CN111928428A - A control method and refrigeration system for an air conditioning system considering demand response - Google Patents

Abstract

The invention provides a control method and a refrigeration system for an air conditioning system considering demand response. According to the energy storage characteristics of the buffer water tank, within the acceptable thermal comfort range for users of the air-conditioned room, the buffer water tank is used to formulate a non-demand response daily operation strategy. And the strategy of daily operation of demand response, while providing stable demand response auxiliary services for the power grid, at the same time obtaining demand response subsidies for air-conditioning users, effectively improving the flexibility and economy of energy consumption of the air-conditioning system, this strategy takes into account the buffer water tank in the air-conditioning system. It can play a role as an active energy storage device when operating under the design load conditions, so that the air conditioning system can effectively use this part of the energy. In addition, adjusting the buffer water tank based on the peak and valley electricity price can effectively save the operating cost of the air conditioning system.

Description

A control method and refrigeration system for an air conditioning system considering demand response

technical field

The invention relates to a control technology of an air-conditioning system of a power plant, in particular to a control method and a refrigeration system of an air-conditioning system considering demand response.

Background technique

As the main source of urban electricity consumption, the continuous increase of building electricity consumption has become one of the important reasons affecting the imbalance of supply and demand in the power grid. Especially in winter and summer, the power consumption of the air-conditioning system increases due to the demand for heating and cooling of buildings, which makes the power grid appear peak in power consumption in winter and summer. Since the demand for heating and cooling is greatly affected by the outdoor temperature, the time period during which the temperature-controlled electricity load generated by the air conditioner is at its peak is usually shorter. The proportion of peak electricity consumption is low. If only through the power supply side to increase the power generation equipment, not only the investment is large, the number of power generation utilization hours is low, the power grid operation efficiency is poor, and it will pollute the environment.

Demand response technology provides an effective technical means to solve the contradiction between supply and demand of the power grid by utilizing and regulating the power consumption resources on the demand side, and responding to the peak regulation or valley filling of the power grid during the peak or valley power demand. As a high-quality demand response resource, air-conditioning systems have great potential to participate in demand response projects.

The cooling load of the air-conditioning system will fluctuate greatly due to changes in the outdoor temperature. Since the air-conditioning equipment is selected according to the design cooling/heating load, and the design cooling/heating load is generally based on the cooling/heating load that meets the maximum demand of the user. Therefore, the actual operation of the air-conditioning system often faces the "big flow, small load problem", especially for the air source heat pump (ASHP) constant-flow air-conditioning system that uses start-stop control, the ASHP frequently starts and stops during actual operation, resulting in the actual operation effect of the system. poor. In order to increase the stability of the air conditioning system, the air conditioning systems on the market are gradually equipped with water storage tanks. There are existing standards for air source heat pump systems that clearly state the need for a buffer tank. In the case of "large flow and small load", the buffer water tank can use the temperature difference in the water tank to stabilize the air conditioning water system. For the demand response of the air-conditioning system, it usually occurs during the period of high cooling/heating load of the building. At this time, the air-conditioning system operates under the design load, the inlet and outlet water temperature of the buffer water tank is equal to the water temperature of the heat pump outlet water, and the buffer water tank becomes a pure active energy storage. If the air-conditioning system stops running during the demand response period or in the previous period when there is no demand response event, this part of energy can be effectively used through regulation, which will help the system to realize flexible energy use and save energy consumption. And reduce the operating cost of the air conditioning system.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the prior art, the present invention provides a demand response energy use method for an air-conditioning system. By regulating the energy storage tank, demand response services are provided for the power grid during the demand response period, and response subsidies are obtained for users. Save system energy consumption and reduce the operating cost of air-conditioning system in the event of an event.

The present invention is achieved through the following technical solutions:

A control method for an air-conditioning system considering demand response, including a demand response day operation strategy and a non-demand response day operation strategy;

Demand response day operation strategy, including the following steps:

Step 01. Use BP neural network to predict the hourly cooling load of the building during the demand response period;

Step 02. Determine a variety of demand response daily operation strategies according to the hourly cooling load of the building and the indoor air dynamic heat balance equation, calculate the variation of the actual indoor temperature corresponding to each strategy, and determine the variation of the indoor temperature according to the variation of the actual indoor temperature The time required to reach the preset temperature;

Step 03: Determine each demand response duration and peak shaving load according to the time required for the indoor temperature to change to the preset temperature, and then select the optimal demand response strategy, and run the strategy on the demand response day;

The demand response strategy is as follows:

According to the energy storage time equation of the buffer water tank, determine the energy storage time required for the buffer water tank to store energy, and use the refrigeration device to store energy in the buffer water tank during non-air-conditioning use periods;

When the end room begins to need air conditioning, turn on the air system to supply air to the room;

During the demand response period, first turn off the refrigeration unit, use the buffer water tank to provide the cooling capacity required by the AHU until it reaches the preset temperature, and then use the refrigeration unit to provide the required cooling capacity for the AHU;

A strategy for running a non-demand response day, including the following steps:

Step 1. According to the operating parameters of the air-conditioning system, combined with the energy storage duration equation and the energy release duration equation of the buffer water tank, determine the energy storage duration of the buffer water tank and the energy release duration of the buffer water tank when the indoor set temperature remains unchanged;

Step 2. Determine the operation strategy on non-demand response days according to the energy storage duration and energy release duration of the buffer water tank, and run the strategy on non-demand response days;

The specific operation strategies for non-demand response days are as follows:

During the non-air-conditioning use period, the air-conditioning refrigeration device is used to store energy in the buffer water tank;

During the initial use period of the air conditioner, start the air conditioner air system to supply air to the room;

According to the energy release time of the buffer water tank, determine the time period before the end of the air conditioning period, and use the buffer water tank to provide the required cooling capacity for the AHU during this time period until the end of the energy release.

Preferably, in step 01, the hourly cooling load of the building, outdoor weather parameters, indoor personnel hot backup and lighting load are collected and input to the BP neural network in the previous period, and the BP neural network predicts the hourly cooling load of the building during the demand response period.

Preferably, the expression of the indoor air dynamic heat balance equation described in step 02 is as follows:

为某时刻下室内空气热量的变化；where:

is the change of indoor air heat at a certain time;

_{∑Q i.out} (t) is the heat exchange between all outer envelope structures, hot air infiltration and indoor air, W;

_{∑Q i.in} (t) is the heat exchange between indoor personnel, lighting, equipment and furnishings and indoor air;

_{∑Q i.AC} (t) is the cooling capacity provided by the end of the variable air volume air conditioner to the room.

Preferably, the method for selecting the optimal demand response strategy in step 03 is as follows:

Select the demand response daily operation strategy with the longest demand response time and the largest peak shaving load, which is the optimal demand response strategy.

Preferably, the specific strategy of the optimal demand response strategy in step 03 is as follows:

During the non-air-conditioning period, run the air-conditioning water system, turn off the air-conditioning air system, and use the refrigeration device to store energy in the buffer water tank;

During the initial use period of the air conditioner, the air system is turned on. At this time, the cold water circulates through the buffer water tank, and the buffer water tank acts as a buffer device to stabilize the circulation of the water system;

During the demand response period, the refrigeration unit is turned off, and the buffer water tank provides the cooling capacity required by the AHU. When the indoor temperature reaches the preset temperature, the refrigeration unit is turned on after the response is completed, and the buffer water tank is closed, and the refrigeration unit is used to provide the required cooling capacity for the AHU. .

Preferably, the expression of the energy storage duration equation is as follows:

Among them, t _S is the time required for the energy storage tank to store energy, V is the volume of the energy storage tank, v is the volume flow of chilled water during energy storage, T ₀ is the initial value of the water temperature in the energy storage tank during energy storage, T ₁ is the end value of the water temperature in the storage tank during energy storage, and ΔT _ASHP is the temperature difference between the supply and return water of the air source heat pump.

Preferably, the expression of the energy release duration equation is as follows:

Among them, t _R the energy release time of the energy storage tank, V is the volume of the energy storage tank, v is the volume flow of the chilled water when the energy is released, T _h.out is the upper limit of the outlet temperature of the chilled water when the energy is released, T _{l .out} is the lower limit of the outlet temperature of the chilled water during energy release, ΔT _AHU is the temperature difference between the supply and return water of the chilled water coil in the combined air conditioning unit.

Preferably, in step 2, the specific operation of the strategy on non-demand response days is as follows:

During the non-air-conditioning period, run the air-conditioning water system, turn off the air-conditioning air system, and use the air-conditioning refrigeration device;

During the initial use period of the air conditioner, the wind system is turned on. At this time, the cold water circulates through the buffer water tank, and the buffer water tank buffers the cold water circulation;

The time period before the end of the air conditioning period is the energy release time of the buffer water tank. During this time period, the buffer water tank is used to provide the required cooling capacity for the AHU until the end of the energy release, and the air conditioning air system is turned off.

A refrigeration system according to the above control method, comprising a refrigeration device, a buffer water tank, a circulating water pump, a combined air-conditioning unit and a variable air volume terminal;

The refrigerating device is connected with the buffer water tank, the buffer water tank is connected with the combined air-conditioning unit through the water supply pipe, the buffer water tank is connected with the circulating water pump through the return pipe, the combined air-conditioning unit is connected with the variable air volume end through the air pipe, and the buffer water tank is provided with A plurality of solenoid valves, which are connected with the control unit, are used to control the working state of the buffer water tank.

Compared with the prior art, the present invention has the following beneficial technical effects:

The invention provides a demand-response energy use method for an air-conditioning system. According to the energy storage characteristics of the buffer water tank, within the acceptable thermal comfort range for users of the air-conditioned room, the buffer water tank is used to formulate a non-demand-response day operation strategy and a demand-response day. The operation strategy not only provides stable demand response auxiliary services for the power grid, but also obtains demand response subsidies for air-conditioning users, effectively improving the flexibility and economy of energy consumption of the air-conditioning system. This strategy takes into account the design load conditions of the buffer water tank in the air-conditioning system. It can play a role as an active energy storage device when running down, so that the air conditioning system can effectively use this part of the energy. In addition, adjusting the buffer water tank based on the peak and valley electricity price can effectively save the operating cost of the air conditioning system.

Description of drawings

Fig. 1 is the flow chart of the method of the present invention;

Fig. 2 is the change curve diagram of system water temperature when there is no buffer water tank in the present invention;

Fig. 3 is the change curve diagram of system water temperature when there is a buffer water tank in the present invention;

Fig. 4 is a system water temperature change curve diagram under the demand response strategy of the present invention;

FIG. 5 is a schematic view of the structure of the device of the present invention.

In the figure: 1, upper computer; 2, control unit; 3, refrigeration device; 4, first solenoid valve; 5, second solenoid valve; 6, third solenoid valve; 7, fourth solenoid valve; 8, buffer water tank ; 9, circulating water pump; 10, combined air conditioning unit; 11, static pressure sensor; 12, temperature sensor; 13, wind speed sensor; 14, variable air volume box; 15, room temperature and humidity sensor.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings, which are to explain rather than limit the present invention.

Referring to Figure 1, a control method for an air conditioning system considering demand response, including a demand response day operation strategy and a non-demand response day operation strategy;

Demand response day operation strategy, including the following steps:

1) Obtain the temperature load parameters of the previous period through the data acquisition and storage module, and the predicted parameters include the hourly cooling load of the building, outdoor meteorological parameters, indoor personnel hot backup and lighting load.

2) According to the temperature load parameters combined with the BP neural network algorithm, the hourly cooling load of the building during the demand response period is predicted, (the external disturbance load _{∑Q i.out} (t) and the internal disturbance load _{∑Q i.in} in the indoor air dynamic heat balance equation (t) and).

3) According to the building hourly cooling load combined with the indoor air dynamic heat balance equation, determine a variety of demand response daily operation strategies, and calculate the variation of the actual indoor temperature corresponding to each strategy to ensure that the indoor air temperature is within the acceptable thermal comfort range for users The time required for the indoor temperature to change to the preset temperature is determined according to the change of the actual indoor temperature, and the required time is the maximum time for the air-conditioning system to participate in the demand response.

4) According to the time required for the indoor temperature to change to the preset temperature, determine each demand response time and peak load, select the optimal demand response strategy according to the maximum load reduction, and report the load aggregator or demand The response platform is uniformly scheduled by the load aggregator or the demand response platform, and the strategy is run on the demand response day.

Then select the optimal demand response strategy and run the strategy on demand response day.

The demand response strategy is as follows:

During the non-air-conditioning use period, the air-conditioning refrigeration device is used to store energy in the buffer water tank.

During the initial use period of the air conditioner, start the air conditioner air system to supply air to the room.

During the demand response period, the air source heat pump is turned off, and by adjusting the four solenoid valves attached to the buffer water tank, the buffer water tank is used to provide the cooling capacity required by the AHU until the preset temperature is reached, and then the cooling device is used to provide the required cooling capacity for the AHU.

Indoor air dynamic heat balance equation:

——某时刻下室内空气热量的变化，W；where:

——The change of indoor air heat at a certain time, W;

_{∑Q i.out} (t)——the heat exchange between all outer envelope structures, hot air infiltration and indoor air, W;

_{∑Q i.in} (t)——the heat exchange between indoor personnel, lighting, equipment and furnishings and indoor air, W;

_{∑Q i.AC} (t)——The cooling capacity provided by the end of the variable air volume air conditioner to the room (represented by a negative value), W;

Q _i.AC =β·(α·C _p ·m·|T _h -T _g |-Q _OA )

In the formula: C _p —— specific heat capacity of chilled water, take 4.18kJ/(kg·℃);

m——mass flow of chilled water, kg/s;

α——The heat exchange coefficient between the surface cooler and the air in the AHU;

_{Th ——AHU} outlet water temperature, °C;

T _g ——AHU inlet water temperature, °C;

Q _OA - cooling load of fresh air, W;

β——The loss coefficient during the air supply process of the air duct.

For example, when there is a demand response day, taking the "peak shaving" demand response as an example, it is assumed that the office building work hours are 9:00-18:00, and the demand response time is 14:00-16:00.

First, use the energy storage time equation to determine the energy storage time required for the buffer water tank to store energy, and then determine the energy storage time period of the air conditioning system according to the energy storage time. is closed.

Turn on the wind system at 9:00 to provide cooling for the terminal room, close the ASHP at 14:00, adjust the four solenoid valves attached to the buffer water tank, and the buffer water tank provides cooling for the AHU. When the indoor air temperature changes to an acceptable thermal comfort temperature for the user When the upper limit temperature is reached, adjust the solenoid valve, short-circuit the buffer water tank, open the ASHP, and supply cold water directly to the AHU without going through the buffer water tank. Turn off all air conditioning equipment at 18:00.

A strategy for running a non-demand response day, including the following steps:

Step 1. According to the operating parameters of the air-conditioning system, combined with the established buffer tank energy storage duration equation and energy release duration equation, determine the buffer tank energy storage duration, and the buffer tank's energy release under the condition that the indoor set temperature remains unchanged duration;

Step 2. Determine the operation strategy on non-demand response days according to the energy storage duration and energy release duration of the buffer water tank, and run the strategy on non-demand response days;

The specific operation strategies for non-demand response days are as follows:

During the non-air-conditioning use period, the air-conditioning refrigeration device is used to store energy in the buffer water tank;

During the initial use period of the air conditioner, start the air conditioner air system to supply air to the room;

According to the energy release time of the buffer water tank, determine the time period before the end of the air conditioning period, and use the buffer water tank to provide the required cooling capacity for the AHU during this time period until the end of the energy release.

The calculation formula of energy storage time:

In the formula: t _S —— the time required for the energy storage tank to store energy, h;

V——Volume of energy storage tank, m ³ ;

v——volume flow of chilled water during energy storage, m ³ /h;

T ₀ ——the initial value of the water temperature in the energy storage tank during energy storage, °C;

T ₁ —— are the end values of the water temperature in the energy storage tank during energy storage, ℃;

ΔT _{ASHP ——The} temperature difference between the supply and return water of the air source heat pump, °C.

The formula for calculating the duration of energy release:

In the formula: t _R —— the duration of energy release of the energy storage tank, h;

V——Volume of energy storage tank, m ³ ;

v——volume flow of chilled water when releasing energy, m ³ /h;

T _h.out — the upper limit of the chilled water outlet temperature during energy release, °C;

T _{l.out ——the} lower limit of the chilled water outlet temperature when releasing energy

ΔT _AHU ——The temperature difference between the supply and return water of the cold water coil in the combined air-conditioning unit, °C;

A control system for an air conditioning system considering demand response, comprising a refrigeration device 3, a buffer water tank 8, a refrigeration device 3, a circulating water pump 9, a combined air conditioning unit 10 and a variable air volume terminal 14

The refrigeration device 3 is connected to the buffer water tank 8, the buffer water tank 8 is connected to the combined air conditioner unit 10 through the water supply pipe, and then connected to the circulating water pump through the return water pipe, and finally the chilled water flows back to the refrigeration device to form the entire cycle of the water system. The combined air conditioner unit 10 is connected to the variable air volume terminal 14 through an air duct to form the entire circulation of the air system.

The first solenoid valve 4 , the second solenoid valve 5 , the third solenoid valve 6 and the fourth solenoid valve 7 are respectively connected with the buffer water tank to control the working state of the buffer water tank.

The first solenoid valve 4 , the second solenoid valve 5 , the third solenoid valve 6 , the fourth solenoid valve 7 , the static pressure sensor 11 , the temperature sensor 12 , the wind speed sensor 13 and the room temperature and humidity sensor 15 are respectively connected to the control unit 2 to control the The unit 2 is connected to the upper computer 1.

The static pressure sensor 11 is used to collect static pressure parameters of the air supply section in the AHU.

The temperature sensor 12 is used to collect air supply temperature parameters of the air supply fan in the AHU.

The wind speed sensor 13 is used to collect air supply wind speed parameters of the blower in the AHU.

The room temperature and humidity sensor 15 is used to collect room temperature and humidity parameters and send them to the control unit.

The upper computer 1 is an industrial control computer, the control unit is Siemens PLC S7-200CPU and EM235 expansion module, the wind speed sensor 5 is a hot wire wind speed sensor, and the variable air volume end is a royal single air duct single cooling type pressure independent variable air volume box, including cross air volume Sensors, electric dampers, controllers and actuators.

As shown in FIG. 2 , a control method of the above-mentioned control system of an air conditioning system considering demand response will be described in detail below.

Demand response day operation strategy, including the following steps:

The first step is to determine the specific parameters required by the indoor heat balance equation at the end of the building according to the actual operation of the air conditioning system.

The second step is to obtain the operation data of the air source heat pump, the operation data of the circulating water pump, the supply and return water temperature of the chilled water, the set temperature and actual temperature of the air-conditioned room, and the operation data of the fan for a period of time through various sensors. These parameters are stored in a time series. The sampling interval can be set to 10 minutes.

The third step is to divide the actual operation data into three groups according to the time period, which are used for training, checking and testing of the neural network model respectively, so as to obtain a reliable load forecasting model. Import the load forecasting model to obtain the hourly cooling load of the building during the demand response period.

The fourth step is to determine the demand response strategy to be adopted according to the demand response period and specific requirements issued by the power grid. Combined with the indoor heat balance equation at the end of the building, the demand response duration and load reduction amount of the air conditioning system under the demand response strategy are predicted a few days ago, and reported. The load aggregator or the demand response platform is dispatched uniformly by the load aggregator or the demand response platform.

The fifth step is to change the operation strategy of the air conditioning system before the start of demand response according to the response command issued by the grid demand response platform or load aggregator, and adopt the regional temperature reset ACES+GTA demand response strategy combined with active energy storage.

In the example, the demand response period is 14:00-16:00, and the specific implementation process of the ACES+GTA demand response strategy is as follows:

14:00 Shut down the air heat source pump ASHP, close the second solenoid valve and the fourth solenoid valve, open the first solenoid valve and the third solenoid valve, release the energy from the buffer water tank to provide the required cooling capacity for the AHU, and pass the indoor temperature and humidity sensor. Collect the change of indoor temperature. When the actual indoor temperature exceeds the set temperature of 26°C, open the second solenoid valve, close the third solenoid valve, and short-circuit the buffer water tank, so that the chilled water does not pass through the buffer water tank, and set the indoor temperature to the set value. Adjust the temperature to 28°C, and turn on the switch of the air heat source pump ASHP. When the actual indoor temperature reaches 28°C, the ASHP system of start-stop control will automatically run, and the set value of the room temperature will be reset to the original set temperature at 16:00. 26°C, the entire regulation is completed.

A strategy for running a non-demand response day, including the following steps:

The first step is to determine the specific parameters required in the calculation formula of the buffer tank’s energy storage duration and energy release duration according to the actual operation of the air-conditioning system, and use the energy storage duration formula to estimate the system energy storage duration. The formula estimates how long the buffer tank can discharge without changing the room temperature setting.

The second step is to formulate and implement a conventional operation strategy for active energy storage.

In the example, the specific implementation process of the active energy storage conventional operation strategy is: at 8:00 in the morning, open the ASHP, open the solenoid valves 2 and 4, close the solenoid valves 1 and 3, and the water flow direction in the buffer tank is bottom in and top out, 9: 00 Turn on the entire air system, 9:00-17:00 The buffer water tank is used as a buffer device, 17:00 close the ASHP, open the solenoid valves 1 and 3, close the solenoid valves 2 and 4, 17:00-18:00 The buffer water tank is used Energy release device.

When implementing the strategy of non-demand response day operation, the control system of the air conditioning system can detect and control the equipment on the cold source side, including the start and stop of the refrigeration unit (air source heat pump, chiller, etc.), and the switching of the solenoid valve attached to the buffer water tank. , control of circulating water pump, etc., monitoring of parameters such as ASHP and AHU inlet and outlet water temperature, buffer water tank inlet and outlet water temperature, chilled water flow and other parameters.

When the control system of the air-conditioning system can realize automatic control of the entire system (air system and water system), the daily operation strategy of demand response can be used at this time, and the temperature reset strategy of the terminal area of the air-conditioning can be combined to achieve a better demand response effect.

The details are as follows. During the demand response period, the buffer water tank is used to release energy to provide the required cooling capacity for the AHU, and the indoor temperature and humidity sensors are used to collect the change of indoor temperature. When the actual indoor temperature exceeds the set temperature, switch the buffer water tank. Valve, short-circuit the buffer water tank, so that the chilled water does not pass through the buffer water tank, reset the indoor temperature set value (set to the upper limit temperature that the user can accept thermal comfort), at this time, turn on the switch of ASHP, when the actual indoor temperature reaches the set value , the ASHP system of start-stop control will run automatically. After the demand response is over, it is only necessary to reset the room temperature set value to the original set temperature, and the whole regulation is completed.

According to the energy storage characteristics of the buffer water tank, the invention uses the buffer water tank to formulate a non-demand response day operation strategy and a demand response day operation strategy within the acceptable thermal comfort range of the air-conditioned room user, and provides stable demand response auxiliary services for the power grid. At the same time, it can obtain demand response subsidies for air-conditioning users, effectively improving the flexibility and economy of energy consumption of the air-conditioning system. This strategy takes into account the role that the buffer water tank can play as an active energy storage device when operating under the design load conditions of the air-conditioning system, so that the air-conditioning system can effectively utilize this part of the energy. In addition, adjusting the buffer water tank based on the peak and valley electricity price can effectively save the operating cost of the air conditioning system.

Based on the existing air conditioning system with buffer water tank, the control device of the present invention collects relevant information such as solenoid valve, ASHP and AHU inlet and outlet water temperatures, fan and VAV-box air supply volume, circulating water pump flow rate, indoor temperature and humidity, etc. through the control unit. The control unit communicates with the Ethernet switch through the communication module, and then connects with the upper computer. The upper computer realizes the optimal control of the buffer water tank by controlling the start and stop of the ASHP, the switching of the solenoid valve, and the frequency of the variable frequency fan. The entire control process is controlled automatically. The control strategy and the device of the present invention are not only applicable to the variable air volume air conditioning system driven by the air source heat pump, but also applicable to the whole air system driven by the chiller and the fan coil unit plus fresh air or other air conditioning systems equipped with a buffer device, and have better performance. applicability.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention all fall within the scope of the claims of the present invention. within the scope of protection.

Claims (9)

1. A control method of an air conditioning system considering demand response is characterized by comprising a demand response daily operation strategy and a non-demand response daily operation strategy;

the demand response daily operation strategy comprises the following steps:

step 01, forecasting the time-by-time cooling load of the building in the demand response time period by using a BP neural network;

step 02, determining multiple demand response daily operation strategies according to a construction hourly cooling load and an indoor air dynamic heat balance equation, calculating the variation of the indoor actual temperature corresponding to each strategy, and determining the time required for the indoor temperature to change to the preset temperature according to the variation of the indoor actual temperature;

step 03, determining each demand response time length and peak clipping load according to the time length required when the indoor temperature changes to the preset temperature, further selecting an optimal demand response strategy, and operating the strategy on a demand response day;

the demand response strategy is specifically as follows:

determining the energy storage time required by the energy storage of the buffer water tank according to the energy storage time equation of the buffer water tank, and storing the energy in the buffer water tank by adopting a refrigerating device in a non-air-conditioner use period;

when the tail end room starts to have air conditioning requirements, an air system is started to supply air to the room;

in the demand response period, firstly, the refrigerating device is closed, the buffer water tank is adopted to provide the cold quantity required by the AHU until the preset temperature is reached, and then the refrigerating device is adopted to provide the required cold quantity for the AHU;

the strategy for non-demand response daily operation comprises the following steps:

step 1, determining the energy storage time of a buffer water tank and the energy release time of the buffer water tank under the condition that the indoor set temperature is not changed according to the operation parameters of an air conditioning system and by combining an energy storage time equation and an energy release time equation of the buffer water tank;

step 2, determining a non-demand response day operation strategy according to the energy storage duration and the energy release duration of the buffer water tank, and operating the strategy on the non-demand response day;

the non-demand response daily operation strategy is as follows:

in the non-air-conditioning use period, an air-conditioning refrigerating device is adopted to store energy in the buffer water tank;

starting an air conditioning air system to supply air to the room in the initial use period of the air conditioner;

and determining a time period before the air conditioning period is ended according to the energy releasing duration of the buffer water tank, and providing the required cold quantity for the AHU by using the buffer water tank in the time period until the energy releasing is ended.

2. The method as claimed in claim 1, wherein the building hourly cooling load, outdoor weather parameters, indoor personnel hot spare and lighting load input in the last period are collected in step 01 and input to the BP neural network, and the BP neural network predicts the building hourly cooling load in the period of demand response.

3. The method as claimed in claim 1, wherein the expression of the indoor air dynamic heat balance equation in step 02 is as follows:

in the formula:

the change of indoor air heat at a certain time;

∑Q_i.out(t) is the heat exchange capacity of all the external enclosure structures, hot air infiltration and indoor air, W;

∑Q_i.in(t) heat exchange between indoor personnel, lighting, equipment and furnishings and indoor air;

∑Q_i.ACand (t) is the cooling capacity provided by the tail end of the variable air volume air conditioner to the indoor space.

4. The method as claimed in claim 1, wherein the method for selecting the optimal demand response strategy in step 03 comprises the following steps:

and selecting a demand response daily operation strategy with the longest demand response time and the largest peak load clipping as an optimal demand response strategy.

5. The method as claimed in claim 1, wherein the optimal strategy of the demand response strategy in step 03 is as follows:

in the non-air-conditioning use period, operating an air-conditioning water system, closing an air-conditioning air system, and storing energy in a buffer water tank by adopting a refrigerating device;

in the initial use period of the air conditioner, an air system is started, at the moment, cold water circularly flows through a buffer water tank, and the buffer water tank is used as a buffer device to play a role in stabilizing the circulation of a water system;

and in the demand response period, the refrigerating device is closed, the buffer water tank provides the cold energy required by the AHU, the indoor temperature reaches the preset temperature, the refrigerating device is started after the response is finished, the buffer water tank is closed, and the refrigerating device is adopted to provide the required cold energy for the AHU.

6. The control method of an air conditioning system considering demand response according to claim 1, wherein the expression of the energy storage duration equation is as follows:

wherein, t_SThe time required for energy storage of the energy storage tank is long, V is the volume of the energy storage tank, V is the volume flow of the chilled water during energy storage, and T₀For an initial value of the temperature of the water in the energy storage tank during energy storage, T₁Water temperature and end value, delta T, in the energy storage tank for energy storage_ASHPThe temperature difference of the water supply and the water return of the air source heat pump is obtained.

7. The control method of an air conditioning system considering demand response according to claim 1, wherein the expression of the energy release duration equation is as follows:

wherein, t_RThe time of energy release of the energy storage tank, V is the volume of the energy storage tank, V is the volume flow of the chilled water during energy release, and T_h.outFor the upper limit value, T, of the outlet temperature of the chilled water during energy release_l.outFor the lower limit value, Δ T, of the outlet temperature of the chilled water during energy release_AHUThe temperature difference of the water supply and the water return of the cold water coil pipe in the combined air conditioning unit.

8. The method as claimed in claim 1, wherein the strategy is specifically operated on the day of non-demand response in step 2 as follows:

in the non-air-conditioning use period, operating an air-conditioning water system, closing an air-conditioning air system, and adopting an air-conditioning refrigerating device;

starting an air system when the air conditioner is initially used, wherein cold water circularly flows through a buffer water tank, and the buffer water tank buffers the cold water circulation;

and the time period before the air-conditioning time period is ended is the energy release duration of the buffer water tank, the buffer water tank is adopted to provide the required cold quantity for the AHU in the time period until the energy release is ended, and the air-conditioning air system is closed.

9. A refrigeration system using the control method according to any one of claims 1 to 8, characterized by comprising a refrigeration device (3), a buffer water tank (8), a circulating water pump (9), a combined air conditioning unit (10), and a variable air volume terminal (14);

refrigerating plant (3) are connected with buffer tank (8), and buffer tank (8) are connected with combined type air conditioning unit (10) through the delivery pipe, and buffer tank (8) are connected with circulating water pump (9) through the wet return, and combined type air conditioning unit (10) are connected with variable air volume end (14) through the tuber pipe, the last a plurality of solenoid valves that set up of buffer tank, the solenoid valve is connected with the control unit for control buffer tank's operating condition.

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