Heat source system and control method therefor

Abstract

The purpose of the present invention is to maintain a water supply temperature close to a target water supply temperature at the time of a change in the number of heat source machines operating. A heat source system of the present invention anticipates a case where a prescribed minimum flow rate is set for heat source machines that are subject to addition or removal, and calculates, as compensation temperatures, hot and cold water outlet temperatures of the heat source machines so that the water supply temperature in such a case will match a target water supply temperature, and changes the hot and cold water outlet temperature settings of the operating heat source machines to the compensation temperatures. After that, the heat source machines that are subject to addition or removal are either started up or stopped, and the set flow rate for the heat source machines that are subject to addition or removal is set to the minimum flow rate.

1 . A heat source system that includes a plurality of heat source machines connected in parallel to a load and that controls operations of the heat source machines such that a supply water temperature of cold/hot water which is supplied to the load corresponds to a target supply water temperature which is determined by a load-side request, the heat source system comprising:
 temperature calculating means for anticipating a case in which a predetermined flow rate is set for the heat source machine to be added or subtracted when changing the number of heat source machines operating and calculating a cold/hot water outlet temperature of the heat source machine in operation as a compensation temperature such that the supply water temperature at that time corresponds to the target supply water temperature; and   temperature setting means for changing a cold/hot water outlet setting temperature of the heat source machine in operation to the compensation temperature,   wherein the heat source machine to be added or subtracted is started or stopped and the setting flow rate of the heat source machine to be added or subtracted is set to the predetermined flow rate, after the supply water temperature is changed with the changing of the cold/hot water outlet setting temperature of the heat source machine in operation.   
     
     
         2 . The heat source system according to  claim 1 , wherein the temperature calculating means calculates the compensation temperature using an operational expression including the cold/hot water outlet temperature of the heat source machine to be added or subtracted, the flow rate of cold/hot water flowing in the heat source machine to be added or subtracted, and the flow rate of cold/hot water in the heat source machine which has already operated and which continuously operates after the addition or subtraction as parameters. 
     
     
         3 . The heat source system according to  claim 1 , wherein the cold/hot water outlet temperatures of all the heat source machines in operation are set to the target supply water temperature at the time of adding the heat source machine when the heat source machine to be added is started and it is determined that the cold/hot water outlet temperature of the heat source machine to be added is in an allowable temperature range set to be close to the target supply water temperature. 
     
     
         4 . The heat source system according to  claim 1 , wherein the cold/hot water outlet setting temperatures of all the heat source machines in operation are set to the target supply water temperature in subtracting the heat source machine when the heat source machine to be subtracted is started and a predetermined amount of time elapses after the heat source is subtracted or water supply means provided to correspond to the heat source machine to be subtracted is stopped. 
     
     
         5 . The heat source system according to  claim 1 , wherein the temperature calculating means sets the compensation temperature to a predetermined temperature upper limit set in advance on the basis of capability of the heat source machine when the compensation temperature is higher than the temperature upper limit. 
     
     
         6 . The heat source system according to  claim 1 , wherein the temperature calculating means sets the compensation temperature to a predetermined temperature lower limit set in advance on the basis of capability of the heat source machine when the compensation temperature is lower than the temperature lower limit. 
     
     
         7 . The heat source system according to  claim 2 , wherein the temperature calculating means calculates the compensation temperature using the flow rate of the heat source machine in operation as a maximum flow rate, and
 wherein the cold/hot water outlet setting temperature of the heat source machine in operation is changed to the compensation temperature and the setting flow rate thereof is changed to the maximum flow rate.   
     
     
         8 . The heat source system according to  claim 2 , wherein the temperature calculating means recalculates the compensation temperature using the flow rate of the heat source machine in operation as a maximum flow rate when the compensation temperature departs from a predetermined temperature upper-lower limit range set in advance on the basis of capability of the heat source machine, and
 wherein the cold/hot water outlet setting temperature of the heat source machine in operation is set to the recalculated compensation temperature and the setting flow rate is set to the maximum flow rate.   
     
     
         9 . The heat source system according to  claim 1 , wherein it is determined whether an operation state of the heat source machine in operation reaches a capability upper limit after at least the cold/hot water outlet setting temperature of the heat source machine in operation is set to the compensation temperature by the temperature setting means at the time of adding the heat source machine, and the heat source machine to be added is immediately started when the operation state of the heat source machine reaches the capability upper limit. 
     
     
         10 . The heat source system according to  claim 2 , further comprising temperature measuring means for measuring a return water temperature from the load,
 wherein the temperature calculating means calculates the compensation temperature using the return water temperature measured by the temperature measuring means as the cold/hot water outlet temperature of the heat source machine to be added or subtracted.   
     
     
         11 . The heat source system according to  claim 2 , wherein the temperature calculating means
 calculates a theoretical value of the return water temperature on the basis of a relationship among a heat source load, a heat quantity of cold/hot water sent out from the system to the external load, and a heat quantity of cold/hot water flowing into the system, and   calculates the compensation temperature using theoretical value of the return water temperature as the cold/hot water outlet temperature of the heat source machine to be added or subtracted.   
     
     
         12 . The heat source system according to  claim 2 , further comprising temperature measuring means for measuring a return water temperature from the load,
 wherein the temperature calculating means   calculates a theoretical value of the return water temperature on the basis of a relationship among a heat source load, a heat quantity of cold/hot water sent out from the system to the external load, and a heat quantity of cold/hot water flowing into the system, and   calculates the compensation temperature using the return water temperature, which is calculated using both the measured value of the return water temperature measured by the temperature measuring means and the theoretical value of the return water temperature as parameters, as the cold/hot water outlet temperature of the heat source machine to be added or subtracted.   
     
     
         13 . The heat source system according to  claim 12 , wherein the temperature calculating means calculates the compensation temperature using a correction value obtained by multiplying a predetermined coefficient equal to or greater than zero and equal to or less than 1 by a value, which is obtained by subtracting theoretical value of the return water temperature from the measured value of the return water temperature measured by the temperature measuring means. 
     
     
         14 . The heat source system according to  claim 1 , wherein a change rate is set to be lower than a predetermined change rate set on the basis of tracking capability of the heat source machine in operation when increasing the cold/hot water flow rate of the heat source machine to be added. 
     
     
         15 . The heat source system according to  claim 1 , wherein the cold/hot water outlet setting temperature of the heat source machine to be subtracted is changed to a predetermined temperature set in advance at a predetermined change rate to lower the load of the heat source machine to be subtracted when subtracting the heat source machine, an operation stop instruction is given to the heat source machine to be subtracted, and the cold/hot water outlet setting temperature of the heat source machine in operation is changed to the target supply water temperature. 
     
     
         16 . The heat source system according to  claim 1 , wherein the change rate is set to a change rate in a range in which an overshoot or an undershoot of the cold/hot water outlet temperature with respect to the cold/hot water outlet setting temperature of the heat source machine in operation does not occur when changing the cold/hot water outlet setting temperature of the heat source machine in operation from the compensation temperature to the target supply water temperature. 
     
     
         17 . The heat source system according to  claim 1 , wherein the compensation temperature is recalculated so as to distribute a heat quantity shortfall of the heat source machines to the other heat source machines in operation of which the capability does not reach the capability upper limit and the cold/hot water outlet setting temperature of the other heat source machines in operation of which the capability does not reach the capability upper limit is set to the recalculated compensation temperature when the operation states of some heat source machines in operation reach the capability upper limit and the cold/hot water outlet temperature of the heat source machines in operation does not reach the compensation temperature after the cold/hot water outlet setting temperature of at least the heat source machines in operation is set to the compensation temperature by the temperature setting means. 
     
     
         18 . The heat source system according to  claim 2 , wherein the temperature calculating means calculates the compensation temperature using the cold/hot water outlet temperature of the heat source machines, or the lower temperature of the cold/hot water outlet temperature and the return water temperature when cooling a heat medium, or the higher temperature of the cold/hot water outlet temperature and the return water temperature when heating the heat medium as the cold/hot water outlet temperature of the heat source machine to be added after the heat source machine to be added is started. 
     
     
         19 . The heat source system according to  claim 2 , further comprising temperature measuring means for measuring a cold/hot water outlet temperature or a cold/hot water inlet temperature of the heat source machine,
 wherein the temperature calculating means calculates the compensation temperature using the measured value, which has been measured by the temperature measuring means provided to correspond to the heat source machine to be added or subtracted, as the cold/hot water outlet temperature of the heat source machine to be added or subtracted.   
     
     
         20 . The heat source system according to  claim 1 , wherein the predetermined flow rate of the heat source machine to be added is set within a range equal to or higher than a minimum flow rate of a cold/hot water pump provided to correspond to the heat source machine to be added and equal to or lower than a minimum flow rate determined on the basis of a specification of the heat source machine to be added. 
     
     
         21 . The heat source system according to  claim 1 , wherein the predetermined flow rate of the heat source machine to be subtracted is set to a minimum flow rate determined on the basis of a specification of the heat source machine to be subtracted. 
     
     
         22 . The heat source system according to  claim 1 , wherein the temperature calculating means has a weighting set on the basis of an influence which the cold/hot water sent out from each heat source machine gives to the supply water temperature for each heat source machine and calculates the compensation temperature using the weighting. 
     
     
         23 . A control method of a heat source system that includes a plurality of heat source machines connected in parallel to a load and that controls operations of the heat source machines such that a supply water temperature of cold/hot water which is supplied to the load corresponds to a target supply water temperature which is determined by a load-side request, the control method comprising:
 a step of anticipating a case in which a predetermined flow rate is set for the heat source machine to be added or subtracted when changing the number of heat source machines operating and calculating a cold/hot water outlet temperature of the heat source machine in operation as a compensation temperature such that the supply water temperature at that time corresponds to the target supply water temperature; and   a step of changing a cold/hot water outlet setting temperature of the heat source machine in operation to the compensation temperature,   wherein the heat source machine to be added or subtracted is started or stopped and the setting flow rate of the heat source machine to be added or subtracted is set to the predetermined flow rate, after the supply water temperature is changed with the changing of the cold/hot water outlet setting temperature of the heat source machine in operation.