Introduction  Gas-steam combined cycle units have been widely used in combined heat and power, but their minimum power generation is limited by heat supply. Especially during the winter heating period in the north, gas-steam combined cycle units cannot reduce their output, thus impeding the grid integration of wind energy and causing wind curtailment.

  Method  To address this issue, this paper investigates whether utilizing the operational flexibility of gas-steam combined cycle units in combined heat and power dispatch can promote wind power accommodation. To this end, a mathematical model was established to describe the diversified operating modes of gas-steam combined cycle units, then an economic dispatch model for combined heat and power considering wind power accommodation was constructed to co-optimize the unit commitment of coal-fired units, the operating modes of gas-steam combined cycle units, and the output distribution and reserve sharing among units.

  Result  Case simulations revealed that during difficult periods of wind power accommodation, switching gas-steam combined cycle units from the two-on-one mode to one-on-one mode can reduce the wind curtailment rate by 1.28%, and switching them from extraction condensing to back pressure mode can reduce the wind curtailment rate by 4.55%.

  Conclusion  Case analysis shows that making full use of the mode switching ability of gas-steam combined cycle units in combined heat and power dispatch can reduce the output of units during periods of high heat load, increase the wind power accommodation space to reduce the wind curtailment, increase the output ranges of units during periods of low heat load, thereby providing spinning reserve for the system and optimizing the reserve sharing among units.