Control methods for multi-split water supply systems

Abstract

This application provides a control method for a water source multi-split air conditioner, including an outdoor unit operating capacity adjustment step S30. Step S30 includes: step S31, obtaining the total operating capacity Q1 of the indoor units currently in operation of the water source multi-split air conditioner; step S32, obtaining the total operating capacity Q2 of the outdoor units currently in operation of the water source multi-split air conditioner; step S33, obtaining the operating parameters of the water source multi-split air conditioner, including the operating parameters of the water system of the water source multi-split air conditioner; step S34, obtaining the outdoor unit operating demand capacity Q3 based on the total operating capacity Q1, the total operating capacity Q2, and the operating parameters of the water source multi-split air conditioner; and step S35, adjusting the number of outdoor units currently in operation and / or the operating parameters of the outdoor units to make the operating capacity of the outdoor units currently in operation reach the outdoor unit operating demand capacity Q3.

Description

Technical Field

[0001] This application relates to air conditioning equipment, and more particularly to a control method for a water source multi-split air conditioning system. Background Technology

[0002] Water-source multi-split systems use water as the refrigerant, and the heat exchange unit that exchanges heat with the external heat source is a water-cooled heat exchanger. Compared to air-source multi-split systems, water-source multi-split systems have an independent, closed water system to meet the heat exchange requirements of condensation or evaporation. Water's thermal conductivity or specific heat capacity is much higher than air's, resulting in faster and more efficient control response for water-source multi-split systems. The water system of a water-source multi-split system is an independent, closed-loop system, which has higher requirements than that of an air-source multi-split system, requiring careful consideration of factors such as water flow rate and temperature. Air-source multi-split systems, on the other hand, are open heat exchanger systems and do not require as much consideration of air conditions, such as whether there is sufficient air.

[0003] The above statements are for the purpose of providing background information in relation to this application only, and do not necessarily constitute prior art. Summary of the Invention

[0004] The purpose of this application is to provide a control method for a water source multi-split air conditioner, which aims to adjust the operating parameters of the outdoor unit of the water source multi-split air conditioner according to the operating parameters of the water system, so as to make the operating parameters of the outdoor unit of the water source multi-split air conditioner more compatible with the operating parameters of the water system.

[0005] This application provides a control method for a multi-split air conditioning system, including an outdoor unit operating capacity adjustment step S30, wherein step S30 includes:

[0006] Step S31: Obtain the total operating capacity Q1 of the indoor units of the water source multi-split air conditioner that are currently in operation;

[0007] Step S32: Obtain the total operating capacity Q2 of the outdoor units of the water source multi-split air conditioner.

[0008] Step S33: Obtain the operating parameters of the water source multi-split unit, including the operating parameters of the water system of the water source multi-split unit;

[0009] Step S34: Obtain the required capacity Q3 of the outdoor unit based on the total capacity Q1 of the indoor unit, the total capacity Q2 of the outdoor unit, and the operating parameters of the water source multi-split unit;

[0010] Step S35: Adjust the number of operating outdoor units and / or the operating parameters of the operating outdoor units of the water source multi-split system so that the operating capacity of the operating outdoor units of the water source multi-split system reaches the outdoor unit operating demand capacity Q3 or the modified outdoor unit demand capacity Qz modified according to the outdoor unit operating demand capacity Q3.

[0011] In some embodiments of the control method for water source multi-split systems,

[0012] Step S31 includes: Q1 = ∑(qk), where k is the number of the currently operating indoor unit of the water source multi-split system, and qk is the nominal operating capacity of the kth currently operating indoor unit; and / or

[0013] Step S32 includes: Q2 = ∑(qh), where h is the number of the operating outdoor unit of the water source multi-split system, and qh is the nominal operating capacity of the h-th operating outdoor unit; and / or

[0014] The operating parameters of the water system of the multi-split air conditioning unit include the average inlet water temperature Tih and the average outlet water temperature Toh of each of the outdoor units currently in operation; and / or

[0015] The operating parameters of the water source multi-split air conditioner include the average indoor ambient temperature Tik of the indoor unit that is currently in operation.

[0016] In some embodiments of the control method for a multi-split water source system, step S34 includes:

[0017] Q3 = ∑(f(Q4) * f(△Th)); where,

[0018] Q4 is the total basic operating capacity of the outdoor unit, f(Q4)=Q1*fo, fo is the percentage of basic operating capacity required by the outdoor unit, fo=f((∑(qk)) / (∑(qm)),Tik,Tih), where m is the number of the indoor unit of the water source multi-split system, and qm is the nominal operating capacity of the m-th indoor unit.

[0019] △Th is the average temperature difference between the inlet and outlet water of the outdoor unit during operation. △Th=ads(Toh-Tih), where ads represents taking the absolute value, and f(△Th) is a percentage function of the temperature difference between the inlet and outlet water of the outdoor unit.

[0020] In some embodiments of the control method for a water source multi-split air conditioner, when the water source multi-split air conditioner is in cooling mode, the higher the average inlet water temperature Tih of the outdoor unit that is running, the higher the percentage of basic operating capacity requirement fo of the outdoor unit.

[0021] When the water source multi-split unit is in heating mode, the higher the average inlet water temperature Tih of the outdoor unit, the lower the percentage of basic operating capacity requirement fo of the outdoor unit.

[0022] In some embodiments of the control method for water source multi-split air conditioning units, the percentage of basic operating capacity requirement fo of the outdoor unit is obtained by fitting experimental data.

[0023] In some embodiments of the control method for a multi-split air conditioning system, the percentage of basic capacity requirement fo for the outdoor unit is a piecewise function segmented based on the average indoor ambient temperature Tik of the indoor unit currently in operation.

[0024] In some embodiments of the control method for a multi-split air conditioning system, the percentage of basic operating capacity requirement fo of the outdoor unit is divided into at least three segments based on the average indoor ambient temperature Tik of the currently operating indoor unit.

[0025] When the average indoor temperature Tik is less than or equal to the first preset temperature and greater than the second preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit is a first segment function.

[0026] When the average indoor temperature Tik is less than or equal to the second preset temperature and greater than the third preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit is a second segment function.

[0027] When the average indoor temperature Tik is less than or equal to the third preset temperature and greater than the fourth preset temperature, the percentage of the outdoor unit's basic operational capacity requirement fo is a third-segment function.

[0028] In some embodiments of the control method for water source multi-split systems,

[0029] The first preset temperature ranges from [45, 55]℃;

[0030] The second preset temperature ranges from [33, 43]℃;

[0031] The range of the third preset temperature is [22, 32]℃;

[0032] The fourth preset temperature ranges from [11, 21]℃.

[0033] In some embodiments of the control method for water source multi-split systems,

[0034] When the average indoor temperature Tik is greater than the first preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit adopts the first segment function.

[0035] When the average indoor temperature Tik is less than the fourth preset temperature, the percentage of the outdoor unit's basic operating capacity requirement fo adopts the third segment function.

[0036] In some embodiments of the control method for water source multi-split air conditioners, the percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit is obtained by fitting experimental data.

[0037] In some embodiments of the control method for a multi-split water source unit, when the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit is 0, the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 100%. When the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit is the allowable limit temperature difference, the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 0. The percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit decreases gradually from 100% as the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit changes from 0 to the limit temperature difference, then decreases sharply, and then decreases gradually back to 0.

[0038] In some embodiments of the control method for water source multi-split systems, the extreme temperature difference range is [43, 50]℃.

[0039] In some embodiments of the control method for a multi-split air conditioning system, the operating parameters of the multi-split air conditioning system also include the set average temperature Tgk of the indoor unit currently in operation. Step S35 includes: correcting the outdoor unit's operating demand capacity Q3 based on the set average temperature difference ΔTig of the indoor unit to obtain the corrected outdoor unit operating demand capacity Qz, where ΔTig = Tik - Tgk, and the larger the absolute value of the set average temperature difference ΔTig, the larger the corrected outdoor unit operating demand capacity Qz.

[0040] In the control method of the water source multi-split unit in some embodiments, the outdoor unit output percentage corresponding to the average temperature difference ΔTig is set as ft=ads(Tik-Tgk) / Tgk, Qz=Q3*(1+ft).

[0041] In some embodiments of the control method for a multi-split air conditioning system, step S35 includes adjusting the frequency of the compressor of the outdoor unit that is in operation.

[0042] In some embodiments of the control method for a multi-split water source system, the control method further includes a water system anomaly judgment and handling step S50, which includes:

[0043] Step S51: Obtain the average inlet water temperature Tih of the outdoor unit during operation and / or the average outlet water temperature Toh of the outdoor unit during operation.

[0044] Step S52: Determine whether the water system is normal based on the average inlet water temperature Tih and / or the average outlet water temperature Toh of the outdoor unit. If the water system is normal, the water source multi-split unit continues to operate. If the water system is abnormal, the water source multi-split unit stops.

[0045] In some embodiments of the control method for a multi-unit water source system, steps S51 and S52 are executed once every preset time period.

[0046] In some embodiments of the control method for water source multi-unit systems, the preset time period ranges from [25, 30] s.

[0047] In some embodiments of the control method for a multi-split water source unit, step S52 includes:

[0048] If Tmin < Tih < Tmax, and ΔTmin ≤ ΔTh ≤ ΔTmax, then the water system is considered normal; and / or

[0049] If Tih ≥ Tmax or Tih ≤ Tmin, then the water system is judged to be abnormal;

[0050] Where Tmin is the minimum allowable inlet water temperature, Tmax is the maximum allowable inlet water temperature, and Tmin < Tmax, △Th is the average temperature difference between the inlet and outlet water of the outdoor unit during operation, △Th = ads(Toh - Tih), where ads represents taking the absolute value, △Tmin is the minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit, and △Tmax is the maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit.

[0051] In some embodiments of the control method for water source multi-split systems,

[0052] The minimum allowable inlet water temperature Tmin is within the range of [-15, -10]℃; and / or

[0053] The maximum allowable inlet water temperature Tmax is within the range of [55, 60]℃; and / or

[0054] The minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit, ΔTmin, is within the range of [-10, -5]℃; and / or

[0055] The maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit, ΔTmax, is within the range of [45, 50]℃.

[0056] In some embodiments of the control method for a multi-split water source unit, the control method further includes a capacity matching anomaly judgment and handling step S70, wherein step S70 includes:

[0057] Step S71: Obtain the total basic capacity Q5 of the indoor units of the water source multi-split air conditioner.

[0058] Step S72: Obtain the total basic capacity Q6 of the outdoor unit of the water source multi-split air conditioner.

[0059] Step S73: Determine whether the capacity matching of the water source multi-split unit is normal based on the total basic capacity Q5 of the indoor unit and the total basic capacity Q6 of the outdoor unit. If the capacity matching is normal, the water source multi-split unit is allowed to operate; if the capacity matching is abnormal, the water source multi-split unit is prohibited from operating.

[0060] In some embodiments of the control method for water source multi-split systems,

[0061] Step S71 includes: Q5 = ∑(qm), where m is the indoor unit number of the water source multi-split air conditioning system, and qm is the nominal operating capacity of the m-th indoor unit; and / or

[0062] Step S72 includes: Q6=∑(qn), where n is the number of the outdoor unit of the water source multi-split unit, and qn is the nominal operating capacity of the nth outdoor unit.

[0063] In some embodiments of the control method for a multi-split water source unit, step S73 includes:

[0064] If Xmin≤Q5 / Q6≤Xmax, then the capacity matching is considered normal;

[0065] If Q5 / Q6 > Xmax or Q5 / Q6 < Xmin, then the capacity mismatch is determined to be abnormal.

[0066] Where Xmin is the minimum allowed capacity matching value, Xmax is the maximum allowed capacity matching value, and Xmin < Xmax.

[0067] In some embodiments of the control method for water source multi-split systems,

[0068] The minimum capacity matching allowable value Xmin ranges from 10% to 50%, and / or

[0069] The maximum capacity matching allowable value Xmax ranges from 150% to 200%.

[0070] Based on the control method for a water-source multi-split air conditioner provided in this application, in the outdoor unit operating capacity adjustment step, the required outdoor unit operating capacity Q3 is obtained based on the total operating indoor unit capacity Q1, the total operating outdoor unit capacity Q2, and the operating parameters of the water-source multi-split air conditioner, including the operating parameters of the water system. The number of operating outdoor units and / or the operating parameters of the operating outdoor units are adjusted so that the operating capacity of the operating outdoor units reaches the required outdoor unit operating capacity Q3 or a modified outdoor unit operating capacity Qz based on the required outdoor unit operating capacity Q3. Since the operating parameters of the water system of the water-source multi-split air conditioner participate in adjusting the operating parameters of the outdoor units, the operating parameters of the outdoor units are adjusted to have a higher degree of compatibility with the operating parameters of the water system, which is beneficial for the water-source multi-split air conditioner to operate in a more optimal state.

[0071] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0072] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0073] Figure 1A and Figure 1B This is a schematic diagram of an exemplary water source multi-split system, suitable for the control method of the water source multi-split system in the embodiments of this application.

[0074] Figure 2 This diagram illustrates the relationship between the percentage of basic capacity requirement fo for outdoor unit operation and the average indoor ambient temperature Tik of the indoor unit currently in operation, as well as the average inlet water temperature Tih of each outdoor unit currently in operation.

[0075] Figure 3 This is a schematic diagram showing the relationship between the percentage function of the inlet and outlet water temperature difference of the outdoor unit and the change of the average inlet and outlet water temperature difference ΔTh of the outdoor unit during operation.

[0076] Figure 4 This is a flowchart illustrating the outdoor unit operating capacity adjustment step in the control method of the water source multi-split air conditioner according to an embodiment of this application.

[0077] Figure 5 This is a flowchart illustrating the steps for judging and handling water system anomalies in the control method of the water source multi-unit system according to an embodiment of this application.

[0078] Figure 6 This is a flowchart illustrating the capacity matching anomaly judgment and handling steps in the control method of the water source multi-unit system according to an embodiment of this application. Detailed Implementation

[0079] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0080] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0081] In the description of this application, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0082] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0083] This application provides a control method for a multi-split air conditioning system, including an outdoor unit operating capacity adjustment step S30, which includes:

[0084] Step S31: Obtain the total operating capacity Q1 of the indoor units of the water source multi-split air conditioner that are currently in operation;

[0085] Step S32: Obtain the total operating capacity Q2 of the outdoor units of the water source multi-split air conditioner.

[0086] Step S33: Obtain the operating parameters of the water source multi-split unit. The operating parameters of the water source multi-split unit include the operating parameters of the water system of the water source multi-split unit.

[0087] Step S34: Obtain the required capacity Q3 of the outdoor unit based on the total capacity Q1 of the indoor unit, the total capacity Q2 of the outdoor unit, and the operating parameters of the water source multi-split unit;

[0088] Step S35: Adjust the number of operating outdoor units of the water source multi-split system and / or the operating parameters of the operating outdoor units so that the operating capacity of the operating outdoor units of the water source multi-split system reaches the outdoor unit operating demand capacity Q3 or the modified outdoor unit demand capacity Qz modified according to the outdoor unit operating demand capacity Q3.

[0089] The control method for a water source multi-split air conditioner provided in this application embodiment, in its outdoor unit operating capacity adjustment step, obtains the outdoor unit operating demand capacity Q3 based on the total operating indoor unit capacity Q1, the total operating outdoor unit capacity Q2, and the operating parameters of the water source multi-split air conditioner, including the operating parameters of the water system. It then adjusts the number of operating outdoor units and / or the operating parameters of these units to ensure that the operating capacity of the operating outdoor units reaches the outdoor unit operating demand capacity Q3 or a modified outdoor unit demand capacity Qz based on the outdoor unit operating demand capacity Q3. Since the operating parameters of the water system of the water source multi-split air conditioner participate in adjusting the operating parameters of the outdoor units, the operating parameters of the outdoor units can be adjusted to have a higher degree of compatibility with the operating parameters of the water system, which is beneficial for the water source multi-split air conditioner to operate in a more optimal state.

[0090] In some embodiments of the control method for water source multi-split systems,

[0091] Step S31 includes: Q1 = ∑(qk), where k is the number of the operating indoor unit of the water source multi-split system, qk is the nominal operating capacity of the kth operating indoor unit; and / or

[0092] Step S32 includes: Q2 = ∑(qh), where h is the number of the operating outdoor unit of the water source multi-split system, and qh is the nominal operating capacity of the h-th operating outdoor unit; and / or

[0093] The operating parameters of the water system of a multi-split air conditioning unit include the average inlet water temperature Tih and the average outlet water temperature Toh of each operating outdoor unit; and / or

[0094] The operating parameters of a water source multi-split air conditioner include the average indoor ambient temperature Tik of the indoor unit currently in operation.

[0095] In some embodiments of the control method for a multi-split water source unit, step S34 includes:

[0096] Q3 = ∑(f(Q4) * f(△Th)); where,

[0097] Q4 is the total basic operating capacity of the outdoor unit, f(Q4)=Q1*fo, fo is the percentage of basic operating capacity required by the outdoor unit, fo=f((∑(qk)) / (∑(qm)),Tik,Tih), where m is the number of the indoor unit of the water source multi-split system, and qm is the nominal operating capacity of the m-th indoor unit;

[0098] △Th is the average temperature difference between the inlet and outlet water of the outdoor unit during operation. △Th=ads(Toh-Tih), where ads represents taking the absolute value, and f(△Th) is a percentage function of the temperature difference between the inlet and outlet water of the outdoor unit.

[0099] like Figure 2 As shown, in the control method of the water source multi-split air conditioner in some embodiments, when the water source multi-split air conditioner is in cooling mode, the higher the average inlet water temperature Tih of the outdoor unit of the operating outdoor unit, the higher the percentage of basic capacity requirement fo of the outdoor unit; when the water source multi-split air conditioner is in heating mode, the higher the average inlet water temperature Tih of the outdoor unit of the operating outdoor unit, the lower the percentage of basic capacity requirement fo of the outdoor unit.

[0100] In some embodiments of the control method for water source multi-split air conditioning units, the percentage of basic capacity requirement fo for the outdoor unit is obtained by fitting experimental data.

[0101] like Figure 2 As shown, in some embodiments of the control method for water source multi-split air conditioners, the outdoor unit's basic operating capacity requirement percentage fo is a piecewise function segmented based on the average indoor ambient temperature Tik of the currently operating indoor unit.

[0102] like Figure 2 As shown, in some embodiments of the control method for a multi-split air conditioning system, the outdoor unit's basic operating capacity requirement percentage fo is divided into at least three segments based on the average indoor ambient temperature Tik of the currently operating indoor unit. When the average indoor ambient temperature Tik is less than or equal to a first preset temperature and greater than a second preset temperature, the outdoor unit's basic operating capacity requirement percentage fo is a function of the first segment. When the average indoor ambient temperature Tik is less than or equal to the second preset temperature and greater than a third preset temperature, the outdoor unit's basic operating capacity requirement percentage fo is a function of the second segment. When the average indoor ambient temperature Tik is less than or equal to the third preset temperature and greater than a fourth preset temperature, the outdoor unit's basic operating capacity requirement percentage fo is a function of the third segment.

[0103] Test data shows that, under different average indoor temperatures, different capacity correction coefficients (i.e., different percentages of outdoor unit operating capacity requirement, fo) are needed due to differences in refrigerant state parameters to achieve better comfort and energy efficiency, thus improving the cost-effectiveness of water-source multi-shutdown systems. Specifically, the percentage of outdoor unit operating capacity requirement, fo, is a piecewise function segmented based on the average indoor temperature, Tik, of the currently operating indoor unit, which facilitates optimal operating parameters for water-source multi-shutdown systems.

[0104] In the control method of the water source multi-split unit in some embodiments, the first preset temperature ranges from [45, 55]℃; the second preset temperature ranges from [33, 43]℃; the third preset temperature ranges from [22, 32]℃; and the fourth preset temperature ranges from [11, 21]℃.

[0105] In some embodiments of the control method for water source multi-split air conditioners, when the average indoor temperature Tik is greater than a first preset temperature, the percentage of basic operating capacity requirement fo of the outdoor unit adopts a first segment function; when the average indoor temperature Tik is less than a fourth preset temperature, the percentage of basic operating capacity requirement fo of the outdoor unit adopts a third segment function.

[0106] For example, in some embodiments, the first preset temperature is 50°C; the second preset temperature is 38°C; the third preset temperature is 27°C; and the fourth preset temperature is 16°C.

[0107] Setting appropriate segmentation and temperature point values ​​for the outdoor unit's basic operating capacity requirement percentage (fo) helps to adjust the outdoor unit's operating parameters to better match the water system's operating parameters, thus enabling the water source multi-split system to operate in a more optimal state.

[0108] In some embodiments of the control method for water source multi-split air conditioners, the percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit is obtained by fitting experimental data.

[0109] like Figure 3 As shown, in the control method of the water source multi-split air conditioner in some embodiments, when the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit is 0, the value of the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 100%. When the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit is the allowable limit temperature difference, the value of the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 0. The percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit decreases gradually from 100% as the average temperature difference ΔTh between the inlet and outlet water of the operating outdoor unit changes from 0 to the limit temperature difference, then decreases sharply, and then decreases gradually back to 0.

[0110] In some embodiments of the control method for a multi-split water source system, the limiting temperature difference range is [43, 50] °C. For example, in some embodiments, the limiting temperature difference range is 45 °C. The limiting temperature difference can be obtained from experimental data.

[0111] In some embodiments of the control method for a water source multi-split air conditioner, step S35 includes adjusting the frequency of the compressor of the outdoor unit that is in operation.

[0112] In some embodiments of the control method for a multi-split water source air conditioner, the control method further includes a water system anomaly judgment and handling step S50. Step S50 includes: step S51, obtaining the average inlet water temperature Tih and / or the average outlet water temperature Toh of the outdoor unit currently in operation; step S52, judging whether the water system is normal based on the average inlet water temperature Tih and / or the average outlet water temperature Toh of the outdoor unit. If the water system is normal, the multi-split water source air conditioner continues to operate; if the water system is abnormal, the multi-split water source air conditioner stops.

[0113] Setting up water system anomaly detection and handling procedures facilitates the timely detection of water system anomalies, such as water pipe blockage or accidental valve closure, thus promoting the safe and stable operation of the water source multi-unit system.

[0114] In the control method of the water source multi-unit system in some embodiments, steps S51 and S52 are executed once every preset time period.

[0115] Executing steps S51 and S52 once every preset time period helps to detect water system abnormalities in a timely manner.

[0116] In some embodiments of the control method for a multi-split water system, the preset time period ranges from [25, 30] seconds. For example, the preset time period can be 30 seconds. Setting a reasonable preset time period allows for timely detection of water system anomalies without requiring excessively frequent checks.

[0117] In some embodiments of the control method for a multi-split water system, step S52 includes: if Tmin < Tih < Tmax, and △Tmin ≤ △Th ≤ △Tmax, then the water system is judged to be normal; and / or if Tih ≥ Tmax or Tih ≤ Tmin, then the water system is judged to be abnormal; wherein, Tmin is the minimum allowable inlet water temperature, Tmax is the maximum allowable inlet water temperature, and Tmin < Tmax, △Th is the average temperature difference between the inlet and outlet water of the operating outdoor unit, △Th = ads(Toh - Tih), where ads represents taking the absolute value, △Tmin is the minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit, and △Tmax is the maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit.

[0118] In some embodiments of the control method for a multi-split air conditioning system, the minimum allowable inlet water temperature Tmin ranges from [-15, -10]℃; and / or the maximum allowable inlet water temperature Tmax ranges from [55, 60]℃; and / or the minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit ΔTmin ranges from [-10, -5]℃; and / or the maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit ΔTmax ranges from [45, 50]℃.

[0119] In some embodiments, the minimum allowable inlet water temperature Tmin is -10℃, the maximum allowable inlet water temperature Tmax is 60℃, the minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit ΔTmin is -5℃, and the maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit ΔTmax is 45℃.

[0120] Setting reasonable minimum allowable inlet water temperature Tmin, maximum allowable inlet water temperature Tmax, minimum allowable average temperature difference between inlet and outlet water of outdoor unit △Tmin, and maximum allowable average temperature difference between inlet and outlet water of outdoor unit △Tmax is beneficial for timely detection of water system problems and will not cause unnecessary shutdown of water source multi-split units due to operation of judging abnormal water system.

[0121] In some embodiments of the control method for a water source multi-split air conditioner, the control method further includes a capacity matching anomaly judgment and handling step S70. Step S70 includes: step S71, obtaining the total basic capacity Q5 of the indoor units of the water source multi-split air conditioner; step S72, obtaining the total basic capacity Q6 of the outdoor units of the water source multi-split air conditioner; step S73, judging whether the capacity matching of the water source multi-split air conditioner is normal based on the total basic capacity Q5 of the indoor units and the total basic capacity Q6 of the outdoor units. If the capacity matching is normal, the water source multi-split air conditioner is allowed to operate; if the capacity matching is abnormal, the water source multi-split air conditioner is prohibited from operating.

[0122] Setting up capacity mismatch judgment and handling steps helps to promptly detect problems of capacity mismatch between indoor and outdoor units of water source multi-split systems, preventing abnormal operation of the water source multi-split system due to capacity mismatch between indoor and outdoor units.

[0123] In some embodiments of the control method for a water source multi-split air conditioner, step S71 includes: Q5=∑(qm), where m is the number of the indoor unit of the water source multi-split air conditioner, and qm is the nominal operating capacity of the m-th indoor unit; and / or step S72 includes: Q6=∑(qn), where n is the number of the outdoor unit of the water source multi-split air conditioner, and qn is the nominal operating capacity of the n-th outdoor unit.

[0124] In the control method of a multi-split water source unit in some embodiments, step S73 includes: if Xmin≤Q5 / Q6≤Xmax, then the capacity matching is determined to be normal; if Q5 / Q6>Xmax or Q5 / Q6<Xmin, then the capacity matching is determined to be abnormal; wherein, Xmin is the minimum allowable value for capacity matching, Xmax is the maximum allowable value for capacity matching, and Xmin<Xmax.

[0125] In some embodiments of the control method for water source multi-split systems, the minimum capacity matching allowable value Xmin ranges from 10% to 50%, and / or the maximum capacity matching allowable value Xmax ranges from 150% to 200%. For example, the minimum capacity matching allowable value Xmin is 10%, and the maximum capacity matching allowable value Xmax is 200%.

[0126] Setting reasonable minimum capacity matching allowable value Xmin and maximum capacity matching allowable value Xmax is beneficial for timely detection of capacity matching anomalies without causing unnecessary shutdown of the water source multi-unit due to the operation of judging capacity matching anomalies.

[0127] The following combination Figures 1A to 6 The control method of a water source multi-unit system according to an embodiment of this application is described in detail.

[0128] Figure 1A and Figure 1B This is a schematic diagram of a water source multi-split system, suitable for the control method of this application. (See attached diagram.) Figure 1A and 1B The water source multi-split unit shown includes a refrigerant circulation main line 110, a subcooling branch line 120, an enthalpy-increasing branch line 130, a pressurizing branch line 140, a mode converter 150, a water system 160, and a control system.

[0129] The refrigerant circulation main line 110 includes a main refrigerant line 1119 and, connected to the main refrigerant line 1119, an enthalpy-increasing compressor 1101, an oil separator 1102, a first four-way valve 1103, a water-cooled heat exchanger 1104, a heating electronic expansion valve 1105, a liquid receiver 1106, a subcooler 1107, a second four-way valve 1113, a high-pressure gas pipe valve 1114, a check valve 1108, a liquid valve 1109, an indoor unit 1110, a low-pressure gas pipe valve 1111, and a gas-liquid separator 1112. The main refrigerant line 1119 includes a high-pressure gas pipe 11191, a liquid pipe 11192, and a low-pressure gas pipe 11193. This water-source multi-split system forms a three-pipe refrigeration system.

[0130] The subcooling branch 120 includes a subcooling refrigerant line 1209 and a subcooler electronic expansion valve 1201 and a subcooling solenoid valve 1202 connected through the subcooling refrigerant line 1209. The two ends of the subcooling branch 120 are connected to the subcooler 1107 and the vapor-liquid separator 1112, respectively.

[0131] The enthalpy-increasing branch 130 includes an enthalpy-increasing refrigerant line 1309 and an enthalpy-injection electronic expansion valve 1301 connected to the enthalpy-increasing refrigerant line 1309. The two ends of the enthalpy-increasing branch 130 are respectively connected to the subcooling refrigerant line 1209 between the subcooler 1107 and the subcooler electronic expansion valve 1201 and the enthalpy-increasing port of the enthalpy-increasing compressor 1101, and are connected to the intermediate pressure chamber of the enthalpy-increasing compressor 1101 through the enthalpy-increasing port.

[0132] The pressurization branch 140 includes a pressurization refrigerant line 1409 and a capillary tube 1401 and a pressurization valve 1402 connected through the pressurization refrigerant line 1409. The two ends of the pressurization branch 140 are connected to the main refrigerant line 1119 and the liquid receiver 1106 between the oil separator 1102 and the first four-way valve 1103. The pressurization branch 140 draws high-pressure refrigerant from the discharge side of the enthalpy-increasing compressor 1101 and introduces the high-pressure refrigerant into the liquid receiver 1106 through the capillary tube 1401 and the pressurization valve 1402.

[0133] The mode converter 150 is used to switch the operating modes of a water-source multi-split air conditioner, including, for example, cooling mode and heating mode. The mode converter 150 switches the operating modes by changing the connection between the high-pressure gas pipe 11191, liquid pipe 11192 and low-pressure gas pipe 11193 of the main refrigerant pipeline 1119 and the indoor unit.

[0134] The water system 160 is used to ensure the normal heat exchange of the water source multi-split unit. Figure 1A and 1B Only water pipe 1609 is shown. Water pipe 1609 is connected to water-cooled heat exchanger 1104 for heat exchange with the refrigerant passing through water-cooled heat exchanger 1104. Water-cooled heat exchanger 1104 is, for example, a water-cooled plate heat exchanger.

[0135] like Figure 1A and 1B The water source multi-split unit shown also includes an oil return branch 180, which includes an oil return pipe 1809 and an oil return valve 1801 installed on the oil return pipe 1809. The two ends of the oil return branch 180 are respectively connected to an oil separator 1102 and an enthalpy-increasing compressor 1101.

[0136] The control system includes a detection unit and a controller. The detection unit is used to acquire the operating parameters of the water source multi-split unit. The controller is coupled with the detection unit and multiple actuators of the water source multi-split unit. These actuators include enthalpy-increasing compressor 1101, first four-way valve 1103, heating electronic expansion valve 1105, second four-way valve 1113, high-pressure gas pipe valve 1114, check valve 1108, liquid valve 1109, low-pressure gas pipe valve 1111, mode converter 150, etc., to control the operation of the actuators coupled with it according to the operating parameters detected by the detection unit.

[0137] like Figure 1A and Figure 1B As shown, the detection unit may include an exhaust temperature sensor 1701 for detecting the exhaust temperature at the outlet of the enthalpy-increasing compressor 1101, a high-pressure sensor 1702 for detecting the refrigerant pressure at the outlet of the enthalpy-increasing compressor 1101, a heat exchanger inlet refrigerant sensor 1703 for detecting the refrigerant temperature at the refrigerant inlet of the water-cooled heat exchanger 1104, a heat exchanger outlet refrigerant sensor 1704 for detecting the refrigerant temperature at the refrigerant outlet of the water-cooled heat exchanger 1104, and a sensor for detecting the temperature at the vapor-liquid separator 1112. The following sensors are used: a low-pressure sensor 1705 for detecting the refrigerant pressure at the inlet of the gas-liquid separator 1112; a refrigerant temperature sensor 1706 for detecting the refrigerant temperature at the outlet of the gas-liquid separator 1112; a refrigerant temperature sensor 1707 for detecting the refrigerant temperature at the outlet of the gas-liquid separator 1112; a refrigerant temperature sensor 1708 for detecting the refrigerant temperature at the outlet of the indoor unit 1110; and a refrigerant temperature sensor 1709 for detecting the refrigerant temperature at the inlet of the indoor unit 1110.

[0138] The controller may be implemented, for example, as a general-purpose processor, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof for performing the functions described in this disclosure.

[0139] The number of indoor and outdoor units for the above water source multi-split air conditioning system is for illustrative purposes only. The number of indoor and outdoor units can be configured according to needs.

[0140] like Figure 4 As shown, the embodiment of this application includes an outdoor unit operating capacity adjustment step S30. Step S30 includes steps S31 to S35.

[0141] Step S31 obtains the total operating capacity Q1 of the indoor units of the water source multi-split system. Step S31 includes: Q1=∑(qk), where k is the number of the indoor unit of the water source multi-split system that is currently in operation, and qk is the nominal operating capacity of the kth indoor unit that is currently in operation.

[0142] For example, a multi-split air conditioning system has 6 indoor units, with 4 units currently in operation. When calculating the total operating capacity Q1, the 4 operating indoor units are numbered 1, 2, 3, and 4. Here, q1 is the nominal operating capacity (nominal cooling or nominal heating) of the first operating indoor unit, q2 is the nominal operating capacity of the second operating indoor unit, q3 is the nominal operating capacity of the third operating indoor unit, and q4 is the nominal operating capacity of the fourth operating indoor unit. Therefore, Q1 = q1 + q2 + q3 + q4.

[0143] Step S32 obtains the total operating capacity Q2 of the outdoor units of the water source multi-split system. Step S32 includes: Q2=∑(qh), where h is the number of the outdoor unit of the water source multi-split system, and qh is the nominal operating capacity of the h-th outdoor unit.

[0144] For example, a multi-split air conditioning system has 3 outdoor units and 2 indoor units currently in operation. When calculating the total operating capacity Q2 of the outdoor units, the two indoor units in operation are numbered 1 and 2. In this case, q1 is the nominal operating capacity (nominal cooling or nominal heating) of the first operating outdoor unit, and q2 is the nominal operating capacity of the second operating outdoor unit. Therefore, Q2 = q1 + q2.

[0145] Step S33 obtains the operating parameters of the water source multi-split air conditioner. These parameters include the operating parameters of the water system. The water system operating parameters include the average inlet water temperature Tih and the average outlet water temperature Toh of each operating outdoor unit. The operating parameters also include the average indoor ambient temperature Tik of the operating indoor units.

[0146] The average inlet water temperature Tih of the outdoor unit is the average inlet water temperature of all operating outdoor units. The average outlet water temperature Toh of the outdoor unit is the average outlet water temperature of all operating outdoor units. The average indoor ambient temperature Tik is the average indoor ambient temperature of the operating indoor units. These averages can be, for example, an arithmetic mean. Step S34 obtains the required outdoor unit capacity Q3 based on the total operating indoor unit capacity Q1, the total operating outdoor unit capacity Q2, and the operating parameters of the water source multi-split system.

[0147] In step S34, Q3 = ∑(f(Q4) * f(△Th)). Q4 is the total basic operating capacity of the outdoor unit, f(Q4) = Q1 * fo, fo is the percentage of basic operating capacity required by the outdoor unit, fo = f((∑(qk)) / (∑(qm)), Tik, Tih), where m is the indoor unit number of the water source multi-split system, and qm is the nominal operating capacity of the m-th indoor unit. △Th is the average temperature difference between the inlet and outlet water of the currently operating outdoor unit, △Th = ads(Toh - Tih), where ads represents taking the absolute value, and f(△Th) is a function of the percentage of the inlet and outlet water temperature difference of the outdoor unit.

[0148] The percentage of basic operating capacity requirement for the outdoor unit, fo, and the percentage function of the inlet and outlet water temperature difference of the outdoor unit, f(△Th), were both obtained by fitting experimental data.

[0149] The outdoor unit's basic operating capacity requirement percentage fo is a piecewise function divided into three segments based on the average indoor ambient temperature Tih of the currently operating indoor unit. When the water-source multi-split system is in cooling mode, the higher the average inlet water temperature Tih of the currently operating outdoor unit, the higher the outdoor unit's basic operating capacity requirement percentage fo. Figure 3 As shown by the solid line; when the water source multi-split system is in heating mode, the higher the average inlet water temperature Tih of the operating outdoor unit, the lower the percentage of the basic operating capacity requirement fo of the outdoor unit. Figure 3 As shown by the dashed line.

[0150] like Figure 2 As shown, when the average indoor ambient temperature Tik is less than or equal to 50℃ and greater than 38℃, the percentage of basic capacity requirement fo for the outdoor unit is the first segment function fo-1 at the top; when the average indoor ambient temperature Tik is less than or equal to 38℃ and greater than 27℃, the percentage of basic capacity requirement fo for the outdoor unit is the second segment fo-2 in the middle; when the average indoor ambient temperature Tik is less than or equal to 27℃ and greater than 16℃, the percentage of basic capacity requirement fo for the outdoor unit is the third segment function fo-3 at the bottom. When the average indoor ambient temperature Tik is greater than 50℃, the percentage of basic capacity requirement fo for the outdoor unit uses the first segment function. When the average indoor ambient temperature Tik is less than 16℃, the percentage of basic capacity requirement fo for the outdoor unit uses the third segment function.

[0151] like Figure 3As shown, when the average temperature difference between the inlet and outlet water of the outdoor unit is 0, the value of the percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit is 100%. When the average temperature difference between the inlet and outlet water of the outdoor unit is the allowable limit temperature difference, the value of the percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit is 0. The percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit decreases slowly from 100% as the average temperature difference between the inlet and outlet water of the outdoor unit changes from 0 to the limit temperature difference, then decreases sharply, and then decreases slowly back to 0. Figure 3 The extreme temperature difference is 45℃.

[0152] Step S35: Adjust the number of operating outdoor units and / or the operating parameters of the operating outdoor units of the water source multi-split system so that the operating capacity of the operating outdoor units of the water source multi-split system reaches the required capacity Q3 of the outdoor units.

[0153] Step S35 includes adjusting the frequency of the compressor of the outdoor unit that is in operation.

[0154] In some embodiments, the operating parameters of the water source multi-split unit also include the set average temperature Tgk of the indoor unit currently in operation. Step S35 includes: correcting the outdoor unit's operating capacity demand Q3 based on the set average temperature difference ΔTig of the indoor unit to obtain the corrected outdoor unit operating capacity demand Qz, wherein ΔTig = Tik - Tgk, and the larger the absolute value of the set average temperature difference ΔTig, the larger the corrected outdoor unit operating capacity demand Qz.

[0155] In some embodiments, the outdoor unit output percentage corresponding to the average temperature difference ΔTig is set as ft=ads(Tik-Tgk) / Tgk, and Qz=Q3*(1+ft).

[0156] like Figure 5 As shown, the control method of the water source multi-unit system in this application embodiment further includes a water system anomaly judgment and handling step S50, which includes step S51 and step S52.

[0157] Step S51: Obtain the average inlet water temperature Tih of the operating outdoor unit and / or the average outlet water temperature Toh of the operating outdoor unit.

[0158] Step S52 determines whether the water system is normal based on the average inlet water temperature Tih and / or the average outlet water temperature Toh of the outdoor unit. If -10℃ < Tih < 60℃, and -5℃ ≤ ΔTh ≤ 45℃, the water system is considered normal. If the water system is normal, the water source multi-split unit continues to operate. If Tih ≥ 60℃ or Tih ≤ -10℃, the water system is considered abnormal. If the water system is abnormal, the water source multi-split unit shuts down.

[0159] Steps S51 and S52 are executed once every 30 seconds in a preset time period.

[0160] like Figure 6 As shown, the control method of the water source multi-unit system in this application embodiment further includes a capacity matching anomaly judgment and processing step S70, which includes steps S71 to S73.

[0161] Step S71 obtains the total basic capacity Q5 of the indoor units of the water source multi-split air conditioning system. Step S71 includes: Q5 = ∑(qm), where m is the number of the indoor unit of the water source multi-split air conditioning system, and qm is the nominal operating capacity of the m-th indoor unit.

[0162] For example, a multi-split air conditioning system has 6 indoor units. When calculating the total basic capacity Q5 of the indoor units, the 6 indoor units are numbered 1, 2, 3, 4, 5, and 6. In this case, q1 is the nominal operating capacity (nominal cooling or nominal heating) of the first indoor unit, q2 is the nominal operating capacity of the second indoor unit, q3 is the nominal operating capacity of the third indoor unit, q4 is the nominal operating capacity of the fourth indoor unit, q5 is the nominal operating capacity of the fifth indoor unit, and q6 is the nominal operating capacity of the sixth indoor unit. Therefore, Q5 = q1 + q2 + q3 + q4 + q5 + q6.

[0163] Step S72 obtains the total basic capacity Q6 of the outdoor units of the water source multi-split air conditioning system. Step S72 includes: Q6=∑(qn), where n is the number of the outdoor unit of the water source multi-split air conditioning system, and qn is the nominal operating capacity of the nth outdoor unit.

[0164] For example, a multi-split air conditioning system has three outdoor units. When calculating the total basic capacity Q6, the three outdoor units are numbered 1, 2, and 3. In this case, q1 is the nominal operating capacity (nominal cooling or nominal heating) of the first outdoor unit, q2 is the nominal operating capacity of the second outdoor unit, and q3 is the nominal operating capacity of the third outdoor unit. Therefore, Q2 = q1 + q2 + q3.

[0165] Step S73 determines whether the water source multi-split unit's capacity is properly matched based on the total basic capacity Q5 of the indoor unit and the total basic capacity Q6 of the outdoor unit. If 10% ≤ Q5 / Q6 ≤ 200%, the capacity matching is considered normal. If the capacity matching is normal, the water source multi-split unit is allowed to operate. If Q5 / Q6 > 200% or Q5 / Q6 < 10%, the capacity matching is considered abnormal. If the capacity matching is abnormal, the water source multi-split unit is prohibited from operating.

[0166] Water source multi-split air conditioning systems, due to their independent and closed water systems, are affected by water flow rate and inlet water temperature. Especially in water source multi-split air conditioning installations, if the water system does not consider flow rate regulation and instead uses a fixed flow rate, or if there are unforeseen uncontrollable factors such as blockages or accidental valve closures causing abnormal water flow, the following problems can easily occur: Insufficient water flow during cooling can lead to excessively high pressure and excessively high exhaust temperature, resulting in increased power consumption and even frequent compressor protection activation; during heating, it can lead to excessively low pressure and insufficient exhaust superheat, causing compressor liquid slugging and even freezing of the water-cooled heat exchanger; excessive water flow... During high-volume cooling and heating, excessive water flow can cause the water-cooled heat exchanger to flow too fast, reducing its lifespan and potentially leading to leaks. This can result in water entering the cooling circulation system, increasing after-sales costs. Water source multi-split systems, due to their independent and closed water systems, are prone to low-temperature exhaust protection when the inlet water temperature is too low, causing liquid return to the compressor and increasing the risk of compressor damage. Conversely, excessively high inlet water temperature can cause excessively high pressure and exhaust temperature in the water source multi-split system during cooling and heating, increasing power consumption and triggering over-temperature protection mechanisms.

[0167] The control method for a water source multi-split air conditioner in this application embodiment, based on the characteristics of water flow changes in its water system, such as the resulting changes in the average inlet water temperature Tih and the average outlet water temperature Toh of the outdoor unit, conducts numerous experiments. Based on the experimental results, a database is created and fitted as an intermediate function of the control function to reduce chip storage requirements. The relationship between water flow and temperature difference is represented by the water system's temperature difference. The system is then continuously adjusted towards an optimal target state (which can be understood as the optimal state determined through numerous experiments) based on the actual operating state of the water source multi-split air conditioner, ultimately achieving the optimal target state and thus enhancing the adaptability of the water source multi-split air conditioner. Furthermore, it can provide timely protection against abnormal capacity matching and water system anomalies in the water source multi-split air conditioner.

[0168] Those skilled in the art will understand that, in the methods described in the specific embodiments, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this application or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this application.

Claims

1. A control method for a multi-unit water source system, characterized in that, This includes an outdoor unit operating capacity adjustment step S30, which includes: Step S31: Obtain the total operating capacity Q1 of the indoor units of the water source multi-split system, Q1=∑(qk), where k is the number of the indoor unit of the water source multi-split system and qk is the nominal operating capacity of the kth indoor unit. Step S32: Obtain the total operating capacity Q2 of the outdoor units of the water source multi-split system, Q2=∑(qh), where h is the number of the outdoor unit of the water source multi-split system and qh is the nominal operating capacity of the h-th outdoor unit. Step S33: Obtain the operating parameters of the water source multi-split unit. The operating parameters of the water source multi-split unit include the average inlet water temperature Tih and the average outlet water temperature Toh of each outdoor unit that is currently in operation, and the average indoor ambient temperature Tik of each indoor unit that is currently in operation. Step S34: Obtain the required operating capacity Q3 of the outdoor units based on the total operating capacity Q1 of the indoor units, the total operating capacity Q2 of the outdoor units, and the operating parameters of the water source multi-split unit. Q3 = ∑(f(Q4) * f(△Th)), Q4 represents the total basic operating capacity of the outdoor unit, f(Q4) = Q1 * fo, where fo is the percentage of basic operating capacity required by the outdoor unit, fo = f((∑(qk)) / (∑(qm)), Tik, Tih), where m is the indoor unit number of the water source multi-split system, and qm is the nominal operating capacity of the m-th indoor unit. △Th is the average temperature difference between the inlet and outlet water of the outdoor unit during operation. △Th=ads(Toh-Tih), where ads represents taking the absolute value, and f(△Th) is a percentage function of the temperature difference between the inlet and outlet water of the outdoor unit. Step S35: Adjust the number of operating outdoor units and / or the operating parameters of the operating outdoor units of the water source multi-split system so that the operating capacity of the operating outdoor units of the water source multi-split system reaches the outdoor unit operating demand capacity Q3 or the modified outdoor unit demand capacity Qz modified according to the outdoor unit operating demand capacity Q3.

2. The control method for the water source multi-unit system according to claim 1, When the water source multi-split system is in cooling mode, the higher the average inlet water temperature Tih of the outdoor unit, the higher the percentage of basic operating capacity requirement fo of the outdoor unit. When the water source multi-split unit is in heating mode, the higher the average inlet water temperature Tih of the outdoor unit, the lower the percentage of basic operating capacity requirement fo of the outdoor unit.

3. The control method for a multi-unit water source system according to claim 1, characterized in that, The percentage of basic operational capacity requirement fo for the outdoor unit was obtained by fitting experimental data.

4. The control method for a multi-unit water source system according to claim 1, characterized in that, The outdoor unit's basic operational capacity requirement percentage fo is a piecewise function segmented based on the average indoor ambient temperature Tik of the currently operating indoor unit.

5. The control method for a multi-unit water source system according to claim 4, characterized in that, The outdoor unit's basic operational capacity requirement percentage fo is divided into at least three segments based on the average indoor ambient temperature Tik of the currently operating indoor unit. When the average indoor temperature Tik is less than or equal to the first preset temperature and greater than the second preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit is a first segment function. When the average indoor temperature Tik is less than or equal to the second preset temperature and greater than the third preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit is a second segment function. When the average indoor temperature Tik is less than or equal to the third preset temperature and greater than the fourth preset temperature, the percentage of the outdoor unit's basic operational capacity requirement fo is a third-segment function.

6. The control method for a multi-unit water source system according to claim 5, characterized in that, The first preset temperature ranges from [45, 55]℃; The second preset temperature ranges from [33, 43]℃; The range of the third preset temperature is [22, 32]℃; The fourth preset temperature ranges from [11, 21]℃.

7. The control method for a multi-unit water source system according to claim 5, characterized in that, When the average indoor temperature Tik is greater than the first preset temperature, the percentage of the basic operating capacity requirement fo of the outdoor unit adopts the first segment function. When the average indoor temperature Tik is less than the fourth preset temperature, the percentage of the outdoor unit's basic operating capacity requirement fo adopts the third segment function.

8. The control method for a multi-unit water source system according to claim 1, characterized in that, The percentage function f(△Th) of the inlet and outlet water temperature difference of the outdoor unit is obtained by fitting experimental data.

9. The control method for a multi-unit water source system according to claim 1, characterized in that, When the average temperature difference between the inlet and outlet water of the operating outdoor unit is ΔTh, the value of the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 100%. When the average temperature difference between the inlet and outlet water of the operating outdoor unit is the allowable limit temperature difference, the value of the percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit is 0. The percentage function f(ΔTh) of the inlet and outlet water temperature difference of the outdoor unit decreases gradually from 100% as the average temperature difference between the inlet and outlet water of the operating outdoor unit ΔTh changes from 0 to the limit temperature difference, then decreases sharply, and then decreases gradually back to 0.

10. The control method for a multi-unit water source system according to claim 9, characterized in that, The range of the extreme temperature difference is [43, 50]℃.

11. The control method for a multi-unit water source system according to any one of claims 1 to 10, characterized in that, The operating parameters of the water source multi-split air conditioner also include the set average temperature Tgk of the currently operating indoor unit, and step S35 includes: The outdoor unit's operating capacity requirement Q3 is adjusted based on the indoor unit's set average temperature difference △Tig to obtain the adjusted outdoor unit's operating capacity requirement Qz, where △Tig = Tik - Tgk. The larger the absolute value of the set average temperature difference △Tig, the larger the adjusted outdoor unit's operating capacity requirement Qz.

12. The control method for a multi-unit water source system according to claim 11, characterized in that, Set the outdoor unit output percentage corresponding to the average temperature difference △Tig as ft=ads(Tik-Tgk) / Tgk, Qz=Q3*(1+ft).

13. The control method for a multi-unit water source system according to any one of claims 1 to 10, characterized in that, Step S35 includes adjusting the frequency of the compressor of the outdoor unit that is in operation.

14. The control method for a water source multi-split system according to any one of claims 1 to 10, characterized in that, It also includes a water system anomaly detection and handling step S50, which includes: Step S51: Obtain the average inlet water temperature Tih of the outdoor unit during operation and / or the average outlet water temperature Toh of the outdoor unit during operation. Step S52: Determine whether the water system is normal based on the average inlet water temperature Tih and / or the average outlet water temperature Toh of the outdoor unit. If the water system is normal, the water source multi-split unit continues to operate. If the water system is abnormal, the water source multi-split unit stops.

15. The control method for a multi-unit water source system according to claim 14, characterized in that, Steps S51 and S52 are executed once every preset time period.

16. The control method for a multi-unit water source system according to claim 15, characterized in that, The preset time period ranges from [25, 30] seconds.

17. The control method for a multi-unit water source system according to claim 14, characterized in that, Step S52 includes: If Tmin < Tih < Tmax, and ΔTmin ≤ ΔTh ≤ ΔTmax, then the water system is considered normal; and / or If Tih ≥ Tmax or Tih ≤ Tmin, then the water system is judged to be abnormal; Where Tmin is the minimum allowable inlet water temperature, Tmax is the maximum allowable inlet water temperature, and Tmin < Tmax, △Th is the average temperature difference between the inlet and outlet water of the outdoor unit during operation, △Th = ads(Toh-Tih), where ads represents taking the absolute value, △Tmin is the minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit, and △Tmax is the maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit.

18. The control method for a multi-unit water source system according to claim 17, characterized in that, The minimum allowable inlet water temperature Tmin is within the range of [-15, -10]℃; and / or The maximum allowable inlet water temperature Tmax is within the range of [55, 60]℃; and / or The minimum allowable average temperature difference between the inlet and outlet water of the outdoor unit, ΔTmin, is within the range of [-10, -5]℃; and / or The maximum allowable average temperature difference between the inlet and outlet water of the outdoor unit, ΔTmax, is within the range of [45, 50]℃.

19. The control method for a multi-unit water source system according to any one of claims 1 to 10, characterized in that, It also includes a capacity mismatch judgment and processing step S70, which includes: Step S71: Obtain the total basic capacity Q5 of the indoor units of the water source multi-split air conditioner. Step S72: Obtain the total basic capacity Q6 of the outdoor unit of the water source multi-split air conditioner. Step S73: Determine whether the capacity matching of the water source multi-split unit is normal based on the total basic capacity Q5 of the indoor unit and the total basic capacity Q6 of the outdoor unit. If the capacity matching is normal, the water source multi-split unit is allowed to operate; if the capacity matching is abnormal, the water source multi-split unit is prohibited from operating.

20. The control method for a multi-unit water source system according to claim 19, characterized in that, Step S71 includes: Q5 = ∑(qm), where m is the indoor unit number of the water source multi-split air conditioning system, and qm is the nominal operating capacity of the m-th indoor unit; and / or Step S72 includes: Q6=∑(qn), where n is the number of the outdoor unit of the water source multi-split unit, and qn is the nominal operating capacity of the nth outdoor unit.

21. The control method for a multi-unit water source system according to claim 19, characterized in that, Step S73 includes: If Xmin≤Q5 / Q6≤Xmax, then the capacity matching is considered normal; If Q5 / Q6 > Xmax or Q5 / Q6 < Xmin, then the capacity mismatch is determined to be abnormal. Where Xmin is the minimum allowed capacity matching value, Xmax is the maximum allowed capacity matching value, and Xmin < Xmax.

22. The control method for a multi-unit water source system according to claim 21, characterized in that, The minimum capacity matching allowable value Xmin ranges from 10% to 50%, and / or The maximum capacity matching allowable value Xmax ranges from 150% to 200%.

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