Device and method for controlling cogeneration system

Abstract

In a cogeneration system that stores hot water heated by exhaust heat of a generator in a hot water storage tank, a situation in which there is a risk of freezing of water in a water circulating passage is accurately grasped, and thus anti-freezing control prevents the freezing from occurring and unnecessary anti-freezing control is reduced to suppress the drop in efficiency of the system. When determined that an environmental temperature Ta is lower than a lower-limit value Ta_min, it is determined whether or not a temperature difference ΔT (=Tr1−Tr2) between a radiator inlet temperature Tr1 and a radiator outlet temperature Tr2 exceeds a predetermined value ΔT0, and when determined that the temperature difference exceeds the predetermined value ΔT0, it is determined that there is a risk of freezing of the water in the water circulating passage and an command to execute the anti-freezing control is output.

1 . A device for controlling a cogeneration system, which includes:
 a generator for generating electricity that produces heat;   a hot water storage tank that stores water;   a first flow passage that supplies water in the hot water storage tank to a heat exchanging unit of the generator through a cooling radiator;   a second flow passage that supplies hot water heated by the heat exchanging unit of the generator into the hot water storage tank;   a water circulator that circulates water in a water circulating passage including the generator, the hot water storage tank, the first flow passage, and the second flow passage; and   an anti-freezing control unit that executes anti-freezing control when determining that a freezing condition of the water circulating passage is met, the device comprising:   an environmental temperature measuring unit that measures an environmental temperature;   a radiator temperature difference obtaining unit that obtains a temperature difference between an inlet temperature and an outlet temperature of the radiator; and   a freezing condition determining unit that determines that a freezing condition of the water circulating passage is met when the temperature difference between the inlet temperature and the outlet temperature of the radiator is higher than or equal to a predetermined value in a case in which the environmental temperature is lower than a predetermined value.   
     
     
         2 . The device for controlling the cogeneration system according to  claim 1 , further comprising a freezing determination unit that determines that freezing occurs in the water circulating passage when an outlet temperature of the generator of the water circulating passage is higher than or equal to a set upper-limit temperature. 
     
     
         3 . The device for controlling the cogeneration system according to  claim 1 , in which in the freezing condition determining unit determines that the freezing condition of the water circulating passage is met regardless of the temperature difference between the inlet temperature and the outlet temperature of the radiator, when the outlet temperature or the inlet temperature of the radiator is lower than a preset lower-limit temperature in a case in which the environmental temperature is lower than the predetermined value. 
     
     
         4 . The device for controlling the cogeneration system according to  claim 1 , in which in the freezing condition determining unit determines that the freezing condition of the water circulating passage is not met when the outlet temperature or the inlet temperature of the radiator is higher than or equal to a preset upper-limit temperature even in a case in which the environmental temperature is lower than the predetermined value. 
     
     
         5 . A method for controlling a cogeneration system, which includes a generator that generates for generating electricity that produces heat, a hot water storage tank that stores water, a first flow passage that supplies water in the hot water storage tank to a heat exchanging unit of the generator through a cooling radiator, a second flow passage that supplies hot water heated by the heat exchanging unit of the generator into the hot water storage tank, and a water circulator that circulates water in a water circulating passage including the generator, the hot water storage tank, the first flow passage, and the second flow passage, the method comprising:
 measuring an environmental temperature;   obtaining a temperature difference between an inlet temperature and an outlet temperature of the radiator;   determining that a freezing condition of the water circulating passage is met when the temperature difference between the inlet temperature and the outlet temperature of the radiator is higher than or equal to a predetermined value in a case in which the environmental temperature is lower than a predetermined value; and   executing anti-freezing control when the freezing condition of the water circulating passage is met.