The necessity and complexity of developing digital models of thermal heating units, in particular, the PGU-450 during its operation in the heating mode, are shown. A simplified algorithm for constructing flow characteristics for CCGTs with one (GT1) and two (GT2) gas turbines using digital models of gas and steam turbines in the condensation mode is presented. Based on the constructed digital models, the features of the PGU-450 operating modes have been identified with their participation in regulating the electrical load schedules of the station and the power system. To account for them, a methodology has been developed to account for the influence of outdoor air temperature on the maximum and minimum power of the CCGT, on fuel consumption, and expressions for the boundary values of thermal and electrical loads are given. It is shown that the presence of digital models of CCGT in the heating mode allows solving many local problems before solving optimization problems at the station level. An example of illustrating the use of a digital model in solving the local problem of choosing the composition of the included equipment of a power plant with PGU-450 units is given.