Cogeneration system and method for controlling the same

A cogeneration system comprising:

• an engine;
• a generator connected to an output shaft of the engine to generate electricity;
• a heat pump type air conditioner including a compressor, a directional valve, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger;
• a pre-heater to pre-heat outdoor air blown toward the outdoor heat exchanger;
• a compressor discharge line heater to heat a refrigerant passing through a discharge line of the compressor;
• and
• a waste heat controller to concentratedly transfer waste heat of the engine to the pre-heater when the outdoor heat exchanger is under a frost condition, and to transfer the waste heat of the engine to the pre-heater and the compressor discharge line heater in a distributed manner when the outdoor heat exchanger is not under the frost condition.

A method for controlling a cogeneration system, comprising:

• an outdoor temperature measuring step of measuring an outdoor temperature or a temperature of an outdoor heat exchanger included in a heat pump type air conditioner;
• and
• a waste heat controlling step comprising the steps of
• concentratedly supplying waste heat of an engine to a pre-heater adapted to pre-heat air blown to the outdoor heat exchanger when the heat pump type air conditioner operates in a heating mode, and the temperature measured in the outdoor temperature measuring step corresponds to a frosting temperature, at which the outdoor heat exchanger is frosted, and
• supplying the waste heat of the engine to a compressor discharge line heater adapted to heat a discharge line of a compressor included in the heat pump type air conditioner and to the pre-heater in a distributed manner when the heat pump type air conditioner operates in the heating mode, and the temperature measured in the temperature measuring step does not correspond to the frosting temperature.