An approach to solving large scale unit-commitment(UC)problem based on integer-coded genetic algorithm(GA)with novel repairing mechanism(r-ICGA)is presented.The GA chromosome consists of integer string

which has shorter length than binary string.Using the proposed repairing mechanism

new chromosomes produced in evolution process are repaired to comply with all constraints.As the alternative to penalty function method

the repairing mechanism turns solutions to feasible ones

and avoid coping with economic load dispatch(ELD)sub-problem for infeasible solutions.The algorithm is tested and validated in 6 cases with different scale up to 100 units.The solutions obtained by r-ICGA have lower operating costs

and the algorithm has approximate linear execution time versus unit number.These simulation results indicate that r-ICGA is more appropriate to large scale unit-commitment problem.