An operation optimization method for a ground source heat pump system

Abstract

The present invention discloses an operation optimization method for a ground source heat pump system, comprising the following steps: taking the minimum energy consumption of the entire ground source heat pump system as the objective function, considering the operation constraints of the system's heat pump host, and combining decision variables to construct a ground source heat pump operation optimization model; determining the relationship between the energy of the heat pump host and the user-side load and water pump power according to whether the system is in cooling mode or heating mode; solving the ground source heat pump operation optimization model, and controlling the user-side outlet water temperature in cooling mode and heating mode to meet the allowable range of cooling and heating conditions. The present invention combines the performance characteristics of the heat pump host to achieve automatic control of the host cooling / heating outlet water temperature and load distribution optimization of the two hosts. Under the premise of meeting user load requirements, it reduces the operating energy consumption of the unit and reduces carbon emissions. It can provide planning and decision-making support for regional flexibility resource allocation, reduce overall flexibility configuration costs, increase comprehensive benefits, and improve the scientific nature of decision-making.

Description

Technical Field

[0001] The present invention belongs to the field of energy technology, and in particular relates to an operation optimization method for a ground source heat pump system. Background Art

[0002] When there are multiple heat pump hosts, the general control strategy for the number of heat pump hosts in operation (taking cooling conditions as an example) is as follows:

[0003] (1) When the user sets the cooling water outlet temperature, if the host detects that the actual cooling water outlet temperature is higher than the set value and lasts for ΔT, a compressor is added; conversely, if the actual cooling water outlet temperature is lower than the set value and lasts for ΔT, a compressor is removed. It is worth noting that each host has two identical compressors. When all the compressors of one host are turned on, the additional compressors come from other hosts.

[0004] (2) When the user sets the cooling water inlet temperature, if the host detects that the actual cooling water inlet temperature is higher than the set value and lasts for ΔT time, a compressor will be added; conversely, if the actual cooling water outlet temperature is lower than the set value and lasts for ΔT time, a compressor will be reduced.

[0005] (3) When the user sets both the cooling water inlet temperature and the cooling water outlet temperature, only one of them is valid. Similarly, the control strategy for the number of heat pump units in operation under heating conditions can be obtained.

[0006] The above heat pump host control strategy is relatively simple, and there is still much room for energy-saving optimization. Summary of the Invention

[0007] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide an operation optimization method for a ground source heat pump system.

[0008] In order to achieve the above-mentioned purpose and the above-mentioned technical effect, the technical solution adopted by the present invention is:

[0009] A method for optimizing the operation of a ground source heat pump system comprises the following steps:

[0010] Taking the minimum energy consumption of the entire ground source heat pump system as the objective function, considering the operation constraints of the system's heat pump host, and combining decision variables, a ground source heat pump operation optimization model is constructed;

[0011] Determine the relationship between the energy of the heat pump host, the user-side load, and the water pump power, depending on whether the system is in cooling mode or heating mode;

[0012] The ground source heat pump operation optimization model is solved to control the user-side water outlet temperature in cooling mode and heating mode to meet the allowable range of cooling and heating conditions.

[0013] Furthermore, the objective function is:

[0014] minP=P cmp +P u，p +P h，p

[0015] Where: P cmp is the total power of all compressors, P u，p is the total power of all user-side water pumps, P h，p is the total power of all heat source side water pumps.

[0016] Furthermore, the system includes a heat pump host No. 1 and a heat pump host No. 2, each of which includes two compressors, and the operating constraints of the heat pump hosts are:

[0017] P cmp =P cmp，1 +P cmp，2

[0018]

[0019] Where: P cmp，1 is the compressor power of heat pump host No. 1, P cmp，2 is the compressor power of heat pump host No. 2, P cmp，1，max is the maximum power of the two compressors in the No. 1 heat pump host when they are fully opened, P cmp，2，max The maximum power when the two compressors in the No. 2 heat pump main unit are fully opened;

[0020] The decision variables are I1, I2, I3, I4, I5, and I6;

[0021] I1, I2, and I3 represent the start and stop status of heat pump host No. 1, with a value range of 0-1. I1+I2+I3=1. When I1=1, heat pump host No. 1 is shut down. When I2=1, heat pump host No. 1 has only one compressor turned on. When I3=1, both compressors of heat pump host No. 1 are fully turned on.

[0022] I4, I5, and I6 represent the start and stop status of the No. 2 heat pump host. The value range is 0-1, I4+I5+I6=1. When I4=1, it means that the No. 2 heat pump host is shut down. When I5=1, it means that only one compressor of the No. 2 heat pump host is turned on. When I6=1, it means that both compressors of the No. 2 heat pump host are fully turned on.

[0023] Furthermore, the ground source heat pump operation optimization model is expressed as:

[0024] COP=f(T h，in , T u，out )

[0025] Where: T h，in is the inlet water temperature on the heat source side, T u，out The outlet water temperature at the user side.

[0026] Furthermore, the maximum power P cmp，1，max 、P cmp，2，max The calculation formula is:

[0027] P cmp，1，max =f(T h，in , T u，out，1 )

[0028] P cmp，2，max =f(T h，in , T u，out，2 )

[0029] Where: T h，in is the water inlet temperature on the heat source side, T h，in Same, T u，out，1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u，out，2 The outlet water temperature on the user side of the No. 2 heat pump main unit.

[0030] Furthermore, according to whether the system is in cooling mode or heating mode, the step of determining the relationship between the energy of the heat pump host and the user-side load and the water pump power includes:

[0031] The relationship between the cooling / heating energy of the No. 1 and No. 2 heat pump hosts of the system and the user-side cooling / heating load and the user-side water pump power is expressed as follows:

[0032]

[0033] When the system is in cooling mode, L1 is the cooling capacity of heat pump host No. 1, L2 is the cooling capacity of heat pump host No. 2, and L u It is the cooling load on the user side;

[0034] When the system is in heating mode, L1 is the heating capacity of heat pump host No. 1, L2 is the heating capacity of heat pump host No. 2, L u is the heat load on the user side;

[0035] The calculation formulas for the cooling / heating energy L1 and L2 of the No. 1 and No. 2 heat pump hosts are:

[0036]

[0037] Where: L 1，max is the maximum cooling / heating capacity of heat pump host No. 1, and is the water inlet temperature T on the heat source side. h，in and the user side outlet water temperature T of No. 1 heat pump host u，out，1Function of L 2，max is the maximum cooling / heating capacity of heat pump host No. 2, and is the water inlet temperature T on the heat source side. h，in and the user side outlet water temperature T of the No. 2 heat pump host u，out，2 function.

[0038] Furthermore, the user-side outlet water temperature in the cooling mode and the heating mode is controlled to meet the allowable range of the cooling and heating conditions, which is expressed as:

[0039] T u，out，min ≤T u，out，1 , T u，out，2 ≤T u，out，max

[0040] Where: T u，out，min is the minimum value of the user side water outlet temperature, T u，out，max is the maximum outlet water temperature on the user side, T u，out，1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u，out，2 The outlet water temperature on the user side of the No. 2 heat pump main unit.

[0041] Furthermore, the user-side outlet water temperature in the cooling mode satisfies the allowable range of the cooling condition, which is expressed as:

[0042] 5≤T u，out，1 , T uout，2 ≤10.

[0043] Furthermore, the user-side outlet water temperature in the cooling mode satisfies the allowable range of the cooling condition, which is expressed as:

[0044] 40≤T u，out1 , T u，out，2 ≤55.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention discloses an operation optimization method for a ground source heat pump system, comprising the following steps: taking the minimum energy consumption of the entire ground source heat pump system as the objective function, considering the operation constraints of the system's heat pump host, and combining decision variables to construct a ground source heat pump operation optimization model; determining the relationship between the energy of the heat pump host and the user-side load and water pump power according to whether the system is in cooling mode or heating mode; solving the ground source heat pump operation optimization model, and controlling the user-side outlet water temperature in cooling mode and heating mode to meet the allowable range of cooling and heating conditions. The operation optimization method for a ground source heat pump system provided by the present invention, combined with the performance characteristics of the heat pump host, realizes automatic control of the host cooling / heating outlet water temperature and load distribution optimization of the two hosts, heat pump host No. 1 and heat pump host No. 2, and reduces the operating energy consumption of the unit and carbon emissions while meeting the user load requirements. It can provide planning and decision-making support for regional flexibility resource allocation, reduce overall flexibility configuration costs, improve comprehensive benefits, and improve the scientific nature of decision-making. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a structural diagram of a ground source heat pump system in the prior art. DETAILED DESCRIPTION

[0048] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0049] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0050] The present invention is directed to Figure 1 The existing geothermal heat pump system shown in the figure discloses an operation optimization method for the geothermal heat pump system. The geothermal heat pump system includes two main units, heat pump main unit 1 and heat pump main unit 2. Heat pump main unit 1 and heat pump main unit 2 each include two compressors with three adjustment settings of 0-50%-100%. The operation optimization method mainly includes the following steps:

[0051] Step 1: Taking the minimum energy consumption of the entire ground source heat pump system as the objective function, considering the operating constraints of the system's heat pump host, and combining decision variables, a ground source heat pump operation optimization model is constructed; the expression of the objective function is:

[0052] minP=P cmp +P u，p +Ph，p

[0053] Where: P cmp is the total power of all compressors, P u，p is the total power of all user-side water pumps, P h，p is the total power of all water pumps on the heat source side;

[0054] The ground source heat pump belongs to the water-water heat pump unit. The condenser and evaporator of the heat pump unit both exchange heat with water. Under cooling conditions, the user-side water pump is the evaporator pump, and the heat source-side water pump is the condenser pump. Under heating conditions, the opposite is true. The multivariate polynomial model and the DOE-2 model are commonly used semi-empirical mathematical models that can reflect the operating characteristics of the water-water heat pump unit. Both models use the heat source side inlet water temperature T h，in , user side water outlet temperature T u，out The three variables, heat pump power consumption and cooling / heating load factor r, are the determining factors affecting the heat pump's power consumption or COP. The effect of water flow on the user side or heat source side on the main unit COP is negligible; changes in flow rate primarily affect the pump's power. Since the flow rate is constant on the user side and the ground source side, the impact of flow rate on the main unit COP and pump power is not necessary. The ground source heat pump operation optimization model can be expressed as:

[0055] COP=f(T h，in , T u，out , r)

[0056] The heat pump main unit adopts a fixed frequency scroll compressor. h，in 、T u，out ) is determined, the cooling / heating capacity of the host is also determined, that is, r is always equal to 1, so the above formula can be simplified to:

[0057] COP=f(T h，in , T u，out )

[0058] The operating constraints of the heat pump host are:

[0059] P cmp =P cmp，1 +P cmp，2

[0060]

[0061] Where: P cmp，1 is the compressor power of heat pump host No. 1, P cmp，2 is the compressor power of heat pump host No. 2, P cmp，1，max is the maximum power of the two compressors in the No. 1 heat pump host when they are fully opened, P cmp，2，max is the maximum power of the two compressors in the No. 2 heat pump host when they are fully opened. The calculation formula is:

[0062] P cmp，1，max =f(T h，in , T u，out，1 )

[0063] P cmp，2，max =f(T h，in , T u，out，2 )

[0064] The decision variables are I1, I2, I3, I4, I5, and I6;

[0065] I1, I2, and I3 represent the start and stop status of heat pump host No. 1, with a value range of 0-1. I1+I2+I3=1. When I1=1, heat pump host No. 1 is shut down. When I2=1, heat pump host No. 1 has only one compressor turned on. When I3=1, both compressors of heat pump host No. 1 are fully turned on.

[0066] I4, I5, and I6 represent the start and stop status of the No. 2 heat pump host. The value range is 0-1, and I4+I5+I6=1. When I4=1, it means that the No. 2 heat pump host is off. When I5=1, it means that only one compressor of the No. 2 heat pump host is turned on. When I6=1, it means that both compressors of the No. 2 heat pump host are fully turned on.

[0067] Where: T h，in is the water inlet temperature on the heat source side, T h，in Same, T u，out，1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u，out，2 The outlet water temperature on the user side of the No. 2 heat pump main unit.

[0068] Step 2: Determine the relationship between the energy of the heat pump host, the user side load, and the water pump power based on whether the system is in cooling mode or heating mode.

[0069] The relationship between the cooling / heating energy of the No. 1 and No. 2 heat pump units and the user-side cooling / heating load and the user-side water pump power is expressed as follows:

[0070]

[0071] When the system is in cooling mode, L1 is the cooling capacity of heat pump host No. 1, L2 is the cooling capacity of heat pump host No. 2, and L u The cooling load on the user side can be calculated from real-time sensor data or predicted from historical data;

[0072] When the system is in heating mode, L1 is the heating capacity of heat pump host No. 1, L2 is the heating capacity of heat pump host No. 2, L u is the heat load on the user side;

[0073] The calculation formulas for the cooling / heating energy L1 and L2 of the No. 1 and No. 2 heat pump hosts are:

[0074]

[0075] Where: L 1，max is the maximum cooling / heating capacity of heat pump host No. 1, and is the water inlet temperature T on the heat source side. h，in and the user side outlet water temperature T of No. 1 heat pump host u，out，1 Function of L 2，max is the maximum cooling / heating capacity of heat pump host No. 2, and is the water inlet temperature T on the heat source side. h，in and the user side outlet water temperature T of the No. 2 heat pump host u，out，2 Function of the heat source side inlet water temperature T h，in It is a known quantity that can be measured by a sensor.

[0076] Step 3: Solve the ground source heat pump operation optimization model to control the user-side outlet water temperature in cooling mode and heating mode to meet the allowable range of cooling and heating conditions, which can be expressed as:

[0077] T u，out，min ≤T u，out，1 , T u，out，2 ≤T u，out，max

[0078] Where: T u，out，min is the minimum value of the user side water outlet temperature, T u，out，max is the maximum outlet water temperature on the user side, T u，out，1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u，out，2 The outlet water temperature on the user side of the No. 2 heat pump host;

[0079] The user-side outlet water temperature in cooling mode meets the allowable range of cooling conditions, expressed as:

[0080] 5≤T u，out，1 , T u，out，2 ≤10.

[0081] The user-side outlet water temperature in cooling mode meets the allowable range of cooling conditions, expressed as:

[0082] 40≤T u，out，1 , T u，out，2 ≤55.

[0083] The operation optimization model is a mixed integer nonlinear programming model, which can be solved using the professional solver CPLEX. In order to improve the control speed in actual operation, the cooling load L of different user sides can be set before operation. u and the heat source side water inlet temperature T h，inThe optimal solution under the given conditions is obtained and stored, and the optimal result can be directly called during runtime.

[0084] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0085] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for optimizing the operation of a ground source heat pump system, characterized in that: The following steps are involved: Taking the minimum energy consumption of the entire ground source heat pump system as the objective function, considering the operation constraints of the system's heat pump host, and combining decision variables, a ground source heat pump operation optimization model is constructed; Determine the relationship between the energy of the heat pump host, the user-side load, and the water pump power, depending on whether the system is in cooling mode or heating mode; Solve the ground source heat pump operation optimization model to control the user-side water outlet temperature in cooling mode and heating mode to meet the allowable range of cooling and heating conditions; The objective function is: minP=P cmp +P u,p +P h,p Where: P cmp is the total power of all compressors, P u,p is the total power of all user-side water pumps, P h,p is the total power of all water pumps on the heat source side; The system includes heat pump host No. 1 and heat pump host No. 2, each of which includes two compressors. The operating constraints of the heat pump host are: P cmp =P cmp,1 +P cmp,2 Where: P cmp,1 is the compressor power of heat pump host No. 1, P cmp,2 is the compressor power of heat pump host No. 2, P cmp,1,max is the maximum power of the two compressors in the No. 1 heat pump host when they are fully opened, P cmp,2,max The maximum power when the two compressors in the No. 2 heat pump main unit are fully opened; The decision variables are I1, I2, I3, I4, I5, and I6; I1, I2, and I3 represent the start and stop status of heat pump host No. 1, with a value range of 0-1. I1+I2+I3=1. When I1=1, heat pump host No. 1 is shut down. When I2=1, heat pump host No. 1 has only one compressor turned on. When I3=1, both compressors of heat pump host No. 1 are fully turned on. I4, I5, and I6 represent the start and stop status of the No. 2 heat pump host. The value range is 0-1, and I4+I5+I6=1. When I4=1, it means that the No. 2 heat pump host is off. When I5=1, it means that only one compressor of the No. 2 heat pump host is turned on. When I6=1, it means that both compressors of the No. 2 heat pump host are fully turned on. The ground source heat pump operation optimization model is expressed as: COP=f(T h,in ,T u,out ) Where: T h,in is the inlet water temperature on the heat source side, T u,out The outlet water temperature at the user side; The maximum power P cmp,1,max 、P cmp,2,max The calculation formula is: P cmp,1,max =f(T h,in ,T u,out,1 ) P cmp,2,max =f(T h,in ,T uout,2 ) Where: T h,in is the water inlet temperature on the heat source side, T h,in Same, T u,out,1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u,out,2 The outlet water temperature on the user side of the No. 2 heat pump host; Depending on whether the system is in cooling mode or heating mode, the steps for determining the relationship between the energy of the heat pump host, the user-side load, and the water pump power include: The relationship between the cooling / heating energy of the No. 1 and No. 2 heat pump hosts of the system and the user-side cooling / heating load and the user-side water pump power is expressed as follows: When the system is in cooling mode, L1 is the cooling capacity of heat pump host No. 1, L2 is the cooling capacity of heat pump host No. 2, and L u It is the cooling load on the user side; When the system is in heating mode, L1 is the heating capacity of heat pump host No. 1, L2 is the heating capacity of heat pump host No. 2, L u is the heat load on the user side; The calculation formulas for the cooling / heating energy L1 and L2 of the No. 1 and No. 2 heat pump hosts are: Where: L 1,max is the maximum cooling / heating capacity of heat pump host No. 1, and is the water inlet temperature T on the heat source side. h,in and the user side outlet water temperature T of No. 1 heat pump host u,out,1 Function of L 2,max is the maximum cooling / heating capacity of heat pump host No. 2, and is the water inlet temperature T on the heat source side. h,in and the user side outlet water temperature T of the No. 2 heat pump host u,out,2 function.

2. The operation optimization method of a ground source heat pump system according to claim 1, characterized in that: The user-side outlet water temperature in cooling mode and heating mode is controlled to meet the allowable range of cooling and heating conditions, which can be expressed as: T u,out,min ≤T u,out，1 ,T u,out，2 ≤T u,out,max Where: T u,out,min is the minimum value of the user side water outlet temperature, T u,out,max is the maximum outlet water temperature on the user side, T u,out,1 is the outlet water temperature on the user side of the No. 1 heat pump host, T u,out,2 The outlet water temperature on the user side of the No. 2 heat pump main unit.

3. The method for optimizing the operation of a ground source heat pump system according to claim 2, characterized in that: The user-side outlet water temperature in the cooling mode meets the allowable range of the cooling condition, which is expressed as: 5≤T u，out，1 ,T u，out，2 ≤10。 4. The method for optimizing the operation of a ground source heat pump system according to claim 2, wherein: The user-side outlet water temperature in the heating mode meets the allowable range of the heating condition, which is expressed as: 40≤T u，out，1 ,≤T u，out，2 ≤55。

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