Method and apparatus for controlling a heating, ventilation, and air conditioning system

Abstract

The application discloses a control method and device of a heating ventilation air conditioning system, and the method comprises the following steps: acquiring a first load demand quantity of a current period, unit state information and a first running unit quantity of a last period before the current period and closest to the current period; in the case that the first running unit quantity meets the first load demand quantity and the heating ventilation air conditioning system is in a steady state, determining a unit demand quantity of the current period according to the first load demand quantity and the unit state information; in the case that the first running unit quantity meets the first load demand quantity and the heating ventilation air conditioning system is in a non-steady state, determining the first running unit quantity as the unit demand quantity of the current period; and adjusting a running unit of the current period according to the unit demand quantity. The method can effectively solve the problem that the unit quantity cannot be flexibly adjusted, realizes dynamic adjustment of the unit quantity, can improve the possibility that the running unit quantity matches the actual demand, and can improve the operation efficiency of the heating ventilation air conditioning system.

Description

Technical Field

[0001] The present invention belongs to the technical field of HVAC control, and in particular relates to a control method and device for a HVAC system. Background Art

[0002] As a vital system responsible for ventilation and air conditioning within a building, the HVAC system uses water and air as the medium to transfer heat and cold through pipes, achieving precise control of indoor temperature. In this process, precise control of water temperature and the proper allocation of the number of operating units are crucial.

[0003] The number of chillers in operation is directly related to the energy efficiency of the HVAC system. Too many chillers will increase the system's energy consumption and operating costs, while insufficient chillers may not be able to meet the building's load requirements.

[0004] However, current HVAC system unit counts often rely on manual experience. However, a building's heating and cooling loads are affected by a variety of factors, such as changes in the outdoor environment, indoor occupant activity, and equipment operating status. These factors can cause real-time load fluctuations. Traditional manual setting methods cannot flexibly adjust to these real-time changes, often resulting in a mismatch between unit count and actual load demand, which in turn reduces system efficiency. Summary of the Invention

[0005] Embodiments of the present invention provide a control method and device for a heating, ventilation and air conditioning system, which can achieve dynamic adjustment of the number of operating units and effectively improve the operating efficiency of the heating, ventilation and air conditioning system.

[0006] In a first aspect, an embodiment of the present application provides a method for controlling a heating, ventilation and air conditioning system, the method comprising:

[0007] Obtain the first load demand of the current cycle, unit status information, and the number of first operating units in the previous cycle that is before the current cycle and closest to the current cycle;

[0008] When it is determined that the first number of operating units meets the first load demand and the HVAC system is in a steady state, determining the unit demand for the current cycle according to the first load demand and the unit state information;

[0009] When it is determined that the first number of operating units meets the first load demand and the HVAC system is in a non-steady state, determining the first number of operating units as the unit demand for the current cycle;

[0010] Adjust the operating units in the current cycle according to the unit demand.

[0011] As an optional implementation, before determining that the first number of operating units meets the first load demand and the HVAC system is in a steady state, the method further includes:

[0012] Obtain the unit temperature control information of the current cycle, which includes the unit set temperature, the unit actual water supply temperature, and the unit temperature change rate;

[0013] Obtain the number of second operating units within the preset time period of the previous cycle;

[0014] When the number of the second operating units is the same as the number of the first operating units and the unit temperature control information meets the first preset condition, it is determined that the HVAC system is in a steady state. The first preset condition includes at least one of the following: the difference between the unit set temperature and the actual water supply temperature of the unit is less than the first preset threshold, and the unit temperature change rate is less than the second preset threshold.

[0015] As an optional implementation, before determining that the first number of operating units meets the first load demand and the HVAC system is in a steady state, the method further includes:

[0016] Obtain the unit set temperature, unit actual water supply temperature and unit temperature change rate of the current cycle;

[0017] When the difference between the set temperature of the unit and the actual water supply temperature of the unit is greater than the third preset threshold and the rate of change of the unit temperature is lower than the fourth preset threshold, it is determined that the first number of operating units meets the first load demand.

[0018] As an optional implementation, the method further includes:

[0019] When it is determined that the first number of operating units does not meet the first load demand, the unit demand of the current cycle is determined according to the first load demand and the unit power of a single unit.

[0020] As an optional implementation, obtaining the first load demand of the current cycle includes:

[0021] Obtain the second load demand of the previous cycle, the unit thermal load of the current cycle, and the environmental information of the energy supply area;

[0022] When it is determined that the HVAC system is in a non-dehumidification mode and in a steady state, the unit thermal load is determined as the first load demand of the current cycle;

[0023] When it is determined that the HVAC system is in a non-dehumidification mode and a non-steady state, the second load demand is determined as the first load demand of the current cycle.

[0024] As an optional implementation method, obtaining the unit thermal load of the current cycle includes:

[0025] Obtaining the actual return water temperature, actual supply water temperature, water flow rate of the running unit in the current cycle and a first reference heat exchange amount of the running unit determined by a sensor installed on the running unit;

[0026] determining a second reference heat exchange amount according to the actual return water temperature, the actual supply water temperature and the water flow rate;

[0027] The larger value of the first reference heat exchange amount and the second reference heat exchange amount is determined as the thermal load of the unit in the current cycle.

[0028] As an optional implementation, obtaining the first load demand of the current cycle includes:

[0029] Obtain the return air ratio of the HVAC system, the indoor ambient air enthalpy value of the energy supply area, and the outdoor ambient air enthalpy value;

[0030] Determine the mixed air enthalpy value based on the return air ratio, the indoor ambient air enthalpy value and the outdoor ambient air enthalpy value;

[0031] When it is determined that the HVAC system is in dehumidification mode, the first load demand E of the current cycle is determined according to the following expression:

[0032] E=m air ·(h mix -h dew )

[0033] Where h dew is the enthalpy value of the wet air corresponding to the indoor temperature and humidity set value when it reaches the dew point temperature of saturation, m air is the mass flow rate of air entering the air conditioning system, h mix is the enthalpy of mixed air.

[0034] As an optional implementation method, obtaining the unit set temperature of the current cycle includes:

[0035] Obtain the return air ratio of the HVAC system, the indoor air humidity of the energy supply area, the outdoor air humidity, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value;

[0036] Determine the mixed air enthalpy value based on the return air ratio, the indoor ambient air enthalpy value and the outdoor ambient air enthalpy value;

[0037] Determine the mixed air humidity based on the return air ratio, indoor air humidity and outdoor air humidity;

[0038] determining the terminal air inlet temperature according to a conversion function of the mixed air moisture content, the mixed air enthalpy and the first wet air parameter;

[0039] The unit set temperature is determined based on the terminal air inlet temperature and the first load demand.

[0040] As an optional implementation, determining the unit set temperature according to the terminal air inlet temperature and the first load demand includes:

[0041] Solve the unit set temperature according to the following expression

[0042]

[0043] Where E is the first load demand, is the terminal air inlet temperature, G water is the chilled water flow rate, G air is the air flow rate, Q0 is the load calibration quantity, is the inlet temperature calibration quantity, is the unit outlet water temperature calibration quantity, is the chilled water flow calibration quantity, The air flow calibration quantity.

[0044] In a second aspect, a control device for a heating, ventilation and air conditioning system is provided, the device comprising:

[0045] A first acquisition module is used to obtain the first load demand of the current cycle, the unit status information, and the number of first operating units in the previous cycle that is before the current cycle and closest to the current cycle;

[0046] a first determining module, configured to determine the unit demand for the current cycle according to the first load demand and the unit state information, when it is determined that the number of the first operating units meets the first load demand and the HVAC system is in a steady state;

[0047] a second determining module, configured to determine the first number of operating units as the unit demand for the current cycle when it is determined that the first number of operating units meets the first load demand and the HVAC system is in an unsteady state;

[0048] The adjustment module is used to adjust the operating units in the current cycle according to the unit demand.

[0049] In a third aspect, an embodiment of the present application provides an electronic device comprising a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein when the program or instruction is executed by the processor, the steps of the method for controlling a HVAC system of any one of the first aspects of the present application are implemented.

[0050] In a fourth aspect, an embodiment of the present application provides a computer storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the control method of the HVAC system of any one of the first aspects of the present application is implemented.

[0051] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes a computer program. When the computer program is processed and executed, it implements the control method of the HVAC system of any one of the first aspects of the present application.

[0052] The HVAC system control method and apparatus of the embodiments of the present application can, by acquiring the first load demand and unit status information of the current cycle in real time, adjust the unit demand based on the actual first load demand and unit status information when the first number of operating units meets the first load demand and the HVAC system is operating smoothly, thereby facilitating a unit demand that is more suitable for the actual load demand. Furthermore, when the first number of operating units meets the first load demand and the HVAC system is operating unsteadily, the first number of operating units from the previous cycle is used as the operating units for the current cycle, helping to maintain system stability and avoiding frequent unit switching that can lead to unstable system operation. Furthermore, adjusting the operating units for the current cycle based on the unit demand ensures that the HVAC system can quickly respond to load changes, allowing the HVAC system to more accurately match actual demand, effectively resolving the issue of the inability to flexibly adjust the number of units in related technologies. This dynamic adjustment of the number of units increases the likelihood that the number of operating units matches actual demand, effectively improving the operating efficiency of the HVAC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 This is a flow chart of a method for controlling a heating, ventilation, and air conditioning system according to an embodiment of the present application;

[0055] Figure 2 This is a flowchart of a specific implementation method of S102 provided in one embodiment of the present application;

[0056] Figure 3 This is a flowchart of a specific implementation method of S104 provided in one embodiment of the present application;

[0057] Figure 4 This is a flowchart of a specific implementation method for obtaining the first load demand in S101 provided in one embodiment of the present application;

[0058] Figure 5 This is a flowchart of a specific implementation method for obtaining the thermal load of the unit in S401 provided in one embodiment of the present application;

[0059] Figure 6 This is a flowchart of another specific implementation method of obtaining the first load demand in S101 provided in one embodiment of the present application;

[0060] Figure 7 This is a flowchart of a specific implementation method for obtaining the set temperature of the unit in the current cycle in S1021 provided in one embodiment of the present application;

[0061] Figure 8 This is a specific implementation scenario provided by an embodiment of the present application;

[0062] Figure 9 This is a schematic diagram of the structure of a control device for a heating, ventilation and air conditioning system provided by an embodiment of the present application;

[0063] Figure 10 This is a schematic diagram of the structure of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0064] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0065] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0066] HVAC systems typically provide both cooling and heating to meet people's needs for indoor comfort in different seasons and climates. They primarily use water or air as a heat transfer medium to transfer heat and cooling through pipes. Specifically, in the summer, or when cooling is needed, HVAC systems provide cooling through a refrigeration cycle. Refrigeration units generate low-temperature chilled water, which is delivered via pipes to various areas of the building. Inside the HVAC units, the chilled water exchanges heat with the air, cooling the air before it is delivered indoors, thereby lowering the indoor temperature. In the winter, or when heating is needed, HVAC systems provide heating through a heating cycle. Boilers or water heaters generate high-temperature hot water, which is also delivered through pipes to various areas of the building. Inside the HVAC units, the hot water exchanges heat with the air, heating the air before it is delivered indoors, thereby raising the indoor temperature.

[0067] Currently, HVAC system unit counts are largely set manually based on experience. However, this approach is inadequate for real-time fluctuations in a building's heating and cooling loads. These load fluctuations are often influenced by a variety of factors, including, but not limited to, sudden changes in the outdoor environment, changes in indoor occupant activity, and adjustments to equipment operating status. Because these factors are constantly changing, traditional manual setting methods struggle to accurately adjust unit counts in real time, often resulting in a mismatch between unit counts and actual load requirements. This not only impacts system efficiency but can also lead to energy waste.

[0068] In order to solve the above technical problems, the embodiments of the present application provide a control method and device for a heating, ventilation and air conditioning system. The control method for a heating, ventilation and air conditioning system provided by the embodiments of the present application is first introduced below.

[0069] Figure 1 FIG. 1 is a flow chart of a method for controlling a heating, ventilation and air conditioning system according to an embodiment of the present application. Figure 1 As shown, the control method of the HVAC system provided in the embodiment of the present application may include the following steps: S101 to S107.

[0070] S101, obtaining the first load demand of the current cycle, unit status information, and the number of first operating units in the previous cycle that is before the current cycle and closest to the current cycle;

[0071] S102, determining whether the number of the first operating units meets the first load demand. If it is determined that the number of the first operating units does not meet the first load demand, executing S103. If it is determined that the number of the first operating units meets the first load demand, executing S104.

[0072] S103, determining the unit demand of the current cycle according to the first load demand and the unit power of a single unit, and executing S107;

[0073] S104, determining whether the HVAC system is in a steady state. If it is determined that the HVAC system is in a steady state, executing S105; if it is determined that the HVAC system is in a non-steady state, executing S106;

[0074] S105, determining the unit demand of the current cycle according to the first load demand and the unit status information, and executing S107;

[0075] S106, determining the first number of operating units as the unit demand in the current cycle, and executing S107;

[0076] S107: Adjust the operating units in the current cycle according to the unit demand.

[0077] By obtaining the first load demand and unit status information of the current cycle in real time, the unit demand can be adjusted according to the actual first load demand and unit status information when the first number of operating units meets the first load demand and the HVAC system operates smoothly, which helps to obtain a unit demand that is more suitable for the actual load demand. When the first number of operating units meets the first load demand and the HVAC system operates unsteadily, using the first number of operating units in the previous cycle as the operating units in the current cycle helps maintain the stability of the system and avoid frequent unit switching that leads to unstable system operation. Furthermore, adjusting the operating units of the current cycle based on the unit demand can ensure that the HVAC system responds quickly to load changes, allowing the HVAC system to more accurately match actual demand, solving the problem of the inability to flexibly adjust the number of units in traditional methods. This dynamic adjustment of the number of units can increase the possibility of matching the number of operating units with actual demand, and can effectively improve the operating efficiency of the HVAC system.

[0078] In some embodiments, in S101, the cycle may refer to different time units and time lengths. The length and unit of the cycle may be adjusted according to the specific needs of the user and the frequency of data collection. As an example, the cycle may include a cycle in minutes and a cycle in hours. The first load demand refers to the total cooling or heating required to be provided by the HVAC system in the current cycle, that is, the load demand of the HVAC system in the current cycle. The first number of operating units refers to the number of units started for the first time in the current cycle. In the current cycle, the number of units put into operation in the HVAC system is usually the same as the number of first operating units put into operation in the previous cycle closest to the current cycle.

[0079] In some embodiments, the unit status information may include the unit's rated power and actual workload factor. The unit's rated power refers to the maximum power the unit can continuously output under standard conditions. The actual workload factor refers to the ratio of the load the unit bears during actual operation to its rated power. The actual workload factor reflects the actual load of the unit during operation and is typically less than 1.

[0080] In some embodiments, in S102, whether the first operating unit meets the first load demand can be determined based on whether an additional unit is needed. Figure 2 As shown, the aforementioned S102 may specifically include the following steps: S1021 to S1024.

[0081] S1021, obtaining the unit set temperature, the unit actual water supply temperature, and the unit temperature change rate of the current cycle;

[0082] S1022, determining whether the difference between the set temperature of the unit and the actual water supply temperature of the unit is greater than a third preset threshold and whether the rate of change of the unit temperature is lower than a fourth preset threshold. If the determination result is yes, execute S1023; if the determination result is no, execute S1024;

[0083] S1023, determining that the number of the first operating units meets the first load demand;

[0084] S1024: Determine whether the first number of operating units does not meet the first load demand.

[0085] In some embodiments, during implementation, in S1021, the set temperature of the unit for each cycle can be recorded and stored in a database. The actual water supply temperature of the unit can be determined based on the actual measured temperature of the current outlet water. The actual measured temperature of the current outlet water can be obtained by installing a temperature sensor in the HVAC system for real-time monitoring.

[0086] The unit temperature change rate refers to the rate of temperature change per minute in the unit, usually expressed in °C / min. This can include the cooling rate and heating rate. The cooling rate refers to the rate at which the supply water temperature decreases in the summer, while the heating rate refers to the rate at which the supply water temperature increases in the winter.

[0087] In some embodiments, in S1022, the third preset threshold and the fourth preset threshold can be determined according to the climatic conditions of the unit. By setting a suitable third preset threshold and fourth preset threshold, it can be effectively ensured that the increase in the unit's power-on is based on the trend of the unit's temperature change, rather than from short-term fluctuations in the unit.

[0088] It's worth noting that the unit count control module manages the number of operating units in the HVAC system. This module is divided into winter / summer mode and transition mode based on seasonal variations. During the transition season, the units are shut down, and the number of groundwater pumps can be adjusted accordingly based on temperature differences to achieve energy-efficient operation. In both summer and winter modes, the third and fourth preset thresholds can be set by the user based on local climate conditions, building characteristics, and historical system operation data.

[0089] In some embodiments, when the difference between the unit set temperature and the unit's actual water supply temperature is large and the unit's temperature change rate is low, it generally indicates that the HVAC system is operating stably and the difference between the unit's actual water supply temperature and the unit's set temperature is within a controllable range. In this case, the first number of operating units is sufficient to meet the system's load demand, because the system can stably maintain the set temperature and the temperature changes relatively slowly, and no additional units are needed to cope with sudden load changes. When the difference between the unit set temperature and the unit's actual water supply temperature is small, or the unit's temperature change rate is high, it may indicate a sudden increase in the system's load demand. In this case, the first number of operating units may not be able to meet the system's load demand, and the number of units must be increased to address the instability of the system's operation. Therefore, based on the difference between the unit set temperature and the unit's actual water supply temperature and the unit's temperature change rate, it is possible to more accurately determine whether the HVAC system's current operating status and the number of units are sufficient to meet the load demand.

[0090] In some embodiments, in S103, when it is determined that the first number of operating units does not meet the first load demand, the first load demand is divided by the unit power of a single unit, and then rounded up to obtain the unit demand for the current cycle. This ensures that the number of selected units is sufficient to meet the actual first load demand, thereby effectively avoiding the occurrence of insufficient number of units.

[0091] In some embodiments, as Figure 3 As shown, the aforementioned S104 may specifically include the following steps: S1041 to S1044.

[0092] S1041, obtaining the unit temperature control information of the current cycle, where the unit temperature control information includes the unit set temperature, the unit actual water supply temperature, and the unit temperature change rate.

[0093] Among them, the unit set temperature, the unit actual water supply temperature and the unit temperature change rate of the current cycle are the same as those in the aforementioned S1021. For details, please refer to the detailed description of the aforementioned S1021 and will not be repeated here.

[0094] S1042: Obtain the number of second operating units within the preset time period of the previous cycle.

[0095] The preset time period may be equal to or greater than the length of the previous cycle. The preset time period is user-defined based on actual needs and is not limited here. The second number of operating units refers to the number of units put into operation within the preset time period.

[0096] S1043, determine whether the number of the second operating units is the same as the number of the first operating units. If the judgment result is no, proceed to S1044; if the judgment result is yes, proceed to S1045.

[0097] In some embodiments, the load demand in the energy supply area of ​​the HVAC system may change, and the HVAC system may need to increase or decrease the number of units in operation to meet the load demand. If the second number of operating units is the same as the first number of operating units, it indicates that the unit demand in the energy supply area has not changed during the preset time period, indicating that the HVAC system is in a suspected steady state.

[0098] S1044, determine that the HVAC system is in an unsteady state.

[0099] S1045, determine whether the unit temperature control information meets the first preset condition, the first preset condition includes at least one of the following: the difference between the unit set temperature and the unit actual water supply temperature is less than the first preset threshold, and the unit temperature change rate is less than the second preset threshold. If the judgment result is yes, execute S1046, if the judgment result is no, execute S1044.

[0100] S1046, determine that the HVAC system is in a steady state.

[0101] The first and second preset thresholds can be customized by the user based on experience or actual needs and are not limited here. When the difference between the unit's set temperature and the unit's actual water supply temperature is less than the first preset threshold, it indicates that the HVAC system's temperature control accuracy is high and the HVAC system's output temperature is very close to the user's set temperature, indicating that the HVAC system is in a stable operating state. When the unit's temperature change rate is less than the second preset threshold, it indicates that the HVAC system's temperature fluctuations are small and the unit's temperature adjustment is stable, indicating that the HVAC system is in a stable operating state.

[0102] Steady state refers to a relatively stable HVAC system operating state, with unit demand and temperature control information consistent with expectations, without significant fluctuations or changes. Therefore, if the HVAC system is suspected to be in steady state, judging the unit temperature control information can accurately determine whether the HVAC system is in steady state, that is, whether the unit cooling capacity is balanced with the cooling load of the energy supply area, or whether the unit heating capacity is balanced with the heating load of the energy supply area.

[0103] In this embodiment of the present application, changes in unit demand can affect the heating or cooling capacity of the HVAC system. Unit temperature control information satisfying a first preset condition indicates stable unit temperature regulation. By incorporating unit temperature control information and the number of second operating units within a preset time period into the HVAC system's steady-state determination, not only is the stability of the number of HVAC system units considered, but also the stability of the HVAC system's unit operating status. This more comprehensively reflects the actual operating conditions of the HVAC system, effectively improving the accuracy of determining whether the HVAC system is in a steady-state state.

[0104] Next, in S105, as a specific example, when it is determined that the HVAC system is in a steady state, the unit demand for the current cycle can be calculated using formula (1):

[0105]

[0106] In formula (1), P cool represents the rated power of the unit, β is the actual workload factor of the unit (the value is less than 1), and ceil represents rounding up.

[0107] In S106, when it is determined that the HVAC system is in a non-steady state, the first number of operating units can be determined as the unit demand in the current cycle. The HVAC system will respond to the demand more quickly, which helps maintain the stability of the system and avoids frequent unit switching that may cause unstable system operation, thereby helping to improve efficiency, thereby maximizing the operating efficiency of the HVAC system and ensuring normal operation of the system.

[0108] In S107, adjusting the operating units in the current cycle according to the actual unit demand can effectively avoid unnecessary energy waste and improve the energy utilization efficiency of the system.

[0109] In some embodiments, as Figure 4 As shown, obtaining the first load demand of the current cycle in S101 may specifically include the following steps: S401 to S404.

[0110] S401, obtaining the second load demand of the previous cycle, the thermal load of the unit in the current cycle, and the environmental information of the energy supply area.

[0111] In some embodiments, the previous cycle may refer to the previous cycle that is closest to the current cycle, where the cycle may refer to different time units and time lengths. The HVAC system is usually equipped with a special monitoring device or system to record and store load data within each cycle. By consulting these records, the second load demand of the previous cycle can be obtained. In addition, the second load demand of the previous cycle can also be obtained through manual recording and calculation. The thermal load of the unit refers to the amount of cooling or heat provided by the refrigeration equipment or heating equipment per unit time, usually expressed in unit power, specifically, it can include the cooling capacity of the unit and the heating capacity of the unit. The environmental information of the energy supply area may include temperature information and humidity information. The environmental information of the energy supply area can be obtained through weather station data and sensor monitoring.

[0112] S402: Determine a mode of the HVAC system according to environmental information of the energy supply area.

[0113] In some embodiments, the HVAC system mode may include a summer dehumidification mode, a summer non-dehumidification mode, and a winter mode. In the summer mode, if the dew point temperature corresponding to the indoor temperature and humidity set points is greater than the outdoor ambient dew point temperature, the dehumidification mode is activated; otherwise, the non-dehumidification mode is activated.

[0114] S403 : When it is determined that the HVAC system is in a non-dehumidification mode and a steady state, the thermal load of the unit is determined as the first load demand of the current cycle.

[0115] In some embodiments, if dehumidification is required in the system, the energy consumption of the dehumidification process will also affect the overall system load. The energy consumed by the dehumidification process will increase the total thermal load of the system. Therefore, when determining the unit thermal load, the impact of the dehumidification process on the load needs to be considered to ensure the effective operation of the system. Under steady-state conditions, the system operating state is relatively stable, which means that the load demand of the current cycle is relatively stable. The unit thermal load of the current cycle can be used to approximate the first load demand of the current cycle.

[0116] S404 : When it is determined that the HVAC system is in a non-dehumidification mode and a non-steady state, the second load demand is determined as the first load demand of the current cycle.

[0117] In some embodiments, if there is no dehumidification demand in the system, the unit thermal load in the current cycle is also relatively unstable under non-steady-state conditions. In this case, the unit thermal load in the current cycle cannot be used directly to represent the first load demand in the current cycle. This may cause large load fluctuations in the system over a short period of time, increasing system operational instability. Therefore, the second load demand in the previous cycle should be determined as the first load demand in the current cycle to smooth out load fluctuations.

[0118] By monitoring the steady state of the HVAC system and implementing the corresponding plan according to the corresponding steady state to calculate the first load demand of the energy supply area in the current cycle, the current load characteristics and demand changes of the energy supply area can be predicted and met more accurately.

[0119] In some embodiments, as Figure 5 As shown, obtaining the thermal load of the unit in the current cycle in S401 may specifically include the following steps: S4011 to S4013.

[0120] S4011, obtaining the actual return water temperature, actual supply water temperature, water flow rate of the running unit in the current cycle and a first reference heat exchange amount of the running unit determined by a sensor installed on the running unit.

[0121] In some embodiments, a temperature sensor and flow meter can be installed on the operating unit to monitor the actual return water temperature, actual supply water temperature, and water flow rate of the operating unit. The actual return water temperature refers to the temperature of the water returned from the unit to the HVAC system. Specifically, it can be measured by a temperature sensor installed in the water collector at the unit's return water outlet. The actual supply water temperature refers to the temperature of the water delivered from the unit's heat source / cold source to the user end (such as a radiator / air outlet, etc.).

[0122] S4012: Determine a second reference heat exchange amount according to the actual return water temperature, the actual supply water temperature, and the water flow rate.

[0123] In some embodiments, the actual return water temperature, actual supply water temperature, and water flow rate can be acquired in real time through a data acquisition system or a control system of a heating, ventilation, and air conditioning system, and the second reference heat exchange amount Q can be calculated using formula (2):

[0124] Q=(c·m water ·(T back -T cool )) (2)

[0125] Where c is the specific heat capacity of water, T back is the actual return water temperature, T back is the actual water supply temperature, m water For water flow.

[0126] S4013: Determine the larger value of the first reference heat exchange amount and the second reference heat exchange amount as the unit thermal load of the current cycle.

[0127] In order to effectively solve the problem of uneven return water mixing in the water collector, which may lead to large deviations in return water temperature measurement, the larger value of the first reference heat exchange amount and the second reference heat exchange amount can be selected as the thermal load of the unit, thereby effectively ensuring that the system can still operate normally under the highest load, avoiding the situation where the system cannot meet the demand or malfunctions due to a sudden increase in load, so as to ensure stable system operation.

[0128] like Figure 6 As shown, in some embodiments, in S101 , obtaining the first load demand of the current cycle may include the following steps: S601 to S603 .

[0129] S601: Obtain a return air ratio of a heating, ventilation and air conditioning system, an indoor ambient air enthalpy value of a power supply area, and an outdoor ambient air enthalpy value.

[0130] The return air ratio refers to the ratio of return air volume to total supply air volume in an HVAC system, describing the proportion of return air in a room. Specifically, the return air ratio = indoor return air mass flow / total mass flow.

[0131] As a specific example, the indoor ambient air enthalpy value h of the energy supply area can be calculated by formula (3): room :

[0132] [h room ,d room ]=f(T room ,RH room ) (3)

[0133] Where, T room is the indoor temperature, RH room is the indoor relative humidity, h room is the enthalpy of indoor ambient air, d room is the indoor air humidity content, and f is the conversion function of the wet air parameters.

[0134] Based on this, the specific calculation process of the above formula (3) is as follows:

[0135] T=273.15+T room (3a)

[0136]

[0137]

[0138] h room =(1.01·T room +10 -3 ·d room ·(2501+1.84·T room))·10 3 (3d)

[0139] In one example, assuming the indoor temperature T room =a, RH room =b.

[0140] First, T room =a is substituted into formula (3a) to calculate the value of T. Then, T = a + 273.15, RH room =b is substituted into formula (3b) to calculate the value of Pq. Then, the calculated value of Pq is substituted into formula (3c) to obtain d room Finally, the calculated d room The value of T room =aSubstitute into formula (3d) and calculate h room As a specific example, the outdoor ambient air enthalpy value h of the energy supply area can be calculated by formula (4): env :

[0141] [h env ,d env ]=f(T env ,RH env ) (4)

[0142] Where, T env is the outdoor ambient temperature, RH env is the relative humidity of the outdoor environment, d env is the humidity of the outdoor environment, and f is the conversion function of the wet air parameters.

[0143] S602: Determine the mixed air enthalpy value according to the return air ratio, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value.

[0144] As a specific example, the mixed air enthalpy value h can be calculated by formula (5): mix :

[0145] h mix =α·h env +(1-α)·h room (5)

[0146] Where h mix is the mixed air enthalpy value, α is the return air ratio, h room is the enthalpy of indoor ambient air, h env is the enthalpy of the outdoor ambient air.

[0147] S603, when it is determined that the HVAC system is in dehumidification mode, determine a first load demand based on the enthalpy value of the humid air at the dew point temperature when it reaches the saturated state at the indoor temperature and humidity set value, the mass flow rate of the air entering the air conditioning system, and the mixed air enthalpy value.

[0148] As a specific example, the first load demand E of the current cycle can be determined by formula (6):

[0149] E=m air ·(h mix -h dew ) (6)

[0150] Where h dew is the enthalpy value of the wet air corresponding to the indoor temperature and humidity set value when it reaches the dew point temperature of saturation, h dew The corresponding relative humidity is 100%, m air is the mass flow rate of air entering the air conditioning system, h mix is the enthalpy of mixed air.

[0151] Combining the enthalpy of the humid air at the dew point temperature when it reaches saturation at the indoor temperature and humidity setpoint, the mass flow rate of air entering the air conditioning system, and the mixed air enthalpy can improve the accuracy of calculating the first load demand in dehumidification mode, allowing the HVAC system to respond more quickly to changes in the indoor environment.

[0152] HVAC systems in the energy supply area often use a fixed water temperature setting, where the supply water temperature (hot water outlet temperature or chilled water outlet temperature) is set to a fixed value. This setting often leads to a mismatch between the load demand in the energy supply area and the unit load, deviating from the optimal operating conditions of the HVAC system. Furthermore, the supply water temperature, which relies on manual experience, has a significant system lag and cannot respond in real time to dynamic changes in the energy supply area's load.

[0153] Based on the above reasons, Figure 7 As shown, in some embodiments, in S1021, obtaining the set temperature of the unit in the current cycle may include the following steps: S701 to S705.

[0154] S701: Obtain the return air ratio of the HVAC system, the indoor air humidity of the energy supply area, the outdoor air humidity, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value.

[0155] S702: Determine the mixed air enthalpy value according to the return air ratio, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value.

[0156] In some embodiments, the mixed air enthalpy value can be determined by the above formula (5), which will not be described in detail here.

[0157] S703: Determine the mixed air humidity content according to the return air ratio, the indoor air humidity content, and the outdoor air humidity content.

[0158] As a specific example, the indoor air humidity d can be determined by formula (3): room , determine the outdoor environment humidity d by formula (4) env The mixed air humidity d can be determined by formula (7) mix :

[0159] d mix =α·d env +(1-α)·d room (7)

[0160] Where, d env is the enthalpy of outdoor ambient air, d room is the indoor air humidity content, and α is the return air ratio.

[0161] S704: Determine the terminal air inlet temperature according to a conversion function of the mixed air moisture content, the mixed air enthalpy value, and the first wet air parameter.

[0162] As a specific example, the terminal air inlet temperature T can be determined by formula (8): mix :

[0163] T mix =g(h mix ,d mix ) (8)

[0164] Where g is the conversion function of moist air parameters, h mix is the mixed air enthalpy, d mix is the humidity content of mixed air.

[0165] In one example, the specific calculation process of the above formula (8) is as follows:

[0166]

[0167] S705: Determine the set temperature of the unit according to the terminal air inlet temperature and the first load demand.

[0168] By adjusting the unit set temperature according to the terminal air inlet temperature and the first load demand, the system can more accurately control the indoor temperature, avoid over-cooling or heating, and thus save energy consumption.

[0169] As a specific example, the unit set temperature can be determined by formula (9):

[0170]

[0171] Where E is the first load demand, is the terminal air inlet temperature, G water is the chilled water flow rate, G air is the air flow rate, Q0 is the load calibration quantity, is the inlet temperature calibration quantity, is the unit outlet water temperature calibration quantity, is the chilled water flow calibration quantity, The air flow calibration quantity.

[0172] It should be noted that the calibration part in the above formula (9) can be obtained through experimental measurement. Furthermore, after the unit set temperature is obtained, it can be output to the unit control module through first-order trajectory planning to avoid sudden changes in the unit set temperature.

[0173] Next, the control method of the HVAC system of the present application will be further explained in conjunction with a specific implementation scenario.

[0174] In this embodiment, it is assumed that the summer cooling rate threshold is set to Y = 0.03°C / min, the actual workload factor of the unit is β = 0.85, and the return air ratio is α = 0.15.

[0175] like Figure 8 As shown in the figure, from top to bottom are the outdoor temperature and humidity curve, the indoor temperature and humidity curve, the unit cooling temperature set value and estimated load curve, the system total energy consumption curve, and the human comfort index curve. In the calculation method of the estimated load, the unit thermal load is determined as the first load demand of the current cycle, which is method A, and the second load demand of the previous cycle is determined as the first load demand of the current cycle, which is method B. Figure 8 It can be seen that the estimated load is updated when the steady-state assumption is reached. After the building load increases, the unit number module determines whether to add units.

[0176] Through actual building measurements, the algorithm can save energy by about 20% in an environment with a maximum outdoor temperature of 32°C in summer.

[0177] Based on the control method of the HVAC system provided in the above embodiment, the present application also provides a specific implementation of the control device of the HVAC system. Please refer to the following embodiments.

[0178] like Figure 9 As shown, a control device 900 of a heating, ventilation and air conditioning system provided in an embodiment of the present application may include:

[0179] The first acquisition module 901 is configured to acquire the first load demand of the current cycle, the unit status information, and the number of first operating units in the previous cycle that is before the current cycle and closest to the current cycle;

[0180] A first determining module 902 is configured to determine the unit demand for the current cycle according to the first load demand and the unit state information when it is determined that the number of the first operating units meets the first load demand and the HVAC system is in a steady state;

[0181] A second determining module 903 is configured to determine the first number of operating units as the unit demand for the current cycle when it is determined that the first number of operating units meets the first load demand and the HVAC system is in an unsteady state;

[0182] The adjustment module 904 is used to adjust the operating units in the current cycle according to the unit demand.

[0183] The HVAC system control device provided in the embodiment of the present application uses a first acquisition module 901 to obtain the first load demand and unit status information of the current cycle in real time. When the first number of operating units meets the first load demand and the HVAC system is operating smoothly, the first determination module 902 adjusts the unit demand based on the actual first load demand and unit status information, thereby facilitating a unit demand that is more suitable for the actual load demand. When the first number of operating units meets the first load demand and the HVAC system is operating unsteadily, the second determination module 903 uses the first number of operating units from the previous cycle as the operating units for the current cycle, thereby maintaining system stability and preventing frequent unit switching that can lead to unstable system operation. Furthermore, the adjustment module 904 adjusts the operating units for the current cycle based on the unit demand, ensuring that the HVAC system responds quickly to load changes and more accurately matches actual demand. This addresses the inability of conventional methods to flexibly adjust the number of units. This dynamic adjustment of the number of units increases the likelihood that the number of operating units matches actual demand, effectively improving the operating efficiency of the HVAC system.

[0184] As an implementation of the present application, in order to more accurately determine whether the current operating status of the HVAC system and the number of units are sufficient to meet the load demand, the control device may further include:

[0185] The second acquisition module is used to obtain the unit temperature control information of the current cycle, the unit temperature control information including the unit set temperature, the unit actual water supply temperature and the unit temperature change rate, and obtain the number of second operating units in the preset time period of the previous cycle;

[0186] The third determination module is used to determine that the HVAC system is in a steady state when the number of the second operating units is the same as the number of the first operating units and the unit temperature control information meets a first preset condition. The first preset condition includes at least one of the following: the difference between the unit set temperature and the actual water supply temperature of the unit is less than a first preset threshold, and the unit temperature change rate is less than a second preset threshold.

[0187] As an implementation of the present application, in order to accurately determine whether the HVAC system is in a steady state, the control device may further include:

[0188] The third acquisition module is used to obtain the unit set temperature, the unit actual water supply temperature and the unit temperature change rate of the current cycle;

[0189] The fourth determination module is used to determine whether the first number of operating units meets the first load demand when the difference between the unit set temperature and the unit actual water supply temperature is greater than the third preset threshold and the unit temperature change rate is lower than the fourth preset threshold.

[0190] As an implementation of the present application, in order to reasonably configure the number of units and more efficiently utilize energy, the control device may also include:

[0191] The fourth determining module is used to determine the unit demand of the current cycle according to the first load demand and the unit power of a single unit when it is determined that the number of the first operating units does not meet the first load demand.

[0192] As an implementation of the present application, in order to more accurately predict and meet the current load characteristics and demand changes in the energy supply area, the first acquisition module 901 may include:

[0193] The first acquisition submodule is used to obtain the second load demand of the previous cycle, the thermal load of the unit in the current cycle, and the environmental information of the energy supply area;

[0194] A first determining submodule is configured to determine the unit thermal load as the first load demand of the current cycle when it is determined that the HVAC system is in a non-dehumidification mode and a steady state;

[0195] The second determining submodule is configured to determine the second load demand as the first load demand of the current cycle when it is determined that the HVAC system is in a non-dehumidification mode and a non-steady state.

[0196] As an implementation of the present application, in order to effectively solve the problem of uneven mixing of return water in the water collector, the first acquisition submodule may specifically include:

[0197] an acquisition unit, configured to acquire an actual return water temperature, an actual supply water temperature, a water flow rate of the running unit in the current cycle, and a first reference heat exchange amount of the running unit determined by a sensor installed on the running unit;

[0198] a first determining unit, configured to determine a second reference heat exchange amount according to an actual return water temperature, an actual supply water temperature, and a water flow rate;

[0199] The second determining unit is configured to determine the larger value of the first reference heat exchange amount and the second reference heat exchange amount as the unit thermal load of the current cycle.

[0200] As an implementation of the present application, in order to more quickly respond to changes in the indoor environment, the first acquisition module 901 may include:

[0201] The second acquisition submodule is used to obtain the return air ratio of the HVAC system, the indoor ambient air enthalpy value of the energy supply area, and the outdoor ambient air enthalpy value;

[0202] a third determining submodule, configured to determine a mixed air enthalpy value according to a return air ratio, an indoor ambient air enthalpy value, and an outdoor ambient air enthalpy value;

[0203] The fourth determination submodule is configured to determine the first load demand E of the current cycle according to the following expression when it is determined that the HVAC system is in the dehumidification mode:

[0204] E=m air ·(h mix -h dew )

[0205] Where h dew is the enthalpy value of the wet air corresponding to the indoor temperature and humidity set value when it reaches the dew point temperature of saturation, m air is the mass flow rate of air entering the air conditioning system, h mix is the enthalpy of mixed air.

[0206] As an implementation of the present application, in order to more accurately control the indoor temperature, avoid excessive cooling or heating, and thus save energy consumption, the second acquisition module may include:

[0207] The third acquisition submodule is used to obtain the return air ratio of the HVAC system, the indoor air humidity content of the energy supply area, the outdoor air humidity content, the indoor ambient air enthalpy value and the outdoor ambient air enthalpy value;

[0208] a fifth determining submodule, configured to determine a mixed air enthalpy value according to a return air ratio, an indoor ambient air enthalpy value, and an outdoor ambient air enthalpy value;

[0209] a sixth determining submodule, configured to determine a mixed air humidity content according to a return air ratio, indoor air humidity content, and outdoor air humidity content;

[0210] a seventh determination submodule, configured to determine the terminal air inlet temperature according to a conversion function of the mixed air moisture content, the mixed air enthalpy value, and the first wet air parameter;

[0211] The eighth determination submodule is configured to determine the set temperature of the unit according to the terminal air inlet temperature and the first load demand.

[0212] As an implementation of the present application, the eighth determination submodule is used to solve the unit set temperature according to the following expression:

[0213]

[0214] Where E is the first load demand, is the terminal air inlet temperature, G water is the chilled water flow rate, G air is the air flow rate, Q0 is the load calibration quantity, is the inlet temperature calibration quantity, is the unit outlet water temperature calibration quantity, is the chilled water flow calibration quantity, The air flow calibration quantity.

[0215] Based on the same inventive concept, an embodiment of the present application also provides an electronic device.

[0216] Figure 10 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application is shown.

[0217] The electronic device may include a processor 1001 and a memory 1002 storing computer program instructions.

[0218] Specifically, the processor 1001 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0219] The memory 1002 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 1002 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory 1002 may include removable or non-removable (or fixed) media. Where appropriate, the memory 1002 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 1002 is a non-volatile solid-state memory.

[0220] The memory 1002 may include read-only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical or other physical / tangible memory storage devices. Thus, generally, the memory 1002 includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0221] The processor 1001 reads and executes computer program instructions stored in the memory 1002 to implement any one of the control methods for the HVAC system in the above embodiments.

[0222] In one example, the electronic device may further include a communication interface 1003 and a bus 1010. Figure 10 As shown, the processor 1001, the memory 1002, and the communication interface 1003 are connected via a bus 1010 and communicate with each other.

[0223] The communication interface 1003 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0224] Bus 1010 comprises hardware, software or both, couples the parts of electronic equipment to each other.For example, and not limitation, bus can comprise accelerated graphics port (AGP) or other graphics bus, enhanced industry standard architecture (EISA) bus, front side bus (FSB), hypertransport (HT) interconnection, industry standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory bus, micro channel architecture (MCA) bus, peripheral component interconnection (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations.In suitable cases, bus 1010 can comprise one or more buses.Although the present application embodiment describes and shows specific bus, the application considers any suitable bus or interconnection.

[0225] The electronic device can execute the control method of the HVAC system in the embodiment of the present application, thereby realizing the combination Figure 1 and Figure 9 A method and apparatus for controlling a heating, ventilation and air conditioning system are described.

[0226] In addition, in conjunction with the HVAC system control method in the above embodiments, embodiments of the present application may provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when the computer program instructions are executed by a processor, any of the HVAC system control methods in the above embodiments is implemented.

[0227] In addition, the present application also provides a computer program product, which includes a computer program. When the computer program is processed and executed, it implements the aforementioned control method for the HVAC system.

[0228] It should be understood that the present application is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of the present application is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present application.

[0229] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0230] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps. In other words, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0231] Aspects of the present disclosure have been described above with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the function / action specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor or a field programmable logic circuit. It is also understood that each box in the block diagram and / or flowchart and the combination of the boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0232] The above description is only a specific embodiment of the present application. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A method for controlling a heating, ventilation and air conditioning system, characterized in that: The method comprises: Obtaining a first load demand for a current cycle, unit status information, the number of first operating units in the previous cycle that is immediately before the current cycle and closest to the current cycle, unit temperature control information for the current cycle, and the number of second operating units within a preset time period to which the previous cycle belongs, wherein the unit temperature control information includes a set unit temperature, an actual unit water supply temperature, and a rate of change of unit temperature; When the number of the second operating units is the same as the number of the first operating units and the unit temperature control information satisfies a first preset condition, determining that the HVAC system is in a steady state, the first preset condition comprising at least one of the following: a difference between a set unit temperature and an actual water supply temperature of the unit is less than a first preset threshold, and a rate of change of the unit temperature is less than a second preset threshold; Obtain the unit set temperature, unit actual water supply temperature and unit temperature change rate of the current cycle; When the difference between the set temperature of the unit and the actual water supply temperature of the unit is greater than a third preset threshold and the rate of change of the temperature of the unit is lower than a fourth preset threshold, determining that the first number of operating units meets the first load demand; When it is determined that the first number of operating units meets the first load demand and the HVAC system is in a steady state, determining the unit demand for the current cycle according to the first load demand and the unit status information; When it is determined that the first number of operating units meets the first load demand and the HVAC system is in a non-steady state, determining the first number of operating units as the unit demand for the current cycle; Adjust the operating units in the current cycle according to the unit demand.

2. The method according to claim 1, characterized in that The method further comprises: When it is determined that the first number of operating units does not meet the first load demand, the unit demand for the current cycle is determined according to the first load demand and the unit power of a single unit.

3. The method according to claim 1 or 2, characterized in that The obtaining of the first load demand of the current cycle includes: Obtaining the second load demand of the previous cycle, the unit thermal load of the current cycle, and environmental information of the energy supply area; When it is determined that the HVAC system is in a non-dehumidification mode and a steady state, the thermal load of the unit is determined as the first load demand of the current cycle; When it is determined that the HVAC system is in a non-dehumidification mode and a non-steady state, the second load demand is determined as the first load demand of the current cycle.

4. The method according to claim 3, characterized in that The obtaining of the unit thermal load of the current cycle includes: Acquire an actual return water temperature, an actual supply water temperature, a water flow rate of the running unit in the current cycle, and a first reference heat exchange amount of the running unit determined by a sensor installed on the running unit; determining a second reference heat exchange amount according to the actual return water temperature, the actual supply water temperature, and the water flow rate; The larger value of the first reference heat exchange amount and the second reference heat exchange amount is determined as the thermal load of the unit in the current cycle.

5. The method according to claim 1 or 2, characterized in that The obtaining of the first load demand of the current cycle includes: Obtaining a return air ratio of the HVAC system, an indoor ambient air enthalpy value of a power supply area, and an outdoor ambient air enthalpy value; Determining a mixed air enthalpy value according to the return air ratio, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value; When it is determined that the HVAC system is in dehumidification mode, the first load demand of the current cycle is determined according to the following expression: : Where, is the enthalpy value of the wet air corresponding to the indoor temperature and humidity set value when it reaches the dew point temperature of the saturated state, is the mass flow rate of air entering the air conditioning system, is the enthalpy of mixed air.

6. The method according to claim 1, characterized in that The obtaining of the set temperature of the unit in the current cycle includes: Obtaining the return air ratio of the HVAC system, the indoor air humidity content of the energy supply area, the outdoor air humidity content, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value; Determining a mixed air enthalpy value according to the return air ratio, the indoor ambient air enthalpy value, and the outdoor ambient air enthalpy value; determining a mixed air humidity content according to the return air ratio, the indoor air humidity content, and the outdoor air humidity content; determining a terminal air inlet temperature according to a conversion function of the mixed air moisture content, the mixed air enthalpy value, and a first wet air parameter; The unit set temperature is determined according to the terminal air inlet temperature and the first load demand.

7. The method according to claim 6, characterized in that Determining the unit set temperature according to the terminal air inlet temperature and the first load demand includes: Solve the unit set temperature according to the following expression : Where, is the first load demand, is the terminal air inlet temperature, is the chilled water flow, is the air flow rate, is the load calibration quantity, is the inlet temperature calibration quantity, is the unit outlet water temperature calibration quantity, is the chilled water flow calibration quantity, The air flow calibration quantity.

8. A control device for a heating, ventilation and air conditioning system, characterized in that: The device comprises: A first acquisition module is configured to acquire a first load demand of a current cycle, unit status information, the number of first operating units in a previous cycle that is immediately before the current cycle and closest to the current cycle, unit temperature control information of the current cycle, and the number of second operating units in a preset time period to which the previous cycle belongs, wherein the unit temperature control information includes a set unit temperature, an actual water supply temperature of the unit, and a rate of change of unit temperature; a third determining module, configured to determine that the HVAC system is in a steady state when the number of the second operating units is the same as the number of the first operating units and the unit temperature control information satisfies a first preset condition, the first preset condition comprising at least one of the following: a difference between a set temperature of the unit and an actual water supply temperature of the unit is less than a first preset threshold, and a rate of change of the unit temperature is less than a second preset threshold; The third acquisition module is used to obtain the unit set temperature, the unit actual water supply temperature and the unit temperature change rate of the current cycle; a fourth determining module, configured to determine that the first number of operating units meets the first load demand if the difference between the set unit temperature and the actual water supply temperature of the unit is greater than a third preset threshold and the rate of change of the unit temperature is less than a fourth preset threshold; and a first determining module, configured to determine the unit demand for the current cycle based on the first load demand and the unit status information if it is determined that the first number of operating units meets the first load demand and the HVAC system is in a steady state; a second determining module, configured to, when it is determined that the first number of operating units meets the first load demand and the HVAC system is in an unsteady state, determine the first number of operating units as the unit demand for the current cycle; The adjustment module is used to adjust the operating units in the current cycle according to the demand of the units.

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