Combined power generation system and operation control method thereof

A method of controlling an operation of a combined power generation system comprising:

• a gas turbine comprising a compressor configured to compress air, a combustor configured to combust a mixture of the compressed air and fuel and generate combustion gases, and a turbine section configured to rotate a turbine with the combustion gases and discharge exhaust gases;
• a heat recovery steam generator (HRSG) in which steam is generated by heat of the exhaust gases from the gas turbine;
• a steam turbine driven by the steam generated by the HRSG;
• and a plurality of heat exchangers provided in the HRSG, located within a flow path of the exhaust gases in which the exhaust gases flow, to cool the compressed air by performing heat exchange between the compressed air and the exhaust gases and supply cooled compressed air, the method comprising:
• determining whether the temperature measured by a temperature sensor installed in a cooling air flow path connecting, and flowing the cooled compressed air, from the heat exchangers to the turbine section is within a target range;
• when the measured temperature is not within the target range and is lower than a target value, increasing an opening degree of a bypass valve installed in a bypass flow path connecting, and flowing the compressed air, from a compressed air flow path to the cooling air flow path;
• when the measured temperature is not within the target range and is higher than the target value, decreasing the opening degree of the bypass valve;
• and
• when the measured temperature is within the target range, completing the adjustment of the opening degree of the bypass valve.

A method of controlling an operation of a combined power generation system comprising:

• a gas turbine comprising a compressor configured to compress air, a combustor configured to combust a mixture of the compressed air and fuel and generate combustion gases, and a turbine section configured to rotate a turbine with the combustion gases and discharge exhaust gases;
• a heat recovery steam generator (HRSG) in which steam is generated by heat of the exhaust gases from the gas turbine;
• a steam turbine driven by the steam generated by the HRSG;
• and a plurality of heat exchangers provided in the HRSG, located within a flow path of the exhaust gases in which the exhaust gases flow, to cool the compressed air by performing heat exchange between the compressed air and the exhaust gases and supply cooled compressed air, the method comprising:
• determining whether the temperature measured by a temperature sensor installed in a cooling air flow path connecting, and flowing the cooled compressed air, from the heat exchangers to the turbine section is within a target range;
• determining whether temperature control by a bypass valve installed in a bypass flow path connecting, and flowing the compressed air, from a compressed air flow path to the cooling air flow path has failed, the compressed air flow path connecting, and flowing the compressed air, from the compressor to the plurality of heat exchangers;
• when the temperature control by the bypass valve is determined to have failed, adjusting an opening degree of a main valve installed in the compressed air flow path;
• when the temperature control by the bypass valve is determined to not have failed, determining whether the measured temperature is lower than a target value;
• when the measured temperature is lower than the target value, increasing an opening degree of the bypass valve installed in the bypass flow path;
• when the measured temperature is higher than the target value, decreasing the opening degree of the bypass valve;
• and
• when the measured temperature is within the target range, completing the adjustment of the opening degree of the bypass valve.