temperature value determined by the target storage temperature control strategy, combined with the current evaporator outlet superheat signal read in real time from the refrigeration circuit sensor, and sends a control signal containing the target opening value to the electronic expansion valve.

[0130] Furthermore, the calculation process for the target opening value of the electronic expansion valve includes:

[0131] (1) The central controller extracts a new target temperature value from the target warehouse temperature control strategy; the new target temperature value is a precise temperature control point determined based on cargo attributes and heat load trends;

[0132] (2) Retrieve the baseline superheat parameter that matches the new target temperature value;

[0133] (3) The central controller obtains the actual temperature and pressure values ​​of the refrigerant in real time through the temperature sensor and pressure sensor installed at the outlet of the evaporator in the refrigeration circuit. Combined with the pre-stored physical property parameter table of the refrigerant, it queries the corresponding saturation temperature according to the pressure value, and then subtracts the saturation temperature from the actual temperature to obtain the current superheat.

[0134] (4) Perform three consecutive sampling verifications on the current superheat. If the deviation of the three results is within the preset range, the data is confirmed to be valid. If the deviation is too large, the backup sensor data is activated or the sensor fault alarm is triggered.

[0135] (5) After confirming the validity of the data, compare the current superheat with the reference superheat to obtain the deviation: if the current superheat is greater than the reference superheat, it means that the refrigerant flow is insufficient and the opening of the electronic expansion valve needs to be increased; if the current superheat is less than the reference superheat, it means that the refrigerant flow is excessive and the opening of the electronic expansion valve needs to be reduced; if the deviation is within the allowable range, no adjustment is required. At the same time, record the absolute value of the deviation.

[0136] (6) The central controller calls the pre-stored superheat deviation-opening contraction comparison table to obtain the current opening value of the electronic expansion valve;

[0137] (7) Adjust the opening value of the current electronic expansion valve according to the new target temperature value. If the new target temperature value is low, increase the adjustment range under the same deviation, such as by 10%, to speed up the refrigerant flow adjustment speed to meet the strong cooling demand. If the new target temperature value is high, such as in the cold storage area, reduce the adjustment range, such as by 10%, to ensure stable adjustment.

[0138] (8) The current opening value of the electronic expansion valve is superimposed with the adjustment range to obtain the initial target opening value. Then, it is checked whether the target opening value is within the preset safe opening range, such as not less than 10% and not more than 90%. If it is lower than the minimum safe opening, it is forcibly set to the minimum safe opening to avoid evaporator frosting; if it is higher than the maximum safe opening, it is forcibly set to the maximum safe opening to prevent compressor liquid slugging.

[0139] (9) After safety verification, the central controller determines the final target value of the opening of the electronic expansion valve, and records the superheat deviation, the new target temperature value and the basis for correction corresponding to the target value.

[0140] S3.4: The central controller synchronously performs system-level energy planning based on the same heat load change trend data and the determined target storage temperature control strategy. It calculates the operating combination of refrigeration units that meet the predicted heat load value within a preset time period and their optimal operating frequency, and generates specific start-up or frequency conversion commands accordingly, which are then sent to the corresponding refrigeration units as start-up control commands.

[0141] Furthermore, the specific steps in S3.4 include:

[0142] (1) The central controller extracts the predicted heat load value, heat load change rate and total heat load demand of each time node within the preset period from the heat load change trend data, and clarifies the intensity of cold demand in different periods. At the same time, it obtains the target temperature range, cold adjustment direction and control priority of each temperature zone from the determined target warehouse temperature control strategy. For example, it assigns higher priority to the temperature zone where goods with short shelf life are located to ensure that their cold supply is guaranteed.

[0143] (2) The central controller retrieves all the pre-stored performance parameter databases of the refrigeration units, including the rated cooling capacity of a single unit, the cooling efficiency curves at different operating frequencies, the minimum and maximum operating frequency range, start-up energy consumption, operating noise and other parameters. At the same time, it updates the current status data of each unit in real time, such as whether it is in standby, running or fault state, current operating frequency and cumulative running time.

[0144] (3) Divide the preset time period into multiple sub-time periods according to the rate of change of heat load. The sub-time periods with large heat load fluctuations are divided more densely, while the sub-time periods with small fluctuations are divided more sparsely. For each sub-time period, calculate the required cooling capacity based on the predicted heat load value. Combine the cooling capacity adjustment direction in the target warehouse temperature control strategy to determine the amount of cooling capacity to be increased or decreased in that sub-time period. Among them, the time periods with large heat load fluctuations, such as the time periods when the warehouse door is frequently opened, are divided densely, such as a sub-time period of 15 minutes, and sparsely, such as a sub-time period of 1 hour.

[0145] (4) For the cooling demand of each sub-period, the central controller adopts a combination screening algorithm: first, with the goal of matching the total cooling capacity with the demand and the lowest total energy consumption, the operating combination is screened from the available units, and then the energy efficiency of each combination is evaluated, the energy consumption value per unit cooling capacity is calculated, and the combination with the highest energy efficiency ratio is selected first; if there are multiple combinations with similar energy efficiency, the number of start-ups and operating noise are further compared. For example, the combination with fewer start-ups is selected first to reduce start-up and shutdown losses, or the combination with noise that meets environmental requirements is selected first, and finally the optimal unit combination for each sub-period is determined.

[0146] (5) For each unit in the selected optimal unit combination, the central controller initially allocates the proportion of cooling capacity to be undertaken by a single unit based on the total cooling demand and the number of units in the sub-period. Then, in combination with the cooling efficiency curve of the unit, it finds the operating frequency that matches the proportion of cooling capacity. Usually, the unit has the highest energy efficiency in the range of 50%-80% of the rated frequency, so the frequency is set in this range first.

[0147] (6) The central controller performs multi-dimensional verification on the determined unit combination and operating frequency: First, it verifies whether the total cooling capacity can cover 1.1 times the predicted heat load value; second, it verifies whether the operating frequency of each unit is within the safe range and will not cause the grid load to exceed the limit, such as when multiple units start at the same time, the total current does not exceed the power distribution system capacity; third, it verifies the unit switching frequency to ensure that the unit combination change in adjacent sub-time periods does not exceed 2 units. If there are any unsatisfactory items, return to the previous step to adjust the unit combination or frequency until all verifications are passed.

[0148] (7) The central controller integrates the optimal unit combination and operating frequency of each sub-period in chronological order to form a time-series control scheme within the preset time period. Among them, for units that need to be started, the start time, initial frequency and continuous running duration are specified; for units that need to be stopped, the stop time, frequency reduction gradient and standby state after shutdown are specified; for operating units that need to adjust the frequency, the time, magnitude and transition rate of frequency adjustment are specified. All instructions include the unit number, operation type and specific parameters to ensure that the instructions are clear and executable.

[0149] (8) The timing instructions are classified and summarized by unit to form a complete operation sequence for each unit. At the same time, the execution priority of each instruction is marked. Finally, the central controller converts the format of the instructions to make them conform to the communication protocol requirements of the refrigeration unit control module.

[0150] The specific steps of S4 include:

[0151] S4.1: After the refrigeration system enters the operating state according to the generated start-up control command, the central controller starts the built-in central oil circuit management module; the central oil circuit management module obtains the real-time oil level through the oil level sensor installed on each compressor; the oil level sensor is a liquid level switch or a continuous oil level transmitter;

[0152] S4.2: The central oil circuit management module calls the preset safety threshold and compares each real-time oil level in the oil level monitoring dataset with the preset safety threshold one by one; the preset safety threshold includes a low oil level alarm threshold and a low oil level shutdown threshold;

[0153] If the real-time oil level of the compressor is lower than the low oil level alarm threshold but higher than the low oil level shutdown threshold, an oil replenishment warning command will be generated.

[0154] If the real-time oil level of the compressor is lower than the low oil level shutdown threshold, an emergency shutdown command will be generated.

[0155] S4.3: The oil replenishment warning command and the shutdown emergency command together constitute the oil circuit adjustment command.

[0156] The specific steps of S5 include:

[0157] S5.1: The central controller parses the oil circuit adjustment command to determine the compressor with insufficient oil and the compressor with sufficient oil.

[0158] S5.2: Send a start command to the intelligent oil pump connected to the oil source compressor, and at the same time control the corresponding solenoid valves connecting the oil source compressor and the oil shortage compressor on the parallel oil circuit to open, and build a dedicated oil delivery path from the oil source compressor to the oil shortage compressor based on the parallel oil circuit; the parallel oil circuit is a common oil circuit connecting the oil tanks of all refrigeration system compressors, and it is equipped with multiple solenoid valves controlled by the central controller. The oil delivery path is dynamically configured by controlling the opening and closing of different solenoid valves.

[0159] S5.3: After the intelligent oil pump starts running, it delivers the refrigerant oil in the oil source compressor to the oil-deficient compressor according to the dedicated oil delivery path until the central oil circuit management module detects that the real-time oil level of the oil-deficient compressor has recovered to the preset safe range, then stops the operation of the intelligent oil pump and closes the corresponding solenoid valve.

[0160] S5.4: During the oil replenishment process, the central controller uses the superheat or pressure value at the evaporator outlet of the corresponding refrigeration circuit as the process variable for each refrigeration circuit, and simultaneously retrieves the preset target superheat or target pressure of each refrigeration circuit as the set value. It calculates the deviation between the process variable and the set value, and inputs the deviation value into the PID algorithm for calculation to obtain the control quantity of the electronic expansion valve. The PID algorithm is the prior art in this field and is not an inventive solution of this application, so it will not be described in detail here.

[0161] Furthermore, the target superheat setting is dynamically corrected by the heat load change trend data: when the heat load change rate is greater than zero, the target superheat setting is appropriately reduced to improve the system cooling efficiency; when the heat load change rate is less than zero, the target superheat setting is appropriately increased to prevent liquid slugging, and the corrected target superheat setting is always within the preset safe operating range.

[0162] S5.5: Convert the control quantity of the electronic expansion valve into the opening adjustment signal of the electronic expansion valve, and send it to the electronic expansion valve of the corresponding refrigeration circuit.

[0163] The central controller communicates with temperature sensors, humidity sensors, warehouse door status sensors, and cargo information identification terminals distributed in each temperature zone via an industrial bus or Internet of Things protocol, and acquires the initial real-time monitoring dataset in a periodic or event-triggered manner.

[0164] The cargo attribute information is obtained by the cargo information identification terminal; the cargo information identification terminal is an RFID reader, a QR code scanner, or a manual input terminal; the cargo attribute information includes at least the cargo type, warehousing time, preset storage temperature range, and preset storage humidity range.

[0165] The cold storage door opening and closing status parameters include the number of times the cold storage door is opened, the duration of each opening, and the opening range. The central controller's built-in algorithm calculates the instantaneous cooling loss caused by the opening of the cold storage door based on the cold storage door opening and closing status parameters, and feeds the instantaneous cooling loss as an input parameter into the dynamic load prediction model.

[0166] Example 2:

[0167] Please see Figure 3 Another embodiment of the present invention provides a multi-temperature zone coordinated refrigeration system for a variable temperature cold storage, comprising:

[0168] Data sensing module, decision-making module, refrigeration execution module, oil circuit management module, feedback and optimization module;

[0169] The data perception module is used to acquire the initial real-time monitoring dataset, providing the original basis for subsequent control decisions;

[0170] The decision module is used to receive the initial real-time monitoring dataset and perform analysis, prediction, and decision-making to generate power-on control commands.

[0171] The refrigeration execution module is used to receive the start-up control command, execute refrigeration and temperature zone adjustment actions, and realize the output and distribution of cooling capacity;

[0172] The oil circuit management module is used to monitor and maintain the refrigeration oil balance of the compressor to ensure the safe operation of the equipment;

[0173] The feedback and optimization module is used to aggregate the operating data of the actuator and the monitoring data of the sensor to form a closed-loop feedback.

[0174] The decision-making module includes: a central controller unit, a dynamic load forecasting unit, and a strategy generation unit;

[0175] The central controller unit, consisting of an industrial-grade PLC or an embedded processor, is used to generate electronic expansion valve adjustment commands, unit start-up and shutdown commands, and oil circuit control commands.

[0176] The dynamic load forecasting unit is used to calculate the heat load change trend data of each temperature zone for a preset period based on the initial real-time monitoring dataset;

[0177] The strategy generation unit combines heat load change trend data with cargo temperature and humidity requirements to generate a target warehouse temperature control strategy, calculates the target value of electronic expansion valve opening and the optimal operating combination of refrigeration unit, and outputs start-up control commands.

[0178] The refrigeration execution module includes: a refrigeration unit and an electronic expansion valve unit;

[0179] The refrigeration unit consists of multiple independently operating high-temperature and low-temperature refrigeration units, used to start, stop or switch operation according to start-up control commands, and output cooling capacity to match the heat load demand by adjusting the compressor frequency;

[0180] The electronic expansion valve unit receives the opening adjustment signal from the central controller and controls the refrigerant flow by changing the valve opening. It works with the evaporator to achieve precise temperature control and makes dynamic fine adjustments based on superheat or pressure feedback in the closed-loop control. Each refrigeration circuit is equipped with one electronic expansion valve.

[0181] The oil circuit management module includes: a central oil circuit management unit, an oil level monitoring unit, and an intelligent oil transfer unit;

[0182] The central oil circuit management unit is used to receive oil level monitoring data, compare it with the preset safety threshold, and generate oil replenishment early warning instructions or shutdown emergency instructions, i.e., oil circuit adjustment instructions.

[0183] The oil level monitoring unit is used to collect the compressor's oil level data in real time, form an oil level monitoring dataset, and transmit it to the central oil circuit management unit.

[0184] The intelligent oil delivery unit consists of an intelligent oil pump, a parallel common oil circuit, and a solenoid valve group. It is used to construct an oil delivery path by opening and closing the solenoid valves according to the oil circuit adjustment command. The intelligent oil pump delivers the refrigerant oil from the oil source compressor with sufficient oil level to the compressor with insufficient oil level until the oil level is restored to a safe range.

[0185] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments under the guidance of the present invention without departing from the spirit and scope of the present invention. All of these variations are within the protection scope of the present invention.

Claims

1. A multi-temperature zone energy-saving control method for variable-temperature cold storage, characterized in that, include: S1: Obtain the initial real-time monitoring dataset through the central controller; the initial real-time monitoring dataset includes the internal temperature, internal humidity, cargo attribute information, and warehouse door opening and closing status parameters of each temperature zone; S2: Based on the initial real-time monitoring dataset, the dynamic load prediction model built into the central controller is called to calculate the heat load change trend data for each temperature zone during a preset period. S3: Based on the heat load change trend data and the temperature and humidity requirements corresponding to the cargo attribute information, adjust the electronic expansion valve of the refrigeration circuit and generate a start-up control command. Then, start, stop or switch the refrigeration unit according to the start-up control command to put the refrigeration system into operation. S4: During the operation of the refrigeration system, the central controller starts the central oil circuit management module to monitor the real-time oil level of the compressor in each refrigeration system to obtain an oil level monitoring dataset, and compares the real-time oil level in the oil level monitoring dataset with a preset safety threshold to generate an oil circuit adjustment command. S5: Start the intelligent oil pump according to the oil circuit adjustment command, and transport the refrigeration oil in the oil source compressor with sufficient oil level to the oil shortage compressor through the parallel oil circuit. At the same time, the central controller uses the superheat or pressure value of the evaporator outlet of each refrigeration circuit as a feedback signal to independently close the electronic expansion valve of the corresponding refrigeration circuit. S6: Summarize the operating data of the actuators and the monitoring data of the sensors and feed them back to the central controller; the actuators include a refrigeration unit, an electronic expansion valve, and an intelligent oil pump.

2. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 1, characterized in that, The dynamic load prediction model is a time-series prediction model based on long short-term memory network. Its input is the historical time series data and real-time data in the initial real-time monitoring dataset, and its output is the predicted heat load value of each temperature zone within a preset period. The heat load change trend data includes at least the predicted heat load value of each temperature zone at a preset time node and the heat load change rate calculated based on the predicted heat load value at continuous time nodes.

3. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 2, characterized in that, The electronic expansion valve that regulates the refrigeration circuit and generates start-up control commands includes: The central controller analyzes the heat load change trend data to obtain the predicted change direction and magnitude of the heat load within a preset period. At the same time, the central controller calls the acquired cargo attribute information and uses the preset storage temperature range in the cargo attribute information as the control target boundary. If the analysis determines If the rate of change of heat load is greater than zero, a target storage temperature cooling control strategy will be generated. However, the temperature zone temperature after the target storage temperature cooling control strategy is implemented must not be lower than the lower limit of the control target boundary. express Predicted heat load value at time of day This represents the predicted heat load value at time t; If the analysis determines If the rate of change of heat load is less than zero, a target warehouse temperature rise control strategy is generated, but the temperature zone temperature after the target warehouse temperature rise control strategy is executed must not exceed the upper limit of the control target boundary. The target warehouse temperature cooling control strategy and the target warehouse temperature heating control strategy are combined to form the target warehouse temperature control strategy. The central controller calculates the target opening value of the electronic expansion valve based on the new target temperature value determined by the target storage temperature control strategy, combined with the current evaporator outlet superheat signal read in real time from the refrigeration circuit sensor, and sends a control signal containing the target opening value to the electronic expansion valve. The central controller synchronously performs energy planning based on the same heat load change trend data and the determined target storage temperature control strategy. It calculates the operating combination of refrigeration units that meet the predicted heat load value within a preset time period and their optimal operating frequency, and generates start-stop commands or frequency conversion commands, which are then sent to the corresponding refrigeration units as start-up control commands.

4. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 3, characterized in that, The specific steps of S4 include: After the refrigeration system enters the operating state according to the generated start-up control command, the central controller starts the built-in central oil circuit management module; the central oil circuit management module obtains the real-time oil level through the oil level sensor installed on each compressor; the oil level sensor is a liquid level switch or a continuous oil level transmitter; The central oil circuit management module calls the preset safety threshold and compares each real-time oil level in the oil level monitoring dataset with the preset safety threshold one by one; the preset safety threshold includes a low oil level alarm threshold and a low oil level shutdown threshold. If the real-time oil level of the compressor is lower than the low oil level alarm threshold but higher than the low oil level shutdown threshold, an oil replenishment warning command will be generated. If the real-time oil level of the compressor is lower than the low oil level shutdown threshold, an emergency shutdown command will be generated. The oil replenishment warning command and the shutdown emergency command together constitute the oil circuit adjustment command.

5. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 4, characterized in that, The specific steps of S5 include: The central controller analyzes the oil circuit adjustment command to determine the compressor that is short of oil and the compressor that has oil supply. A start command is sent to the intelligent oil pump connected to the oil source compressor, and at the same time, the corresponding solenoid valves connecting the oil source compressor and the oil shortage compressor on the parallel oil circuit are opened. A dedicated oil delivery path from the oil source compressor to the oil shortage compressor is constructed based on the parallel oil circuit. The parallel oil circuit is a common oil circuit connecting the oil tanks of all refrigeration system compressors. It is equipped with multiple solenoid valves controlled by the central controller. The oil delivery path is dynamically configured by controlling the opening and closing of different solenoid valves. After the intelligent oil pump starts running, it delivers the refrigerant oil in the oil source compressor to the oil-deficient compressor according to the dedicated oil delivery path. The pump continues until the central oil circuit management module detects that the real-time oil level of the oil-deficient compressor has returned to the preset safe range. Then, the intelligent oil pump stops running and the corresponding solenoid valve is closed.

6. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 5, characterized in that, The specific steps of S5 also include: During the oil replenishment process, the central controller uses the superheat or pressure value at the evaporator outlet of the corresponding refrigeration circuit as the process variable for each refrigeration circuit. At the same time, it retrieves the preset target superheat or target pressure of each refrigeration circuit as the set value, calculates the deviation between the process variable and the set value, and inputs the deviation value into the PID algorithm for calculation to obtain the control quantity of the electronic expansion valve. The control quantity of the electronic expansion valve is converted into the opening adjustment signal of the electronic expansion valve and sent to the electronic expansion valve of the corresponding refrigeration circuit.

7. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 6, characterized in that, The central controller communicates with temperature sensors, humidity sensors, warehouse door status sensors, and cargo information identification terminals distributed in each temperature zone via an industrial bus or Internet of Things protocol, and acquires the initial real-time monitoring dataset in a periodic or event-triggered manner. The cargo attribute information is obtained by the cargo information identification terminal; the cargo information identification terminal is an RFID reader, a QR code scanner, or a manual input terminal; the cargo attribute information includes at least the cargo type, warehousing time, preset storage temperature range, and preset storage humidity range. The cold storage door opening and closing status parameters include the number of times the cold storage door is opened, the duration of each opening, and the opening range. The central controller's built-in algorithm calculates the instantaneous cooling loss caused by the opening of the cold storage door based on the cold storage door opening and closing status parameters, and feeds the instantaneous cooling loss as an input parameter into the dynamic load prediction model.

8. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 7, characterized in that, The refrigeration unit uses a variable frequency compressor; the optimal operating frequency in the start-up control command is the frequency control signal sent to the corresponding variable frequency compressor.

9. The multi-temperature zone energy-saving control method for variable temperature cold storage as described in claim 8, characterized in that, It also includes an emergency backup control mode: when the central controller detects abnormal sensor data or communication interruption in at least two temperature zones, it automatically switches to preset emergency operating parameters until the fault is cleared and normal control mode is restored.

10. A multi-temperature zone coordinated refrigeration system for a variable-temperature cold storage, used to implement the multi-temperature zone energy-saving control method for a variable-temperature cold storage as described in any one of claims 1-9, characterized in that, include: Data sensing module, decision-making module, refrigeration execution module, oil circuit management module, feedback and optimization module; The data sensing module is used to acquire the initial real-time monitoring dataset; The decision-making module is used to receive the initial real-time monitoring dataset, perform analysis, prediction, and decision-making, and generate power-on control commands. The refrigeration execution module is used to receive power-on control commands and perform refrigeration and temperature zone adjustment actions; The oil circuit management module is used to monitor and maintain the refrigeration oil balance of the compressor; The feedback and optimization module is used to aggregate the operating data of the actuator and the monitoring data of the sensor, and then provide feedback.

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