Fan-coil centralized monitoring and energy-saving control system and method

Abstract

This invention discloses a centralized monitoring and energy-saving control system and method for fan coil units. The system includes a control panel with a serial communication interface, pipeline sensors, a communication gateway server, a PLC, and an energy management data platform. Each panel is connected to the gateway via a serial communication bus, and the PLC communicates with the gateway and platform via an industrial Ethernet ring network. The control method includes: the gateway achieving device self-discovery and data mapping through broadcast frames; the PLC dynamically limiting and controlling the temperature setting range based on outdoor temperature; the PLC quantifying and diagnosing the blockage rate based on the pressure difference before and after the filter and issuing graded alarms; the PLC monitoring indoor temperature changes to diagnose electric valve jamming; and the system establishing a baseline energy consumption and calculating standardized energy consumption through a correction factor to verify the energy saving rate. This invention achieves centralized monitoring and proactive maintenance, effectively reducing energy consumption.

Description

Technical Field

[0001] This application relates to the field of automatic control technology for air conditioning in industrial and civil buildings, specifically to a centralized monitoring and energy-saving management system and control method for fan coil terminal equipment and cold and hot pipe network terminals, which is particularly suitable for industrial plants with multi-zone, decentralized terminal air conditioning systems, such as cigarette factories and pharmaceutical factories. Background Technology

[0002] In large industrial plants such as cigarette factories and pharmaceutical factories, there are numerous and widely distributed fan coil unit terminal devices. Their operation and management level directly affects the accuracy of temperature and humidity control in the production environment and the total energy consumption of the entire plant.

[0003] However, most current fan coil systems use independent local control panels for adjustment. Most of these panels do not have network communication capabilities, requiring managers to inspect each unit individually and operate them locally, resulting in high maintenance costs.

[0004] In the absence of centralized management, air conditioning systems commonly suffer from overcooling or overheating, with continuous operation of air conditioning in unoccupied areas being particularly prominent, resulting in significant energy waste. To address the need for centralized monitoring, some existing technologies attempt to achieve remote data transmission via wireless communication. However, the complex industrial environment, electromagnetic interference from large variable frequency motors and switchgear, and the attenuation of wireless signals by dense building structures make it difficult to guarantee the reliability and real-time performance of wireless transmission.

[0005] From a monitoring perspective, existing systems are mostly limited to controlling the start-up and shutdown status of terminal fan coil units and indoor temperature. They do not include key operating parameters such as supply and return water pressure, temperature, flow rate, and filter differential pressure at the end of the hot and cold water network in the monitoring scope, and lack the ability to fully perceive the overall operating conditions of the system.

[0006] At the energy conservation management level, existing systems have not yet established a complete closed-loop logic that includes status awareness, fault early warning, remote control and strategy optimization. Energy conservation operations often rely on the experience and judgment of on-site personnel and lack automated strategy execution and effect evaluation mechanisms.

[0007] Existing technologies are often limited to the control of single units or localized areas, or focus on improving control algorithms but lack system-level hardware architecture support, failing to achieve unified monitoring and energy-saving scheduling of terminal equipment and pipeline terminals at the plant level. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a centralized monitoring and energy-saving control system and method for fan coil units. Through a "three-layer, two-network" architecture design, it achieves remote centralized monitoring and refined management of the distributed fan coil unit terminals and cold and hot pipe network terminals throughout the plant.

[0009] At the system architecture level, this invention adopts a hierarchical networking design concept, constructing a complete hardware framework with an end execution layer, a regional acquisition layer, and a centralized management and control layer, and achieving vertical connectivity between the layers through a serial communication bus and an industrial Ethernet ring network.

[0010] The end-efficiency layer is equipped with a control panel with a serial communication interface, as well as various types of sensors installed on the supply and return water pipes and filters, enabling the system to simultaneously possess the dual capabilities of execution control and status awareness at the local device level.

[0011] The regional acquisition layer completes the aggregation and access of distributed devices through intelligent communication acquisition stations. Each acquisition station includes a communication gateway server and an industrial Ethernet switch. The communication gateway server is equipped with multiple serial communication interfaces and Ethernet interfaces, and has a built-in programmable mapping script parsing module. Each control panel is connected to the serial communication interface of the communication gateway server in a daisy-chain manner to achieve unified convergence of field data.

[0012] The centralized control layer consists of a programmable logic controller (PLC) and an energy management data platform. The PLC connects to a redundant industrial Ethernet ring network via an industrial Ethernet interface and completes the acquisition and processing of sensor signals through analog input modules. It is also equipped with a clock module and a temperature limiting algorithm program, thereby realizing global scheduling and calculation at the centralized control level. The energy management data platform is deployed on a server and maintains communication with the PLC and communication gateway server through the industrial Ethernet ring network, providing data aggregation and control channels for upper-level management.

[0013] At the control method level, this invention discloses a complete processing flow covering device access, parameter adjustment, fault diagnosis and effect verification.

[0014] First, after the communication gateway server is powered on, it sends broadcast frames to each serial communication interface to collect device information from the online control panel. Then, it uses mapping scripts to periodically write the data variables of each panel into the preset data blocks of the PLC, completing device self-discovery and data mapping, thus laying the data foundation for subsequent centralized control.

[0015] Secondly, the PLC acquires the outdoor temperature sampling value in real time. In cooling mode, it calculates the minimum set temperature based on the outdoor temperature plus a preset offset. In heating mode, it calculates the maximum set temperature based on the outdoor temperature minus the preset offset. When the change in outdoor temperature exceeds the preset hysteresis range and lasts for more than a preset time, the PLC refreshes the limit value and sends it to each control panel to realize dynamic temperature limit control based on the outdoor temperature difference, avoiding energy waste caused by excessive cooling or heating.

[0016] Secondly, the PLC collects the pressure difference before and after the filter in real time, and calculates the clogging rate based on the ratio of the difference between the filter and the initial pressure difference to the maximum allowable pressure difference change. When the clogging rate reaches different preset thresholds, it triggers a warning or alarm respectively, forming a closed-loop logic for quantitative diagnosis of the filter clogging degree.

[0017] In addition, the PLC also monitors the indoor temperature of the room where each panel is located. If the indoor temperature change is less than the preset temperature change threshold within a preset time during the cooling or heating mode, the corresponding electric valve is determined to be faulty and a maintenance alarm is triggered, thereby realizing early diagnosis of actuator faults such as valve jamming.

[0018] The above steps are not strictly limited in terms of execution time. They can be coordinated in a periodic or event-driven manner according to the actual operating conditions to form the complete control logic of the system.

[0019] Beneficial effects:

[0020] This invention enables centralized monitoring and refined management of fan coil unit terminals and heating / cooling pipe network terminals throughout the entire plant. Through the comprehensive deployment of control panels and pipe network sensor clusters in the terminal execution layer, coupled with the aggregation and access of the regional acquisition layer and the scheduling and processing of the centralized control layer, a complete data flow from terminal devices to the management platform is formed. Operation and management personnel can remotely view the status of equipment in each area, set parameters, and switch modes, eliminating the need for on-site inspections of each room and significantly improving management efficiency. The system can also formulate differentiated control strategies based on the usage characteristics of different buildings and rooms, achieving true classification-based policy implementation and refined management.

[0021] This invention offers significant advantages in energy conservation and consumption reduction. Through remote panel locking and dynamic temperature setting range limiting, it effectively prevents over-cooling or over-heating caused by users arbitrarily changing the set temperature. Combined with automatic shutdown control, it avoids waste caused by continuous operation of the air conditioner in unoccupied rooms. In particular, the dynamic temperature limiting control based on outdoor temperature can automatically raise the minimum set temperature in cooling mode and automatically lower the maximum set temperature in heating mode, ensuring that the temperature setpoint remains within a reasonable range. Simultaneously, multi-parameter monitoring at the end of the pipeline network provides a data foundation for hydraulic balance optimization and adjustment of cold and heat source operation strategies, further reducing the overall system energy consumption. Calculations show that the system's energy saving rate can reach 15% to 25%.

[0022] This invention improves the operational reliability of air conditioning systems. Through a quantitative diagnostic function for filter clogging, the system can calculate the clogging rate in real time and trigger warnings and alarms when different preset thresholds are reached, allowing maintenance personnel to schedule cleaning and maintenance before the clogging worsens. Through a fault diagnosis function for electric valve jamming, the system can detect early valve jamming based on monitoring indoor temperature trends and trigger maintenance alarms. These diagnostic functions transform traditional reactive repairs into proactive early warning maintenance, effectively avoiding decreased heat exchange efficiency and equipment damage caused by filter clogging or valve jamming, and extending the service life of fan coil units, valves, water pumps, and other equipment. Simultaneously, the system ensures that user comfort is not affected through supply air temperature monitoring and control effect verification.

[0023] This invention significantly reduces operation and maintenance costs. Remote centralized monitoring replaces a large amount of manual on-site inspections and repetitive operations, reducing manpower input. A data-driven maintenance decision-making mechanism replaces traditional experience-based judgment, avoiding both resource waste caused by over-maintenance and equipment failures caused by under-maintenance. Furthermore, the system architecture of this invention fully utilizes existing PLC stations and industrial Ethernet ring networks in industrial plants, avoiding redundant investment and additional wiring, reducing system construction costs, and demonstrating good economic viability and promotional value. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is an architecture diagram of a centralized monitoring and energy-saving control system for fan coil units;

[0026] Figure 2 This is a flowchart of a centralized monitoring and energy-saving control method for fan coil units. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0028] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The following description provides multiple embodiments of this application, which can be substituted or combined with each other. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0029] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0030] See Figure 1 , Figure 1 This is an architecture diagram of a centralized monitoring and energy-saving control system for fan coil units provided in an embodiment of this application. In this embodiment, the system includes:

[0031] The end-efficiency layer includes multiple control panels with serial communication interfaces, as well as temperature sensors, pressure sensors, differential pressure sensors, and flow meters installed on the supply and return water pipes and filters; the control panels control electric valves and fans via relay outputs.

[0032] The regional acquisition layer includes multiple intelligent communication acquisition stations. Each acquisition station includes a communication gateway server and an industrial Ethernet switch. The communication gateway server is equipped with multiple serial communication interfaces and one Ethernet interface, and has a built-in programmable mapping script parsing module. Each control panel is connected to the serial communication interface in a daisy-chain manner via a serial communication bus.

[0033] The centralized control layer includes a programmable logic controller (PLC) and an energy management data platform. The PLC connects to a redundant industrial Ethernet ring network composed of industrial Ethernet switches via an industrial Ethernet interface and acquires signals from temperature sensors, pressure sensors, and differential pressure sensors via analog input modules. The PLC has a built-in clock module and temperature limiting algorithm program. The energy management data platform is deployed on a server and communicates with the PLC and communication gateway server via the industrial Ethernet ring network.

[0034] The fan coil unit multi-parameter centralized monitoring and energy-saving management system of this invention adopts a "three-layer, two-network" architecture design. The three layers are, in order, the end-point execution layer, the regional acquisition layer, and the centralized control layer; the two networks refer to the serial communication bus of the field device layer and the industrial Ethernet ring network of the factory backbone layer. Among them, the field device layer uses RS-485 bus to connect each control panel in a daisy-chain manner, and the factory backbone layer uses a fiber optic redundant ring network, supporting Profinet and MODBUS TCP protocols.

[0035] In terms of the specific implementation of the system architecture, the LCD control panel in the terminal execution layer is installed at the end of each fan coil unit and serves as the execution unit for local control and remote communication. The entire plant is equipped with multiple LCD thermostats with RS-485 communication interfaces. Each panel displays parameters such as indoor temperature, set temperature, operating mode, fan speed, and valve status on a large LCD screen. It also supports local manual adjustment of temperature setpoints, switching of operating modes, and adjustment of fan speed.

[0036] The panel features a built-in RS-485 communication interface, supports the MODBUS RTU protocol, and controls the opening and closing of the electric two-way valve via relay output. It also enables automatic or manual fan speed adjustment via three-speed relay output. Furthermore, the panel has a remote locking function; the energy management data platform can send a locking command to the control panel via PLC to prevent local operating modules from modifying the temperature setpoint, thus effectively achieving energy-saving management.

[0037] In addition to the control panel, the terminal execution layer is also equipped with a pipeline terminal sensor system for comprehensive monitoring of the operating conditions of the hot and cold circulating water system.

[0038] Temperature sensors are installed in the main supply and return water pipes of the air conditioning room in each area, the terminal branch pipes of each floor, and the air outlets of the fan coil units in key rooms. They are used to monitor the supply water temperature of the cold and heat sources, the supply and return water temperature and temperature difference at the terminal, and the actual supply air temperature.

[0039] Pressure and differential pressure sensors are installed at the end of each area, before and after the main pipeline and the filter, respectively, to assess the hydraulic balance, determine the degree of filter clogging, and monitor the clogging of the fan coil unit filter.

[0040] Flow meters are installed on the main supply and return water pipelines of each area to monitor the cooling and heating consumption of each area. To address the difficulty of manual air venting in high-level areas, mechanical automatic air vents are installed on the pipelines, automatically venting air when there is air in the network, eliminating the need for electric control.

[0041] The intelligent communication acquisition station in the regional acquisition layer is the core node for communication integration of fan coil units in each region. Based on the building distribution and proximity principle, multiple sets of intelligent communication acquisition stations are set up throughout the plant. Each acquisition station consists of a communication gateway server, an industrial Ethernet switch, a power module, and a control box.

[0042] The communication gateway server acts as a protocol conversion and data aggregation device between the fan coil unit control panel and the upper-level network. It is equipped with multiple RS-485 serial ports and one RJ45 Ethernet interface, supporting conversion between MODBUS RTU and MODBUS TCP protocols. Each RS-485 port connects multiple fan coil unit control panels in a daisy-chain configuration, and a single gateway can support up to 64 fan coil units.

[0043] The gateway server also supports simultaneous access from multiple host devices, meeting the needs of local monitoring and remote energy management platforms for simultaneous data reading. The RS-485 port has a built-in opto-isolation circuit, which can effectively prevent surges and interference on the communication line from damaging the equipment.

[0044] The communication gateway server has a built-in programmable mapping script parsing module that supports script programming and trigger functions, enabling logic control and data mapping.

[0045] The industrial Ethernet switches are industrial-grade products, providing multiple electrical ports for connecting communication gateway servers, PLC systems and upper-level ring networks. Each switch has a spare electrical port for future system expansion and adopts DIN rail mounting to adapt to industrial environment requirements.

[0046] The power supply and control box provides a stable power supply for communication gateways, switches and auxiliary equipment. It is equipped with electrical components such as circuit breakers, surge protectors and filters. The control box has an IP54 protection rating and is suitable for industrial environments such as power centers and air-conditioned rooms.

[0047] The PLC control system in the centralized management layer is responsible for the acquisition of multiple parameters at the end of the pipeline network, the linkage control of the hot and cold water systems, and the data interaction with the energy management platform.

[0048] The PLC is a small programmable controller with a Profinet interface, equipped with analog input modules and communication expansion modules. The analog input modules input 4-20 mA signals from temperature sensors, pressure sensors, and differential pressure transmitters into the PLC for processing. The communication expansion modules are configured with dual network segments: one segment connects the lower-level field devices to the gateway, and the other segment connects to the upper-level factory information network, achieving network routing isolation.

[0049] The PLC has a built-in clock module and temperature limiting algorithm program, which collects parameters such as temperature, pressure, and differential pressure at monitoring points in real time, performs filtering, engineering quantity conversion, and threshold judgment, and intelligently judges blockages, valve failures, and sensor failures based on the changing trends of pressure, temperature, and other parameters. The PLC connects to the industrial Ethernet ring network of the factory's energy management center via Profinet communication to achieve real-time data interaction with the energy management platform.

[0050] The energy management data platform is deployed on high-performance industrial servers and monitoring screens in the data center. It communicates with lower-level PLCs and gateways via an industrial Ethernet ring network to achieve data aggregation, analysis, and display. The platform collects data from various intelligent communication acquisition stations and PLC systems in real time, establishes a fan coil unit operation database, and provides functions such as status monitoring, remote control, and parameter management. It can also perform fault early warning, energy consumption analysis, and intelligent alarms based on operational data trend analysis.

[0051] In the above system architecture, standardized data transmission is achieved between different layers through a pre-defined data mapping mechanism, ensuring the reliable operation of the system in an industrial environment.

[0052] The hierarchical structure design of the terminal execution layer, regional acquisition layer and centralized management and control layer aims to enable distributed terminal devices to achieve unified access through the regional acquisition layer, and then achieve global scheduling through the centralized management and control layer, forming a vertical connection from physical devices to the management platform.

[0053] The communication gateway server acts as a hub connecting the field serial communication bus and the upper-level industrial Ethernet ring network, realizing the conversion and unification of different communication protocols and data formats; the PLC, as the core control unit of the centralized management and control layer, undertakes multiple functions such as data acquisition, logic operation, instruction issuance and fault diagnosis.

[0054] The energy management data platform reads and writes PLC data blocks through a standard data exchange protocol. When batch control instructions are issued, the PLC temporarily stores the instructions in a temporary buffer queue and sends them one by one. If a single device does not respond within a timeout period, it will automatically retry a preset number of times. If the retry fails, an execution report containing the reason for the failure will be generated.

[0055] Specifically, the timeout for a single device is set to 2 seconds, the number of automatic retries is set to 3, and the execution report generated after the batch operation is completed clearly lists the number of successful devices, the number of failed devices, and the specific reasons for failure.

[0056] See Figure 2 This application also provides a method for centralized monitoring and energy-saving control of fan coil units, applied to the above-mentioned system, the method including the following steps:

[0057] S1. Device self-discovery and data mapping: After the communication gateway server is powered on, it sends broadcast frames to each serial communication interface to collect device information from the online control panel, and periodically maps the data variables of each panel into the preset data block of the PLC through a preset mapping script.

[0058] Specifically, after the system is powered on or reset, the communication gateway server automatically executes the initialization process, sends broadcast frames to each RS-485 serial port, requests the MODBUS device identifier, model and version information of all online devices, and collects the responses of each port slave within a preset time window to generate an online device list, thereby realizing automatic discovery and data mapping of the terminal control panel.

[0059] For example, the gateway sends a broadcast frame to each RS-485 serial port. The address field of the broadcast frame is set to device identifier 0x00, and the function code is "Read Device Information," requesting all online control panels to report their MODBUS device identifier, model, and version information. After sending the broadcast frame, the gateway opens a response receiving window with a duration of 500 milliseconds. Within this time window, it collects response frames returned by each serial port slave, parses and verifies the response frames, discards invalid responses with verification errors or abnormal formats, and categorizes the valid response data by port and slave address to generate a list of online devices corresponding to each port.

[0060] If multiple devices using the same slave address are detected under the same RS-485 serial port, automatic arbitration is performed using a preset physical location and device address lookup table. This lookup table is established by engineers during the system installation and debugging phase based on the actual installation location of each control panel and the assigned MODBUS slave address, and entered into the gateway. During arbitration, the gateway identifies non-target devices with duplicate addresses based on the physical location information and assigns new available addresses, or a dialog box pops up on the host computer interface prompting manual intervention.

[0061] After the online device list is established, the gateway uses its built-in script editor to write a variable mapping script. This script is written in JavaScript and defines the register addresses, data types, and read / write attributes of variables such as running status words, set temperature values, indoor temperature feedback values, fan speed levels, operating modes, valve status, and fault codes in the MODBUS registers of each panel. These variables are categorized as Boolean, integer, and floating-point types. The script uses a timer-triggered method to perform a read operation every second, reading data from the corresponding registers of each panel via the MODBUS RTU protocol. After data format conversion, the data is periodically written to the corresponding offset address in the PLC's preset data block via the MODBUS TCP protocol or Profinet protocol, achieving standardized mapping and real-time synchronization of data across the entire system.

[0062] S2. Dynamic temperature limiting control based on outdoor temperature difference: The PLC acquires the outdoor temperature sampling value T_out in real time. In cooling mode, the minimum set temperature is calculated according to the formula T_min = max(preset lower limit, T_out + preset offset). In heating mode, the maximum set temperature is calculated according to the formula T_max = min(preset upper limit, T_out - preset offset). When the change in outdoor temperature exceeds the preset hysteresis interval and lasts for more than the preset time, the PLC refreshes the limit value and sends it to each control panel.

[0063] Specifically, the PLC acquires outdoor temperature sampling values ​​in real time. The PLC reads the 4 to 20 mA signal from the temperature and humidity sensor of the on-site weather station through the analog input module, converts it into an actual temperature value through engineering input, and sets the sampling period to 1 minute.

[0064] Under cooling conditions, the PLC calculates the minimum set temperature according to the formula T_min = max(16, T_out + 2). The physical meaning of this formula is: if the result of adding the current outdoor temperature to the preset offset of 2℃ is lower than 16℃, then 16℃ is taken as the minimum set temperature; if the result is higher than 16℃, then T_out + 2℃ is taken as the minimum set temperature. That is, the minimum set temperature is always not lower than 16℃ and does not deviate from the reasonable range of outdoor temperature plus 2℃.

[0065] In heating mode, the PLC calculates the maximum set temperature according to the formula T_max = min(30, T_out - 2). The physical meaning of this formula is: after subtracting the current outdoor temperature from the preset offset of 2℃, if the result is higher than 30℃, then 30℃ is taken as the maximum set temperature; if the result is lower than 30℃, then T_out - 2℃ is taken as the maximum set temperature. That is, the maximum set temperature is always not higher than 30℃ and does not deviate from the reasonable range of outdoor temperature minus 2℃.

[0066] The PLC reads the outdoor temperature every 10 minutes and compares the current reading with the outdoor temperature value used in the last calculation. If the difference between the two exceeds the preset hysteresis range of ±1℃ and this excess state lasts for more than 5 minutes, the PLC re-executes the limit value calculation and refreshes the corresponding set upper and lower temperature limits. The updated limit value is written to the setting parameter register of each control panel through a mapping script. After receiving the updated limit value, each panel uses it as the boundary value of the user-adjustable temperature range in the local operation interface, thereby achieving energy-saving management through panel locking and temperature range limiting.

[0067] When outdoor temperature fluctuations are small, the limit value will not change frequently, and the system will operate stably. In addition, the PLC has three preset seasonal modes: summer, winter, and transitional season. The PLC determines the value of the preset offset based on the current seasonal mode and updates the preset offset synchronously when switching seasonal modes. For example, the offset is 2℃ in summer mode, 3℃ in winter mode, and 1℃ in transitional season mode, thereby achieving more precise energy-saving control under different seasonal conditions.

[0068] S3. Quantitative diagnosis of filter clogging: The PLC collects the pressure difference before and after the filter in real time, calculates the clogging rate based on the ratio of the difference between the pressure difference before and after the filter and the initial pressure difference to the maximum allowable pressure difference change, and issues an early warning when the clogging rate reaches the first preset threshold and an alarm when it reaches the second preset threshold.

[0069] Specifically, the PLC collects 4 to 20 mA signals from the differential pressure sensors on both sides of the filter in real time, and converts them into actual differential pressure values ​​through engineering calculations. To prevent false alarms caused by instantaneous water pressure fluctuations, the PLC performs moving average filtering on the differential pressure samples. The window duration for the moving average filtering is set to 30 seconds, meaning that the arithmetic mean of all differential pressure samples collected within the previous 30 seconds is used as the filtered result for the current differential pressure.

[0070] After the system is put into stable operation for the first time or after the filter cleaning is completed, the maintenance personnel can trigger a differential pressure zeroing calibration command through the host computer interface. After receiving the calibration command, the PLC will automatically record the current filter differential pressure value as the initial differential pressure. The initial differential pressure represents the normal resistance value of the filter in a clean state. This value is automatically recorded by the system and stored in the non-volatile storage area of ​​the PLC to ensure that the initial differential pressure data will not be lost when the system restarts.

[0071] During subsequent operation, the PLC performs clogging rate calculation cyclically according to a preset cycle. The clogging rate is calculated as follows: the clogging rate is equal to the difference between the current differential pressure and the initial differential pressure, divided by the difference between the maximum allowable differential pressure and the initial differential pressure, and then multiplied by 100%. That is, when the differential pressure approaches a certain percentage of the maximum allowable differential pressure, the clogging rate approaches 100% by the same percentage, thereby transforming the physical clogging state of the filter into a quantifiable and sortable clogging rate indicator.

[0072] The maximum permissible differential pressure is preset according to the filter model and system design parameters, representing the limit differential pressure value when the filter is clogged to the point that it needs to be forcibly replaced.

[0073] If the calculated congestion rate reaches the first preset threshold of 60% for 30 consecutive seconds, a yellow alert is triggered. The system displays an alert message on the host computer interface and suggests that maintenance personnel arrange an inspection. If the calculated congestion rate reaches the second preset threshold of 70% for 30 consecutive seconds, a red alarm is triggered. The system pops up an alert dialog box on the host computer interface and automatically generates a cleaning work order and pushes it to the maintenance manager. At the same time, the alarm time, alarm area, and congestion rate value are recorded for subsequent maintenance and traceability.

[0074] S4. Electric valve jamming fault diagnosis: The PLC monitors the indoor temperature of the room where each panel is located. If the indoor temperature change is less than the preset temperature change threshold within a preset time during the cooling or heating mode, the corresponding electric valve is determined to be faulty and a maintenance alarm is triggered.

[0075] Specifically, the PLC monitors the indoor temperature changes in the room where each panel is located in real time through the indoor temperature sensor in the control panel. The temperature sampling period is consistent with the panel data mapping period, which is 1 second. In the background program, the PLC maintains a temperature change recording buffer for each panel, which stores the sequence of indoor temperature sampling values ​​within 30 minutes prior to the current moment.

[0076] In cooling or heating mode, the PLC performs a jamming diagnosis calculation every preset judgment cycle (e.g., 10 minutes). Specifically, it retrieves two temperature values ​​from the buffer: the current time and the temperature value from 30 minutes ago, calculates the difference between the two, and if the absolute value of the difference is less than the preset temperature change threshold of 0.5℃, it determines that the electric valve corresponding to the panel may be jammed due to a fault. That is, the electric valve cannot open or close normally, causing hot and cold water to flow through the fan coil unit normally, and the indoor temperature cannot change as expected within the preset time.

[0077] At this time, the PLC marks the fault status as "electric valve stuck" and maps the corresponding panel's fault code and fault description to the data block of the energy management data platform through the communication gateway server. The energy management data platform triggers a graded alarm and maintenance work order. The alarm information includes the physical location of the faulty panel, the time of the fault occurrence, and a description of the fault type. At the same time, the status icon of the corresponding panel in the host computer interface changes from green to orange, prompting the operation and maintenance personnel to handle it in time.

[0078] To improve the reliability of diagnosis, the system is equipped with fault confirmation logic: if the indoor temperature change is less than 0.5℃ for two consecutive judgment cycles, the electric valve jamming fault is finally confirmed and an alarm message is generated; if it is only triggered once, it will be re-evaluated in the next judgment cycle. This confirmation mechanism can effectively avoid false alarms caused by accidental fluctuations in indoor temperature.

[0079] After maintenance personnel complete the overhaul of the electric valve, they trigger a fault reset command through the host computer interface. Upon receiving the reset command, the PLC clears the fault status of the panel and restores normal monitoring logic.

[0080] S5. Energy-saving effect verification steps: In the initial stage of system operation, a baseline energy consumption is established. After running the energy-saving strategy, the actual energy consumption is converted into standardized energy consumption through the degree-day correction coefficient and the production load correction coefficient. The standardized energy consumption is compared with the baseline energy consumption to obtain the true energy-saving rate after eliminating the influence of environmental and production fluctuations.

[0081] Specifically, during the initial stage of system operation, baseline data was collected for four weeks without enabling energy-saving strategies. The daily heating and cooling consumption values ​​of each area were recorded. These values ​​were calculated in real time using flow meters installed on the main supply and return water pipes of each area and the temperature difference between the supply and return water.

[0082] The daily average outdoor temperature and the operating rate of the corresponding production shift are recorded simultaneously as a reference for subsequent adjustments.

[0083] Specifically, the supply and return water temperature difference is calculated from the real-time difference between the supply water temperature sensor and the return water temperature sensor. The flow meter adopts an electromagnetic flow meter or an ultrasonic flow meter with a measurement accuracy of not less than ±0.5% to ensure the reliability of energy consumption data.

[0084] The data collected over the aforementioned four weeks forms an initial baseline energy consumption database, which serves as the basis for subsequent energy-saving effect evaluation. During the establishment of this baseline, the system is only in data acquisition mode and does not implement energy-saving strategies such as limiting control or locking the panel, to ensure that the baseline energy consumption can accurately reflect the normal energy consumption level of the system under conditions without energy-saving intervention.

[0085] After the energy-saving strategy is officially implemented, the system automatically calculates the actual energy consumption value for the day and standardizes it by introducing a correction factor for degree-days and a correction factor for production load.

[0086] The degree-day correction factor is used to eliminate the objective impact of changes in outdoor ambient temperature on air conditioning load. The calculation method is as follows: take the daily average outdoor temperature of the same month in the same season during the baseline collection period as the denominator and the daily average outdoor temperature of the day as the numerator to obtain the degree-day correction factor of the day relative to the baseline date, that is, the adjustment ratio of the energy consumption of the day converted to the temperature conditions of the baseline date.

[0087] The production load correction factor is used to eliminate the impact of changes in production activity levels on air conditioning load. The calculation method is as follows: take the average daily operating rate of the corresponding production shift during the baseline collection period as the benchmark, and use the actual operating rate of the day as the numerator and the benchmark average daily operating rate as the denominator to obtain the production load correction factor for the day.

[0088] The two coefficients mentioned above work together to determine the actual energy consumption value.

[0089] Specifically, standardized energy consumption equals the actual daily energy consumption divided by the product of the degree-day correction factor and the production load correction factor, i.e., standardized energy consumption = actual energy consumption / (degree-day correction factor × production load correction factor). By comparing the converted standardized energy consumption with the same type of daily energy consumption data in the baseline energy consumption database, the true energy saving rate after deducting the impact of outdoor ambient temperature fluctuations and production load changes can be obtained.

[0090] The system also has a built-in automatic evaluation module. When the actual energy saving rate reaches the preset energy saving assessment threshold, it automatically generates an energy saving effect confirmation report. If the energy saving rate does not meet the expected target, the system will automatically output deviation analysis prompts to help maintenance personnel check whether there are any abnormalities in the configuration of energy saving strategy parameters, and provide an objective basis for the continuous optimization of subsequent strategies.

[0091] The system generates monthly energy-saving analysis reports and sorts the energy-saving rates of each region from high to low, making it easier for maintenance personnel to identify the regions with the best and worst energy-saving performance. This allows them to adjust the energy-saving strategy parameters for different regions accordingly, forming a continuous improvement loop from performance evaluation to strategy optimization.

[0092] In the implementation of the above control method, there is a close logical connection between each step. S1 device self-discovery and data mapping provides a unified data foundation for the subsequent S2 temperature limiting control, S3 filter diagnosis and S4 valve fault diagnosis, ensuring that each control function is executed based on standardized data input, which is a prerequisite for the normal execution of the entire system control logic.

[0093] The S2 dynamic temperature limit control step based on outdoor temperature difference uses outdoor temperature as the basis for dynamically adjusting the temperature setting limit value. By pre-setting the hysteresis interval and the continuous judgment time, the judgment of the change in outdoor temperature is filtered, which effectively avoids frequent jumps in the limit value caused by short-term fluctuations in outdoor temperature and ensures the stability of the control process.

[0094] The S3 filter clogging degree quantitative diagnosis step preprocesses the differential pressure sampling value through moving average filtering, eliminating the influence of instantaneous pressure fluctuations on the diagnostic results. By setting the initial differential pressure and the maximum allowable differential pressure, a quantitative calculation model for the clogging rate is established, realizing the upgrade from qualitative judgment to quantitative diagnosis.

[0095] The S4 electric valve jamming fault diagnosis procedure utilizes existing indoor temperature sensor data to achieve early detection of valve faults without additional hardware costs.

[0096] The S5 energy-saving effect verification step introduces a degree-day correction factor and a production load correction factor to convert the actual energy consumption into standardized energy consumption. This allows for the calculation of the true energy-saving rate after deducting the impact of external disturbances such as ambient temperature fluctuations and production load changes. The effect is evaluated based on long-term operating data of the entire system, and the evaluation results are fed back to optimize and adjust the control strategy, forming a complete technical closed loop of "monitoring—control—diagnosis—evaluation—optimization" for the entire system.

[0097] In practical applications, a cigarette factory was used as an example for specific deployment. The entire factory was covered by 311 fan coil units and 37 pipeline monitoring points, covering areas such as the comprehensive office building, living quarters, power department, production workshop and production auxiliary rooms.

[0098] The communication gateway adopts a general-purpose MODBUS gateway that supports script programming. Each gateway is configured with multiple RS-485 serial ports. Each fan coil unit panel is connected to the serial port in a daisy-chain manner via shielded twisted-pair cables. A maximum of 16 units can be connected to a single port. The RS-485 port has a built-in opto-isolation circuit.

[0099] The plant is equipped with 11 intelligent communication acquisition stations, each with an industrial Ethernet switch, which are connected to the industrial Ethernet ring network of the plant's energy management center via fiber optic cable.

[0100] The PLC selected is a Siemens S7-1200 series small programmable controller with a Profinet interface, configured with analog input modules and communication expansion modules. All temperature sensors, pressure sensors and differential pressure transmitters have 4 to 20mA signals connected to the analog input modules. The communication expansion modules are configured with dual IP mode to achieve physical isolation between the industrial ring network and the factory information network.

[0101] The energy management platform is deployed on high-performance industrial servers and monitoring screens in the data center, and communicates with lower-level PLCs and gateways through an industrial Ethernet ring network.

[0102] In terms of software implementation, JS scripts are written in the dedicated software of the communication gateway to establish RS-485 communication between the fan coil unit panel and the analog quantity acquisition module, set the variables to be controlled (including operating mode, temperature setting, indoor temperature, power on / off, keyboard lock, unit fault and wind speed setting, etc.), and map all control variables to the PLC data blocks.

[0103] All control strategies (including timed on / off, mode switching, temperature limiting, and fault diagnosis) are programmed and debugged in the PLC programming software.

[0104] During operation, the PLC periodically scans the analog input, performs engineering quantity conversion and filtering, and then participates in the control logic calculation together with the fan status data mapped by the gateway. The calculation results are converted into MODBUS RTU instructions through the gateway and sent to each panel for execution. The energy management platform polls the PLC data block data in real time to realize the visual monitoring of the entire plant status and the distribution of strategies.

[0105] The above-described specific embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the concept of the present invention, and all such modifications and variations should fall within the scope of protection of the present invention.

[0106] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0107] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0108] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0109] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A centralized monitoring and energy-saving control system for fan coil units, characterized in that, include: The end-efficiency layer includes multiple control panels with serial communication interfaces, as well as temperature sensors, pressure sensors, differential pressure sensors, and flow meters installed on the supply and return water pipes and filters; the control panels control electric valves and fans via relay outputs. The regional acquisition layer includes multiple intelligent communication acquisition stations, each of which includes a communication gateway server and an industrial Ethernet switch. The communication gateway server is equipped with multiple serial communication interfaces and one Ethernet interface, and has a built-in programmable mapping script parsing module; each of the control panels is connected to the serial communication interface in a daisy-chain manner via a serial communication bus. The centralized control layer includes a programmable logic controller (PLC) and an energy management data platform. The PLC connects to a redundant industrial Ethernet ring network composed of industrial Ethernet switches via an industrial Ethernet interface and acquires signals from the temperature sensor, pressure sensor, and differential pressure sensor via an analog input module. The PLC has a built-in clock module and a temperature limiting algorithm program. The energy management data platform is deployed on a server and communicates with the PLC and the communication gateway server via the industrial Ethernet ring network.

2. The system according to claim 1, characterized in that, The serial communication interface of the communication gateway server has a built-in opto-isolation circuit; the communication expansion module of the PLC is configured with dual network segments, wherein the first network segment connects the lower-level field devices and the gateway, and the second network segment connects the upper-level factory information network to achieve network routing isolation.

3. The system according to claim 1, characterized in that, The energy management data platform reads and writes the PLC's data blocks through a standard data exchange protocol. When batch control instructions are issued, the PLC temporarily stores the instructions in a temporary buffer queue and sends them one by one. If a single device does not respond within a timeout period, it will automatically retry a preset number of times. If the retry fails, an execution report containing the reason for the failure will be generated.

4. The system according to claim 1, characterized in that, The control panel has a display module and a local operation module. The energy management data platform sends a locking command to the control panel through the PLC to prevent the local operation module from modifying the temperature setpoint.

5. A method for centralized monitoring and energy-saving control of fan coil units, characterized in that, Applied to the system as described in any one of claims 1 to 4, the method comprises the following steps: S1. Device self-discovery and data mapping: After the communication gateway server is powered on, it sends broadcast frames to each serial communication interface to collect device information from the online control panel, and periodically maps the data variables of each panel into the preset data block of the PLC through a preset mapping script. S2. Dynamic temperature limiting control based on outdoor temperature difference: The PLC acquires the outdoor temperature sampling value T_out in real time. In cooling mode, it calculates the minimum set temperature according to the formula T_min = max(preset lower limit, T_out + preset offset). In heating mode, it calculates the maximum set temperature according to the formula T_max = min(preset upper limit, T_out - preset offset). When the change in outdoor temperature exceeds the preset hysteresis interval and lasts for more than a preset time, the PLC refreshes the limiting value and sends it to each control panel. S3. Quantitative diagnosis of filter clogging: The PLC collects the pressure difference before and after the filter in real time, calculates the clogging rate based on the ratio of the difference between the pressure difference before and after the filter and the initial pressure difference to the maximum allowable pressure difference change, and issues an early warning when the clogging rate reaches the first preset threshold and an alarm when it reaches the second preset threshold. S4. Electric valve jamming fault diagnosis: The PLC monitors the indoor temperature of the room where each panel is located. If the indoor temperature change is less than the preset temperature change threshold within a preset time during the cooling or heating mode, the corresponding electric valve is determined to be faulty and a maintenance alarm is triggered.

6. The method according to claim 5, characterized in that, In step S1, the communication gateway server collects the responses from each serial communication interface slave within a preset time window; if duplicate device identifiers are detected under the same serial communication interface, automatic arbitration is performed through a preset physical location and device address lookup table, or manual intervention is prompted on the host computer interface.

7. The method according to claim 5, characterized in that, In step S3, the PLC responds to the received calibration command and automatically records the current pressure difference as the initial pressure difference.

8. The method according to claim 5, characterized in that, In step S4, after determining that the electric valve is faulty, the PLC maps the fault status to the energy management data platform through the communication gateway server, and the energy management data platform triggers a graded alarm and maintenance work order.

9. The method according to claim 5, characterized in that, It also includes step S5, energy-saving effect verification step: In the initial stage of system operation, a baseline energy consumption is established. After the energy-saving strategy is implemented, the actual energy consumption is converted into standardized energy consumption through the degree-day correction coefficient and the production load correction coefficient. The standardized energy consumption is compared with the baseline energy consumption to obtain the true energy-saving rate after eliminating the influence of environmental and production fluctuations.

10. The method according to claim 5, characterized in that, In step S2, the PLC determines the preset offset based on the current seasonal mode and updates the preset offset synchronously when the seasonal mode is switched.

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