Short-term generation scheduling of thermal units with voltage security and environmental constraints

A dynamic and linear programming-based approach is investigated for the short-term scheduling of thermal power plant units considering the security and environmental constraints of electric power systems. In addition to the basic constraints (i.e. real power limits of the generators, real power demand, spinning reserve, minimum up and down lime of units) a comprehensive set of constraints is considered including: transmission line capacity limits; generators dynamic ramp rate; voltage security margin; and environmental issues. An optimal multiplier continuation method is adopted to effectively calculate the voltage security margin. The constraint relating to the voltage security margin is considered as a transition constraint in the dynamic programming process. The environmental issue is considered as a restriction on the hourly SO₂ emission allowances and other constraints are considered in the dynamic/linear programming procedures. Results of the application of the proposed algorithm to a test system are presented to illustrate the effectiveness of the approach