A new approach for solving extended unit commitment problem

An original approach is presented for solving the extended unit commitment problem using the Lagrangian relaxation method. The unit ramp rates have been incorporated into a dual optimization algorithm, making it possible to use the feasible direction method for primal problem solution. The mathematical model developed also includes transmission capacity limits, regulation reserve requirements of a prespecified group of units, transmission losses, and fuel constraints. Standard unit commitment constraints such as power balance equations, fast spinning reserve constraints, and all local constraints are also taken into account. A computational package has been developed and tested over a 48 h time horizon on a large power system with 100 thermal units. The promising performance of this package makes it suitable for EMS application.