In order to study the economic operation mode of gas-steam combined cycle units under the rated thermoelectric task

this paper uses the modular modeling method to build model for components of the unit.Moreover

based on the thermoelectric ratio of the heat-fixed electricity

the profitability of five operating modes at four heating loads was analyzed. The results show that

the maximum profit difference between different operating modes during pure power generation can reach 6.04%. With the continuous increase of the unit heating load

compared with the pure power generation situation

the benefits of normalization method of electrical power generation efficiency trends changes. The maximum profit difference between different operating modes is 1.52%

which appears when the heating load of the unit is 1 388.89 GJ/h

indicating there are few differences in profitability between each operating mode. On the premise of meeting the demands of power generation and heat supply

it is recommended that the unit be operated in an efficiency mode 1 combing high electricity load with low electricity load as much as possible

especially in the case of pure power generation and high heating load.