CN109373654B - Running control method of water chilling unit or heat pump unit - Google Patents
Running control method of water chilling unit or heat pump unit Download PDFInfo
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- CN109373654B CN109373654B CN201811221330.8A CN201811221330A CN109373654B CN 109373654 B CN109373654 B CN 109373654B CN 201811221330 A CN201811221330 A CN 201811221330A CN 109373654 B CN109373654 B CN 109373654B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
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Abstract
The invention discloses an operation control method of a water chilling unit or a heat pump unit, wherein the unit comprises a plurality of unit units which are connected in parallel and comprise 2-4 compressors. The operation control method comprises the following steps: and acquiring the total load of the unit set, the load of each compressor and the operation load of the unit set. And presetting the sequencing of the unit set and presetting loading or unloading conditions. When the unit set loading control method is in operation, based on preset sequencing, firstly, the unit set operation load values are reordered according to the unit set operation load values, then, the unit set with the operation load value equal to that of the first ordered unit set is selected, then, the unit set with the operation load equal to that of the first ordered unit set is reordered according to the compressor load values, the unit set with the operation load equal to that of the first ordered unit set is selected, and then, the unit set with the operation time is ordered according to the operation time, and at the moment, the first ordered unit set is a loading or unloading target under corresponding sequencing.
Description
Technical Field
The invention belongs to the technical field of operation control of a water chilling unit or a heat pump unit, and particularly relates to an operation control method of the water chilling unit or the heat pump unit, which is suitable for the conditions of water outlet control mode and multi-unit combined control during refrigeration.
Background
The common water chilling unit or heat pump unit adopts a multi-unit joint control strategy, namely the water chilling unit comprises a plurality of unit units which run in parallel, each unit usually has only a single refrigeration mode and mainly comprises 2-4 compressors, a condenser, a throttling component and an evaporator, and a refrigerant flows in the evaporator and the condenser in a single direction; or the heat pump unit comprises a plurality of unit units running in parallel, each unit mainly comprises 2-4 compressors, a condenser, a throttling part, an evaporator and a four-way reversing valve, and the switching of the refrigeration or heating modes is realized through the switching of the four-way reversing valve.
The water chilling unit or the heat pump unit has two control modes, namely a water return control mode (default 12 ℃ in refrigeration) taking the total water return set temperature as a target and a water outlet control mode (default 7 ℃ in refrigeration) taking the total water outlet set temperature as a target; the total return water temperature refers to the return water temperature of a total pipeline, and the total outlet water temperature refers to the mixed outlet water temperature of each unit set.
In the prior art, in the operation control of a water chilling unit or a heat pump unit, when loading is executed, one unit is loaded until the unit runs at 100% full load (namely, all contained compressors run), and then the other unit is loaded; when the load is reduced, firstly reducing the load of one unit set until the unit set stops (all compressors contained in the unit set stop running), and then reducing the load of the other unit set; the term "loading" means starting an operation of a stopped compressor, and the term "unloading" means stopping an operation of an operated compressor. The defects that the operation strategy of the existing load-increasing and load-reducing control unit is easy to occur are illustrated by taking 8 unit units and 4 compressors in each unit as an example. During refrigeration, under a backwater control mode, the compressor is loaded and unloaded by taking the total backwater setting temperature of 12 ℃ as a target. When the load is large, all unit sets run fully, and the figure 1 shows. When the load is small, only the 1# unit set runs fully, and the figure 2 shows. As can be seen from the graph 2, the phenomenon that the outlet water temperature is too low (the outlet water temperature of each unit set is less than 3 ℃) can not occur. During refrigeration, under a water outlet control mode, the compressor is loaded or unloaded by taking the total water outlet set temperature of 7 ℃. When the load is large, all unit sets run fully, and the figure 1 shows. When the load is small, only the 1# unit set runs in full load, as shown in figure 3, the phenomenon that the outlet water temperature is too low (the outlet water temperature of the 1# unit set is 2.6 ℃ and less than 3 ℃) appears; aiming at the problems, the general solution is to increase the total outlet water set temperature, but the method can cause that the outlet water requirement of a user at 7 ℃ cannot be met, or the outlet water temperature alarm value is reduced, but the outlet water temperature is too low, so that the pipeline is easy to freeze, and the subsequent normal operation of the unit is influenced.
The calculation of the effluent temperature values of the unit units in fig. 1 to 3 is explained: when the unit set runs in full load, the refrigerating temperature difference theoretical value of the unit set is 5 ℃ (the difference between the total return water temperature and the outlet water temperature of the unit set is 5 ℃). When the unit set is shut down, the refrigerating temperature difference theoretical value of the unit set is 0 ℃ (the total return water temperature is equal to the outlet water temperature of the unit set); the unit set operates at 75%, 50% or 25% of full load, the refrigeration temperature difference value is gradually reduced, and for convenience of description, an approximate value of the temperature difference is calculated in proportion, for example, when the unit set operates at 50%, the refrigeration temperature difference value is a theoretical value, namely 5 ℃ multiplied by 50% and equals to 2.5 ℃. In fig. 2, the unit set 1 is fully operated, the other unit sets are stopped, the total outlet water temperature is set to be Y, the total return water temperature is set to be 12 ℃, the outlet water temperature of the unit set 1 is 7 ℃, and the total outlet water temperature Y is about 11.4 ℃ according to the formula Y ═ 12-5+12 × 7)/8; in fig. 3, the unit set 1 is fully operated, the other unit sets are stopped, the total return water temperature is X, the total outlet water temperature is 7 ℃, the outlet water temperature of the unit set 1 is X-5, the total return water temperature X is about 7.6 ℃ and the outlet water temperature of the unit set 1 is 2.6 ℃ according to the formula ((X-5) +7X)/8 ═ 7.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to solve the technical problem of providing an operation control method of a water chilling unit or a heat pump unit, which can realize balanced and dispersed operation of the unit, can avoid the over-low temperature of outlet water and meet the requirements of customers.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: an operation control method of a water chilling unit or a heat pump unit is provided, the water chilling unit or the heat pump unit comprises a plurality of unit units, the unit units run in parallel, each unit comprises 2-4 compressors, the control method is used for alternately loading and unloading the compressors in the unit units one by one to realize balanced and dispersed operation, and the control method comprises the following steps:
s1, calculating the minimum common multiple 12 of the number of the compressors of 2, 3 and 4 as the total load of the unit set; calculating the ratio of the total load of the unit set to the number of the compressors in the unit set, and calculating the ratio as the load of each compressor; and calculating the product of the load of each compressor in the unit set and the running number of the compressors in the unit set, and calculating the product as the running load of the unit set.
S2, the order of the unit groups is set in advance.
S3, presetting the loading and unloading conditions of the water chilling unit or the heat pump unit; when the load condition is satisfied, step S4 is executed, and when the unload condition is satisfied, step S5 is executed.
S4, when the water chilling unit or the heat pump unit operates, based on the preset sequence in the step S2, the unit units are reordered from small to large according to the operation load value of the unit units;
picking out all the unit units with the same running load value as the first unit in the sequence;
the picked unit machines are reordered from small to large according to the corresponding load of each compressor;
picking out all the unit sets with the same load of each compressor which is sequenced first at the time;
the picked unit units are reordered from small to large according to the running time of the corresponding unit;
at the moment, the unit set with the first sequence is a loading target;
s5, when the water chilling unit or the heat pump unit operates, based on the preset sequence in the step S2, the unit units are reordered from large to small according to the operation load value of the unit units;
picking out all the unit units with the same running load value as the first unit in the sequence;
the picked unit machines are reordered from small to large according to the corresponding load of each compressor;
picking out all the unit sets with the same load of each compressor which is sequenced first at the time;
the picked unit units are reordered from big to small according to the running time of the corresponding unit;
and the unit set ranked first is the load shedding target.
Preferably, in the above technical solution, the step S3 of presetting the loading and unloading conditions of the chiller or the heat pump specifically includes:
during refrigeration, the loading and unloading conditions of the water chilling unit or the heat pump unit are preset in a water outlet control mode; the method specifically comprises the steps of taking the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time to be larger than a first loading preset value as the loading condition, and taking the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time to be smaller than a first deloading preset value as the deloading condition.
Or when refrigerating, presetting the loading and unloading conditions of the water chilling unit or the heat pump unit in a return water control mode; the method specifically comprises the steps of using the total return water temperature of the water chilling unit or the heat pump unit detected in real time to be greater than a second loading preset value and as the loading condition, and using the total return water temperature of the water chilling unit or the heat pump unit detected in real time to be less than a second deloading preset value as the deloading condition.
Preferably, in the above technical scheme, the first preset loading value is equal to the sum of the preset total outlet water temperature value and the preset control temperature difference; the first deloading preset value is equal to the difference between the total outlet water temperature preset value and the preset control temperature difference; the second loading preset value is equal to the sum of the total return water preset value and the preset control temperature difference; and the second deloading preset value is equal to the difference between the total return water temperature preset value and the preset control temperature difference.
Preferably, in the technical scheme, during refrigeration, the total outlet water temperature is preset to be 7 ℃, the total return water temperature is preset to be 12 ℃, and the control temperature difference is 1 ℃.
Preferably, in the above technical scheme, during refrigeration, the chiller unit or the heat pump unit each include 8 unit units, each unit includes 4 compressors, and the running time of each of the 8 unit units is T.
The 8 unit units are respectively 1# unit to 8# unit.
The order of the 8 unit groups is set to 1# unit group, 2# unit group, 3# unit group, 4# unit group, 5# unit group, 6# unit group, 7# unit group, and 8# unit group in advance.
In the above technical solution, preferably, during refrigeration, the chiller unit or the heat pump unit each include 4 unit units, and the 4 unit units are respectively a 1# unit to a 4# unit.
The 1# unit group includes 3 the compressor, the 2# unit group includes 2 the compressor, the 3# unit group with the 4# unit group all includes 4 the compressor, just the operating time of 1# unit group is T, the operating time of 2# unit group is T +1, the operating time of 3# unit group is T +3, the operating time of 4# unit group is T + 2.
The 4 unit groups are previously sorted into 1# unit group, 2# unit group, 3# unit group, and 4# unit group.
After the technical scheme is adopted, the invention has the beneficial effects that:
when the operation control of the invention executes the loading or the load shedding, the invention does not need to firstly load or shed one unit set until the unit set runs fully or stops, and then loads or shed another unit set; the compressors in different unit sets are alternately loaded and unloaded one by one according to the loading and unloading methods of the steps S4 and S5 so as to realize balanced and dispersed operation and achieve the aim of energy saving, thereby meeting the requirements of customers;
particularly, in the refrigeration and water outlet control mode, the operation control method can ensure the water outlet temperature required by a user, and can effectively avoid the phenomena of low water outlet temperature of the unit units in operation and icing of unit pipelines caused by the fact that the single unit runs in full load and other unit units stop running.
Drawings
FIG. 1 is a schematic diagram of the outlet water temperature when 8 unit sets are fully operated in full load in a backwater or outlet water control mode in the prior art for refrigeration;
FIG. 2 is a schematic diagram of the outlet water temperature when the 1# unit set is in full load operation and other unit sets are stopped in a backwater control mode in the prior art for refrigeration;
FIG. 3 is a schematic diagram of the outlet water temperature when the 1# unit set is fully operated and other unit sets are stopped in the existing refrigeration and outlet water control mode;
FIG. 4 is a schematic flow chart of the method for controlling the operation of a chiller or heat pump unit according to the present invention when the loading condition is satisfied;
FIG. 5 is a schematic flow chart of the operation control method of the chiller or heat pump unit according to the present invention when the load shedding condition is satisfied;
FIG. 6 is a schematic diagram of the water outlet temperature when 4 unit sets are operated at 25% load and the remaining 4 unit sets are shut down in a return water control mode in the first embodiment of the present invention;
FIG. 7 is a schematic diagram showing the outlet water temperature when 4 unit sets are operated at 25% load and the remaining 4 unit sets are shut down in the outlet water control mode in the first embodiment of the present invention;
FIG. 8 is a schematic diagram of the outlet water temperature of 4 unit sets respectively operating at 33.3%, 50%, 25% and 25% loads in a backwater control mode during refrigeration according to the second embodiment of the present invention;
fig. 9 is a schematic diagram of the outlet water temperature when 4 unit groups operate at 33.3%, 50%, 25%, and 25% loads respectively in the outlet water control mode during refrigeration according to the second embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, an operation control method of the present invention is described in detail with reference to the accompanying drawings and examples.
The first embodiment is as follows:
the water chilling unit or the heat pump unit comprises 8 unit units, the 8 unit units run in parallel, each unit comprises 4 compressors, the running time of the 8 unit units is T, and T is 2; the 8 unit groups are respectively a 1# unit group, a 2# unit group, a 3# unit group, a 4# unit group, a 5# unit group, a 6# unit group, a 7# unit group and an 8# unit group.
The operation control method is used for alternately loading and unloading the compressors in 8 unit units one by one to realize balanced and dispersed operation, and comprises the following steps:
s1, calculating the minimum common multiple 12 of the number 2, 3 and 4 which can be selected by the compressor as the total load of the unit set; calculating the ratio of the total load of the unit set to the number of compressors in the unit set, and calculating the load of each compressor; and calculating the product of the load of each compressor in the unit set and the running number of the compressors in the unit set, and counting the product as the running load of the unit set.
S2, the sequence of the plurality of unit groups is set in advance, that is, the sequence of 8 unit groups is set in advance as 1# unit group, 2# unit group, 3# unit group, 4# unit group, 5# unit group, 6# unit group, 7# unit group, and 8# unit group.
S3, presetting the loading and unloading conditions of a water chilling unit or a heat pump unit; step S4 is executed when the load condition is satisfied, and step S5 is executed when the load shedding condition is satisfied.
As shown in fig. 4, when the chiller or heat pump unit is running, step S4 specifically includes the following steps:
a. and based on the preset sequence in the step S2, reordering the unit units from small to large according to the unit operation load value. When the values are equal during sorting, positions are not exchanged, that is, the original order is not changed, and the specific sorting method is well known by those skilled in the art and is not described herein. (for example, a predetermined sequence is a 5, B5, C3, D4; a sequence of values from large to small is a 5, B5, D4, C3; a sequence of values from small to large is a 3, D4, a sequence of values from small to large is a 5, B5).
b. And c, selecting all the unit groups with the operation load value equal to that of the first unit group sequenced in the step a.
c. And (c) reordering the unit sets picked out in the step (b) from small to large according to the load of each compressor, and not exchanging positions when the values are equal, namely not changing the original sequence.
d. And c, picking out all unit groups with the load equal to that of each compressor sequenced first in the step c.
e. And d, reordering the unit units selected in the step d from small to large according to the unit running time, and not exchanging positions when the unit units meet the same value, namely not changing the original sequence.
f. At this time, the unit group ranked first in step e is a loading target.
And (b) if the loading condition is met after one compressor is loaded (see table I), returning to the step (a) to enter the next round of loading cycle until the loading condition is not met (entering the condition of meeting the holding condition or the load shedding condition and the like, see table I), and ending the loading cycle formed by the steps, wherein the loading period can be defaulted to 90 seconds.
As shown in fig. 5, when the chiller or heat pump unit is running, step S5 specifically includes the following steps:
h. and based on the preset sequence in the step S2, reordering the unit units according to the operation load values of the unit units from big to small. Also, when equal values are encountered, no position exchange is performed, i.e., the original order is not changed.
i. And h, selecting all the unit sets with the operation load value equal to that of the first unit set sequenced in the step h.
j. And (e) reordering the unit units selected in the step (i) from small to large according to the load of each compressor. Also, when equal values are encountered, no position exchange is performed, i.e., the original order is not changed.
k. And (d) picking out all unit groups with the load equal to the load of each compressor sequenced first in the step j.
And l, reordering the unit units selected in the step k according to the unit running time from big to small. Also, when equal values are encountered, no position exchange is performed, i.e., the original order is not changed.
m, the unit set ranked first in the step l is the load shedding target.
And if the load shedding of one compressor is finished, the load shedding condition is met (see a table I), then returning to the step h to enter the next load shedding cycle until the load shedding condition is not met, ending the load shedding cycle formed by the steps, wherein the default of the load shedding cycle can be 30 seconds, and if the emergency stop condition is met, reducing the load shedding cycle by 30 seconds to 5 seconds.
Wherein: the step S3 of presetting the loading and unloading conditions of the chiller or heat pump set specifically includes:
during refrigeration, the loading and unloading conditions of a water chilling unit or a heat pump unit are preset in a water outlet control mode; the method specifically comprises the steps of taking the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time as a loading condition, and taking the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time as a load shedding condition, wherein the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time is smaller than a first load shedding preset value.
Or, when refrigerating, presetting the loading and unloading conditions of a water chilling unit or a heat pump unit in a return water control mode; the method specifically comprises the steps of taking the total return water temperature of the water chilling unit or the heat pump unit detected in real time as a loading condition when the total return water temperature is larger than a second loading preset value, and taking the total return water temperature of the water chilling unit or the heat pump unit detected in real time as a load shedding condition when the total return water temperature is smaller than a second load shedding preset value.
The first loading preset value is equal to the sum of the total effluent temperature preset value and the preset control temperature difference; the first deloading preset value is equal to the difference between the total outlet water temperature preset value and the preset control temperature difference; the second loading preset value is equal to the sum of the total return water preset value and the preset control temperature difference; the second deloading preset value is equal to the difference between the total return water temperature preset value and the preset control temperature difference.
In the first embodiment of the present invention, in order to clearly illustrate the presetting of the loading and unloading conditions, a parameter setting table of the loading and unloading conditions of the chiller or the heat pump unit is further provided, as shown in table one. The specific parameters in the tables are exemplary only, and not all of these values are applicable.
Watch 1
The above steps are described in detail below with specific examples:
the first embodiment of the present invention further provides a data selection table in which the compressors in 8 unit units execute loading according to step S4, where "total load of unit is 12, load of each compressor is 12/4 is 3, and unit operation time is 2" and the loading condition is satisfied after the start-up, as shown in table two.
The specific data in the table are also merely exemplary and not limited to these values, and the loading target selection process for loading from the state where 8 unit trains are all stopped to the state where 1 compressor in 1# unit train (25% running), one compressor in 2# unit train (25% running), one compressor in 3# unit train (25% running), one compressor in 4# unit train (25% running), and the remaining 4 unit trains are still stopped is schematically listed.
Watch two
When the unit set runs in full load, the refrigerating temperature difference theoretical value of the unit set is 5 ℃ (the difference between the total return water temperature and the outlet water temperature of the unit set is 5 ℃). When the unit set is shut down, the refrigerating temperature difference theoretical value of the unit set is 0 ℃ (the total return water temperature is equal to the outlet water temperature of the unit set); when the unit set operates at 75%, 50%, 33.3%, 25% and the like of the full load, the refrigeration temperature difference value gradually becomes smaller, so that the approximate value of the temperature difference is calculated proportionally, for example, when the unit set operates at 25%, the refrigeration temperature difference value is that the theoretical value is 5 ℃ and the value is multiplied by 25% and is equal to 1.25 ℃.
If the loading step is executed in a backwater control mode, the satisfied loading condition is a preset loading condition in the backwater control mode; the first 4 unit sets are all operated at 25%, and the outlet water temperature when the rest 4 unit sets are shut down is shown in figure 6; the total water outlet temperature is about 11.4 ℃, the water outlet temperature of 25 percent of the running unit set is about 10.8 ℃, and the water outlet temperature of the shutdown unit set is 12 ℃.
Calculation process of temperature value: the total outlet water temperature is set as Y, the total return water temperature is set as 12 ℃, the outlet water temperature of the 1# unit set and the 4# unit set is 12-5/4 and approximately equals to 10.8 ℃, the total outlet water temperature is obtained according to the formula Y which is (10.8 multiplied by 4+12 multiplied by 4)/8, and the total outlet water temperature Y is approximately 11.4 ℃.
If the loading step is executed in the water outlet control mode, namely the satisfied loading condition is a preset loading condition in the water outlet control mode; the first 4 unit sets are all operated at 25%, and the outlet water temperature when the rest 4 unit sets are shut down is shown in figure 7; the total return water temperature is about 7.6 ℃, the outlet water temperature of 25% of the running unit set is 6.4 ℃, and the outlet water temperature of the shutdown unit set is 7.6 ℃.
Calculation process of temperature value: the total backwater temperature is set as X, the total water outlet temperature is set as 7 ℃, the water outlet temperature of the 1# unit set-4 # unit set is X-5/4, the total backwater temperature is about 7.6 ℃ and the water outlet temperature of the 1# unit set-4 # unit set is about 6.4 ℃ according to the formula ((X-5/4) +7X)/8 ═ 7.
As can be seen from the comparison between FIG. 6 and FIG. 2, and between FIG. 7 and FIG. 3, the temperature difference of each unit set is not large, the total output is the same, and the phenomenon that the outlet water temperature is too low does not occur. The water outlet temperature of the unit in any state can be indicated according to the calculation formula, and the water outlet temperature is not listed one by one.
Example two:
the concept of the second embodiment is basically the same as that of the first embodiment, the only difference is that the number of unit sets, the number of compressors in the unit sets and the setting of the unit operation time are different, and the second embodiment is described below only with respect to the difference.
The water chilling unit or the heat pump unit comprises 4 unit units, wherein the 4 unit units are a No. 1 unit, a No. 2 unit, a No. 3 unit and a No. 4 unit respectively; the 1# unit set comprises 3 compressors, and the load of each compressor is 4; the 2# unit set comprises 2 compressors, and the load of each compressor is 6; the 3# unit set and the 4# unit set each include 4 compressors, the load of each compressor is 3, the operation time of the 1# unit set is T2, the operation time of the 2# unit set is T + 1-3, the operation time of the 3# unit set is T + 3-5, and the operation time of the 4# unit set is T + 2-4; the 4 unit groups are previously sorted into 1# unit group, 2# unit group, 3# unit group, and 4# unit group. For convenience of explaining the concept of the invention, the sequence of the 4 unit groups is sorted from small to large according to the number, and other sequences can also be adopted.
The loading cycle step and the unloading cycle step are completely the same as those described in the first embodiment, and are not described herein again, see fig. 4 and fig. 5 for details.
The second embodiment of the present invention further provides that "the total load of the unit set is 12, and the load of each compressor of the 1# unit set is 4 (equivalent to 33.3%); the load per compressor of the unit 2# is 6 (equivalent to 50%); the load of each compressor of the unit group # 3 and the unit group # 4 is 3 (equivalent to 25%), the unit operation times are 2, 3, 5, and 4 ", respectively, and the loading conditions are satisfied after the start-up, and the compressors in the unit groups # 4 execute the loaded data selection table according to step S4, as shown in table three.
The specific data in the table are also only exemplary and not limited to these values, and the loading target selection process for loading from the all-off state of 4 unit groups to the all-full-load operation state of 4 unit groups one by one is only schematically listed.
Watch III
The 9 th row of data in table three is given as an example: the current unit state displayed according to the preset unit sequencing is as follows: the 1# unit set has 2 compressors running at this time, and the running load of the unit set is 8; the 2# unit set has 1 compressor running and the unit set running load is 6; the 3# unit set has 2 compressors to operate, and the operation load of the unit set is 6; the 4# unit set has 2 compressors to operate, and the operation load of the unit set is 6; the unit at the moment meets the loading condition, a loading circulation step is carried out, and the sequence after the step a is executed is 2# unit, 3# unit, 4# unit and 1# unit; b, selecting a 2# unit set, a 3# unit set and a 4# unit set after the step b is executed; c, sorting into a 3# unit set, a 4# unit set and a 2# unit set after the step c is executed; d, selecting a 3# unit set and a 4# unit set after the step d is executed; and e, sequencing the 4# unit set and the 3# unit set after the step e is executed, wherein the loading target is determined at the moment, and one compressor in the 4# unit set is preferentially loaded during loading.
If the loading step is executed in a backwater control mode, the satisfied loading condition is a preset loading condition in the backwater control mode; the outlet water temperatures of the 4 unit sets respectively operating at 33.3%, 50%, 25% and 25% loads (each unit set operates a compressor) are shown in fig. 8; the total outlet water temperature is about 10.4 ℃, the outlet water temperature of the 1# unit set is 10.3 ℃, the outlet water temperature of the 2# unit set is 9.5 ℃, the outlet water temperature of the 3# unit set is 10.8 ℃, and the outlet water temperature of the 4# unit set is 10.8 ℃.
Calculation process of temperature value: setting the total outlet water temperature as Y, setting the total return water temperature as 12 ℃, and respectively setting the outlet water temperature of the 1# unit set and the outlet water temperature of the 4# unit set to be 12-5/3 and approximately equal to 10.3 ℃; 12-5/2 is approximately equal to 9.5 ℃; 12-5/4 ≈ 10.8 deg.C, 12-5/4 ≈ 10.8 deg.C, according to formula Y ═ 10.3+9.5+10.8 × 2)/4, the total water temperature Y is about 10.4 deg.C.
If the loading step is executed in the water outlet control mode, namely the satisfied loading condition is a preset loading condition in the water outlet control mode; the outlet water temperatures of the 4 unit sets respectively operating at 33.3%, 50%, 25% and 25% loads (each unit set operates a compressor) are shown in fig. 9; the total return water temperature is about 8.7 ℃, the outlet water temperature of the 1# unit set is 7 ℃, the outlet water temperature of the 2# unit set is 6.2 ℃, the outlet water temperature of the 3# unit set is 7.5 ℃, and the outlet water temperature of the 4# unit set is 7.5 ℃.
Calculation process of temperature value: setting the total return water temperature as X, setting the total outlet water temperature as 7 ℃, and setting the outlet water temperatures of the 1# unit set and the 4# unit set as X-5/3 respectively; x-5/2; x-5/4; x-5/4, the temperature value being given according to the formula (X-5/3+ X-5/2+ X-5/4+ X-5/4)/4 ═ 7.
The temperature difference of each unit set is not large, and the phenomenon that the outlet water temperature is too low is avoided. The outlet water temperature of the unit in any state can be shown according to the above calculation formula, and the above description is omitted.
The second embodiment of the invention also provides that the total load of the unit set is 12, and the load of each compressor of the 1# unit set is 4; the load of each compressor of the 2# unit set is 6; the load of each compressor of the unit group 3 and the unit group 4 is 3, the unit operation times are 2, 3, 5 and 4 "respectively, and meet the load shedding condition after the start, and the compressors in the unit groups 4 execute the data selection table for load shedding according to the step S5, as shown in table four.
The specific data in the table are also only exemplary and not limited to these values, and the load shedding target selection process from the full load operation state of all the 4 unit groups to the shutdown state of all the 4 unit groups is only schematically listed.
Watch four
The outlet water temperature of the unit in any state can be shown according to the above calculation formula, and the above description is omitted.
By the above control method, the following conclusions can be directly derived:
when each unit set comprises 2-N compressors (N is more than or equal to 2), the total load of the unit set is as follows: the least common multiple of all integers between 2 and N inclusive. That is, when each unit set comprises 2-6 compressors (N is more than or equal to 2), the total load of the unit set is as follows: 2. a least common multiple 60 of all integers between 3, 4, 5, 6 and N and including 2 and N; and taking the next time as a basic parameter for comparison in the following steps, and carrying out loading or loading control according to the steps.
Or each unit set comprises 2, 3, 4 or 6 compressors, and the total load of the unit sets is as follows: 2. 3, 4 and 6, and sequentially serving as basic parameters for comparison in the following steps, and carrying out loading or loading control according to the steps.
The water chilling unit or the heat pump unit comprises a controller and a temperature sensor for detecting a temperature value, a person skilled in the art can compile a corresponding program in the controller according to the steps and the judgment condition of the table I, the temperature sensor uploads the detected temperature value to the controller, and the controller executes the steps to load or unload the compressors one by one according to the compiled program based on a temperature signal; the conversion between the method and the program will not be described herein.
In summary, the operation control of the present invention does not "load or unload one unit set first until the unit set is fully operated or stopped, and then load or unload another unit set" when the load or unload is executed; the compressors in different unit sets are alternately loaded and unloaded one by one according to the loading and unloading methods of the step S4 and the step S5 to realize balanced and dispersed operation and achieve the aim of energy saving, thereby meeting the requirements of customers. The system is suitable for operation control in a water outlet control mode or a water return control mode during refrigeration; the heat pump unit can also apply the operation control method of the invention to the operation control under the water outlet control mode or the water return control mode when heating.
Especially, in the refrigeration and water outlet control mode, the operation control method has more outstanding advantages compared with the traditional operation control method. The operation control method can ensure the water outlet temperature required by a user, and can effectively avoid the phenomena of low water outlet temperature of the unit in operation and icing of unit pipelines caused by the fact that a single unit runs in full load and other unit units stop running.
While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made. Any modification and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. An operation control method of a water chilling unit or a heat pump unit, wherein the water chilling unit or the heat pump unit comprises a plurality of unit units, the unit units run in parallel, each unit comprises 2-4 compressors, and the operation control method is used for alternately loading and unloading the compressors in the unit units one by one to realize balanced and dispersed operation, and comprises the following steps:
s1, calculating the minimum common multiple 12 of the number of the compressors of 2, 3 and 4 as the total load of the unit set; calculating the ratio of the total load of the unit set to the number of the compressors in the unit set, and calculating the ratio as the load of each compressor; calculating the product of the load of each compressor in the unit set and the running number of the compressors in the unit set, and counting the product as the running load of the unit set;
s2, setting the sequence of the unit units in advance;
s3, presetting the loading and unloading conditions of the water chilling unit or the heat pump unit; executing step S4 when the loading condition is satisfied, and executing step S5 when the unloading condition is satisfied;
s4, when the water chilling unit or the heat pump unit operates, based on the preset sequence in the step S2, the unit units are reordered from small to large according to the operation load value of the unit units;
picking out all the unit units with the same running load value as the first unit in the sequence;
the picked unit units are reordered from small to large according to the corresponding load of each compressor;
picking out all the unit sets with the same load of each compressor which is sequenced first at the time;
the picked unit units are reordered from small to large according to the running time of the corresponding unit;
at the moment, the unit set with the first sequence is a loading target;
s5, when the water chilling unit or the heat pump unit operates, based on the preset sequence in the step S2, the unit units are reordered from large to small according to the operation load value of the unit units;
picking out all the unit units with the same running load value as the first unit in the sequence;
the picked unit units are reordered from small to large according to the corresponding load of each compressor;
picking out all the unit sets with the same load of each compressor which is sequenced first at the time;
the picked unit units are reordered from big to small according to the running time of the corresponding unit;
at the moment, the unit set with the first sequence is a load shedding target;
the step S3 of presetting the loading and unloading conditions of the chiller or the heat pump specifically includes:
during refrigeration, the loading and unloading conditions of the water chilling unit or the heat pump unit are preset in a water outlet control mode; the method specifically comprises the steps that the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time is larger than a first loading preset value and is used as the loading condition, and the total outlet water temperature of the water chilling unit or the heat pump unit detected in real time is smaller than a first unloading preset value and is used as the unloading condition;
or when refrigerating, presetting the loading and unloading conditions of the water chilling unit or the heat pump unit in a return water control mode; the method specifically comprises the steps of using the total return water temperature of the water chilling unit or the heat pump unit detected in real time to be greater than a second loading preset value and as the loading condition, and using the total return water temperature of the water chilling unit or the heat pump unit detected in real time to be less than a second deloading preset value as the deloading condition.
2. The method for controlling the operation of a chiller or heat pump unit of claim 1 wherein the first preset load value is equal to the sum of the preset total leaving water temperature value and a preset control temperature difference; the first deloading preset value is equal to the difference between the total outlet water temperature preset value and the preset control temperature difference; the second loading preset value is equal to the sum of the total return water temperature preset value and the preset control temperature difference; and the second deloading preset value is equal to the difference between the total return water temperature preset value and the preset control temperature difference.
3. The operation control method of the water chilling unit or the heat pump unit according to claim 2, wherein the total outlet water temperature is preset to 7 ℃, the total return water temperature is preset to 12 ℃, and the control temperature difference is 1 ℃ during refrigeration.
4. The operation control method of a chiller or a heat pump unit according to claim 3, wherein during refrigeration, the chiller or the heat pump unit comprises 8 unit units, each unit comprises 4 compressors, and the operation time of the 8 unit units is T;
the 8 unit units are respectively 1# unit to 8# unit;
the order of the 8 unit groups is set to 1# unit group, 2# unit group, 3# unit group, 4# unit group, 5# unit group, 6# unit group, 7# unit group, and 8# unit group in advance.
5. The operation control method of a chiller or a heat pump unit according to claim 3, wherein during refrigeration, the chiller or the heat pump unit comprises 4 unit units, and the 4 unit units are respectively 1# unit to 4# unit;
the 1# unit set comprises 3 compressors, the 2# unit set comprises 2 compressors, the 3# unit set and the 4# unit set respectively comprise 4 compressors, the running time of the 1# unit set is T, the running time of the 2# unit set is T +1, the running time of the 3# unit set is T +3, and the running time of the 4# unit set is T + 2;
the 4 unit groups are previously sorted into 1# unit group, 2# unit group, 3# unit group, and 4# unit group.
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| CN110864417A (en) * | 2019-11-27 | 2020-03-06 | 无锡同方人工环境有限公司 | Energy-saving control method, device and system for air conditioning system |
| CN113864973B (en) * | 2021-09-23 | 2022-08-05 | 珠海格力电器股份有限公司 | Control method, device and system for clustered heat pump unit and air conditioning equipment |
| CN114413456B (en) * | 2022-01-14 | 2023-09-08 | 埃能科技(广州)有限公司 | Group control method and equipment for chilled water system of central air conditioner |
| CN115854608A (en) * | 2022-11-16 | 2023-03-28 | 广东开利暖通空调股份有限公司 | Variable-frequency air source heat pump water chilling unit and parallel control method thereof |
| CN115654786B (en) * | 2022-12-28 | 2023-04-11 | 北京绿建软件股份有限公司 | Method and device for automatically determining operation strategy of water chilling unit |
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