Introduction  Optimizing output curve of thermal power plants by using pumped storage power plants is an important means to improve the economy of power system.

  Method  In this paper, a mathematical model of combined optimal operation of pumped storage power plants and thermal power plants was established first. Then, an actual power system containing pumped storage power plants and thermal power plants was taken as an example for simulation. Finally, the mechanism of coal saving of combined optimal operation of pumped storage power plants and thermal power plants was revealed.

  Result  The simulation results show that combined optimal operation of pumped storage power plants and thermal power plants reduce the coal consumption of power system.

  Conclusion  We suggest that output curve of thermal power plants should be optimized by making full use of pumped storage to improve running efficiency of power system.