Automatic control method and system for cooling and heating system

Abstract

The present invention discloses an automatic control method and system for a cooling and heating system, the method comprising: collecting the temperature and flow parameters of the end user, controlling the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and flow parameters, and feeding back the current temperature and flow parameters of the end user to the energy station; determining the supply and return water temperature difference that meets the load requirements of the end user, and determining the pipe network operating temperature difference of the cooling and heating system according to the supply and return water temperature difference; the energy station adjusts the outlet temperature of the refrigerator according to the pipe network operating network temperature difference, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user. The present invention can accurately control the terminal return water temperature, and on the premise of meeting the end user load, improve the overall operating temperature difference of the partial load pipe network and reduce the circulating water flow. At the same time, the present invention improves the water supply temperature of the pipe network under partial load, that is, increases the outlet temperature of the refrigeration host, and improves the operating energy efficiency of the refrigeration host.

Description

Technical Field

[0001] The present invention relates to the technical field of energy saving, and in particular to an automatic control method and system for cooling and heating systems. Background Art

[0002] The energy transfer of large-scale centralized cooling / heating systems mainly uses chilled / high-temperature water as a medium, and distributes energy through heat exchange at the energy demand side heat exchanger to meet the temperature control requirements of the demand side. The following introduces this control method using centralized cooling as an example. Large-scale centralized cooling systems have many end users and may have hundreds of end heat exchangers. However, these heat exchangers have large differences in distance from the cold source (refrigeration host), load size, and hydraulic loss. In order to meet the requirements of all users in the system, the equipment selection in the design stage of the cooling system is based on the hydraulic loss and cooling demand of the most disadvantaged user. According to the current increasingly high energy consumption requirements for buildings, centralized cooling and other systems, the hydraulic transmission system and refrigeration system also need to take corresponding energy-saving measures, such as the use of energy-saving equipment and high-efficiency units, and a more intelligent control system in the system control strategy.

[0003] At present, the control of hydraulic transmission, water temperature and flow rate in the chilled water system of the HVAC industry during operation is mainly based on the premise of meeting the pressure and cooling capacity of the most unfavorable users to formulate the temperature and flow control strategy of the entire chilled water. Although this method can meet the system operation requirements under various working conditions, the energy-saving effect is not good and there is still much room for improvement.

[0004] Therefore, the prior art still needs to be improved and enhanced. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an automatic control method and system for a cooling and heating system in view of the above-mentioned defects of the prior art, aiming to solve the problem of poor energy-saving effect in the control methods of hydraulic transportation, water temperature and flow in the prior art.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides an automatic control method for a cooling and heating system, wherein the method comprises:

[0008] Collect the temperature and flow parameters of the end user, control the regulating valve and the mixing pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station;

[0009] Determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference;

[0010] The energy station adjusts the outlet temperature of the refrigerator according to the temperature difference of the pipeline network, and controls the flow and lift of the delivery pump based on the current temperature and flow parameters of the end user.

[0011] In one implementation, controlling the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameter includes:

[0012] Obtaining the return water temperature of the end user, and comparing the return water temperature with a preset return water temperature value;

[0013] If the return water temperature is different from the preset value, controlling the regulating valve;

[0014] The regulating flow of the regulating valve is obtained, and the mixing water pump is controlled according to the regulating flow.

[0015] In one implementation, controlling the water mixing pump according to the adjusted flow rate includes:

[0016] If the regulated flow rate is lower than 30% of the rated flow rate of the single regulating valve, the mixing water pump is started.

[0017] In one implementation, the calculation formula for the supply and return water temperature difference of the load demand of the end user is:

[0018]

[0019] Among them, T h Indicates the chilled water return temperature; T g represents the chilled water supply temperature; ΔT represents the chilled water inlet and outlet temperature difference; Q represents the chilled water flow rate; W d Represents the actual load of the user; K represents the specific heat capacity of chilled water.

[0020] In one implementation, determining the pipe network operating temperature difference of the cooling and heating system according to the supply and return water temperature difference includes:

[0021] Determine the most disadvantaged user according to the supply and return water temperature difference, wherein the most disadvantaged user is the user with the largest supply and return water temperature difference;

[0022] The supply and return water temperature difference of the most disadvantageous user is used as the operating temperature difference of the pipeline network.

[0023] In one implementation, the energy station adjusts the outlet temperature of the refrigerator according to the temperature difference of the pipeline network, including:

[0024] The outlet temperature of the refrigerator is obtained by subtracting the temperature difference of the pipe network from the preset return water temperature value.

[0025] In one implementation, the control of the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user includes:

[0026] Determining a total flow rate based on a current flow rate parameter of the end user;

[0027] The number of delivery pumps is determined according to the total flow rate.

[0028] In one implementation, the controlling the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user includes: determining the load combination information of the end user based on the current temperature and flow rate parameters of the end user;

[0029] The lift of the delivery pump is controlled according to the load combination information.

[0030] In a second aspect, an embodiment of the present invention further provides an automatic control system for a cooling and heating system, wherein the system comprises: a terminal control module, which is used to collect temperature and flow parameters of the end user, control the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station;

[0031] A data processing module, used to determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference;

[0032] The energy station control module is used to determine that the energy station adjusts the outlet temperature of the refrigerator according to the temperature difference of the pipeline network, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user.

[0033] In a third aspect, an embodiment of the present invention further provides a control terminal, which includes a memory, a processor, and an automatic control program for a cooling and heating system stored in the memory and executable on the processor. When the processor executes the automatic control program for the cooling and heating system, the steps of the automatic control method for the cooling and heating system as in any one of the above-mentioned schemes are implemented.

[0034] Beneficial effects: Compared with the prior art, the present invention provides an automatic control method for a cooling and heating system. The present invention collects the temperature and flow parameters of the end user, controls the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameters, and feeds back the current temperature and flow parameters of the end user to the energy station. Then, the supply and return water temperature difference that meets the load demand of the end user is determined, and the pipe network operating temperature difference of the cooling and heating system is determined according to the supply and return water temperature difference. Finally, the energy station adjusts the outlet temperature of the refrigerator according to the pipe network operating network temperature difference, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user. The present invention can accurately control the terminal return water temperature, and on the premise of meeting the end user load, improve the overall operating temperature difference of the partial load pipe network and reduce the circulating water flow. At the same time, the present invention improves the water supply temperature of the pipe network under partial load, that is, increases the outlet temperature of the refrigeration host, and improves the operating energy efficiency of the refrigeration host. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a specific implementation of the automatic control method for a cooling and heating system provided in an embodiment of the present invention.

[0036] Figure 2 This is a flow control diagram for end users in the automatic control method for a cooling and heating system provided in an embodiment of the present invention.

[0037] Figure 3 This is a diagram of the hydraulic characteristics of the pipe network in the automatic control method of the cooling and heating system provided in an embodiment of the present invention.

[0038] Figure 4 This is a principle block diagram of a data processing module in an automatic control system of a cooling and heating system provided in an embodiment of the present invention.

[0039] Figure 5 A functional block diagram of a control terminal provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] At present, the chilled water system in the HVAC industry has the following modes for hydraulic transmission and water temperature control during operation:

[0042] In terms of chilled water supply and return temperature: the chilled water return temperature is constant at 12°C, and the supply water temperature is generally set to 3°C or 6.5°C. Select a higher / lower supply water temperature according to the user's load size. Generally, if the chilled water outlet temperature of the refrigeration host increases by 1°C, the host efficiency will increase by about 3%. There are only two supply water temperatures, which is not conducive to energy saving under partial load.

[0043] There are two methods for flow control:

[0044] A pressure detection point is set at the inlet main pipe of the chilled water circulation pump. According to the hydraulic characteristics of the chilled water system, a pressure setting value is pre-set to control the operating characteristics of the chilled water delivery pump to meet the preset pressure setting requirements at the return main pipe. This method is characterized by a simple control system, few measuring points, and simple logic, but it does not reflect the hydraulic conditions and cooling demand at the specific end, so the energy saving performance is poor. This method is generally suitable for building central air-conditioning systems or small centralized cooling substations.

[0045] The pressure difference / temperature detection point is set at the chilled water inlet / outlet position of the heat exchange end of the end user, and the operating characteristics of the circulating water pump are to meet the hydraulic pressure head demand / cooling capacity of the most unfavorable user among all the end users as its operating condition point. The characteristics of this control method are that there are more measurement points, the system is more complex, and the control logic is more complex, but the control is also more accurate and energy-saving.

[0046] In order to solve the problems in the prior art, this embodiment provides an automatic control method for a cooling and heating system. Based on the method of this embodiment, the regulating valve and the mixing water pump can be controlled to achieve precise control of the return water temperature of the end user, thereby achieving energy saving. This embodiment can collect the temperature and flow parameters of the end user, and determine the supply and return water temperature difference that meets the load demand of the end user based on the temperature and the flow parameters. Then, based on the supply and return water temperature difference, the pipe network operating temperature difference of the cooling and heating system is determined, and a control signal is output based on the pipe network operating temperature difference; finally, based on the control signal, the regulating valve and the mixing water pump in the cooling and heating system are controlled.

[0047] Exemplary Methods

[0048] The method of this embodiment can be applied to a terminal device, which can be a control terminal. The control terminal can execute the automatic control method of the cooling and heating system. Specifically, the control terminal can be an intelligent device such as a computer, such as Figure 1 As shown in , when the control terminal executes the automatic control method of the cooling and heating system, it includes the following steps:

[0049] Step S100, collecting the temperature and flow parameters of the end user, controlling the regulating valve and the mixing pump in the cooling and heating system according to the temperature and the flow parameters, and feeding back the current temperature and flow parameters of the end user to the energy station.

[0050] The automatic control system of the cooling and heating system of this embodiment is provided with a data acquisition module, which can collect the temperature and flow parameters of each end user in the automatic control system of the cooling and heating system. After collecting the temperature and the flow parameters, this embodiment can control the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameters.

[0051] In one implementation, step S100 in this embodiment specifically includes:

[0052] Step S101, obtaining the return water temperature of the end user, and comparing the return water temperature with a preset return water temperature value;

[0053] Step S102: If the return water temperature is different from the preset value, the regulating valve is controlled;

[0054] Step S103: acquiring the regulating flow of the regulating valve, and controlling the water mixing pump according to the regulating flow.

[0055] Specifically, the return water temperature of the end user is obtained, and then the return water temperature is compared with a preset return water temperature value. If the return water temperature is different from the preset value, the regulating valve is controlled. The purpose of this embodiment is to control the return water temperature of the end user to remain stable.

[0056] Therefore, if the collected return water temperature of the heat exchanger is different from the set return water temperature value (such as 12°C), Figure 2The regulating device in the embodiment is adjusted to adjust the outlet temperature of the refrigerator to reach the set return water temperature. Specifically, the data processing module of the present embodiment is a PLC control component. After receiving the control signal, the PLC control component can control the regulating valve and the mixing water pump in the cooling and heating system, so as to maintain the system return water temperature at a set value, such as 12°C. A centralized cooling system in the present embodiment is composed of multiple terminals, each of which is independently controlled on site. When adjusting, the present embodiment first uses the regulating valve to adjust the flow rate and obtains the regulating flow rate of the regulating valve. If the regulating valve has been adjusted and can no longer meet the control accuracy requirements (such as when the regulating flow rate is less than 30%), the mixing water pump is started and controlled. In other words, the operating flow rate of the mixing water pump satisfies the flow rate of the regulating valve by more than 30%. The present embodiment feeds back the current temperature and flow parameters of the end user to the energy station so as to control the energy station.

[0057] Step S200: determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference.

[0058] Specifically, after collecting and analyzing the temperature and flow parameters transmitted by each end user, this embodiment summarizes the temperature, flow parameters and other information of the end user, and then calculates the supply and return water temperature difference that meets the load demand of the end user, specifically as follows:

[0059]

[0060] Among them, T h Indicates the chilled water return temperature; T g represents the chilled water supply temperature; ΔT represents the chilled water inlet and outlet temperature difference; Q represents the chilled water flow rate; W d Represents the actual load of the user; K represents the specific heat capacity of chilled water.

[0061] After determining the supply and return water temperature difference that meets the load demand of the end user, this embodiment determines the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference. The pipe network operating temperature difference is the temperature difference allowed by the pipe network of the cooling and heating system.

[0062] In one implementation, this embodiment includes the following steps when determining the operating temperature difference of the pipe network:

[0063] Step S201, determining the most disadvantaged user according to the supply and return water temperature difference, wherein the most disadvantaged user is the user with the largest supply and return water temperature difference;

[0064] Step S202: Taking the supply and return water temperature difference of the most disadvantageous user as the operating temperature difference of the pipe network.

[0065] Specifically, when determining the operating temperature difference of the pipe network, this embodiment first determines the supply and return water temperature difference that meets the load demand of the end user, compares the supply and return water temperature differences of each end user, determines the user with the largest supply and return water temperature difference, that is, obtains the most disadvantaged user, and then uses the supply and return water temperature difference of the most disadvantaged user as the operating temperature difference of the pipe network. In specific applications, due to the hysteresis of large-scale centralized cooling water supply, this embodiment reserves a certain temperature difference margin.

[0066] ΔT w =ΔT max +T

[0067] Where, ΔT w is the allowable temperature difference of the pipe network, ΔT max , the most unfavorable user temperature difference, T is the temperature margin.

[0068] The temperature difference margin in this embodiment has different values ​​according to different pipe network lengths, and is generally taken as 0.3°C / km.

[0069] Step S300: The energy station adjusts the outlet temperature of the refrigerator according to the temperature difference of the pipeline network, and controls the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user.

[0070] This embodiment determines the outlet temperature of the refrigerator according to the operating temperature difference of the pipeline network. Specifically, the outlet temperature of the refrigerator is obtained by subtracting the operating network temperature difference of the pipeline network from the preset return water temperature value to adjust the outlet temperature. Next, the energy station of this embodiment also determines the total flow rate based on the current flow rate parameters of the end user. Then, the number of delivery pumps is determined based on the total flow rate. In addition, this embodiment also determines the load combination information of the end user based on the current temperature and flow parameters of the end user. Then, the head of the delivery pump is controlled based on the load combination information.

[0071] In specific applications, this embodiment calculates the hydraulic characteristics of all possible operating conditions of the chilled water system according to the layout of pipelines and equipment and the operating conditions of the hydraulic system. The hydraulic operating condition characteristics are the hydraulic characteristic distribution of each end user under any combination of 0-100% load, such as Figure 3 As shown. Figure 3It can be seen that each flow corresponds to multiple resistance points, or each resistance point corresponds to multiple flows. This is because there are many end users and their distribution positions are different. Under different cold load combinations, even if the flow is the same, it corresponds to multiple different pipe network resistances, so the hydraulic characteristics of the entire pipe network drawn are a regional graph. Specifically, this embodiment determines the load combination information of the end user based on the current temperature and flow parameters of the end user, and determines the pipe network hydraulic characteristics corresponding to the load combination. The pipe network hydraulic characteristics reflect the corresponding relationship between the load and the pipe network resistance. Then, this embodiment determines the operating performance point required by the delivery pump based on the pipe network hydraulic characteristics. Finally, the running number, speed and frequency of the delivery pump are calculated based on the running performance point, and the delivery pump is controlled to run at the calculated running number, speed and frequency. In specific applications, this embodiment is based on the principle that the pump has the highest efficiency at the rated point, and the single pump is maintained as close to the rated point as possible. And the system operating flow Q is divided by the single pump flow Qd, and the result is rounded up to the integer value, which is the number of running water pumps n. The speed and frequency are calculated as follows:

[0072] The operating speed of the water pump N = rated speed × (actual flow / rated flow).

[0073] The operating frequency of the water pump f = rated frequency × (actual flow / rated flow).

[0074] It can be seen that this embodiment can achieve accurate control of the return water temperature of the end user and reduce the circulating water volume of the pipe network. In addition, the water supply temperature of the refrigeration host meets the temperature difference of the most unfavorable load user. In addition, this embodiment also controls the operating point of the water pump according to the measured load combination of the end user based on the hydraulic characteristic curve of the pipe network under different load combinations of the end user calculated in advance, so as to achieve energy saving.

[0075] This embodiment can obtain the appropriate operating point of the delivery pump that satisfies all users according to the different load combinations of the end users, reduce the operating energy consumption, and improve the overall COP. In addition, this embodiment adds a few devices and instruments on the existing basis, and does not change the existing system and equipment. The investment cost is low and the changes are small. This embodiment also establishes a user load collection and analysis system, which can detect and record the user's cold load operation status in real time, providing conditions for predicting the cold storage capacity and prejudging the operation measurement in the future.

[0076] Exemplary Systems

[0077] Based on the above embodiments, the present invention also provides an automatic control system for a cooling and heating system. Figure 4As shown in , the system includes: a terminal control module 10, a data processing module 20, and an energy station control module 30. Specifically, the terminal control module 10 is used to collect the temperature and flow parameters of the end user, control the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station. The data processing module 20 is used to determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system according to the supply and return water temperature difference. The energy station control module 30 is used to determine that the energy station adjusts the outlet temperature of the refrigerator according to the pipe network operating network temperature difference, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user.

[0078] In one implementation, the terminal control module 10 includes:

[0079] A temperature comparison unit, used to obtain the return water temperature of the end user and compare the return water temperature with a preset return water temperature value;

[0080] A regulating valve control unit, used for controlling the regulating valve if the return water temperature is different from the preset value;

[0081] The mixing water pump control unit is used to obtain the regulated flow of the regulating valve and control the mixing water pump according to the regulated flow.

[0082] In one implementation, the mixing pump control unit includes:

[0083] The control subunit is used to start the mixing water pump if the regulated flow rate is lower than 30%.

[0084] In one implementation, the calculation formula for the supply and return water temperature difference of the load demand of the end user is:

[0085]

[0086] Among them, T h Indicates the chilled water return temperature; T g represents the chilled water supply temperature; ΔT represents the chilled water inlet and outlet temperature difference; Q represents the chilled water flow rate; W d Represents the actual load of the user; K represents the specific heat capacity of chilled water.

[0087] In one implementation, the data processing module 20 includes:

[0088] A most disadvantageous user determination unit, used for determining the most disadvantageous user according to the supply and return water temperature difference, wherein the most disadvantageous user is the user with the largest supply and return water temperature difference;

[0089] The pipe network operation temperature difference determination unit is used to use the supply and return water temperature difference of the most disadvantageous user as the pipe network operation temperature difference.

[0090] In one implementation, the pipe network operating temperature difference determination unit includes:

[0091] The calculation subunit is used to obtain the outlet temperature of the refrigerator by subtracting the temperature difference of the pipe network from the preset return water temperature value.

[0092] In one implementation, the energy station control module 30 includes:

[0093] A traffic sum determination unit, configured to determine the traffic sum based on the current traffic parameters of the end user;

[0094] A pump quantity determination unit, used for determining the quantity of delivery pumps according to the total flow rate;

[0095] A load combination determination unit, configured to determine load combination information of an end user based on current temperature and flow parameters of the end user;

[0096] A lift control unit is used to control the lift of the delivery pump according to the load combination information.

[0097] The working principles of each module in the automatic control system of the cooling and heating system of this embodiment are the same as the principles of each step in the above method embodiment, and will not be repeated here.

[0098] Based on the above embodiment, the present invention further provides a control terminal, the principle block diagram of the control terminal can be as follows: Figure 5 As shown. The control terminal includes a processor and a memory connected through a system bus, and the processor and the memory are arranged in a host. Among them, the processor of the control terminal is used to provide computing and control capabilities. The memory of the control terminal includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the control terminal is used to communicate with an external terminal through a network communication connection. When the computer program is executed by the processor, an automatic control method for a cooling and heating system is implemented.

[0099] Those skilled in the art will understand that Figure 5 The principle block diagram shown in the figure is only a block diagram of a partial structure related to the scheme of the present invention, and does not constitute a limitation on the control terminal to which the scheme of the present invention is applied. The specific control terminal may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0100] In one embodiment, a control terminal is provided, the control terminal comprising a memory, a processor, and an automatic control method program for a cooling and heating system stored in the memory and executable on the processor. When the processor executes the automatic control method program for the cooling and heating system, the following operation instructions are implemented:

[0101] Collect the temperature and flow parameters of the end user, control the regulating valve and the mixing pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station;

[0102] Determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference;

[0103] The energy station adjusts the outlet temperature of the refrigerator according to the temperature difference of the pipeline network, and controls the flow and lift of the delivery pump based on the current temperature and flow parameters of the end user.

[0104] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, operating database or other media used in the embodiments provided by the present invention may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double operational data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0105] In summary, the present invention discloses an automatic control method and system for a cooling and heating system, the method comprising: collecting the temperature and flow parameters of the end user, controlling the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and flow parameters, and feeding back the current temperature and flow parameters of the end user to the energy station; determining the supply and return water temperature difference that meets the load requirements of the end user, and determining the pipe network operating temperature difference of the cooling and heating system according to the supply and return water temperature difference; the energy station adjusts the outlet temperature of the refrigerator according to the pipe network operating network temperature difference, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user. The present invention can accurately control the terminal return water temperature, and on the premise of meeting the end user load, improve the overall operating temperature difference of the partial load pipe network and reduce the circulating water flow. At the same time, the present invention improves the water supply temperature of the pipe network under partial load, that is, increases the outlet temperature of the refrigeration host, and improves the operating energy efficiency of the refrigeration host.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic control method for a cooling and heating system, It is characterized in that The method comprises: Collect the temperature and flow parameters of the end user, control the regulating valve and the mixing pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station; Determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference; The energy station adjusts the outlet temperature of the refrigerator according to the operating temperature difference of the pipeline network, and controls the flow rate and head of the delivery pump based on the current temperature and flow rate parameters of the end user; The controlling of the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameter includes: Obtaining the return water temperature of the end user, and comparing the return water temperature with a preset return water temperature value; if the return water temperature is different from the preset return water temperature value, controlling the regulating valve; using the regulating valve to adjust the flow, and obtaining the adjusted flow of the regulating valve; if the regulating valve has been adjusted and cannot meet the control accuracy requirement, starting the mixing pump and controlling the mixing pump; The control of the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user includes: Based on the current temperature and flow parameters of the end user, determine the load combination information of the end user, and determine the hydraulic characteristics of the pipe network corresponding to the load combination, wherein the hydraulic characteristics of the pipe network reflect the corresponding relationship between the load and the resistance of the pipe network; determine the required operating performance point of the delivery pump according to the hydraulic characteristics of the pipe network; and control the head of the delivery pump according to the load combination information and the operating performance point; The controlling the water mixing pump according to the adjusted flow rate comprises: If the regulated flow rate is lower than 30% of the rated flow rate of a single regulating valve, the mixing water pump is started; The calculation formula for the supply and return water temperature difference of the end user's load requirement is: Among them, T h Indicates the chilled water return temperature; T g represents the chilled water supply temperature; ΔT represents the chilled water inlet and outlet temperature difference; Q represents the chilled water flow rate; W d Indicates the actual load of the user; K indicates the specific heat capacity of chilled water; Determining the pipe network operation temperature difference of the cooling and heating system according to the supply and return water temperature difference includes: Determine the most disadvantaged user according to the supply and return water temperature difference, wherein the most disadvantaged user is the user with the largest supply and return water temperature difference; A certain temperature difference margin is reserved for the supply and return water temperature difference of the most disadvantageous user as the operating temperature difference of the pipe network; ΔT w =ΔT max +T, where ΔT w is the network operating temperature difference, ΔT max is the supply and return water temperature difference of the most unfavorable user, T is the temperature difference margin, and the temperature difference margin has different values ​​according to the length of the pipe network, and is taken as 0.3℃ / km; The energy station adjusts the outlet temperature of the refrigerator according to the operating temperature difference of the pipeline network, including: Subtract the pipe network operating temperature difference from the preset return water temperature value to obtain the outlet temperature of the refrigerator; The control of the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user includes: Determining a total flow rate based on a current flow rate parameter of the end user; Determine the number of delivery pumps according to the total flow rate; The operating temperature difference of the pipe network is the temperature difference allowed by the pipe network of the cooling and heating system; The method of controlling the flow rate and lift of the delivery pump based on the current temperature and flow rate parameters of the end user further includes: Calculating the running quantity, speed and frequency of the delivery pump according to the running performance point, and controlling the delivery pump to run at the calculated running quantity, speed and frequency, The system operating flow is divided by the single pump flow, and the result is rounded up to the integer value, which is the number of operating pumps. The speed and frequency are calculated as follows: The running speed of the water pump N = rated speed × (actual flow / rated flow); The operating frequency of the water pump f = rated frequency × (actual flow / rated flow).

2. An automatic control system using the automatic control method for a cooling and heating system according to any one of claims 1, It is characterized in that The system comprises: The terminal control module is used to collect the temperature and flow parameters of the end user, control the regulating valve and the mixing water pump in the cooling and heating system according to the temperature and the flow parameters, and feed back the current temperature and flow parameters of the end user to the energy station; A data processing module, used to determine the supply and return water temperature difference that meets the load demand of the end user, and determine the pipe network operating temperature difference of the cooling and heating system based on the supply and return water temperature difference; The energy station control module is used to determine that the energy station adjusts the outlet temperature of the refrigerator according to the operating temperature difference of the pipeline network, and controls the flow and head of the delivery pump based on the current temperature and flow parameters of the end user.

3. A control terminal, It is characterized in that The control terminal includes a memory, a processor, and an automatic control program for the cooling and heating system stored in the memory and executable on the processor. When the processor executes the automatic control program for the cooling and heating system, the steps of the automatic control method for the cooling and heating system as recited in any one of claim 1 above are implemented.

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