Security Constrained Unit Commitment (SCUC) formulation and its solving with Modified Imperialist Competitive Algorithm (MICA)

Abstract

One of the most important optimization problems in operation planning of power systems is unit commitment (UC). Consideration of transmission lines and operation constraints in UC problem leads to a more general problem known as Security Constrained Unit Commitment (SCUC). The SCUC can be formulated as a very large scale mixed-integer problem in practical utility grids. Solving SCUC can take tremendous time due to its huge dimension. In this paper, a formulation of SCUC problem, considering practical constraints and nonlinear characteristics including bus voltage limits, line flow limits, in addition to prevailing constraints such as hourly power demand, system spinning reserves, ramp up and down limits, minimum up and down time (MUT/MDT) limits, and emission limits, is presented. The Modified Imperialistic Competitive Algorithm (MICA), using a priority list (PL) for defining the initial state, is used to solve the mentioned optimization problem. The effectiveness of MICA method to solve the SCUC problem is shown on IEEE 30-bus and 118-bus test systems and is compared with the application of some heuristic methods i.e. genetic algorithm (GA), particle swarm optimization (PSO) and other mathematical approaches i.e. mixed integer programming (MIP).