JP6644559B2 - Heat source control system, control method and control device - Google Patents

Description

  The present invention relates to a primary / secondary pump type heat source control system using a primary chilled water pump and a secondary chilled water pump, a control method, and a control device.

  As one of the piping systems of a heat source control system in an air conditioner, there has been known a primary and secondary pump system in which a head on a refrigerator side and an air conditioning load side are divided by two types of pumps at a boundary between an outgoing header and a return header. I have. In the piping system of the primary / secondary pump system, the secondary chilled water that is heat-exchanged by the air-conditioning load (heat exchanger) and returned to each of the plurality of refrigerators through the return header is passed through the return header. There are provided a plurality of primary chilled water pumps for sending out the primary chilled water as secondary chilled water, and a secondary chilled water pump for sending out the primary chilled water from the refrigerator through an outgoing header to the air conditioning load as outgoing secondary chilled water. The primary chilled water pump circulates the primary chilled water from the return header to the refrigerator and from the refrigerator to the outgoing header, and uses the sum of the pipe resistance from the outgoing header and the return header and the water pressure loss of the refrigerator as the head. The secondary chilled water pump is responsible for the sum of the pipe resistance of the chilled water secondary outgoing pipe and the chilled water secondary return pipe and the water pressure loss of the heat exchanger part of the air conditioning load as the head. The outgoing header and the return header are connected by a bypass pipe.

  Here, in the design of the heat source control system of the primary and secondary pump systems, it is customary to take the control target value of the chilled water supply temperature to the heat exchanger of the air conditioning load by the chilled water outlet temperature on the primary side, The actual secondary chilled water outgoing temperature during operation depends on the chilled water outlet temperature of the chiller, the flow rate of the primary chilled water, the flow from the bypass pipe, and the like. Therefore, in the control of the above-mentioned heat source control system, the primary chilled water flow rate in the steady state is basically set so that the primary chilled water at the refrigerator chilled water outlet temperature is sent out to the air conditioning load from the outgoing header at the same temperature. Control is performed such that the flow rate becomes larger than the cold water flow rate. When the primary chilled water flow rate is larger than the secondary chilled water flow rate, the difference flow rate returns to the refrigerator via the bypass pipe, and the chilled water flows from the outgoing header to the return header (in the following description). And the flow from the outgoing header to the return header in the bypass pipe is defined as a positive flow).

On the other hand, when the difference between the secondary chilled water forward temperature and the secondary chilled water return temperature (secondary chilled water temperature difference ΔT2) is smaller than its design value (eg, ΔT2 = 5 ° C.), the secondary chilled water flow rate increases. This is the case where the heat source flow control system as a variable flow constant temperature difference system is set up, and the secondary chilled water temperature difference ΔT2 should be a design value regardless of the load fluctuation, but in the middle period when the load is actually small. , The secondary chilled water temperature difference ΔT2 becomes smaller as the winter season progresses. The causes of such a small temperature difference include an excessively large control valve differential pressure and control valve size, an excessive coil flow rate as a heat exchanger, and the like for many air conditioning loads on the secondary side. There are many sites that are not the situation.
As a result, the primary chilled water determined based on the secondary chilled water flow rate at which a large temperature difference is ensured, calculated from the designed secondary chilled water temperature difference ΔT2 by matching the primary-side total chilled heat amount with the secondary-side total heat amount. If the primary side is subjected to the variable flow rate control with the flow rate, the actual secondary chilled water flow rate may become larger than the primary chilled water flow rate.

  As a result, when the flow rate of the secondary chilled water becomes larger than the flow rate of the primary chilled water, the chilled water having a high return header temperature flows back to the forward header via the bypass pipe, and the secondary chilled water upstream temperature rises, thereby reducing the air conditioning load. There is a possibility that the cooling capacity of the configured air conditioner may decrease. Therefore, when the secondary chilled water outgoing temperature increases, the stopped heat source (refrigerator) is additionally started to increase the chilled water circulation amount on the primary side, so that the return header from the bypass pipe to the outgoing header is increased. Countermeasures are taken to prevent backflow.

Japanese Patent No. 55515166 Japanese Patent No. 4600139

  In the prior art, in order to maintain the secondary chilled water outlet temperature at the chiller chilled water outlet temperature and to increase the chilled water primary flow rate in order to prevent backflow from the return header to the outgoing header, the primary chilled water pump Extra energy may be consumed due to an increase in the power for transporting the primary cold water or an increase in the number of operating heat sources. If the variable flow constant temperature difference type heat source flow control system is set up, the secondary chilled water temperature difference ΔT2 should be a design value regardless of the load fluctuation, but the secondary chilled water temperature difference ΔT2 actually becomes small. In addition to the fact that the primary chilled water flow rate is further increased in response to the current situation, the only difference is that the pump transport power at the time of design, the heat source operating power at the time of design, and the number of operating units are greatly increased.

  Further, as described above, when the primary chilled water flow rate is increased with the required amount of chilled heat required by the air conditioning load being the same, the difference between the primary chilled water outlet temperature and the primary chilled water inlet temperature (primary chilled water temperature difference ΔT1) However, if the primary chilled water temperature difference ΔT1 becomes small, the refrigerator will be in a light load operation state, and even if the capacity of the compressor is reduced, the amount of suction from the evaporator to the compressor cannot be reduced. In order to prevent the failure of chilled water freezing due to a drop in evaporation pressure from the state, control to stop the compressor of the refrigerator is performed by the safety circuit of the refrigerator side panel, and a fixed time interval is required for restarting the refrigerator compressor. Therefore, when the compressor of the refrigerator stops, the secondary chilled water upstream temperature rises.

  In order to solve these problems, the flow rate of the primary chilled water is reduced by allowing a reverse flow in which the heated secondary cooled water flows from the return header to the outward header in the bypass pipe between the outgoing header and the return header. There are a few heat source control systems that aim for an appropriate primary chilled water flow that does not need to be greater than the secondary chilled water flow.

  For example, in Japanese Patent Application Laid-Open No. H11-163, the control means for executing the primary flow rate control includes a bypass which becomes a proper inlet heating medium temperature of a load device by mixing a delivery heating medium from a refrigerator and a secondary return heating medium from a bypass pipe. In use primary flow control, to control the operating flow ratio, which is the ratio of the primary flow to the secondary flow, the measured value of the inlet heat medium temperature of the load device and the appropriate inlet heat medium temperature to be processed to the required target state It is disclosed that the primary flow rate is adjusted in accordance with the deviation on the side where the deviation is eliminated.

  Patent Document 2 discloses that mixing of the internal heat medium of each header is performed between an outgoing header including an outgoing primary header and an outgoing secondary header and a returning header including a returning primary header and a returning secondary header. A balance pipe is placed in a good place and detected by the heat source water temperature detection means, the return water primary temperature detection means, the return water secondary temperature detection means and the balance pipe water temperature detection means for detecting the temperature of the heat medium in the outgoing header. By providing control means for controlling the temperature of the heat source and the flow rate control by the heat source pump based on the temperature obtained, it is possible to prevent the cold water having the increased water supply temperature from being sent to the air-conditioning load, increase the load, and increase the secondary side return water. Discloses that a backflow flowing from a return header to an outgoing header in a balance pipe is detected quickly and temperature control of a heat medium from a refrigerator is performed.

  However, in Patent Literature 1, a situation in which the inlet heat medium temperature of the load device becomes a relatively excess capacity temperature in an intermediate period or the like, which is a cause of the difference between the inlet and outlet heat medium temperature of the load device being smaller than a design value. There is no specific description, the load equipment can process the processing target to the required target state, and the appropriate inlet heating medium temperature near the limit temperature required for processing, the heat source system component equipment According to the predetermined determination method based on the characteristic information, only the concept is shown and there is no specific description.

  Furthermore, in Patent Literature 1, the primary flow rate, which is the heat medium flow rate on the heat source unit side, is such that the operating flow rate, which is the ratio of the primary flow rate to the secondary flow rate, can be adjusted to an increase or decrease from 100%. However, it is adjusted only by the deviation between the measured value of the inlet heat medium temperature of the load equipment and the set value of the appropriate inlet heat medium temperature. Since no consideration is given, the safety circuit of the refrigerator may be operated, and the heat source control is incomplete.

  In Patent Document 2, it is possible to install a thermometer at a uniformly mixed place such as a heat source water temperature detecting means, a return water primary temperature detecting means, a return water secondary temperature detecting means and a balance pipe water temperature detecting means. The heat source control system mainly relies on difficult headers and temperature measurement values in the balance pipe between headers, and uses a complicated calculation using the temperature measurement values to prevent backflow in the balance pipe as much as possible.

  As described above, even in these conventional techniques, the primary chilled water outlet temperature is optimized and the primary chilled water flow rate is adjusted as a heat source control system in which a new control target value is provided for the secondary chilled water upstream temperature in the primary secondary pump system. There is still room for improvement in the energy-saving control of the transport power of the primary chilled water while performing the stable control of the secondary chilled water outgoing temperature, which must be supplied to the air conditioning load at a constant temperature by optimization.

  An object of the present invention is to stably control the secondary chilled water outgoing temperature, which has been determined by the conventional control as a result, to increase the power for transporting the primary chilled water in the primary chilled water pump and to operate the number of heat sources in comparison with the conventional control. An object of the present invention is to provide a heat source control system, a control method, and a control device in which increase is easily suppressed and a compressor of a refrigerator is hard to stop.

A heat source control system, which is an example of the present invention, includes a refrigerator, a first outgoing header connected to a chilled water outlet side of the chilled water by a first outgoing pipe, and a primary chilled water pump. A return header connected to the chilled water inlet side by a chilled water primary outgoing pipe, a bypass pipe connecting the first outgoing header and the return header, and an outgoing header to the first outgoing header via a secondary chilled water pump. A second outgoing header connected by piping, an air conditioning load connected between the second outgoing header and the return header via a chilled water secondary outgoing pipe and a chilled water secondary return pipe, and the second outgoing header or a secondary往温meter in the cold secondary往配tube, wherein the second place a thermometer for measuring the secondary chilled water instead temperature in a header or the cold secondary place pipe place, secondary to the cold secondary place pipe a secondary flow meter that measures the coolant flow rate, the refrigerator and controlling the primary chilled water pumps A control device, the control device comprising: a secondary chilled water temperature difference that is a difference between a measurement value of the secondary return thermometer at the outlet of the air conditioning load and a measurement value of the secondary going thermometer at the entrance of the air conditioning load. when There be less than the design value, the the heat load of the secondary instead thermometer and secondary side calculated from the measured value of the secondary往温meter and the secondary flow meter, the second cold water instead temperature Under the condition that the measured value, the refrigerator cold water outlet temperature and the amount of heat generated on the primary side obtained by calculation from the primary cold water flow rate are equal, and the primary cold water sent by the primary cold water pump and the bypass pipe, The secondary chilled water forward temperature is set such that the secondary chilled water forward temperature, at which the secondary returned chilled water flowing from the return header into the first forward header merges, becomes the set value of the secondary chilled water forward temperature that is the control target value. Using the set value of the above, the secondary chilled water return temperature, and the secondary chilled water flow rate, A first control set value for controlling the temperature and a second control set value for controlling the primary chilled water flow rate are obtained, and based on the first control set value and the second control set value. To control the refrigerator and the primary chilled water pump.

The control method of the heat source control system, which is an example of the present invention, includes a refrigerator, a first header connected to a chilled water outlet side of the refrigerator by a chilled water primary piping, and a primary chilled water pump. A return header connected to the chilled water inlet side of the refrigerator by a chilled water primary outgoing pipe, a bypass pipe connecting the first outgoing header and the return header, and a second chilled water pump through the first outgoing header A second outgoing header connected to the outgoing header pipe, an air conditioning load connected between the second outgoing header and the return header via a chilled water secondary outgoing pipe and a chilled water secondary return pipe, A second-outgoing thermometer for the second outgoing header or the chilled water secondary outgoing pipe, a second-outgoing thermometer for measuring the second chilled water returning temperature in the return header or the chilled water secondary returning pipe, and the chilled water secondary returning pipe heat control comprises a secondary flowmeter for measuring the secondary coolant flow rate, and a control device, to the sheet A control method of the system, wherein a secondary chilled water temperature difference, which is a difference between a measured value of the secondary return thermometer at the outlet of the air conditioning load and a measured value of the secondary forward thermometer at the inlet of the air conditioning load, is less than a design value When the secondary return thermometer, the secondary load calorie calculated from the measured values of the secondary forward thermometer and the secondary flow meter, the measured value of the secondary chilled water return temperature , and the refrigerator The primary chilled water pumped by the primary chilled water pump and the primary chilled water supplied by the primary chilled water pump under the condition that the chilled water outlet temperature and the amount of heat generated on the primary side calculated from the primary chilled water flow rate are equal to each other. The control device is configured to control the secondary chilled water outflow temperature so that the secondary chilled water outflow temperature, which is combined with the secondary return chilled water flowing into the first outflow header, becomes the set value of the secondary chilled water outflow temperature that is the control target value. Using the set value of the above, the secondary chilled water return temperature, and the secondary chilled water flow rate, A first control set value for controlling the mouth temperature and a second control set value for controlling the primary chilled water flow rate are obtained, and the control device determines the first control set value and the second control set value. And controls the refrigerator and the primary chilled water pump based on the control set value of
A control device, which is an example of the present invention, includes a chiller, a chilled water outlet side of the chilled water, a first outgoing header connected to a chilled water primary outgoing pipe, and a chilled water pump of the chilled water. A return header connected to the inlet side by a cold water primary outgoing pipe, a bypass pipe connecting the first outgoing header and the return header, and an outgoing header pipe to the first outgoing header via a secondary cold water pump. A second outward header, an air-conditioning load connected between the second outward header and the return header via a chilled water secondary outward pipe and a chilled water secondary return pipe, and the second outward header or a secondary往温meter in the cold secondary往配tube, the changing header or a secondary place a thermometer for measuring the secondary chilled water instead temperature to the cold secondary place pipe, the cold water secondary place secondary cold water pipe controller der applied to a heat source control system comprising a secondary flow meter that measures the flow rate, the When the secondary chilled water temperature difference, which is the difference between the measured value of the secondary return thermometer at the outlet of the air conditioning load and the measured value of the secondary going thermometer at the inlet of the air conditioning load, becomes smaller than the design value, The secondary-side load calorie calculated from the measured values of the secondary return thermometer, the secondary outgoing thermometer, and the secondary flow meter, the measured value of the secondary chilled water return temperature , the refrigerator cold water outlet temperature, and the primary Under the condition that the amount of heat generated on the primary side calculated from the flow rate of the chilled water becomes equal, and the primary chilled water supplied by the primary chilled water pump flows into the first header from the return header via the bypass pipe. The set value of the secondary chilled water outgoing temperature and the secondary chilled water returning temperature are set such that the secondary chilled water outgoing temperature where the secondary cooled chilled water joins becomes the set value of the secondary chilled water outgoing temperature which is the control target value. And a first control device for controlling the chiller chilled water outlet temperature using the secondary chilled water flow rate. A value and a second control set value for controlling the primary chilled water flow rate, and the refrigerator and the primary chilled water based on the first control set value and the second control set value. And a process of controlling the pump.

  ADVANTAGE OF THE INVENTION According to the heat-source control system, control method, and control apparatus of this invention, the secondary chilled water outflow temperature which was determined by the conventional control by the result can be controlled stably, and the primary chilled water in the primary chilled water pump is compared with the conventional. In addition, it is possible to easily suppress the increase in the transfer power and the increase in the number of operating heat sources, and to make it difficult to stop the compressor of the refrigerator.

The figure which shows the example of a structure of the heat source control system of a primary and secondary pump system The figure which shows the example of input / output with the central monitoring apparatus, PLC0, PLC1, and a refrigerator in a heat-source control system. Flow chart showing the operation of the entire heat source control system 3 is a flowchart showing a control example of PLC0 in step S103 of FIG. 4 is a flowchart showing a processing example of PLC0 in step S209 of FIG. The figure which shows the example of the relationship between primary chilled water flow volume Vc1 at the time of Q1 = Q2, and primary chilled water temperature difference (DELTA) T1. The figure which shows the operation state of an example of a heat source control system The figure which shows the operation state in the comparative example of a heat source control system The figure which shows the operation state in the Example of a heat-source control system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a case where cold water is used as a cooling medium and a refrigerator is used as a heat source will be described.

  In the present embodiment, in the heat source control system of the primary / secondary pump system, the control target value of the chilled water supply temperature to the secondary-side heat exchanger is changed to the secondary-side chilled water outlet temperature instead of the primary-side chilled water outlet temperature. The secondary chilled water outlet temperature is set (Tcs2_SP), and the refrigerator chilled water outlet temperature (Tcs1) and the primary chilled water flow rate (Vc1) are controlled. In the heat source control system according to the present embodiment, the backflow from the return header to the forward header via the bypass pipe is allowed, and the primary chilled water from the heat source and the high-temperature cold water of the return header flowing back to the forward header are mixed. Then, by sending water to the secondary-side heat exchanger, the secondary cold water outgoing temperature (Tcs2) is stably controlled.

  FIG. 1 shows a configuration example of a heat source control system of a primary and secondary pump type in the present embodiment.

  The heat source control system 100 includes n refrigerators (heat sources R1-Rn) 10, n primary chilled water pumps 11, a first forward header 12, a second forward header 13, and a first return header 14, , A second return header 15, a secondary chilled water pump 16, an air conditioner (AHU) 17 as an air conditioning load, and PLCs (Programmable Logic Controllers) 0 and PLC1. Further, the first forward header 12 and the first return header 14 are connected via a bypass pipe 18. Although only one air conditioner 17 is shown in the example of FIG. 1 for simplicity, the number and types of the air conditioners 17 are actually plural. A control valve such as a proportional two-way valve (not shown) is installed near the air conditioner 17 in a one-to-one or many-to-one manner in a heat exchanger of the air conditioner. The secondary-side cold water flow rate is adjusted according to.

  The refrigerator (heat source R) 10 is, for example, a turbo refrigerator, an inverter turbo refrigerator, an absorption refrigerator, a cold / hot water generator, a screw chiller, a heat pump chiller, or the like. Although the n refrigerators 10 included in the heat source control system 100 may have different performances, in the present embodiment, the basic operation of the refrigeration load such as the refrigeration capacity and the operation priority is performed. Correspondence is the same or similar. The inputs and outputs of the refrigerator side panel 10a that controls each refrigerator 10 are connected to PLC0 and PLC1, respectively. The refrigerator side panel 10a contains a refrigerator protection circuit and an interlock circuit for auxiliary equipment necessary for the protection circuit. In FIG. 1, the illustration of the refrigerator side panel 10a is omitted.

  Each refrigerator 10 is connected in parallel to the first header 12 by a cold water primary return pipe 21, and is connected in parallel to the first return header 14 by a cold water primary return pipe 22. ing. The cold water primary outgoing pipe 21 is a pipe that supplies cold water cooled by the refrigerator 10 to the first outgoing header 12 on the primary side of the cold water. The chilled water primary return pipe 22 is a pipe for sending return chilled water, in which chilled water whose temperature has risen due to heat exchange in the air conditioner 17 merges, from the first return header 14 to the refrigerator 10 on the primary side of the chilled water. It is.

  Each cold water primary outgoing pipe 21 connected to each refrigerator 10 is provided with a temperature sensor 23 for measuring the refrigerator cold water outlet temperature Tcs1. PV (Process Value: measured value) of the refrigerator cold water outlet temperature Tcs1 measured by each temperature sensor 23 is output to PLC0 and PLC1, respectively.

  In each of the chilled water primary return pipes 22 connected to each of the chillers 10, the primary chilled water pump 11 and the primary chilled water flow rate Vc1_Ri (i is the A flow meter 24 for measuring a temperature of the refrigerator cold water inlet temperature Tcr1 is provided. The PV of the refrigerator cold water inlet temperature Tcr1 measured by each temperature sensor 25 is output to PLC0 and PLC1, respectively. The PV of the primary chilled water flow rate Vc1_Ri measured by each flow meter 24 is output to the PLC 0 and the PLC 1 and the flow rate controller (FIC) 26. Further, the primary chilled water pump 11 includes an inverter (INV) 27 for a pump motor. One flow rate instruction controller 26 is provided for each of the plurality of heat sources, and receives a PV of the primary chilled water flow rate Vc1_Ri and an instruction (pVc1_SP) of the PLC 0 (pVc1_SP) as will be described later. Controls the flow rate (rotation speed). The rotation speed of the primary chilled water pump 11 is variable by the inverter 27 controlling the frequency of the power supply.

  As described above, in the heat source control system 100 shown in FIG. 1, the first free header 12 and the first free header 14 and the n refrigeration units connected in parallel between the first forward header 12 and the first free header 14. The primary side of the heat source is constituted by the machine 10 and the piping connecting these elements.

  On the other hand, in the heat source control system 100 shown in FIG. 1, on the secondary side of the heat source, a second outgoing header 13 is connected downstream of the first outgoing header 12, and a second The return header 15 is connected. Further, the first outgoing header 12 and the second outgoing header 13 are connected by a plurality of pipes 31 in each of which the secondary chilled water pump 16 is arranged. In addition, the rotation speed of each secondary chilled water pump 16 is variable by the inverter 32 controlling the frequency of the power supply.

  Although the rotation speed of the secondary chilled water pump 16 is varied according to the total amount of required chilled water of all air conditioners located on the secondary side, for example, the secondary chilled water pump 16 is installed at any position in the secondary side chilled water piping system. If the amount of chilled water flowing into the heat exchanger is reduced by the control valve of each air conditioner 17 according to the air conditioning load, the rotation speed of the secondary chilled water pump 16 remains unchanged. Control is performed to increase the PV value of the pressure gauge and decrease the rotation speed of the secondary chilled water pump 16 according to the deviation from the set pressure. Although an example based on pressure has been described as an example of the secondary variable flow rate control, the present invention is not limited to this, and the flow rate or heat quantity may be used, and any secondary variable flow rate control may be used.

  Further, the second outgoing header 13 is provided with a temperature sensor 33 for measuring the secondary cold water outgoing temperature Tcs2. The PV of the secondary chilled water upstream temperature Tcs2 measured by the temperature sensor 33 is output to the PLC0 and the PLC1. Further, the first return header 14 is provided with a temperature sensor 34 for measuring the secondary chilled water return temperature Tcr2. The PV at the secondary chilled water return temperature Tcr2 measured by the temperature sensor 34 is output to the PLC0 and the PLC1. Further, between the second return header 15 and the first return header 14, a flow meter 35 for measuring the secondary chilled water flow rate Vc2 is provided. The PV of the secondary chilled water flow rate Vc2 measured by the flow meter 35 is output to the PLC0 and the PLC1.

  And between the 2nd outgoing header 13 and the 2nd return header 15, the cold water 2nd outgoing piping 36 which connects the 2nd outgoing header 13 and the air conditioner 17, the air conditioner 17 and the 2nd return header 15 Are connected, and the second outgoing header 13 and the second returning header 15 are connected to the air conditioner 17 by these pipes. The cold water secondary outgoing pipe 36 is a pipe that supplies cold water cooled by the refrigerator 10 from the second outgoing header 13 to the air conditioner 17 on the secondary side of the cold water. The chilled water secondary return pipe 37 is a pipe that supplies the chilled water whose temperature has been increased by the heat exchange in the air conditioner 17 from the air conditioner 17 to the second return header 15 on the secondary side of the chilled water.

  As described above, in the heat source control system 100 shown in FIG. 1, the first forward header 12 and the second forward header 13, the first return header 14 and the second return header 15, the air conditioner 17, and these elements are connected. The secondary side is constituted by the piping which performs.

  PLC0 and PLC1 are controllers that share and execute the control of the heat source control system 100. PLC0 and PLC1, for example, are respectively connected to a central monitoring device of a building in which an air conditioner is installed, and receive instructions from the central monitoring device. In FIG. 1, illustration of the central monitoring device is omitted.

  FIG. 2 is a diagram illustrating an example of input and output with the central monitoring device, the PLC0, the PLC1, and the refrigerator n in the heat source control system 100. FIG. 2 shows only one refrigerator n out of the n refrigerators 10, and the connections between PLC0 and PLC1 and the other refrigerators are the same or similar, and thus redundant description is omitted. In FIG. 2, the connections of the temperature sensors 23, 25, 33, 34 and the flow meters 24, 35 to the PLCs 0, 1 are not shown.

  PLC0 is an example of a control device, and controls the primary-chiller chilled water outlet temperature and the primary chilled water flow rate. The PLC0 may be installed at the same time as the PLC1, or may be installed after the existing heat source control system having the PLC1.

  For example, as shown in FIG. 2, the PLC 0 receives a set value Tcs2_SP (SP: Set Point) of the secondary chilled water upstream temperature, which is a control target value, from the central monitoring device. Further, the PLC 0 outputs the set value Tcs1_SP of the refrigerator cold water outlet temperature to the refrigerator side panel 10a, and receives a signal indicating the operation state (ON / OFF) of the refrigerator n from the refrigerator side panel 10a. The PLC0 can acquire information on the number N of operating the refrigerators 10 in the entire system from the operation state signals received from the respective refrigerator side panels 10a. Further, the PLC 0 outputs the set value pVc1_SP of the primary chilled water flow rate ratio to the flow rate instruction controller 26.

  Here, as shown in FIG. 2, the flow indicator controller 26 receives pVc1_SP from the PLC 0 and receives the PV of the primary chilled water flow rate Vc1_Ri from the flow meter 24. Further, the flow rate indicating controller 26 outputs a flow rate signal for inverter control to the inverter 27 of the primary chilled water pump 11. Then, the inverter 27 of the primary chilled water pump 11 controls the frequency of the power supply of the primary chilled water pump 11 according to the flow signal received from the flow rate indicating controller 26, and varies the rotation speed of the primary chilled water pump 11. Thereby, the primary cold water flow rate by the primary cold water pump 11 can be adjusted. In addition, the inverter 27 of the primary chilled water pump 11 is connected to the refrigerator side panel 10 a, and ON / OFF of the primary chilled water pump 11 is controlled so as to be linked with the operation state of the refrigerator 10.

  The PLC 1 executes a control (a heat source number control) for changing the number of operating chillers 10 in the entire system. For example, as shown in FIG. 2, the PLC 1 receives a heat source group start / stop command (on / off of the heat source in the entire system) from the central monitoring device. The PLC 1 outputs a start / stop command (on / off of each heat source) to the refrigerator side panel 10a, and outputs a signal indicating the operation state (on / off) of the refrigerator n from the refrigerator side panel 10a. receive.

  Next, a control example of the heat source control system of the present embodiment will be described.

  FIG. 3 is a flowchart showing the operation of the entire heat source control system. The process in FIG. 3 is started when the central monitoring device outputs a heat source group start command (the heat source is turned on in the entire system).

  In step S100, the PLC 1 activates the heat source group. In step S101, the PLC0 and the PLC1 acquire information on design values (upper and lower limits of various parameters, etc.) of each device from, for example, a memory or the like provided in the PLC. In step S102, the PLC 1 starts the base unit of the heat source group.

  Then, in step S103, the PLC0 and the PLC1 perform the fixed-cycle loop control of the heat source control system 100. For example, these controls are continuously performed until a stop instruction of the heat source group is received from the central monitoring device.

  The PLC0 in step S103 executes control of the primary-side refrigerator cold water outlet temperature and the primary cold water flow rate. FIG. 4 shows an example of the control of the PLC 0 in step S103. Similarly, the PLC 1 in step S103 executes the heat source number control. In the following description of the control of the number of heat sources, additionally starting the refrigerator is referred to as step-up, and stopping the refrigerator is referred to as step-down.

  Here, the control of the number of heat sources of the PLC 1 in the present embodiment may be the same as the known control. However, in addition to the step increase determination and the step reduction determination based on the secondary load heat amount, the secondary chilled water upstream temperatures Tcs2 and Tcs2 It is preferable that the PLC 1 controls the number of heat sources so that the secondary chilled water return temperature Tcr2 follows the set value Tcs2_SP of the secondary chilled water forward temperature. In this case, for example, the PLC 1 determines the step-up determination temperature (the refrigeration capacity shortage determination based on the secondary-side chilled water upstream temperature) by adding the value of the adjustment parameter (for example, about 1 to 2 ° C.) to the set value Tcs2_SP of the secondary chilled water upstream temperature. ), The number of heat sources is increased by one, and the value of the adjustment parameter (for example, about 0.5 ° C. to 2 ° C.) is added to the set value Tcs2_SP of the secondary chilled water upstream temperature. When the secondary chilled water return temperature Tcr2 is lower than the step reduction determination temperature (refrigeration capacity excess determination based on the difference between the secondary chilled water return temperature and the secondary chilled water forward temperature), the heat source is reduced by one heat source. If the control of the number of heat sources of the PLC 1 is performed in the same manner as the known control, for example, when the PLC 0 is retrofitted to an existing heat source control system to realize the heat source control system 100 of the present embodiment, the number of heat sources of the PLC 1 There is an advantage that the system can be easily introduced because the control algorithm does not need to be changed from the existing one.

  FIG. 4 is a flowchart showing a control example of the PLC0 in step S103 of FIG. In the following description of the control example, in the heat source configuration of the heat source control system 100, both the upper limit value and the lower limit value (such as the refrigerator outlet temperature, the chilled water flow rate, the ratio of the chilled water flow rate to the rating, and the bypass flow rate) of each heat source are set. The description will be made on the assumption that the set value Tcs1_SP of the chiller chilled water outlet temperature and the set value pVc1_SP of the primary chilled water flow rate ratio are set to be the same (that is, the equal capacity method) in each heat source.

  In step S200, the PLC 0 receives the set value Tcs2_SP of the secondary chilled water upstream temperature, which is the control target value, from the central monitoring device. In addition, the set value Tcs2_SP of the secondary chilled water outflow temperature may be automatically determined according to the date by, for example, a schedule management process executed by the central monitoring device, or a facility manager operating the central monitoring device may manually determine the setting value Tcs2_SP. May be set. The device that transmits the set value Tcs2_SP of the secondary chilled water upstream temperature, which is the control target value, to the PLC 0 may be devices other than the central monitoring device.

  In step S201, the PLC 0 acquires the PV of the refrigerator cold water outlet temperature Tcs1, the refrigerator cold water inlet temperature Tcr1, the secondary cold water forward temperature Tcs2, and the secondary cold water return temperature Tcr2 from the temperature sensors 23, 25, 33, and 34, respectively. . In addition, the PLC 0 acquires the PVs of the primary chilled water flow rate Vc1_Ri and the secondary chilled water flow rate Vc2 from the flow meters 24 and 35, respectively. Further, the PLC 0 acquires information on the number N of operating the refrigerators 10 in the entire system from the operation state signals received from the respective refrigerator side panels 10a.

In step S202, the PLC 0 calculates the secondary load calorific value Q2 by the following equation (1) using the secondary chilled water forward temperature Tcs2, the secondary chilled water return temperature Tcr2, and each PV of the secondary chilled water flow rate Vc2. Here, “k” is a coefficient collectively indicating the physical constant of the specific heat of water and the physical constant of the density of water.
Q2 = (Tcr2−Tcs2) × Vc2 × k [kW] (1)
In step S203, the PLC 0 calculates the upper limit value Vc1_MAX of the primary chilled water flow rate during the N-unit operation based on the number N of the refrigerators 10 operated by the following equation (2), and calculates the primary chilled water during the N-unit operation. The lower limit value Vc1_MIN of the flow rate is calculated by the following equation (3). Further, the PLC 0 calculates the maximum value Q1_MAX of the primary generated heat amount during the operation of the N units by the following equation (4).
Vc1_MAX = Vc1_MAX_Ri × N [m ³ / h] (2)
Vc1_MIN = Vc1_MAX × pVc1_MIN_Ri [m ³ / h] (3)
Q1_MAX = Q1_MAX_Ri × N [kW] (4)
Here, “Vc1_MAX_Ri” is the upper limit of the primary chilled water flow rate in the refrigerator 10 of the number i. “PVc1_MIN_Ri” is a lower limit value of the primary chilled water flow rate ratio in the refrigerator 10 of the number i. “Q1_MAX_Ri” is a rated generated heat amount in the refrigerator 10 of the number i. These parameters are obtained in the process of step S100 in FIG.

  When the flow rate of the primary chilled water in the evaporator tube of the refrigerator is too high, not only the pressure loss increases, but also erosion occurs in the tube, so the upper limit value is set by the refrigerator manufacturer. ing. Conversely, if the flow rate of the primary chilled water is too slow in the evaporator tube, there is a risk of corrosion due to a decrease in heat transfer and sedimentation of foreign matter in the flowing water. The lower limit is set as the ratio of the rated values of.

In step S204, the PLC 0 calculates the heat source load factor pQ1 by the following equation (5) using the secondary load heat quantity Q2 and the maximum value Q1_MAX of the primary heat generation quantity.
pQ1 = Q2 / Q1_MAX × 100 [%] (5)
In step S205, the PLC 0 determines whether the number N of operating refrigerators is appropriate for the secondary load heat quantity Q2. Specifically, PLC0 is such that the heat source load factor pQ1 is equal to or more than the lower limit value (pQ1_MIN_Ri) of the generated heat amount ratio in the refrigerator 10 of the number i, and the heat source load factor pQ1 is equal to or less than the maximum value (pQ1_MAX) of the heat source load factor pQ1. Is determined (pQ1_MIN_Ri ≦ pQ1 ≦ pQ1_MAX). Here, pQ1_MAX = 100 [%], and pQ1_MIN_Ri is determined by a design value.

  If pQ1_MIN_Ri ≦ pQ1 ≦ pQ1_MAX, the current operating number N of the refrigerator 10 is appropriate for the secondary load heat quantity Q2, and the process proceeds to step S206. On the other hand, if pQ1_MIN_Ri ≦ pQ1 ≦ pQ1_MAX is not satisfied, the current operating number N of the refrigerator 10 is not appropriate for the secondary load heat quantity Q2, and the process proceeds to step S210.

In step S206, the PLC 0 calculates the secondary chilled water temperature difference ΔT2 between the outlet and the inlet of the air conditioning load by using the secondary chilled water forward temperature Tcs2 and the secondary chilled water return temperature Tcr2 according to the following equation (6). .
ΔT2 = Tcr2-Tcs2 [° C.] (6)
In step S207, the PLC 0 determines whether the secondary chilled water temperature difference ΔT2 is sufficiently obtained. Specifically, the PLC 0 determines whether or not the secondary chilled water temperature difference ΔT2 is equal to or greater than a design value of the secondary chilled water temperature difference (ΔT2_DV = 5 ° C.). If the secondary chilled water temperature difference ΔT2 is equal to or larger than the design value of the secondary chilled water temperature difference (ΔT2 ≧ ΔT2_DV), the process proceeds to step S208. On the other hand, when the secondary chilled water temperature difference ΔT2 is smaller than the design value of the secondary chilled water temperature difference (ΔT2 <ΔT2_DV), the process proceeds to step S209.

  In step S208, the secondary chilled water temperature difference ΔT2 is equal to or larger than the design value of the secondary chilled water temperature difference, and the secondary chilled water temperature difference ΔT2 is sufficiently obtained. Control is performed so that the primary chilled water refrigerator outlet temperature = the secondary chilled water forward temperature.

Specifically, the PLC 0 makes the set value Tcs1_SP of the refrigerator cold water outlet temperature, which is the first control set value, equal to the set value Tcs2_SP of the secondary chilled water forward temperature (Tcs1_SP = Tsc2_SP). In addition, the PLC 0 calculates a set value pVc1_SP of the primary chilled water flow rate ratio, which is the second control set value, by the following equation (7). After step S208, the PLC 0 ends the processing in FIG.
pVc1_SP = Vc2 / Vc1_MAX × 100 [%] (7)
In step S209, the PLC0 performs the first condition such that the refrigerator 10 can safely operate under the condition (Q2 = Q1) that the secondary load heat amount Q2 and the primary-side generated heat amount Q1 are equal. The solution of the control set value (Tcs1_SP) and the second control set value (pVc1_SP) is calculated. FIG. 5 shows an example of the processing in step S209.

  Here, in step S209, the secondary chilled water forward temperature at which the primary chilled water fed by the primary chilled water pump 11 and the secondary cooled chilled water flowing from the return header to the first forward header 12 via the bypass pipe 18 are merged. PLC0 uses the secondary chilled water forward temperature set value Tcs2_SP, the secondary chilled water return temperature Tcr2, and the secondary chilled water flow rate Vc2 so that A first control set value (Tcs1_SP) and a second control set value (pVc1_SP) are calculated. In this calculation, a solution corresponding to these temporary values can be calculated by substituting the temporary refrigerator cold water outlet temperature tTcs1 or the temporary primary cold water flow rate tVc1. After step S209, the PLC 0 ends the processing in FIG.

  Here, in the control of step S209, the secondary chilled water return temperature Tcr2 is a temperature higher than the refrigerator cold water outlet temperature Tcs1. That is, the PLC0 in step S209 sets the chilled water outlet temperature of the refrigerator of the primary chilled water supplied based on the first control set value and the second control set value to a temperature lower than the set value of the secondary chilled water forward temperature. Alternatively, the temperature is the same. In the PLC 0, the secondary chilled water forward temperature Tcs2 obtained by mixing the primary chilled water fed from the refrigerator 10 and the secondary return chilled water flowing backward from the bypass pipe 18 becomes the desired secondary chilled water forward temperature set value Tcs2_SP. (In some cases, the primary chilled water flow rate is equal to the secondary chilled water flow rate and mixing is not performed depending on the values of the first control set value and the second control set value.) Therefore, it is preferable that the set value Tcs2_SP of the secondary chilled water outgoing temperature be set to a temperature higher than the lower limit value Tcs1_MIN of the refrigerator chilled water outlet temperature. Note that the control according to the present embodiment is suitable for operation in winter or an intermediate period where there is no effect even if the set value Tcs2_SP of the secondary chilled water upstream temperature is set high.

  In step S210, the PLC 0 determines whether the number N of operating the refrigerators 10 is insufficient. Specifically, the PLC 0 determines whether the heat source load factor pQ1 is larger than the maximum heat source load factor pQ1_MAX (pQ1> pQ1_MAX). When the heat source load factor pQ1 is larger than the maximum value pQ1_MAX of the heat source load factor, the operating number N of the refrigerators 10 is insufficient, and the process proceeds to step S211. On the other hand, when the heat source load factor pQ1 is equal to or less than the maximum value pQ1_MAX of the heat source load factor, the number of operating refrigerators N is in an excessive state, and the process proceeds to step S212.

  In step S211, since the number of operating chillers 10 is insufficient for the secondary load heat amount Q2, the PLC0 determines that the generated heat amount Q1 on the primary side is the maximum under the condition of the current operating number N of the chillers 10. The control is performed so that Specifically, the PLC 0 lowers the set value Tcs1_SP of the refrigerator cold water outlet temperature that is the first control set value to the lower limit value Tcs1_MIN of the refrigerator cold water outlet temperature (Tcs1_SP = Tsc1_MIN). In addition, the PLC0 sets the set value pVc1_SP of the primary chilled water flow ratio, which is the second control set value, to 100% of the maximum (pVc1_SP = 100 [%]). After step S211, the PLC 0 ends the processing in FIG.

  In step S212, since the number N of operating the refrigerators 10 with respect to the secondary load heat quantity Q2 is excessive, the PLC0 determines the primary chilled water flow rate for minimizing the primary-side generated heat quantity within the control range. Make a decision. Specifically, the PLC0 determines whether the bypass pipe flow rate does not exceed the upper limit value when the primary chilled water flow rate Vc1 is minimized. Specifically, the PLC 0 determines whether a value obtained by subtracting the lower limit value Vc1_MIN of the primary chilled water flow rate from the secondary chilled water flow rate Vc2 is larger than the upper limit value Vbp_MAX of the bypass pipe flow rate (Vbp_MAX <Vc2−Vc1_MIN). If the bypass pipe flow rate exceeds the upper limit when the primary chilled water flow rate Vc1 is minimized, the process proceeds to step S213. If the bypass pipe flow rate does not exceed the upper limit when the primary chilled water flow rate Vc1 is minimized, the process proceeds to step S214.

In step S213, the PLC 0 performs control such that the generated heat amount Q1 on the primary side becomes as small as possible under the condition of the current number N of operating the refrigerators 10. Specifically, the PLC 0 sets the set value Tcs1_SP of the refrigerator cold water outlet temperature, which is the first control set value, to the lower limit value Tcs1_MIN of the refrigerator cold water outlet temperature (Tcs1_SP = Tsc1_MIN). In addition, the PLC 0 calculates the set value pVc1_SP of the primary chilled water flow rate ratio, which is the second control set value, by the following equation (8). After step S213, the PLC 0 ends the processing in FIG.
pVc1_SP = (Vc2−Vbp_MAX) / Vc1_MAX × 100 [%] (8)
In step S214, the PLC 0 performs control such that the generated heat quantity Q1 on the primary side becomes as small as possible under the condition of the current number of operating refrigerators N. Specifically, the PLC 0 sets the set value Tcs1_SP of the refrigerator cold water outlet temperature, which is the first control set value, to the lower limit value Tcs1_MIN of the refrigerator cold water outlet temperature (Tcs1_SP = Tsc1_MIN). Further, the PLC 0 sets the set value pVc1_SP of the primary chilled water flow ratio, which is the second control set value, to the lower limit pVc1_MIN_Ri of the primary chilled water flow ratio in each refrigerator 10 (pVc1_SP = pVc1_MIN_Ri). After step S214, the PLC 0 ends the process of FIG.

  Next, the processing in step S209 in FIG. 4 will be described in detail with reference to FIGS. FIG. 5 is a flowchart showing a processing example of the PLC0 in step S209 of FIG.

  FIG. 6 is a diagram showing an example of the relationship between the ratio of the primary chilled water flow rate Vc1 when Q1 = Q2 and the primary chilled water temperature difference ΔT1 when the rated value is 100%. The vertical axis of FIG. 6 indicates the primary chilled water temperature difference ΔT1, and the horizontal axis of FIG. 6 indicates the ratio of the primary chilled water flow rate Vc1 to the rated value of 100%. The curve in FIG. 6 plots the relationship between the primary chilled water flow rate Vc1 and the primary chilled water temperature difference ΔT1 when Q1 = Q2 = Const. The rated ratio of the amount of heat indicated by the curve of Q1 = Q2 in FIG. 6 is 45%. When the horizontal axis is 100%, the vertical axis is 45%, when the horizontal axis is 67%, the vertical axis is 67%, and when the horizontal axis is 50%. The vertical axis is 90%, and when the vertical axis is 120%, the horizontal axis is 37.5%. Note that the curve shown in FIG. 6 is merely an example, and the curve shifts as Q2 increases or decreases.

  Here, in the control in the step S300s shown in FIG. 5, the secondary-side load calorie Q2 calculated from the measured value is equal to the primary-side generated calorie Q1 calculated, and the outlet of the refrigerator 10 By making the primary chilled water temperature difference ΔT1 between the chiller and the inlet maximum within the control range, the stoppage of the refrigerator compressor due to light load operation is suppressed, and the flow rate of the primary chilled water pump 11 is minimized within the control range. The solutions of the first control set value (Tcs1_SP) and the second control set value (pVc1_SP) are obtained in the order in which the control can reduce the primary chilled water transfer power.

  In step S300, the PLC 0 calculates a solution when the refrigerator cold water outlet temperature is at the lower limit (point (a) in FIG. 6). Specifically, the PLC0 calculates the temporary primary chilled water flow rate tVc1 when the lower limit value Tcs1_MIN of the refrigerator chilled water outlet temperature is substituted for the temporary chilled water outlet temperature tTcs1 in the following equation (9).

Further, the PLC 0 calculates a temporary bypass pipe flow rate tVbp based on the temporary primary chilled water flow rate tVc1 by the following equation (10).
tVbp = Vc2−tVc1 (10)
In step S301, the PLC 0 determines whether the solution calculated in step S300 satisfies the design condition. Specifically, the PLC 0 determines that the design condition is satisfied when the following (condition 1) and (condition 2) are satisfied.
(Condition 1): The provisional primary chilled water flow rate tVc1 is within the range (Vc1_MIN ≦ tVc1 ≦ Vc1_MAX) from the lower limit value to the upper limit value of the primary chilled water flow rate.
(Condition 2): The temporary bypass pipe flow rate tVbp is equal to or less than the upper limit value Vbp_MAX of the bypass pipe flow rate (tVbp ≦ Vbp_MAX).

  If the above design conditions are satisfied, the process moves to step S308. On the other hand, if the above design conditions are not satisfied, the process moves to step S302.

  In step S302, the PLC 0 calculates a solution when the primary chilled water flow rate is at the lower limit (point (b) in FIG. 6). Specifically, the PLC0 calculates a temporary refrigerator cold water outlet temperature tTcs1 when the lower limit value Vc1_MIN of the primary cold water flow rate is substituted for the temporary primary cold water flow rate tVc1 in the following equation (11).

Further, the PLC 0 calculates a temporary primary chilled water temperature difference tΔT 1 based on the temporary refrigerator chilled water outlet temperature tTcs 1 by the following equation (12).
tΔT1 = Tcr2−tTcs1 (12)
In step S303, the PLC 0 determines whether the solution calculated in step S302 satisfies the design condition. Specifically, the PLC 0 determines that the design condition is satisfied when all of the following (condition 11) to (condition 13) are satisfied.
(Condition 11): The temporary refrigerator cold water outlet temperature tTcs1 is within the range from the lower limit to the upper limit of the refrigerator cold water outlet temperature (Tcs1_MIN ≦ tTcs1 ≦ Tcs1_MAX).
(Condition 12): The provisional primary chilled water temperature difference tΔT1 is equal to or larger than the lower limit value ΔT1_MIN of the primary chilled water temperature difference (tΔT1 ≧ ΔT1_MIN).
(Condition 13): The temporary bypass pipe flow rate tVbp is equal to or less than the upper limit value Vbp_MAX of the bypass pipe flow rate (tVbp ≦ Vbp_MAX).

  If the above design conditions are satisfied, the process moves to step S308. On the other hand, if the above design conditions are not satisfied, the process proceeds to step S304.

  In step S304, the PLC 0 calculates a solution when the primary chilled water flow rate is the upper limit value of the bypass pipe flow rate (point (c) in FIG. 6). Specifically, the PLC0 calculates the temporary refrigerator cold water outlet temperature tTcs1 when Vc2−Vbp_MAX is substituted for the temporary primary cold water flow rate tVc1 in the above equation (11). In addition, the PLC0 calculates the temporary primary chilled water temperature difference tΔT1 when the primary chilled water flow rate is the upper limit of the bypass pipe flow rate by the above equation (12).

  The temporary primary chilled water flow rate tVc1 at the time of the upper limit of the bypass pipe flow rate shown in FIG. 6C fluctuates according to the current number N of heat sources. Here, the upper limit value Vbp_MAX of the bypass pipe flow rate is a fixed value (generally, the flow rate for one refrigerator), but the primary chilled water flow rate increases as the number of heat sources N increases, and if the number N of heat sources decreases. Become smaller. Therefore, as the number N of heat sources increases, the temporary primary chilled water flow rate tVc1 at the upper limit of the bypass pipe flow rate becomes a relatively high value, and the position of the point (c) in FIG. Approaching the direction of. Conversely, as the number N of heat sources decreases, the temporary primary chilled water flow rate tVc1 at the upper limit value of the bypass pipe flow rate becomes a relatively low value, and the position of the point (c) in FIG. Approaching the direction of the value.

In step S305, the PLC 0 determines whether the solution calculated in step S304 satisfies the design condition. Specifically, the PLC 0 determines that the PLC 0 satisfies the design condition when all of the following (condition 21) to (condition 23) are satisfied.
(Condition 21): The temporary refrigerator cold water outlet temperature tTcs1 is within the range from the lower limit to the upper limit of the refrigerator cool water outlet temperature (Tcs1_MIN ≦ tTcs1 ≦ Tcs1_MAX).
(Condition 22): The temporary primary chilled water temperature difference tΔT1 is equal to or larger than the lower limit value ΔT1_MIN of the primary chilled water temperature difference (tΔT1 ≧ ΔT1_MIN).
(Condition 23): The provisional primary chilled water flow rate tVc1 is within the range from the lower limit to the upper limit value of the primary chilled water flow rate (Vc1_MIN ≦ tVc1 ≦ Vc1_MAX).

  If the above design conditions are satisfied, the process moves to step S308. On the other hand, when the above design conditions are not satisfied, it is considered that the design conditions cannot be satisfied by a combination of solutions in which a backflow occurs. Therefore, the primary cold water temperature difference ΔT1 between the outlet and the inlet of the refrigerator 10 under the condition that the secondary load calorific value Q2 calculated from the measured value is equal to the primary-side generated calorific value Q1 calculated. Is a state in which the primary chilled water and the secondary chilled water of tTcs1 = Tcs2_SP and tVc1 = Vc2 are balanced. The process shifts to step S306 to determine whether Vc2 is within the flow rate adjustment range of the primary chilled water pump 11 (Vc2 ≦ Vc1_MAX).

  In step S306, the PLC0 determines whether the secondary chilled water flow rate Vc2 is equal to or less than the upper limit value Vc1_MAX of the primary chilled water flow rate calculated from the number of operating refrigerators at that time (Vc2 ≦ Vc1_MAX). If the secondary chilled water flow rate Vc2 is equal to or less than the upper limit value Vc1_MAX of the primary chilled water flow rate, the process proceeds to step S307. On the other hand, if the secondary chilled water flow rate Vc2 is larger than the primary chilled water flow rate upper limit value Vc1_MAX, there is no solution that satisfies the design conditions, and the process proceeds to step S309.

  In step S307, a solution when the primary chilled water flow rate is equal to the secondary chilled water flow rate is calculated. PLC0 sets the temporary primary chilled water flow rate tVc1 to the secondary chilled water flow rate Vc2 (tVc1 = Vc2), and sets the temporary chiller chilled water outlet temperature tTcs1 to the secondary chilled water forward temperature set value Tcs2_SP (tTcs1 = Tcs2_SP). Thereafter, the process proceeds to step S308.

  In step S308, the PLC 0 sets the set value Tcs1_SP of the refrigerator cold water outlet temperature, which is the first control set value, to tTcs (Tcs1_SP = tTsc1). In addition, the PLC 0 sets the set value pVc1_SP of the primary chilled water flow ratio, which is the second control set value, to tVc1 / Vc1_MAX × 100 (pVc1_SP = tVc1 / Vc1_MAX × 100 [%]).

  As described above, by finding the solution in the order of step S301, step S303, step S305, and step S307, the PLC0 calculates the secondary-side load calorie calculated from the measured value and the primary-side generated calorific value Q1 obtained by the calculation. A first control set value (Tcs1_SP) that maximizes the primary chilled water temperature difference ΔT1 between the outlet and the inlet of the refrigerator 10 under the condition of being equal and within the flow rate adjustment range of the primary chilled water pump 11; The solution of the second control set value (pVc1_SP) can be obtained. After step S308, PLC0 ends the processing in FIG.

  In step S309, the PLC 0 sets the refrigerator cooling water outlet temperature set value Tcs1_SP, which is the first control set value, to the lower limit of the refrigerator cooling water outlet temperature Tcs1_MIN (Tcs1_SP = Tsc1_MIN). In addition, the PLC 0 sets the primary chilled water flow rate set value pVc1_SP, which is the second control set value, to 100% (pVc1_SP = 100 [%]). After step S309, PLC0 ends the processing in FIG.

  In the case of step S309, even if the number of operating refrigerators 10 is commensurate with the calorific value, the current number of operating refrigerators may not be able to cover the primary chilled water flow rate of Q1 = Q2. Therefore, the PLC 0 performs control to maximize the amount of generated heat on the primary side as much as possible. In this case, control for increasing the number of heat sources by the PLC 1 is separately performed.

  Next, the operation of the comparative example and the example of the heat source control system will be described with reference to FIGS. 7 to 9 schematically show the configuration of the heat source control system of the primary and secondary pump type, and the illustration of the secondary forward header and the secondary chilled water pump is omitted for simplicity.

  Here, the heat source control system in FIGS. 7 to 9 has three refrigerators R1 to R3. The refrigerator R1 has an INV turbo refrigeration capacity of 530 USRT, the refrigerator R2 has a constant speed turbo refrigeration capacity of 530 USRT, and the refrigerator R3 has a gas absorption type refrigeration capacity of 500 USRT. The outside air conditions are a dry bulb temperature of 15.0 ° C. Db, a relative humidity of 40.0% RH, and a wet bulb temperature of 8.48 ° C. Wb. The secondary load calorie condition is 26%, 406 USRT (1426 kW).

  FIG. 7 shows an operation state under the control in which the secondary chilled water forward temperature is 10 ° C., the secondary chilled water return temperature is 15 ° C., and the secondary chilled water temperature difference ΔT = 5 ° C., and backflow from the return header to the forward header is prohibited. Is shown. In the case of FIG. 7, when one refrigerator R1 is operated at a heat amount ratio of 76.53%, the secondary load heat amount and the generated heat amount on the primary side are balanced, and the primary chilled water flow rate and the secondary chilled water flow rate are also equal. Balance.

  In the example of FIG. 7, the power of the cooling water pump is 8.6 kW, the power of the cooling water pump used for cooling the refrigerator is 8.1 kW, and the power of the fan of the cooling tower used for cooling the refrigerator is 13 kW. 0.3 kw.

FIG. 8 shows an operation state under the control of the comparative example in which the backflow from the return header to the forward header is prohibited when the temperature difference ΔT = 3 ° C. in the secondary chilled water. In the example of FIG. 8, since the secondary chilled water flow rate is increased to 408.8 m ³ / h, the primary chilled water flow rate is increased in order to directly send the chilled water at the chiller chilled water outlet temperature (10 ° C.) to the air conditioner. It is necessary to suppress the backflow. Therefore, in the example of FIG. 8, control is performed to increase the number of operating units based on the flow balance, and the refrigerators R1 and R2 are operated at a heat amount ratio of 38.26%. As a result, the flow rate of the primary chilled water becomes 408.8 m ³ / h, so that the flow rate of the primary chilled water and the flow rate of the secondary chilled water are balanced, so that no backflow occurs.

  In the example of FIG. 8, the power of the cold water pump was 9.6 kW, the power of the cooling water pump was 13.2 kW, and the power of the fan of the cooling tower was 17.1 kW.

  On the other hand, FIG. 9 shows an operation state under control of the example of the present embodiment when the temperature difference ΔT of the secondary chilled water is 3 ° C. In the case of the control of the example of the present embodiment, the backflow is allowed, and the primary chilled water of the primary chilled water pump is combined with the flow from the return header to the forward header from the bypass pipe, and the secondary chilled water of the control target value is combined. Get outbound temperature. That is, in the example of FIG. 9, it is not necessary to make the primary chilled water flow rate equal to or more than the secondary chilled water flow rate as in the example of FIG. What is necessary is just to determine the operating conditions. Therefore, in the example of FIG. 9, one refrigerator R1 may be operated at a heat amount ratio of 76.80% based on the heat balance, and the number of operating refrigerators and chilled water pumps can be suppressed as compared with the example of FIG.

In the example of FIG. 9, the temperature of the water flowing backward from the return header to the forward header in the bypass pipe is 13 ° C., and the flow rate is 204.4 m ³ / h. Therefore, in order to lower the secondary chilled water upstream temperature to the control target value of 10 ° C., the refrigerator cold water outlet temperature is set to 7 ° C., which is lower than the control target value of 10 ° C. In the example of FIG. 9, the primary chilled water temperature difference between the chilled water inlet temperature (13 ° C.) and the chilled water outlet temperature (7 ° C.) is 6 ° C., which is larger than the example of FIG. 8 (ΔT1 = 3 ° C.). It turns out that it becomes.

  In the example of FIG. 9, the power of the cold water pump was 4.8 kW, the power of the cooling water pump was 8.8 kW, and the power of the fan of the cooling tower was 13.3 kW.

  Also, comparing the power of the chilled water pump in the case of FIG. 7 to FIG. 9, it is 8.6 kW in FIG. 7, whereas it is 9.6 kW in FIG. 8, and 4.8 kW in FIG. Become. When comparing the power of the cooling water pump, the power in the case of FIG. 7 is 8.1 kW, whereas the power in the case of FIG. 8 is 13.2 kW, and in the case of FIG. 9 8.8 kW. Similarly, when the power of the cooling tower fan is compared, it is 13.3 kW in FIG. 7, 17.1 kW in FIG. 8, and 13.3 kW in FIG. 9. As described above, in the example of the present embodiment illustrated in FIG. 9, all of the power of the chilled water pump, the motive power of the cooling water pump, and the motive power of the cooling tower fan can be reduced as compared with the comparative example illustrated in FIG. 8. .

  Hereinafter, the operation and effect of the heat source control system of the present embodiment will be described.

  In the heat source control system 100 of the present embodiment, the control device is configured such that, when the secondary chilled water temperature difference ΔT2 is less than the design value, the secondary load heat quantity Q2 and the generated heat quantity Q1 on the primary side are equal, and The secondary chilled water outgoing temperature Tcs2, in which the primary chilled water sent by the primary chilled water pump 11 and the secondary chilled water flowing from the return header into the first forward header 12 via the bypass pipe 18 are combined, is the secondary chilled water outward temperature. The first set value Tcs2_SP of the secondary chilled water forward temperature, the secondary chilled water return temperature Tcr2, and the second chilled water flow rate Vc2 for controlling the chilled water outlet temperature of the refrigerator so that the set value Tcs2_SP A control set value (Tcs1_SP) and a second control set value (pVc1_SP) for controlling the primary chilled water flow rate are obtained.

  That is, in the present embodiment, the backflow is permitted, and the primary chilled water of the primary chilled water pump 11 and the flow from the return header to the forward header from the bypass pipe 18 are merged to control the secondary chilled water forward temperature of the control target value. By this, the rise of the secondary chilled water outgoing temperature Tcs2 can be suppressed, and the secondary chilled water outgoing temperature Tcs2, whose temperature has been determined by the conventional control, can be stably controlled.

  Further, in the present embodiment, the primary chilled water of the primary chilled water pump 11 and the flow from the return pipe from the bypass pipe 18 to the forward header are merged to obtain the secondary chilled water upstream temperature of the control target value. Although the refrigerator cold water outlet temperature Tcs1 may be lower than the secondary cold water forward temperature Tcs2, the refrigerator cold water outlet temperature Tcs1 is determined based on the secondary cold water calorie required at that time. The calculation is determined by considering at least the lower limit and the lower limit of the flow rate of the cold water. Therefore, in the present embodiment, the primary chilled water temperature difference ΔT1 on the primary side can be maximized within the control range. When the primary chilled water temperature difference ΔT1 in the refrigerator becomes small, control is performed to automatically stop the compressor of the refrigerator and enter a light load operation state. According to the present embodiment, however, the primary chilled water temperature difference ΔT1 falls within the control range. , The frequency of shifting to the light load operation state is reduced. Thus, according to the present embodiment, the risk of an increase in the secondary chilled water forward temperature Tcs2 due to the transition of the heat source to the light load operation state in the heat source control system can be suppressed as much as possible by the conventional control.

  Further, in the present embodiment, the primary chilled water of the primary chilled water pump 11 and the flow from the return pipe from the bypass pipe 18 to the forward header are merged to obtain the secondary chilled water upstream temperature of the control target value. Although the refrigerator cold water outlet temperature Tcs1 may be lower than the secondary cold water forward temperature Tcs2, the refrigerator cold water outlet temperature Tcs1 is calculated and determined based on the secondary cold water calorie required at that time. The secondary cold water flow rate Vc1 does not need to be larger than the secondary cold water flow rate Vc2. Therefore, according to the present embodiment, it is possible to reduce the power for transporting the primary cold water as compared with the related art.

  Further, in the conventional control, the primary chilled water flow rate Vc1 is set to be larger than the secondary chilled water flow rate Vc2, so that the primary chilled water temperature difference ΔT1 is inevitably greater than the secondary chilled water temperature difference ΔT2 due to the flow from the forward header to the return header. In some cases, even if the primary chilled water flow rate Vc1 is maximized within the control range, the refrigerator may not be able to generate the rated generated heat. According to the present embodiment, ΔT1 can be maximized within the control range, so that control that exerts the rated capacity of the refrigerator can be performed in more cases than conventional control.

  Further, according to the present embodiment, the primary chilled water of the primary chilled water pump 11 and the flow from the return header to the forward header from the bypass pipe 18 are combined to obtain the secondary chilled water upstream temperature of the control target value. In some cases, the chiller outlet water temperature Tcs1 is set lower than the secondary chiller water outlet temperature Tcs2. However, the chiller outlet water temperature Tcs1 is calculated and determined based on the amount of secondary chilled water heat required at that time. The primary cold water flow rate Vc1 need not be larger than the secondary cold water flow rate Vc2. For this reason, in the present embodiment, the number of operating refrigerators 10 can be controlled by the heat balance of the primary side and the secondary side instead of the flow balance of the primary side and the secondary side, so that the number of operation of the refrigerators 10 is increased due to a rise in temperature compared with the conventional case. It is possible to minimize the unnecessary start-up of unnecessary heat sources.

(Supplementary items of the embodiment)
In the above embodiment, the PLC0 and the PLC1 are described as independent devices, however, a configuration in which some or all of these functions are integrated into another PLC may be adopted. In the above embodiment, each PLC may perform data communication with another PLC, and acquire common information by communication between the PLCs.

  Further, in the control of the above-described embodiment, when a plurality of heat sources are operated, the heat amount is distributed in a uniform distribution proportional manner.However, weighting is performed according to the performance of the heat sources, and priority is given to the heat sources to be operated. It may be provided. For example, the weight coefficient of the heat source may be determined based on the rated COP (Coefficient Of Performance) for each heat source, and the high efficiency heat source may be preferentially operated by increasing the weight coefficient of the high efficiency heat source. . Alternatively, when the upper limit value and the lower limit value are different for each heat source, a table of weighting factors corresponding to the number of operating units N and the secondary load heat quantity Q2 is set, and the heat source to be operated is determined with reference to this table. The control value may be determined within the range of the upper limit and the lower limit of the heat source.

  The features and advantages of the embodiments will be apparent from the above detailed description. It is intended that the appended claims extend to the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. In addition, any person having ordinary skill in the art can easily think of any improvements and changes. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and it is possible to rely on appropriate improvements and equivalents included in the scope disclosed in the embodiments.

100 heat source control system 10 refrigerator (heat sources R1-Rn)
10a Refrigerator side panel 11 Primary chilled water pump 12 First outgoing header 13 Second outgoing header 14 First return header 15 Second return header 16 Secondary chilled water pump 17 Air conditioner (AHU)
18 bypass pipe 21 chilled water primary return pipe 22 chilled water primary return pipe 23 temperature sensor 24 flow meter 25 temperature sensor 26 flow indication controller (FIC)
27 Inverter 31 Outgoing header pipe 32 Inverter 33 Temperature sensor 34 Temperature sensor 35 Flow meter 36 Chilled water secondary outgoing pipe 37 Chilled water secondary return pipe

Claims (6)

A refrigerator,
A first going header connected to a chilled water outlet side of the refrigerator by a chilled water first going pipe;
A return header connected to a chilled water inlet side of the refrigerator via a chilled water primary outgoing pipe via a chilled water pump;
A bypass pipe connecting the first header and the return header;
A second outgoing header connected to the first outgoing header via an outgoing header pipe via a secondary chilled water pump;
An air conditioning load connected between the second outgoing header and the return header via a chilled water secondary outgoing pipe and a chilled water secondary return pipe,
A second return thermometer for the second header or the cold water secondary return pipe, a secondary return thermometer for measuring a secondary cold water return temperature on the return header or the cold water secondary return pipe, A secondary flow meter for measuring the secondary chilled water flow rate in the return pipe,
A control device for controlling the refrigerator and the primary chilled water pump;
With
The control device includes:
When a secondary chilled water temperature difference, which is a difference between a measured value of the secondary return thermometer at the outlet of the air conditioning load and a measurement value of the secondary forward thermometer at the inlet of the air conditioning load, is smaller than a design value, the secondary return is performed. The load heat on the secondary side calculated from the measured values of the thermometer, the secondary outgoing thermometer, and the secondary flow meter, the measured value of the secondary chilled water return temperature , the refrigerator chilled water outlet temperature, and the primary chilled water flow rate Under the condition that the amount of heat generated on the primary side obtained by calculation from Eq. (1) is equal, and the primary chilled water supplied by the primary chilled water pump flows into the first header from the return header via the bypass pipe. The secondary chilled water outgoing temperature, where the secondary chilled water is merged, becomes the set value of the secondary chilled water outgoing temperature, which is the control target value,
Using the set value of the secondary chilled water forward temperature, the secondary chilled water return temperature, and the secondary chilled water flow rate, a first control set value for controlling the chiller chilled water outlet temperature, and the primary chilled water flow rate A second control set value for controlling the chiller and the first chilled water pump based on the first control set value and the second control set value. Heat source control system. The heat source control system according to claim 1,
The control device includes:
A control for setting the refrigerator cold water outlet temperature of the primary chilled water supplied based on the first control set value and the second control set value to a temperature lower than the set value of the secondary cold water forward temperature. A heat source control system characterized by performing. In the heat source control system according to claim 1 or 2,
The control device includes:
The secondary return thermometer, the secondary forward thermometer, and the load heat on the secondary side calculated from the measurement values of the secondary flow meter, the secondary chilled water return temperature measured value, the refrigerator cold water outlet temperature, and The primary chilled water temperature difference between the outlet and the inlet of the refrigerator under the condition that the generated heat amount on the primary side calculated from the primary chilled water flow rate becomes equal and within the flow rate adjustment range of the primary chilled water pump. A heat source control system, wherein the first control set value and the second control set value at a maximum are obtained. The heat source control system according to claim 3,
The control device includes:
A temporary chiller chilled water outlet temperature corresponding to the case where the chilled chilled water outlet temperature is the lower limit value, or the primary chilled water flow rate when the primary chilled water flow rate is the lower limit value, the flow rate of the bypass pipe is the upper limit value. Wherein a solution of the first control set value and the second control set value is obtained by using a temporary primary chilled water flow rate corresponding to any of the cases where is equal to the secondary chilled water flow rate. control
system. A chiller, a first outgoing header connected to a chilled water outlet side of the chiller by a first chilled water outgoing pipe, and a first chilled water pump connected to the chilled water inlet side of the chiller through a first chilled water pump. Return header, a bypass pipe connecting the first header and the return header, a second header connected to the first header via a secondary chilled water pump via a header pipe, An air conditioning load connected between the second outgoing header and the return header via a chilled water secondary outgoing pipe and a chilled water secondary returning pipe; and a second outgoing feed to the second outgoing header or the chilled water secondary outgoing pipe. A thermometer, a secondary return thermometer that measures a secondary chilled water return temperature in the return header or the chilled water secondary return pipe, and a secondary flow meter that measures a secondary chilled water flow rate in the chilled water secondary return pipe, A control device;
A control method for a heat source control system comprising:
When a secondary chilled water temperature difference, which is a difference between a measured value of the secondary return thermometer at the outlet of the air conditioning load and a measurement value of the secondary forward thermometer at the inlet of the air conditioning load, is smaller than a design value, the secondary return is performed. The load heat on the secondary side calculated from the measured values of the thermometer, the secondary outgoing thermometer, and the secondary flow meter, the measured value of the secondary chilled water return temperature , the refrigerator chilled water outlet temperature, and the primary chilled water flow rate Under the condition that the amount of heat generated on the primary side obtained by calculation from Eq. (1) is equal, and the primary chilled water supplied by the primary chilled water pump flows into the first header from the return header via the bypass pipe. The secondary chilled water outgoing temperature, where the secondary chilled water is merged, becomes the set value of the secondary chilled water outgoing temperature, which is the control target value,
The control device is configured to use the set value of the secondary chilled water forward temperature, the secondary chilled water return temperature, and the secondary chilled water flow rate to control a chiller chilled water outlet temperature, and a first control set value. And a second control set value for controlling the primary chilled water flow rate,
The control method of a heat source control system, wherein the control device controls the refrigerator and the primary chilled water pump based on the first control set value and the second control set value. A chiller, a first outgoing header connected to a chilled water outlet side of the chiller by a chilled water primary outgoing pipe, and a chilled water inlet side connected to the chilled water inlet side of the chiller through a primary chilled water pump. Return header, a bypass pipe connecting the first header and the return header, a second header connected to the first header via a secondary chilled water pump via a header pipe, An air conditioning load connected between the second outgoing header and the return header via a chilled water secondary outgoing pipe and a chilled water secondary returning pipe; and a second outgoing feed to the second outgoing header or the chilled water secondary outgoing pipe. A thermometer, a secondary return thermometer that measures a secondary chilled water return temperature in the return header or the chilled water secondary return pipe, and a secondary flow meter that measures a secondary chilled water flow rate in the chilled water secondary return pipe, A control device applied to a heat source control system including:
When a secondary chilled water temperature difference, which is a difference between a measured value of the secondary return thermometer at the outlet of the air conditioning load and a measurement value of the secondary forward thermometer at the inlet of the air conditioning load, is smaller than a design value, the secondary return is performed. The load heat on the secondary side calculated from the measured values of the thermometer, the secondary outgoing thermometer, and the secondary flow meter, the measured value of the secondary chilled water return temperature , the refrigerator chilled water outlet temperature, and the primary chilled water flow rate Under the condition that the amount of heat generated on the primary side obtained by calculation from Eq. (1) is equal, and the primary chilled water supplied by the primary chilled water pump flows into the first header from the return header via the bypass pipe. The secondary chilled water outgoing temperature, where the secondary chilled water is merged, becomes the set value of the secondary chilled water outgoing temperature, which is the control target value,
Using the set value of the secondary chilled water forward temperature, the secondary chilled water return temperature, and the secondary chilled water flow rate, a first control set value for controlling the chiller chilled water outlet temperature, and the primary chilled water flow rate Obtaining a second control set value for controlling
A process of controlling the refrigerator and the primary chilled water pump based on the first control set value and the second control set value;
A control device characterized by performing:

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