Hot water supply apparatus and control method for hot water supply apparatus

Abstract

The hot water supply apparatus includes a heat pump unit operating using electrical energy, a hot water storage tank storing hot water heated by the heat pump unit, and an auxiliary heat source device burning fuel and heating hot water when a stored hot water heat amount is insufficient for a heat amount used for hot water supply. A control device calculates a predicted heat amount for each unit time period based on a past usage record of hot water supply; estimates an error distribution of an actual heat amount relative to the predicted heat amount; calculates an expected value of loss in a target index using the estimated error distribution; obtains an optimal stored hot water heat amount minimizing the expected value; and controls the heat pump unit so that the hot water storage tank stores the optimal stored hot water heat amount.

What is claimed is: 
     
         1 . A hot water supply apparatus, comprising:
 a heat pump unit that operates with electrical energy as a driving source;   a hot water storage tank that stores hot water heated by the heat pump unit;   a hot water supply circuit that supplies hot water from the hot water storage tank;   an auxiliary heat source device for burning fuel and heating hot water to be supplied in response to a stored hot water heat amount of the hot water storage tank being insufficient for a heat amount used for hot water supply; and   a control device that controls the heat pump unit and the auxiliary heat source device,   wherein the control device   calculates a predicted heat amount used for hot water supply for each unit time period based on a past usage record of hot water supply,   estimates an error distribution of an actual heat amount used for hot water supply with respect to the predicted heat amount used for hot water supply,   calculates an expected value of loss in a target index, caused by a hot water storage operation of the heat pump unit and a combustion operation of the auxiliary heat source device in response to generating the actual heat amount used for hot water supply, using the estimated error distribution, and   obtains an optimal stored hot water heat amount that minimizes the expected value of loss, and controls the heat pump unit so that the hot water storage tank stores the optimal stored hot water heat amount.   
     
     
         2 . The hot water supply apparatus according to  claim 1 , wherein the control device estimates the error distribution on an assumption that an error of the actual heat amount used for hot water supply with respect to the predicted heat amount used for hot water supply follows a normal distribution. 
     
     
         3 . The hot water supply apparatus according to  claim 1 , wherein the control device uses cost associated with an operation of the heat pump unit and an operation of the auxiliary heat source device as the target index. 
     
     
         4 . The hot water supply apparatus according to  claim 2 , wherein the control device uses cost associated with an operation of the heat pump unit and an operation of the auxiliary heat source device as the target index. 
     
     
         5 . The hot water supply apparatus according to  claim 3 , wherein the control device
 calculates cost that is lost in a case where the stored hot water heat amount of the hot water storage tank is less than the actual heat amount used for hot water supply and in a case where the stored hot water heat amount of the hot water storage tank is greater than the actual heat amount used for hot water supply, and   calculates the expected value of loss using the calculated cost that is lost and the estimated error distribution.   
     
     
         6 . The hot water supply apparatus according to  claim 4 , wherein the control device
 calculates cost that is lost in a case where the stored hot water heat amount of the hot water storage tank is less than the actual heat amount used for hot water supply and in a case where the stored hot water heat amount of the hot water storage tank is greater than the actual heat amount used for hot water supply, and   calculates the expected value of loss using the calculated cost that is lost and the estimated error distribution.   
     
     
         7 . The hot water supply apparatus according to  claim 3 , wherein the cost associated with the operation of the heat pump unit comprises at least one of primary energy consumption in the heat pump unit, purchase cost of electrical energy, and an amount of CO 2  generated by electrical energy, and
 the cost associated with the operation of the auxiliary heat source device comprises at least one of primary energy consumption in the auxiliary heat source device, purchase cost of fuel, and an amount of CO 2  generated by combustion of fuel.   
     
     
         8 . The hot water supply apparatus according to  claim 4 , wherein the cost associated with the operation of the heat pump unit comprises at least one of primary energy consumption in the heat pump unit, purchase cost of electrical energy, and an amount of CO 2  generated by electrical energy, and
 the cost associated with the operation of the auxiliary heat source device comprises at least one of primary energy consumption in the auxiliary heat source device, purchase cost of fuel, and an amount of CO 2  generated by combustion of fuel.   
     
     
         9 . The hot water supply apparatus according to  claim 7 , wherein in response to the heat pump unit operating with electrical energy transmitted from a power plant as the driving source, the control device sets the cost associated with the operation of the heat pump unit using primary energy consumption based on power generation efficiency of the power plant, power transmission and distribution loss from the power plant, and a coefficient of performance of the heat pump unit, and
 in response to the heat pump unit operating with electrical energy generated by a solar power generation device connected to the heat pump unit as the driving source, the control device sets the cost associated with the operation of the heat pump unit using primary energy consumption based on the coefficient of performance of the heat pump unit.   
     
     
         10 . The hot water supply apparatus according to  claim 8 , wherein in response to the heat pump unit operating with electrical energy transmitted from a power plant as the driving source, the control device sets the cost associated with the operation of the heat pump unit using primary energy consumption based on power generation efficiency of the power plant, power transmission and distribution loss from the power plant, and a coefficient of performance of the heat pump unit, and
 in response to the heat pump unit operating with electrical energy generated by a solar power generation device connected to the heat pump unit as the driving source, the control device sets the cost associated with the operation of the heat pump unit using primary energy consumption based on the coefficient of performance of the heat pump unit.   
     
     
         11 . A control method for controlling a hot water storage operation in a hot water supply apparatus which comprises:
 a heat pump unit that operates with electrical energy as a driving source;   a hot water storage tank that stores hot water heated by the heat pump unit;   a hot water supply circuit that supplies hot water from the hot water storage tank; and   an auxiliary heat source device for burning fuel and heating hot water to be supplied in response to a stored hot water heat amount of the hot water storage tank being insufficient for a heat amount used for hot water supply,   the control method comprising:   calculating a predicted heat amount used for hot water supply for each unit time period based on a past usage record of hot water supply;   estimating an error distribution of an actual heat amount used for hot water supply with respect to the predicted heat amount used for hot water supply;   calculating an expected value of loss in a target index, caused by a hot water storage operation of the heat pump unit and a combustion operation of the auxiliary heat source device in response to generating the actual heat amount used for hot water supply, using the estimated error distribution;   calculating an optimal stored hot water heat amount that minimizes the expected value of loss; and   controlling the heat pump unit so that the hot water storage tank stores the optimal stored hot water heat amount.   
     
     
         12 . The control method according to  claim 11 , wherein estimating the error distribution comprises estimating the error distribution on an assumption that an error of the actual heat amount used for hot water supply with respect to the predicted heat amount used for hot water supply follows a normal distribution. 
     
     
         13 . The control method according to  claim 11 , wherein calculating the expected value of loss comprises:
 calculating cost that is lost due to generation of the actual heat amount used for hot water supply using cost associated with an operation of the heat pump unit and an operation of the auxiliary heat source device as the target index; and   calculating the expected value of loss using the cost that is lost and the error distribution.   
     
     
         14 . The control method according to  claim 12 , wherein calculating the expected value of loss comprises:
 calculating cost that is lost due to generation of the actual heat amount used for hot water supply using cost associated with an operation of the heat pump unit and an operation of the auxiliary heat source device as the target index; and   calculating the expected value of loss using the cost that is lost and the error distribution.   
     
     
         15 . The control method according to  claim 13 , wherein the cost associated with the operation of the heat pump unit comprises at least one of primary energy consumption in the heat pump unit, purchase cost of electrical energy, and an amount of CO 2  generated by electrical energy, and
 the cost associated with the operation of the auxiliary heat source device comprises at least one of primary energy consumption in the auxiliary heat source device, purchase cost of fuel, and an amount of CO 2  generated by combustion of fuel.   
     
     
         16 . The control method according to  claim 14 , wherein the cost associated with the operation of the heat pump unit comprises at least one of primary energy consumption in the heat pump unit, purchase cost of electrical energy, and an amount of CO 2  generated by electrical energy, and
 the cost associated with the operation of the auxiliary heat source device comprises at least one of primary energy consumption in the auxiliary heat source device, purchase cost of fuel, and an amount of CO 2  generated by combustion of fuel.