High back pressure heating technology is widely used in heating retrofitting of large-scale cogeneration units because of its advantages of greatly reducing the loss of cold source and expanding the heating capacity of the units. However

there is no report on heating temperature characteristics and exergy analysis of the high back pressure heating unit. By using the self-developed thermal power integration scheme(TPIS) software

this paper builds up the simulation model of thermal power system and establishes the exergy analysis model of cogeneration units to study he heating temperature characteristics of high back pressure units in different heating supply periods. In order to avoid the restriction of low heating load on the unit power supply load

a method of high back pressure condenser heating-fresh air heating is proposed. The results show that

adopting the high back pressure condenser heating-fresh air heating method can break the limitation of low heating load on the unit supply power load and realize thermo-electric decoupling at the early and last period of heating. Under conditions with the same main steam flow

the total exergy efficiency of thermal power plant is ranked as follows: big-freeze period cold period secondary cold period. The result provides a reference for operation optimization of the cogeneration.