Energy-saving control method and device for central air conditioning chilled water system

Abstract

The application provides an energy-saving control method and device for a central air conditioning chilled water system, which comprises the following steps: generating a terminal load request corresponding to each terminal area according to the temperature deviation of each terminal area and the chilled water regulating valve position; determining the request validity of the terminal load request according to the detection data state and the terminal equipment state of each terminal area, determining the dynamic area weight according to the heat load characteristics of each terminal area, and obtaining the comprehensive demand quantity representing the overall cold quantity demand of the chilled water system; determining the demand response interval, and adjusting the demand reset signal representing the cold quantity supply level of the chilled water system according to the position relationship between the comprehensive demand quantity and the demand response interval; determining the hydraulic regulation state of the chilled water system, and adjusting the chilled water pressure difference set value or the chilled water supply temperature set value according to the demand reset signal and the hydraulic regulation state. By using the above technical scheme, the comfort, stability and comprehensive operation energy efficiency of the chilled water system can be improved.

Description

Technical Field

[0001] This invention relates to the field of building automation control technology, specifically to an energy-saving control method and device for a central air conditioning chilled water system. Background Technology

[0002] A central air conditioning chilled water system typically includes a chiller unit, chilled water pumps, supply and return water mains, terminal heat exchange equipment, and chilled water regulating valves installed on each terminal branch. The chiller unit produces low-temperature chilled water, the chilled water pumps deliver the chilled water to each terminal heat exchange equipment, and the terminal heat exchange equipment uses regulating valves to change the flow rate in each branch to meet the cooling demand of different areas.

[0003] Currently, chilled water systems typically employ fixed chilled water differential pressure setpoints, fixed chilled water supply temperature setpoints, or single closed-loop control methods based on the parameters of the main supply and return water pipes. The pump controller performs proportional-integral-derivative (PI) adjustments based on the main pipe differential pressure, while the chiller unit operates independently according to a fixed outlet water temperature, resulting in high energy consumption. Summary of the Invention

[0004] Based on this, the present invention provides an energy-saving control method and device for a central air conditioning chilled water system, which can realize closed-loop control and improve the comfort, stability and overall operating energy efficiency of the chilled water system.

[0005] An energy-saving control method for a central air conditioning chilled water system includes: Based on the temperature deviation and chilled water regulating valve position of each terminal area, generate the corresponding terminal load request for each terminal area; The validity of the terminal load request is determined based on the detection data status and terminal equipment status of each terminal area. The dynamic area weight is determined based on the heat load characteristics of each terminal area. The terminal load requests are then normalized and aggregated based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system. Based on the operating stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve, and the load status of the chiller unit, the demand response range, including the energy-saving boundary and the load-increasing boundary, is determined. Based on the positional relationship between the comprehensive demand and the demand response range, the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, is adjusted. The hydraulic regulation state of the chilled water system is determined based on the chilled water supply and return pressure difference, the chilled water pump adjustment margin, and the valve position distribution. The chilled water pressure difference setpoint or chilled water supply temperature setpoint is adjusted based on the demand reset signal and the hydraulic regulation state. Specifically, the chilled water pressure difference setpoint is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setpoint is adjusted when the hydraulic regulation margin reaches the preset constraint.

[0006] An energy-saving control device for a central air conditioning chilled water system includes: The generation unit is used to generate the corresponding terminal load request for each terminal area based on the temperature deviation of each terminal area and the valve position of the chilled water regulating valve. The determination unit is used to determine the validity of the terminal load request based on the detection data status and terminal equipment status of each terminal area, determine the dynamic area weight based on the heat load characteristics of each terminal area, and normalize and aggregate each terminal load request based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system. The adjustment unit is used to determine the demand response range, including the energy-saving boundary and the load-increasing boundary, based on the operation stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve, and the load status of the chiller unit, and to adjust the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, based on the positional relationship between the comprehensive demand and the demand response range. The processing unit is used to determine the hydraulic regulation state of the chilled water system based on the chilled water supply and return pressure difference, the chilled water pump adjustment margin, and the valve position distribution, and to adjust the chilled water pressure difference setpoint or the chilled water supply temperature setpoint based on the demand reset signal and the hydraulic regulation state; wherein, the chilled water pressure difference setpoint is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setpoint is adjusted when the hydraulic regulation margin reaches the preset constraint.

[0007] The above describes how terminal load requests are generated based on regional temperature deviations and chilled water regulating valve positions, allowing the system's cooling demand to be characterized by both the actual thermal state and hydraulic demand at the terminals. Determining request validity using detection data and terminal equipment status reduces the impact of false requests from malfunctioning sensors or actuators on system control results. Dynamic regional weights are configured based on regional heat load characteristics, and each terminal load request is normalized and aggregated, ensuring that the resulting comprehensive demand reflects the priority of cooling demand in different regions while maintaining a relatively stable numerical scale even when the number of connected terminals, the number of effective terminals, or regional weights change. Furthermore, energy-saving and load-increasing boundaries are dynamically formed based on system operating stages, valve position distribution, and chiller unit load status. This allows the demand reset signal to decrease during low demand, remain at critical demand, and increase during high demand, thereby reducing response delays or frequent switching caused by fixed thresholds. Finally, the hydraulic regulation state is determined based on the chilled water supply and return pressure difference, chilled water pump adjustment margin, and terminal valve position distribution. Accordingly, the setpoint for either the chilled water pressure difference or the chilled water supply temperature is adjusted. This allows for priority flow regulation to meet demand when there is still hydraulic capacity, and only after hydraulic capacity reaches its limits can the chiller's cooling capacity be increased. This forms a closed-loop control system, from reliable terminal demand identification, global demand aggregation, adaptive response to coordinated output of pressure difference and supply temperature, improving the comfort, stability, and overall operational efficiency of the chilled water system. Attached Figure Description

[0008] Figure 1 This is a flowchart of an energy-saving control method for a central air conditioning chilled water system according to an embodiment of the present invention.

[0009] Figure 2 This is a schematic diagram of the structure of an energy-saving control device for a central air conditioning chilled water system provided in an embodiment of the present invention. Detailed Implementation

[0010] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the specific details described below are only a part of the embodiments of the present invention, and the present invention can be implemented in many other embodiments different from those described herein. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0012] This invention can be applied to central air conditioning chilled water systems with multiple terminal areas and varying cooling demand over time, such as shopping malls, shopping centers, commercial complexes, office buildings, hotels, hospitals, airports, train stations, district cooling stations, and centralized energy stations. It can also be embedded as a control module in building automation systems, programmable logic controllers, or energy management platforms.

[0013] In this embodiment, the terminal area can refer to the space area served by one or more air handling units, fan coil units, chilled water coils, or other terminal heat exchange equipment; the chilled water regulating valve can refer to a two-way valve, three-way valve, or other actuator with adjustable flow rate installed on the chilled water branch of the terminal heat exchange equipment; the valve position represents the actual opening feedback value of the chilled water regulating valve; the chiller unit load status can be characterized by the chiller unit current load rate, cooling capacity load rate, compressor load rate, or other parameters that can represent the load level of the chiller unit.

[0014] In this embodiment, the central air conditioning chilled water system includes a chiller unit, a chilled water pump, a chilled water supply main pipe, a chilled water return main pipe, multiple terminal heat exchange units, and a controller. Each terminal area is equipped with a zone temperature detection device, and each terminal heat exchange unit is equipped with a chilled water regulating valve and a valve position feedback device; some or all terminal branches are equipped with branch differential pressure detection devices; the chilled water main pipe is equipped with a supply water temperature detection device, a return water temperature detection device, and a supply-return water differential pressure detection device; the chilled water pump is equipped with a frequency converter.

[0015] The control cycle can be set from 2 to 15 minutes, for example, 6 minutes, depending on the system's thermal inertia. The evaluation cycle used for parameter assessment and self-correction is longer than the control cycle, for example, 10 control cycles, or approximately 60 minutes.

[0016] See Figure 1 , Figure 1 This is a flowchart of an energy-saving control method for a central air conditioning chilled water system according to an embodiment of the present invention. Figure 1 As shown, the following steps can be performed: S101 generates terminal load requests for each terminal area based on the temperature deviation and the position of the chilled water regulating valve in each terminal area.

[0017] Specifically, temperature deviation reflects whether the terminal area has met the comfort setting requirements, and the chilled water regulating valve position reflects whether the terminal heat exchange equipment is requesting more chilled water flow. When the temperature deviation is large, or the valve position is close to fully open and the area temperature is still higher than the set value, a terminal load request can be generated.

[0018] To prevent frequent changes in requests caused by instantaneous temperature fluctuations or valve position jitter, the request triggering conditions can be required to remain continuously for at least one or more control cycles before generating the end load request.

[0019] For example, obtain the first Effective area temperature of each terminal region , area temperature setpoint Chilled water regulating valve position and the corresponding timestamp, where, This indicates the current control cycle.

[0020] The zone temperature can be the indoor temperature, the return air temperature, or a representative temperature that reflects the thermal state of the zone. For zones with multiple temperature sensors, the median, the truncated average, or the average after outlier removal can be used as the effective zone temperature.

[0021] In this case, the regional temperature deviation is: .in, This indicates that the temperature in the area is higher than the set value, and there is a potential need for cooling in the area.

[0022] End load request It can be a binary request or a discrete-level request. In this embodiment, a binary request is used: Where 1 indicates that the terminal region has issued a cooling request, and 0 indicates that the terminal region has not issued a cooling request.

[0023] In one embodiment, step S101 may include: setting a request start deviation and a request cancellation deviation less than the request start deviation for each terminal region; determining that the terminal region meets the load request triggering condition when the temperature of the terminal region is higher than the sum of the corresponding region temperature setpoint and the request start deviation, or when the chilled water regulating valve of the terminal region reaches a preset high opening degree and the temperature of the terminal region is higher than the corresponding region temperature setpoint; generating a terminal load request for the terminal region after the load request triggering condition is maintained for a preset number of control cycles; and canceling the terminal load request when the temperature of the terminal region drops below the sum of the corresponding region temperature setpoint and the request cancellation deviation and is maintained for a preset number of control cycles after the terminal load request has been generated.

[0024] Specifically, request start-up deviations are set for each end region. And request to cancel deviation And satisfy: .

[0025] An initial request trigger flag is formed when any of the following conditions are met: ;or .

[0026] The first condition indicates that the zone temperature has exceeded the allowable start-up deviation. The second condition indicates that the terminal chilled water regulating valve is almost fully open, but the zone temperature is still higher than the set value, suggesting that there may be insufficient flow or insufficient cooling capacity at the terminal.

[0027] To prevent instantaneous requests caused by personnel briefly passing near the sensor, door opening, activation of a local heat source, or valve position feedback fluctuations, the initial request trigger flag is continuously maintained. Only during a control cycle is it ordered .in, It can be 1 to 3, for example, 2.

[0028] When the end region is already in a requested state, if: and maintain continuously For each control cycle, let: .

[0029] For example, ordinary public areas can be set up , High-priority areas or dining areas can be set up with specific rules. , Therefore, different thresholds are used for generating and canceling requests, creating a temperature hysteresis range between the two thresholds.

[0030] By adopting the above scheme, the time stability of the request status can be improved while maintaining the sensitivity of end-point demand identification. This provides a continuous and reliable basic input for subsequent request validity evaluation, comprehensive demand calculation and demand reset signal adjustment, and reduces the ineffective adjustment of chilled water pumps and chiller units due to frequent switching of end-point requests.

[0031] S102, determine the validity of the terminal load request based on the detection data status and terminal equipment status of each terminal area, determine the dynamic area weight based on the heat load characteristics of each terminal area, and normalize and aggregate each terminal load request based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system.

[0032] Specifically, to obtain the The status of detection data and terminal equipment in each terminal area. The detection data status can include at least the communication status of the temperature detection device, the temperature range, the continuous constant value status, the temperature change rate, and the consistency with adjacent areas. The terminal equipment status can include at least the control commands of the chilled water regulating valve, valve position feedback, valve position change status, and branch differential pressure response status.

[0033] Determine the validity of the request based on the above status. The request validity is satisfied: The higher the validity of a request, the more accurately it represents the actual cooling demand. When the validity of a request is 0, the corresponding request is not included in the calculation of the overall demand.

[0034] According to the The dynamic zone weights are determined by the spatial function, population density, sensible and latent heat loads, equipment heat dissipation, operating hours, historical load fluctuations, and heat transfer load of the building envelope in each terminal area. .

[0035] The load requests from each end point are normalized and aggregated to obtain the overall demand. In one embodiment: .in, This represents the set of valid endpoints in the current control cycle.

[0036] because and All values ​​are between 0 and 1, therefore the total demand usually satisfies: .

[0037] In this embodiment, the comprehensive demand represents the relative cooling demand intensity in the current effective end set after correction of request validity and regional weight.

[0038] In one embodiment, determining the validity of the end-load request includes: determining a temperature request component based on the temperature deviation of each end region and the duration of the temperature deviation; determining a hydraulic request component based on the valve position of the corresponding chilled water regulating valve, the branch pressure difference, and the response relationship between the valve position and the branch pressure difference; determining the temperature channel reliability corresponding to the temperature request component based on the calibration status, communication status, continuous constant value status, temperature change rate, temperature consistency of adjacent regions, and historical temperature fluctuation status of the temperature detection device; determining the hydraulic channel reliability corresponding to the hydraulic request component based on the deviation between the control command and valve position feedback of the chilled water regulating valve, the valve position change status, the correspondence between the valve position change and the branch pressure difference change, and the response status of the region temperature when the chilled water regulating valve is continuously at a high opening; and comparing the temperature channel reliability and the hydraulic channel reliability with their respective first channel threshold and second channel threshold, wherein the first channel threshold is less than the second channel threshold. Channel thresholds are set, and different trust state entry and exit thresholds are set for each channel. When the trustworthiness of the temperature channel and the hydraulic channel are both not lower than their respective second channel thresholds, the request validity is determined based on the temperature request component and the hydraulic request component. When the trustworthiness of one channel is lower than the corresponding first channel threshold and the trustworthiness of another channel is not lower than the corresponding second channel threshold, the use of request components with trustworthiness lower than the first channel threshold is stopped, and the request validity is determined based on the other request component, while limiting the request validity to a preset partial contribution range. When the trustworthiness of at least one channel is between the corresponding first channel threshold and the second channel threshold, a penalty coefficient that varies with the trustworthiness of that channel is used to reduce the contribution of the corresponding request component to the request validity. When the trustworthiness of the temperature channel and the hydraulic channel are both lower than their respective first channel thresholds, the request validity is set to zero, and a fault flag used to characterize the abnormal channel type is output.

[0039] Specifically, evidence for the temperature-side request is formed based on regional temperature deviation, duration of temperature deviation, and temperature change trend. .

[0040] In one embodiment, .in: ; This is a reference value for temperature deviation. To request the number of consecutive periods, The term representing the trend of temperature change, .

[0041] When the regional temperature continues to rise A larger value can be taken; when the regional temperature has dropped significantly, A smaller value can be used to indicate that the request is being fulfilled.

[0042] Based on the valve position of the chilled water regulating valve, the branch pressure difference, and the response relationship between changes in valve position and changes in branch pressure difference, hydraulic-side request evidence is formed. .

[0043] .

[0044] in, Indicates the degree of valve opening. Indicates the degree of insufficient differential pressure in the branch circuit. This indicates whether the branch pressure difference or area temperature responds reasonably after the valve position is increased. .

[0045] For example, ; .in, This is the intermediate reference value for the valve position. This represents the branch pressure differential demand value.

[0046] Temperature-based reliability can be obtained by combining the sensor health coefficient, temperature change rate coefficient, adjacent region consistency coefficient, and historical stability coefficient. .

[0047] The sensor health coefficient can be calculated using the following formula: .

[0048] in, This indicates the number of days since the last calibration. This indicates the number of communication interruptions within a preset time period. Indicates a constant value. This indicates a hardware fault alarm.

[0049] The coefficient of temperature change can be determined using a piecewise function: .

[0050] The consistency coefficient of adjacent areas is cross-validated by adjacent areas on the same floor, of the same type of business, or with a spatial distance not exceeding a preset distance. When the proportion of requests originating from adjacent areas is high, or the temperature deviation between the local area and the average temperature of adjacent areas is small, a higher confidence level is adopted; when isolated requests are generated in the local area and the temperature deviation is significantly greater than that of adjacent areas, the consistency coefficient of adjacent areas is reduced.

[0051] Historical stability coefficient can be based on recent The temperature standard deviation for each control cycle is determined as follows: .in, For temperature standard deviation, This serves as the reference standard deviation. To avoid misinterpreting normal load fluctuations as signal anomalies, the residual standard deviation of the temperature measurement relative to the load forecast can be used instead of the original temperature standard deviation.

[0052] Hydraulic reliability can be obtained by combining valve actuation reliability, branch differential pressure reliability, and valve position-differential pressure response reliability: .

[0053] When the control command of the chilled water regulating valve changes but the valve position feedback does not change accordingly, the reliability of valve execution is reduced; when the valve position is approximately constant over multiple control cycles and the zone temperature continuously deviates from the set value, it is identified as valve position jamming; when the valve position changes frequently, it is identified as valve position oscillation.

[0054] In one embodiment, the valve position state coefficient can be expressed as: .

[0055] When the branch pressure differential or branch flow rate increases as expected after the valve position is increased, improve... When a change in valve position does not cause a change in branch differential pressure, reduce... The anomaly will be preferentially identified as a faulty end effector, a blocked coil, or a local hydraulic fault, rather than being directly identified as insufficient overall cooling of the system.

[0056] Set the threshold for the first channel respectively Second channel threshold ,satisfy: 。 For example, , .

[0057] When the credibility is not lower than the second channel threshold, the channel is in a credible state; when the credibility is between the first channel threshold and the second channel threshold, the channel is in a suspicious state; when the credibility is lower than the first channel threshold, the channel is in an invalid state.

[0058] To avoid frequent switching of trusted states around the threshold, separate thresholds can be set for state entry and state exit. For example, a trust level of 0.65 is required when a channel enters a trusted state from a suspicious state, while a trust level below 0.55 is required when exiting a suspicious state from a trusted state.

[0059] When both the temperature and hydraulic sides are in a reliable state: .in, .

[0060] When one channel is in a trusted state while the other is in an invalid state, only the request evidence from the trusted channel is used, and the validity of the request is limited to a partial contribution: 。 For example, .

[0061] When any channel is in a suspicious state, a penalty function is applied: .

[0062] in, The minimum penalty coefficient for partial contributions, for example, 0.3.

[0063] When both channels are in an invalid state, let: And generate corresponding fault flags.

[0064] When the zone temperature remains above the set value, the chilled water regulating valve remains at a high opening, the branch pressure differential is below the required value, and adjacent zones exhibit the same insufficient cooling condition, the hydraulic request evidence is identified as evidence of insufficient system cooling. Conversely, when the control command and valve position feedback are inconsistent, or when a change in valve position does not cause a change in the corresponding branch pressure differential, it is identified as an abnormal end-point execution, and the high valve opening is prohibited from independently increasing the validity of the request.

[0065] In the above example, by splitting the end-load request into temperature-side request evidence and hydraulic-side request evidence, and evaluating the response relationship between the temperature detection device status and the chilled water regulating valve and branch pressure difference, temperature detection anomalies and end-hydraulic execution anomalies are no longer treated as the same type of fault. By classifying temperature-side confidence and hydraulic-side confidence into reliable, doubtful, and invalid states, and setting different state entry and exit conditions, state hysteresis can be formed near the confidence threshold, reducing frequent changes in reliable states caused by detection noise. When both sides are reliable, the two types of requests are fused. The system seeks evidence and retains a portion of the contribution from the other side when one side is invalid. It continuously penalizes the contribution of one side when it is questionable, and sets the request validity to zero when both sides are invalid. This prevents all requests from being unreasonably retained or deleted due to a single abnormal detection channel. Furthermore, by combining this with indicators such as persistently excessive regional temperatures, high valve opening, insufficient branch pressure differential, and consistency between adjacent areas, the system identifies actual insufficient cooling supply. It also identifies execution anomalies based on inconsistencies between control commands and valve position feedback, or valve position changes not causing changes in branch pressure differential. This avoids misinterpreting local faults such as valve jamming or coil blockage as global insufficient cooling. Therefore, it improves the accuracy of request validity in representing actual cooling demand, suppresses the overall overload of the chilled water system driven by local equipment failures, and avoids missing genuine regional under-cooling demands due to a single signal anomaly.

[0066] Accordingly, obtaining the comprehensive demand quantity characterizing the overall cooling capacity demand of the chilled water system includes: determining the basic area weights based on the spatial function and load priority of each terminal area; determining corresponding load correction factors based on the personnel density, the ratio of sensible heat load to latent heat load, the heat dissipation of regional equipment, the current operating hours, historical load fluctuations during the same period, and the heat transfer load of the building envelope in each terminal area; determining the initial dynamic area weights based on the combination of the basic area weights and the load correction factors, and limiting the initial dynamic area weights within a preset weight range; normalizing each initial dynamic area weight based on the average of the initial dynamic area weights of all terminal areas with valid current data to obtain the dynamic area weights, so that the average of the dynamic area weights of all terminal areas with valid current data remains at a preset benchmark value; and weighting and aggregating the terminal load requests corrected by the request validity using the sum of the dynamic area weights of all terminal areas with valid current data as the normalization benchmark to obtain the comprehensive demand quantity.

[0067] Specifically, this implementation method is used to match the request contribution of different regions with their actual heat load and cooling priority, while ensuring that the overall demand does not drift due to changes in the number of access terminals or the overall weight.

[0068] In one embodiment, the weight of the basic area is determined based on the spatial function, floor location, and cooling priority of the terminal area. As shown in Table 1:

[0069] The basic region weight is used to represent the static priority of a region, but it is not directly used as the final dynamic region weight.

[0070] Furthermore, the population density in the area is: .in, For the population of the region, The area is the region.

[0071] The personnel density correction factor can be: .in, For reference, the personnel density is estimated at 0.25 people per square meter. The number of people can be obtained using passenger flow counting devices, infrared sensors, Wi-Fi probes, or reservation systems.

[0072] Sensible heat ratio: .

[0073] The sensible heat / latent heat correction factor can be: The correction factor increases when the regional latent heat load is high.

[0074] Heat dissipation per unit area of ​​equipment in the region Sure: .in, For example, it is 25W / square meter.

[0075] Determined based on regional business types and time. For example, the dining area is set to 1.2 during 11:00-13:00 and 17:00-19:00; the first-floor lobby is set to 1.1 during peak business hours; and the non-business hours or low-load hours are set to less than or equal to 1.

[0076] Determined based on the standard deviation of cooling load in the region over the same period of several recent days: .in, These are reference values ​​for the standard deviation of load in each region.

[0077] For the ground floor perimeter area, top floor area, or large glass curtain wall area, the determination should be based on outdoor temperature, solar radiation, or heat transfer of the building envelope. For example, when the outdoor temperature is greater than 33℃, the value for the outer area of ​​the first floor is 1.15; and the value for the top floor area is 1.2 in the afternoon during summer.

[0078] The initial dynamic region weights can be expressed as: .

[0079] Limit the initial dynamic region weights: This prevents the weight of a single region from being excessively amplified due to the simultaneous increase of multiple correction factors.

[0080] The current set of valid endpoints is denoted as The number of effective ends is Calculate the average of the initial dynamic weights at the effective end: The final dynamic region weights are: .in, The preset baseline value is 1. After the first normalization, the average dynamic region weight of the effective terminal region is 1.

[0081] Accordingly, the total demand is calculated using the following formula: When all dynamic region weights are multiplied by the same scaling factor, this scaling factor cancels out in the numerator and denominator, and the aggregate demand remains unchanged. When the number of effective endpoints changes, the aggregate demand still represents the relative demand intensity within the effective endpoint set, rather than the total number of unnormalized requests.

[0082] When the denominator is 0 or the number of valid terminals is lower than the minimum requirement, the comprehensive demand update demand reset signal will not be used, and the channel degradation control described later will be entered.

[0083] S103, based on the operating stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve, and the load status of the chiller unit, determine the demand response range including the energy-saving boundary and the load-increasing boundary, and adjust the demand reset signal characterizing the cooling capacity supply level of the chilled water system according to the positional relationship between the comprehensive demand and the demand response range.

[0084] Specifically, this involves acquiring the operating phases of the chilled water system, the distribution of terminal valve positions, and the load status of the chiller units. The operating phases can include at least the startup phase, the stable operation phase, and the chiller unit load increase / decrease transition phase.

[0085] The end valve position distribution can be obtained by averaging the valve position across the entire effective end region. and the proportion of high-opening end areas express: ; .

[0086] in, This represents the set of valid valve position data. This indicates the number of ends in the set. This is a high opening threshold, such as 85% or 90%.

[0087] The load increase boundary is dynamically determined based on the operating stage, average valve position, proportion of high-opening terminal area, and chiller unit load rate. and energy-saving boundary And satisfy: .

[0088] The energy-saving boundary and the load-increasing boundary constitute a maintenance range. This includes the overall demand. Compared with the demand response range: when When, reduce the demand reset signal; when At that time, maintain the demand reset signal; when At that time, the demand for resetting signals is increased.

[0089] The demand reset signal is denoted as Its value ranges from 0% to 100%. The larger the demand reset signal, the higher the level of cooling capacity required by the chilled water system.

[0090] In one embodiment, determining the demand response interval, including an energy-saving boundary and an overload boundary, includes: determining an operation phase correction based on the start-up phase, stable operation phase, or chiller unit load-reduction transition phase of the chilled water system; determining a valve position distribution correction based on the average valve position of all effective terminal areas and the proportion of terminal areas with valve positions higher than a preset high opening threshold, and determining a system load correction based on the chiller unit load rate; determining the overload boundary based on the basic demand boundary, the operation phase correction, the valve position distribution correction, and the system load correction, and determining an energy-saving boundary lower than the overload boundary based on the overload boundary and a preset hysteresis width; wherein, when the valve position distribution indicates insufficient cooling in multiple terminal areas or the chiller unit is under high load, the response tolerance corresponding to the demand response interval is reduced; when the valve position distribution indicates sufficient overall cooling in the terminal areas or the chiller unit is under low load, the response tolerance corresponding to the demand response interval is increased; after the chiller unit load-reduction transition phase ends, the operation phase correction is gradually restored to the correction corresponding to the stable operation phase over multiple control cycles.

[0091] Specifically, this implementation method dynamically determines the energy-saving boundary and the load-increasing boundary based on the system operation stage, valve position distribution, and chiller unit load status.

[0092] Set the basic load boundary In embodiments where the total demand is between 0 and 1, It can be set to a value between 0.05 and 0.30, and tuned according to system size and comfort requirements.

[0093] Operational phase correction factor It can be set as: .

[0094] Raising the load threshold during startup or unit switchover is equivalent to increasing the system's tolerance for a small number of requests and reducing ineffective load increases during the transition period.

[0095] After the unit's load increase / decrease transition phase ends, the operation phase correction coefficient does not immediately jump to 1, but gradually recovers over two or more control cycles: .in, .

[0096] Valve position distribution correction factor It can be set as: .

[0097] A large number of terminals with high opening indicates that the overall cooling supply of the system may be insufficient, and the load limit should be lowered to improve response sensitivity; a large number of terminals with low opening indicates that the cooling supply is sufficient, and the load limit should be raised to allow the system to save energy further.

[0098] The load status of chiller units can be expressed using relative load indices. The load condition correction factor can be: .

[0099] In this case, the load limit is: .

[0100] The energy-saving boundary is: .in, The hysteresis width.

[0101] By setting two boundaries, the demand reset signal remains unchanged when the overall demand fluctuates slightly between the two boundaries, thereby reducing the probability of frequent switching between the Trim and Respond directions.

[0102] Accordingly, adjusting the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, includes: reducing the demand reset signal by a preset energy-saving step size when the overall demand is lower than the energy-saving boundary; maintaining the demand reset signal when the overall demand is between the energy-saving boundary and the overload boundary; determining the overload step size based on the excess demand exceeding the overload boundary when the overall demand is higher than the overload boundary, and increasing the demand reset signal by the overload step size, wherein the overload step size increases with the excess demand and is limited to a preset maximum overload step size; limiting the demand reset signal between a preset minimum and a preset maximum value, and limiting the change amplitude of the demand reset signal between adjacent control cycles; freezing the demand reset signal or limiting the demand reset signal with a change amplitude smaller than that of the stable operation stage during a preset protection period after the chilled water system starts up or during the chiller unit load increase / decrease period; gradually increasing the allowable change amplitude after the preset protection period or the chiller unit load increase / decrease period ends, until it returns to the change amplitude corresponding to the stable operation stage.

[0103] Specifically, when At that time, energy-saving adjustment is implemented: .in, For energy saving increments, for example, 2 percentage points.

[0104] when hour, .

[0105] when At that time, calculate the normalized excess demand: .in, This represents the total incremental demand corresponding to an equivalent request.

[0106] The load increment step is: .

[0107] The demand reset signal has been updated to: .

[0108] For example, It could be 3 percentage points. It can be 7 percentage points. Therefore, the greater the excess demand, the greater the load increase, but the load increase within a single control cycle is limited.

[0109] During the protection period after system startup, the demand reset signal can be kept at a preset initial value, or the allowable variation of the demand reset signal in a single cycle can be limited to 20% to 50% of that during stable operation. During the protection period, the demand response boundary can still be calculated, but the comparison result does not directly change the frozen demand reset signal.

[0110] After the protection period ends, gradually increase the allowable variation range until the normal adjustment step size of the stable operation phase is restored. This avoids a large step change in the reset signal required when the freeze is lifted.

[0111] S104, determine the hydraulic regulation state of the chilled water system based on the chilled water supply and return pressure difference, the chilled water pump adjustment margin, and the valve position distribution, and adjust the chilled water pressure difference setting value or the chilled water supply temperature setting value based on the demand reset signal and the hydraulic regulation state; wherein, the chilled water pressure difference setting value is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setting value is adjusted when the hydraulic regulation margin reaches the preset constraint.

[0112] Specifically, this involves obtaining the actual pressure difference between the chilled water supply and return water. chilled water pump operating frequency upper limit of chilled water pump frequency Differential pressure and valve position distribution of each effective terminal branch.

[0113] Based on the remaining amount of the chilled water supply and return pressure difference from the upper limit of the pressure difference, the remaining amount of the chilled water pump from the upper limit of the frequency, the proportion of the branch pressure difference insufficient area, and the proportion of the high-opening terminal area, it is determined whether the system still has the margin to increase the hydraulic transmission capacity.

[0114] When the system has hydraulic regulation margin, the chilled water differential pressure setpoint is adjusted according to the demand reset signal. and set the chilled water supply temperature. Maintain within the energy-saving temperature range.

[0115] When the system hydraulic regulation margin reaches the preset constraint, and the overall demand still indicates a high cooling demand, maintain the chilled water differential pressure setting value or limit it to the upper limit of the differential pressure, and reduce the chilled water supply temperature setting value according to the demand reset signal.

[0116] The chilled water differential pressure setpoint is sent to the chilled water pump frequency converter control loop, and the chilled water supply temperature setpoint is sent to the chiller unit controller, thus forming a coordinated control chain between terminal demand, hydraulic delivery, and chiller unit cooling capacity.

[0117] In one embodiment, step S104 may include: determining the hydraulic regulation margin of the chilled water system based on the difference between the actual differential pressure between the chilled water supply and return water and the upper limit of the differential pressure, the difference between the current operating frequency of the chilled water pump and the upper limit of the frequency, the proportion of the terminal area where the branch differential pressure is lower than the corresponding branch differential pressure demand value, and the proportion of the terminal area with high opening degree; when the hydraulic regulation margin does not reach the preset constraint and the demand reset signal increases, increasing the chilled water differential pressure setting value according to the demand reset signal between the lower limit and the upper limit of the chilled water differential pressure, and keeping the chilled water supply temperature setting value within the energy-saving temperature range; when the chilled water differential pressure setting value reaches the upper limit of the chilled water differential pressure or the chilled water... When the pump operating frequency reaches the upper limit of the frequency and the comprehensive demand is higher than the load increase boundary for multiple consecutive control cycles, the chilled water pressure differential setting value is maintained, and the chilled water supply temperature setting value is reduced according to the demand reset signal between the upper limit of the chilled water supply temperature and the lower limit of the chilled water supply temperature. When the comprehensive demand is lower than the energy saving boundary for multiple consecutive control cycles, the chilled water supply temperature setting value is first increased, and after the chilled water supply temperature setting value reaches the upper limit of the chilled water supply temperature, the chilled water pressure differential setting value is reduced. This forms a two-way progressive adjustment that first increases the hydraulic conveying capacity and then increases the main unit's cooling capacity when the load is increased, and first reduces the main unit's cooling capacity and then reduces the hydraulic conveying capacity when the load is reduced.

[0118] Specifically, this embodiment uses multiple hydraulic state parameters to determine whether the system still has the ability to increase the terminal flow rate by increasing the pressure differential.

[0119] Pressure differential normalized margin: .in, and These are the upper and lower limits of the allowable differential pressure, respectively.

[0120] Frequency normalization margin: .

[0121] The percentage of areas with insufficient differential pressure on branch roads is: .in, This refers to the number of terminals with valid hydraulic monitoring data. The proportion of high-opening terminal areas is calculated using the aforementioned method. .

[0122] The hydraulic regulation margin index can be: .in: .

[0123] when If the chilled water pressure differential setting is lower than the pressure differential limit and the chilled water pump frequency is lower than the frequency limit, it is determined that the hydraulic regulation margin has not reached the preset constraint.

[0124] when If the chilled water pressure differential setting has reached the upper limit of the pressure differential, or the chilled water pump frequency has reached the upper limit of the frequency, the hydraulic regulation margin is determined to have reached the preset constraint.

[0125] When the hydraulic regulation margin does not reach the preset constraint, the chilled water differential pressure setpoint can be determined according to the following formula: .in, It is a monotonically non-decreasing mapping function.

[0126] In a piecewise linear embodiment: .in, For example, 70%.

[0127] when When the setting value of chilled water differential pressure increases from 0% to 70%, the setting value of chilled water differential pressure increases linearly from 80 kPa to 100 kPa; at this time, the setting value of chilled water supply temperature remains at an energy-saving temperature of, for example, 9°C.

[0128] When the hydraulic regulation margin reaches the preset constraint, and the comprehensive demand is continuous When the control cycle exceeds the overload limit, maintain the chilled water differential pressure setpoint and reduce the chilled water supply temperature setpoint according to the following formula: In a piecewise linear embodiment: .

[0129] when When the percentage increases from 70% to 100%, the chilled water supply temperature setpoint decreases linearly from 9℃ to 7℃.

[0130] Before lowering the chilled water supply temperature, the chiller unit's minimum allowable outlet water temperature, evaporator minimum flow rate, compressor load rate, and equipment protection status should be checked. If any safety constraint is not met, further reduction of the supply water temperature is prohibited.

[0131] When the overall demand is below the energy-saving boundary for several consecutive control cycles, the chilled water supply temperature setting value should be increased first; after it recovers to the upper limit of the energy-saving temperature, the chilled water pressure differential setting value should be reduced.

[0132] When increasing the load, first increase the hydraulic conveying capacity and then increase the main unit's cooling capacity; when reducing the load, first decrease the main unit's cooling capacity and then decrease the hydraulic conveying capacity. This can reduce long-term low-temperature water supply and high-flow operation during low-load periods.

[0133] This results in a bidirectional progressive adjustment with opposite directions of load increase and decrease, reducing the energy consumption increase caused by independent or simultaneous excessive adjustment of the chilled water pump and chiller unit, and improving the synergy between terminal flow guarantee and main unit cooling capacity.

[0134] In some optional embodiments, the energy-saving control method further includes: establishing a cooling demand calculation channel for generating the terminal load request and calculating the comprehensive demand, and a hydraulic state calculation channel for determining the valve position distribution and hydraulic regulation state; determining whether the temperature detection data of each terminal area is valid based on the communication status, range status, continuous constant value status, and temperature change rate of the temperature detection device; determining whether the hydraulic detection data of each terminal area is valid based on the correspondence between the chilled water regulating valve control command and the valve position feedback, the valve position change state, and the response state of the branch pressure difference to the valve position change; when the temperature detection data is valid but the hydraulic detection data is invalid, retaining the terminal load request formed based on the temperature deviation of the corresponding terminal area, and stopping the use of the corresponding chilled water regulating valve position and branch pressure difference to determine the valve position distribution and hydraulic regulation state; when the temperature detection data is invalid but the hydraulic detection data is valid, stopping the use of the temperature deviation of the corresponding terminal area to generate... The system requests end-point loads and prohibits increasing the overall demand solely based on the high opening degree of the chilled water regulating valve, while retaining the contribution of the chilled water regulating valve position and branch pressure difference in the hydraulic state calculation channel. When the effective end-point area coverage in any calculation channel is lower than the corresponding preset coverage condition, a corresponding backup calculation result is generated based on the chilled water system main pipe operating parameters and historical operating data to replace the output of that calculation channel, while keeping the other calculation channel running normally. When the effective end-point area coverage in both calculation channels is lower than the corresponding preset coverage condition, the update of the demand reset signal based on the end-point area data is stopped, and the chilled water pressure difference setpoint and chilled water supply temperature setpoint are kept within a preset safety range. When switching between normal calculation results and backup calculation results, the calculation results before and after the switch are gradually merged to limit abrupt changes in the demand reset signal, chilled water pressure difference setpoint, or chilled water supply temperature setpoint.

[0135] Specifically, this embodiment establishes a cooling demand calculation channel and a hydraulic status calculation channel. The cooling demand calculation channel is used to generate terminal load requests and calculate the overall demand; the hydraulic status calculation channel is used to determine valve position distribution, the proportion of areas with insufficient branch pressure difference, and hydraulic regulation status.

[0136] The validity of temperature detection data is determined based on the communication status, range status, continuous constant value status, and temperature change rate of the temperature detection device.

[0137] For example, if the temperature value exceeds 5°C to 40°C, remains unchanged for multiple consecutive cycles, has a change rate exceeding 3°C / min between adjacent cycles, or the detection device generates a hardware fault alarm, the corresponding temperature detection data will be determined as invalid or suspicious.

[0138] Based on the correspondence between the control command and valve position feedback of the chilled water regulating valve, the valve position change status, and the response status of the branch pressure difference to the valve position change, determine whether the hydraulic detection data is valid.

[0139] When the valve position control command changes but the valve position feedback does not change, or when the valve position changes but the branch pressure difference does not change for a long period of time, the corresponding hydraulic detection data will be judged as invalid or suspicious.

[0140] When the temperature detection data of a certain terminal area is valid but the hydraulic detection data is invalid, the terminal load request based on the temperature deviation of that terminal area is retained so that it can continue to participate in the cooling demand calculation; at the same time, the calculation of the average valve position, the proportion of high opening area and hydraulic regulation status is stopped using the valve position and branch pressure difference of that area.

[0141] Therefore, a valve or branch differential pressure detection failure will not cause the actual temperature exceedance request to be completely ignored, nor will an abnormal valve position mislead the hydraulic regulation judgment.

[0142] When temperature detection data is invalid but hydraulic detection data is valid, stop using the temperature deviation of that area to generate end load requests and prohibit increasing the overall demand solely based on the high valve position; at the same time, retain the valid valve position and branch pressure difference in the hydraulic state calculation.

[0143] Therefore, a temperature sensor malfunction will not generate false cooling demand, but the effective terminal hydraulic status can still be used to determine the overall valve position distribution and hydraulic regulation margin of the system.

[0144] Furthermore, the effective coverage of the cooling demand calculation channel is as follows: .

[0145] The effective coverage of the hydraulic state calculation channel is: .

[0146] in, and These represent the number of valid endpoints in the corresponding channels.

[0147] When the coverage of the cooling demand calculation channel is lower than the preset coverage conditions, the demand reserve can be formed based on the total cooling load of the chilled water system and the historical demand during the same period.

[0148] The total cooling load of the chilled water system can be estimated using the following formula: .in, For the density of water, For the specific heat capacity of water, This represents the chilled water flow rate.

[0149] The required reserve capacity can be: .in, This represents the total demand during the same historical period. .

[0150] When the coverage of the hydraulic state calculation channel is lower than the preset coverage conditions, a hydraulic standby state can be formed based on the differential pressure of the chilled water supply and return main pipes, the operating frequency of the chilled water pumps, and the status of the bypass valves.

[0151] When switching between normal calculation results and backup calculation results, a gradual fusion method is used: 。 in, The value gradually increases from 0 to 1 over multiple control cycles.

[0152] When the effective coverage of both computing channels is lower than the corresponding coverage conditions, stop resetting the signal according to the data update requirements of the terminal area, and keep the chilled water differential pressure setting and chilled water supply temperature setting within the preset safe range.

[0153] Thus, by establishing separate channels for calculating cooling demand and hydraulic status, information such as regional temperature and terminal load requests are used to determine the required cooling capacity of the system, while information such as chilled water regulating valve positions and branch pressure differences are used to determine valve position distribution and hydraulic regulation status. This avoids the complete rejection of detection signals of different natures when a fault occurs. When temperature detection data is valid but hydraulic detection data is invalid, the terminal load request formed by the actual temperature deviation is retained, while abnormal valve positions and branch pressure differences are prohibited from participating in hydraulic status judgment. This prevents terminal actuator failures from masking actual regional undercooling or misleading system hydraulic control. When temperature detection data is invalid but hydraulic detection data is valid... At the same time, abnormal temperatures are prohibited from generating cooling requests and increasing the overall demand solely based on high valve positions. Meanwhile, valid hydraulic signals are retained to participate in hydraulic regulation state calculations. This can suppress false load increases caused by temperature sensor failures and avoid losing valuable end-point hydraulic information. When the effective coverage of any calculation channel is insufficient, only the backup result based on the main pipe parameters and historical data is used for that channel, while the other channel is kept running normally, thus limiting the impact of the fault to the corresponding control path. Furthermore, by gradually integrating the normal results and the backup results, it is possible to avoid abrupt changes in demand reset signals, differential pressure setpoints, or supply water temperature setpoints caused by control channel switching.

[0154] In some embodiments, the energy-saving control method further includes implementing single-parameter isolation correction according to an evaluation period longer than the update period of the demand reset signal.

[0155] The single-parameter isolation correction includes: determining the current control target to be improved based on the regional comfort compliance rate, chilled water pump power, chilled water supply and return temperature difference, and the number of times the demand reset signal adjustment direction is switched, according to the priority decreasing in the order of equipment operation safety, regional comfort, control stability, and operation efficiency; selecting a type of parameter to be corrected corresponding to the current control target to be improved based on the preset correspondence between the control target and the control parameter category, saving the current parameter value and the evaluation index before correction of the parameter to be corrected, and generating candidate parameter values; applying the candidate parameter values ​​to subsequent control, locking other control parameter categories within a preset observation period, and selecting from historical operating data the parameters during business hours, outdoor environmental conditions, and chiller unit operation. Data that meets preset similarity conditions in terms of quantity and system load level are used to form a benchmark for comparison under the same operating condition. The evaluation indicators within the preset observation period are compared with the benchmark for comparison under the same operating condition and the evaluation indicators before correction. When the target indicator corresponding to the current control target to be improved meets the preset improvement conditions, and the evaluation indicator with a higher priority than the current control target to be improved does not meet the corresponding deterioration rejection conditions, the candidate parameter value is retained. When the target indicator does not meet the preset improvement conditions, or any high-priority evaluation indicator meets the corresponding deterioration rejection conditions, the parameter to be corrected is restored to the parameter value before correction. After retaining the candidate parameter value or restoring the parameter to be corrected, new control parameter corrections are stopped within a preset cooling period.

[0156] Specifically, in this embodiment, the control parameters are isolated and corrected once for a class of parameters according to an evaluation period longer than the update period of the demand reset signal.

[0157] The regional comfort standard compliance rate is: .in, For comfort evaluation bias that is independent of the request start bias.

[0158] The power specifications of the chilled water pump are as follows: .

[0159] The temperature difference between the chilled water supply and return water is: .

[0160] The number of demand reset signal adjustment direction switching counts is the cumulative number of times the demand reset signal changes from increasing to decreasing or from decreasing to increasing within the evaluation period, denoted as . .

[0161] The current control objectives to be improved are determined according to the following priority order: equipment operation safety, regional comfort, control stability, and operation energy efficiency, which decrease in that order.

[0162] For example, when there is a device safety alarm, energy-saving parameter optimization is not performed; when the regional comfort compliance rate is lower than the target value, comfort is improved first; when comfort meets the requirements but the demand reset signal switches frequently, control stability is improved first; when both comfort and stability meet the requirements, system energy efficiency is optimized.

[0163] Establish the correspondence between control objectives and parameter categories. Parameter categories should include at least request validity parameters, area weight parameters, demand response interval parameters, demand reset signal adjustment parameters, and hydraulic state determination parameters.

[0164] Save the current value of the parameter to be corrected and the evaluation index before correction, form a parameter baseline snapshot, and generate candidate parameter values ​​according to the preset correction step size.

[0165] For example: when the comfort compliance rate is consistently below 95%, the basic load increase boundary can be lowered; when the comfort compliance rate is 100%, the pump power ratio is below 0.7, and the supply and return water temperature difference is not less than 4℃, the basic load increase boundary can be raised; when the number of demand reset signal direction switching times is greater than 8 times / hour, the hysteresis width can be increased or the maximum load increase step size can be reduced; when a specific area is consistently cold, the basic area weight of that area can be increased; when an area is consistently comfortable and there are no complaints, the request start deviation can be appropriately increased.

[0166] Within the same observation period, only one type of parameter is selected for modification, while other parameter categories remain locked.

[0167] Select data from historical operating data that meet similar conditions in terms of operating hours, outdoor environmental conditions, number of chiller units in operation, and system load level.

[0168] Among them, the working distance can be defined: .in, Indicates the characteristics of the current operating condition. Indicates historical operating conditions. This indicates the corresponding weight.

[0169] when When this period of historical data is selected, it is included in a set of data under similar operating conditions. The average or median evaluation index of the set of data under similar operating conditions is used to form a benchmark.

[0170] Candidate parameter values ​​are applied within a preset observation period, while other parameter categories are locked. After the observation period ends, the target index is compared with the baseline under the same working conditions and the index before correction.

[0171] When the improvement of the target indicator reaches the preset improvement condition, and all evaluation indicators with higher priority than the current target have not reached the deterioration rejection condition, the candidate parameter value is retained.

[0172] For example, when optimizing energy efficiency, even if the water pump power decreases, the candidate parameter value will not be accepted if the regional comfort compliance rate drops below the comfort rejection threshold.

[0173] When the target indicator fails to meet the preset improvement conditions, or when any high-priority evaluation indicator meets the deterioration rejection conditions, the parameter value before correction is restored based on the parameter baseline snapshot.

[0174] After retaining candidate parameter values ​​or restoring parameters, a preset cooldown period is set. During the cooldown period, new parameter adjustments are stopped, allowing the system sufficient time to reach a new stable state and preventing the unattributable impact of multiple consecutive parameter changes.

[0175] The above scheme enables control parameters to have verifiable, rollback, and attributable online adaptability, gradually optimizing operating parameters in the event of changes in building types, seasonal variations, and equipment performance degradation, while reducing the risk of rule-based adaptive regulation going out of control.

[0176] A large shopping mall in Shenzhen (with a building area of ​​approximately 120,000 square meters) 2 Taking a three-story building with one basement level, encompassing multiple business formats including catering, retail, and entertainment, and connected to a total of 48 terminal temperature sensors as an example, the specific parameter configuration and operational effect of the control method of this invention are explained.

[0177] Core control parameters:

[0178] Regional weighting configuration: A total of 48 terminal sensors are allocated IM_base,i according to floor and business type. During peak dining hours, k_time=1.2, k_occ increases (increased personnel density), and k_shr increases (high latent heat load of catering). The combination of these three factors increases the overall weight of the 3F catering area by about 60%~80%, ensuring priority response of cooling supply during peak hours.

[0179] The system was powered on at 9:00. After Td=15min, a reset was initiated with an initial Reset=100%, CHWDP_sp=100kPa, and CHWST_sp=7℃.

[0180] To verify the technical effectiveness of the present invention, it was tested in the same project (a shopping mall in Shenzhen, 120,000 m²). 2 A comparative operation test was conducted on 48 end sensors using three control modes. Test conditions: typical summer weekdays (outdoor temperature 32~35℃), continuous operation for 7 days, with daily average values ​​recorded. The three modes are as follows: Mode A: Fixed differential pressure (100kPa) + fixed water supply temperature (7℃) - traditional PID control.

[0181] Mode B: Standard T&R control (fixed I=3, static weight IM, no credibility evaluation, no feedback correction).

[0182] Mode C: The present invention.

[0183] Comparative analysis conclusions: 1. Improved Energy Efficiency: Compared to Mode A, Mode C saves 21.8% on water pump power, 11.0% on chiller power, and increases the overall system COP by 13.0%. Key energy savings include: dynamic I(t) allowing for deeper trims during low-load periods (I(t) can reach 5-6), and cascade reset maintaining the supply water temperature at 9℃ instead of a fixed 7℃ when Reset < 70%, resulting in an approximately 11% increase in main unit COP.

[0184] 2. Improved Comfort: The temperature compliance rate in key areas increased from 82.3% to 98.5% (+16.2 percentage points), and the overall average compliance rate increased from 76.5% to 95.8%. The improvements are attributed to: a six-factor dynamic weighting system ensuring higher cooling priority for high-heat-load areas (high population density and latent heat during peak dining hours), and a feedback correction mechanism that automatically adjusted the δ threshold of the 3F dining area from 0.5℃ to 0.3℃, improving the response speed in sensitive areas.

[0185] 3. Valve position distribution optimization: The average valve position at the end decreased from 72% to 58%, and the proportion of high-opening valve positions decreased from 38% to 8%, indicating a more balanced flow distribution in the system. This is thanks to the k_valve factor in the dynamic I(t): when V_avg>85% is detected, the I value is automatically reduced to speed up the response, allowing the system to increase load in a timely manner when the valve is at a high opening, avoiding the end being in the extreme condition of "the valve is fully open but still not satisfied" for a long time.

[0186] 4. Control Stability: The number of Reset fluctuations decreased from 35 times / h in Mode B to 12 times / h (-65.7%), the frequency increase / decrease of the inverter decreased from 28 times / h to 5 times / h (-82.1%), and the duration of oscillations during transition conditions decreased from 45 minutes / day to 5 minutes / day. The improvements include: the dynamic I(t)'s k_start amplifies the I value by 1.5 times during the startup phase to suppress start-up oscillations; the k_stage amplifies the I value by 1.2 times during load increases and decreases to avoid transitional jumps; and the feedback correction rule C automatically increases the I value and decreases SPres_max when N_reset > 8 is detected.

[0187] 5. Improved supply and return water temperature difference: ΔT increased from 3.2℃ to 5.3℃, approaching the design temperature difference of 5℃, eliminating the inefficient operation of "high flow rate and small temperature difference". This is mainly due to the cascade reset prioritizing the Trim differential pressure setting value (reducing it from 100kPa to 80kPa) during low load periods, reducing the water pump flow rate, and maintaining the supply water temperature at 9℃ to avoid inefficient operation of the chiller.

[0188] The aforementioned correction records demonstrate that the feedback correction mechanism can automatically optimize parameters based on actual operational results without manual intervention. In particular, the two decreasing corrections to the δ threshold in the 3F dining area gradually increased the peak-hour comfort compliance rate in this area from 82% to 96%, fully demonstrating the effectiveness of the self-learning closed loop.

[0189] The terminal room temperature was stably maintained at 24~26℃, with a room temperature compliance rate of ≥98.5% in key areas (1F lobby and 3F catering), and no complaints of overcooling / overheating. The average daily operating frequency of the water pumps decreased by about 18% (compared to the fixed differential pressure control before the renovation), and the measured daily water pump power saving rate was about 21.8%. The average water supply temperature of the main unit increased from a fixed 7℃ before the renovation to about 8.1℃ (off-peak hours), and the main unit COP increased by about 11%. After 10 days of operation, the feedback correction module automatically adjusted the δ threshold of the 3F catering area from 0.5℃ to 0.3℃, and the cooling response speed during peak dining hours was significantly improved. The system had no abnormal oscillations throughout the day, the frequency increase and decrease of the inverter decreased by about 82%, and the number of unit start-ups and shutdowns decreased by about 67%.

[0190] See Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy-saving control device for a central air conditioning chilled water system according to an embodiment of the present invention. The energy-saving control device 200 for the central air conditioning chilled water system may include: The generation unit 210 is used to generate the terminal load request corresponding to each terminal area based on the temperature deviation of each terminal area and the valve position of the chilled water regulating valve. The determining unit 220 is used to determine the validity of the terminal load request based on the detection data status and terminal equipment status of each terminal area, determine the dynamic area weight based on the heat load characteristics of each terminal area, and normalize and aggregate each terminal load request based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system. The adjustment unit 230 is used to determine the demand response range, including the energy-saving boundary and the load-increasing boundary, based on the operation stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve and the load status of the chiller unit, and to adjust the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, based on the positional relationship between the comprehensive demand and the demand response range. The processing unit 240 is used to determine the hydraulic regulation state of the chilled water system based on the chilled water supply and return pressure difference, the chilled water pump regulation margin, and the valve position distribution, and to adjust the chilled water pressure difference setpoint or the chilled water supply temperature setpoint based on the demand reset signal and the hydraulic regulation state; wherein, the chilled water pressure difference setpoint is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setpoint is adjusted when the hydraulic regulation margin reaches the preset constraint.

[0191] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0192] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications, substitutions, and improvements without departing from the concept of the present invention, and these should all be covered within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the claims.

Claims

1. An energy-saving control method for a central air conditioning chilled water system, characterized in that, include: Based on the temperature deviation and chilled water regulating valve position of each terminal area, generate the corresponding terminal load request for each terminal area; The validity of the terminal load request is determined based on the detection data status and terminal equipment status of each terminal area. The dynamic area weight is determined based on the heat load characteristics of each terminal area. The terminal load requests are then normalized and aggregated based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system. Based on the operating stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve, and the load status of the chiller unit, the demand response range, including the energy-saving boundary and the load-increasing boundary, is determined. Based on the positional relationship between the comprehensive demand and the demand response range, the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, is adjusted. The hydraulic regulation state of the chilled water system is determined based on the chilled water supply and return pressure difference, the chilled water pump adjustment margin, and the valve position distribution. The chilled water pressure difference setpoint or chilled water supply temperature setpoint is adjusted based on the demand reset signal and the hydraulic regulation state. Specifically, the chilled water pressure difference setpoint is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setpoint is adjusted when the hydraulic regulation margin reaches the preset constraint.

2. The energy-saving control method according to claim 1, characterized in that, The generation of end-load requests corresponding to each end region includes: Set a request start deviation and a request cancellation deviation that is less than the request start deviation for each end region; When the temperature of the terminal area is higher than the sum of the corresponding area temperature setpoint and the requested start deviation, or when the chilled water regulating valve of the terminal area reaches the preset high opening degree and the temperature of the terminal area is higher than the corresponding area temperature setpoint, it is determined that the terminal area meets the load request triggering condition. After the load request triggering condition is maintained for a preset number of control cycles, an end load request for the end region is generated. If an end-load request has been generated, the end-load request will be cancelled when the temperature in the end region drops below the sum of the corresponding region temperature setpoint and the request cancellation deviation, and this continues for a preset number of control cycles.

3. The energy-saving control method according to claim 1, characterized in that, Determining the validity of the end-load request includes: The temperature request component is determined based on the temperature deviation of each terminal area and the duration of the temperature deviation, and the hydraulic request component is determined based on the valve position of the corresponding chilled water regulating valve, the branch pressure difference, and the response relationship between the valve position and the branch pressure difference. The reliability of the temperature channel corresponding to the temperature request component is determined based on the calibration status, communication status, continuous constant value status, temperature change rate, temperature consistency of adjacent areas, and historical temperature fluctuation status of the temperature detection device. Based on the deviation between the control command and valve position feedback of the chilled water regulating valve, the valve position change status, the correspondence between the valve position change and the branch pressure difference change, and the response status of the regional temperature when the chilled water regulating valve is continuously at a high opening, the reliability of the hydraulic channel corresponding to the hydraulic request component is determined. The reliability of the temperature channel and the reliability of the hydraulic channel are compared with their respective first channel threshold and second channel threshold, wherein the first channel threshold is less than the second channel threshold, and different reliability state entry thresholds and reliability state exit thresholds are set for each channel. When the reliability of the temperature channel and the reliability of the hydraulic channel are both not lower than their respective second channel thresholds, the validity of the request is determined based on the temperature request component and the hydraulic request component. When the credibility of one channel is lower than the corresponding first channel threshold and the credibility of another channel is not lower than the corresponding second channel threshold, the use of the request component with credibility lower than the first channel threshold is stopped, and the validity of the request is determined based on the other request component, while the validity of the request is limited to a preset partial contribution range. When the credibility of at least one channel is between the corresponding first channel threshold and the second channel threshold, a penalty coefficient that varies with the credibility of that channel is used to reduce the contribution of the corresponding request component to the validity of the request. When the reliability of the temperature channel and the reliability of the hydraulic channel are both lower than their respective first channel thresholds, the validity of the request is set to zero, and a fault flag is output to characterize the abnormal channel type.

4. The energy-saving control method according to claim 1 or 3, characterized in that, The comprehensive demand quantity, which characterizes the overall cooling capacity requirement of the chilled water system, includes: The weight of the basic area is determined based on the spatial function and load priority of each terminal area; Based on the personnel density in the terminal area, the ratio of sensible heat load to latent heat load, the heat dissipation of equipment in the area, the current business hours, the load fluctuations of the same period in history, and the heat transfer load of the building envelope, the corresponding load correction factors are determined respectively. The initial dynamic region weight is determined based on the combination of the basic region weight and each load correction factor, and the initial dynamic region weight is limited to a preset weight range. Based on the average value of the initial dynamic region weights of all valid end regions, the initial dynamic region weights are scaled and normalized to obtain the dynamic region weights, so that the average value of the dynamic region weights of all valid end regions is kept at a preset benchmark value. Using the sum of the dynamic regional weights of each valid end region as the normalization benchmark, the end load requests corrected by the request validity are weighted and aggregated to obtain the comprehensive demand.

5. The energy-saving control method according to claim 1, characterized in that, The determination of the demand response range, including the energy-saving boundary and the load-increasing boundary, includes: The adjustment amount for the operation stage is determined based on the startup stage, stable operation stage, or chiller unit load increase / decrease transition stage of the chilled water system. The valve position distribution correction is determined based on the average valve position of all effective terminal areas and the proportion of terminal areas where the valve position is higher than the preset high opening threshold. The system load correction is determined based on the chiller unit load rate. Based on the basic demand boundary, the operation phase correction amount, the valve position distribution correction amount, and the system load correction amount, the load increase boundary is determined, and an energy-saving boundary lower than the load increase boundary is determined according to the load increase boundary and the preset hysteresis width. Specifically, when the valve position distribution indicates insufficient cooling in multiple terminal areas or the chiller is under high load, the response tolerance corresponding to the demand response range is reduced; when the valve position distribution indicates sufficient overall cooling in the terminal areas or the chiller is under low load, the response tolerance corresponding to the demand response range is increased; after the chiller load reduction transition phase ends, the operation phase correction amount is gradually restored to the correction amount corresponding to the stable operation phase over multiple control cycles.

6. The energy-saving control method according to claim 1 or 5, characterized in that, The adjustment of the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, includes: When the overall demand is lower than the energy-saving boundary, the demand reset signal is reduced according to a preset energy-saving step size. When the overall demand is between the energy-saving boundary and the overload boundary, the demand reset signal is maintained; When the total demand exceeds the load limit, the load increase step size is determined based on the excess demand amount of the total demand exceeding the load limit, and the demand reset signal is increased according to the load increase step size. The load increase step size increases with the excess demand amount and is limited to a preset maximum load increase step size. The demand reset signal is limited to a preset minimum value and a preset maximum value, and the change amplitude of the demand reset signal between adjacent control cycles is limited. During the preset protection period after the chilled water system starts up or during the load increase / decrease of the chiller unit, the demand reset signal is frozen or the demand reset signal is limited by a change range smaller than that of the stable operation phase. After the preset protection period or the load increase / decrease of the chiller unit ends, the allowable change range is gradually increased until it returns to the change range corresponding to the stable operation phase.

7. The energy-saving control method according to claim 1, characterized in that, The adjustment of the chilled water differential pressure setting or the chilled water supply temperature setting includes: The hydraulic regulation margin of the chilled water system is determined based on the difference between the actual pressure difference between the chilled water supply and return water and the upper limit of the pressure difference, the difference between the current operating frequency of the chilled water pump and the upper limit of the frequency, the proportion of the terminal area where the branch pressure difference is lower than the corresponding branch pressure difference requirement, and the proportion of the terminal area with high opening degree. When the hydraulic regulation margin does not reach the preset constraint and the demand reset signal increases, the chilled water pressure differential setting value is increased according to the demand reset signal between the lower limit and the upper limit of the chilled water pressure differential, and the chilled water supply temperature setting value is kept within the energy-saving temperature range. When the chilled water differential pressure setting value reaches the upper limit of the chilled water differential pressure or the chilled water pump operating frequency reaches the upper limit of the frequency, and the comprehensive demand is higher than the load limit for multiple consecutive control cycles, the chilled water differential pressure setting value is maintained, and the chilled water supply temperature setting value is reduced according to the demand reset signal between the upper limit of the chilled water supply temperature and the lower limit of the chilled water supply temperature. When the overall demand is lower than the energy-saving boundary for several consecutive control cycles, the set value of the chilled water supply temperature is first increased. After the set value of the chilled water supply temperature reaches the upper limit of the chilled water supply temperature, the set value of the chilled water pressure difference is then reduced. This forms a two-way progressive adjustment that first increases the hydraulic conveying capacity and then increases the main unit's cooling capacity when the load is increased, and first reduces the main unit's cooling capacity and then reduces the hydraulic conveying capacity when the load is reduced.

8. The energy-saving control method according to claim 1, characterized in that, Also includes: Establish a cooling demand calculation channel for generating the terminal load request and calculating the comprehensive demand, and a hydraulic state calculation channel for determining the valve position distribution and hydraulic regulation state; Based on the communication status, range status, continuous constant value status, and temperature change rate of the temperature detection device, determine whether the temperature detection data of each terminal area is valid; based on the correspondence between the control command and valve position feedback of the chilled water regulating valve, the valve position change status, and the response status of the branch pressure difference to the valve position change, determine whether the hydraulic detection data of each terminal area is valid. When the temperature detection data is valid but the hydraulic detection data is invalid, the terminal load request formed by the temperature deviation in the corresponding terminal area is retained, and the valve position distribution and hydraulic regulation status are determined by the corresponding chilled water regulating valve position and branch pressure difference are stopped. When the temperature detection data is invalid but the hydraulic detection data is valid, stop using the temperature deviation of the corresponding end area to generate the end load request, and prohibit increasing the comprehensive demand solely based on the high opening degree of the chilled water regulating valve, while retaining the contribution of the chilled water regulating valve position and branch pressure difference in the hydraulic state calculation channel. When the effective end area coverage in any calculation channel is lower than the corresponding preset coverage condition, a corresponding backup calculation result is generated based on the chilled water system main pipe operating parameters and historical operating data to replace the output of that calculation channel and keep another calculation channel running normally. When the effective end area coverage in both calculation channels is lower than the corresponding preset coverage condition, stop updating the demand reset signal based on the end area data, and keep the chilled water pressure differential setting value and chilled water supply temperature setting value within the preset safety range. When switching between normal calculation results and backup calculation results, the calculation results before and after the switch are gradually merged to limit the step changes of the demand reset signal, chilled water differential pressure setting value, or chilled water supply temperature setting value.

9. The energy-saving control method according to claim 1, characterized in that, It also includes implementing single-parameter isolation correction according to an evaluation period longer than the update period of the aforementioned demand reset signal, wherein the single-parameter isolation correction includes: Based on the regional comfort compliance rate, chilled water pump power, chilled water supply and return temperature difference, and the number of times the demand reset signal adjustment direction is switched, the current control targets to be improved are determined in descending order of priority: equipment operation safety, regional comfort, control stability, and operation efficiency. Based on the preset correspondence between control objectives and control parameter categories, select a type of parameter to be corrected that corresponds to the current control objective to be improved, save the current parameter value and the evaluation index before correction of the parameter to be corrected, and generate candidate parameter values. The candidate parameter values ​​are applied to subsequent control, other control parameter categories are locked within a preset observation period, and data that meet preset similar conditions in terms of business hours, outdoor environmental conditions, number of chiller units in operation, and system load level are selected from historical operating data to form a benchmark for comparison under the same operating conditions. The evaluation indicators within the preset observation period are compared with the benchmark under the same working conditions and the evaluation indicators before correction. When the target indicator corresponding to the current control target to be improved reaches the preset improvement condition, and the evaluation indicator with higher priority than the current control target to be improved does not reach the corresponding deterioration rejection condition, the candidate parameter value is retained. When the target indicator fails to meet the preset improvement conditions, or when any high-priority evaluation indicator meets the corresponding deterioration rejection conditions, the parameter to be corrected will be restored to its value before correction. After retaining the candidate parameter values ​​or restoring the parameters to be corrected, the initiation of new control parameter corrections will be stopped within a preset cooling cycle.

10. An energy-saving control device for a central air conditioning chilled water system, characterized in that, include: The generation unit is used to generate the corresponding terminal load request for each terminal area based on the temperature deviation of each terminal area and the valve position of the chilled water regulating valve. The determination unit is used to determine the validity of the terminal load request based on the detection data status and terminal equipment status of each terminal area, determine the dynamic area weight based on the heat load characteristics of each terminal area, and normalize and aggregate each terminal load request based on the request validity and the dynamic area weight to obtain the comprehensive demand that characterizes the overall cooling capacity demand of the chilled water system. The adjustment unit is used to determine the demand response range, including the energy-saving boundary and the load-increasing boundary, based on the operation stage of the chilled water system, the valve position distribution of each terminal chilled water regulating valve, and the load status of the chiller unit, and to adjust the demand reset signal, which characterizes the cooling capacity supply level of the chilled water system, based on the positional relationship between the comprehensive demand and the demand response range. The processing unit is used to determine the hydraulic regulation state of the chilled water system based on the chilled water supply and return pressure difference, the chilled water pump adjustment margin, and the valve position distribution, and to adjust the chilled water pressure difference setpoint or the chilled water supply temperature setpoint based on the demand reset signal and the hydraulic regulation state; wherein, the chilled water pressure difference setpoint is adjusted when the hydraulic regulation margin does not reach the preset constraint, and the chilled water supply temperature setpoint is adjusted when the hydraulic regulation margin reaches the preset constraint.

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