Unit commitment problem with ramp rate constraint using a binary-real-coded genetic algorithm

• The unit commitment problem (UCP) with the ramp rate constraint is studied.
• A binary-real-coded genetic algorithm (GA) is proposed as the solution technique of the UCP.
• The binary part of the GA deals with the scheduling of units of the UCP.
• The real part of the GA determines the amounts of power generated by committed units.
• Some mechanisms are also incorporated in the GA for repairing infeasible solutions.

The unit commitment problem (UCP) is a nonlinear mixed-integer optimization problem, encountered as one of the toughest problems in power systems. The problem becomes even more complicated when dynamic power limit based ramp rate constraint is taken into account. Due to the inadequacy of deterministic methods in handling large-size instances of the UCP, various metaheuristics are being considered as alternative algorithms to realistic power systems, among which genetic algorithm (GA) has been investigated widely since long back. Such proposals have been made for solving only the integer part of the UCP, along with some other approaches for the real part of the problem. Moreover, the ramp rate constraint is usually discussed only in the formulation part, without addressing how it could be implemented in an algorithm. In this paper, the GA is revisited with an attempt to solve both the integer and real parts of the UCP using a single algorithm, as well as to incorporate the ramp rate constraint in the proposed algorithm also. In the computational experiment carried out with power systems up to 100 units over 24-h time horizon, available in the literature, the performance of the proposed GA is found quite satisfactory in comparison with the previously reported results.

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