“…However, these methods also own the same disadvantages such as limited applicability for problems with complicated constraints and less efficiency for large scale problem. To avoid overlapping such drawbacks of deterministic methods, many meta heuristic approaches have been constructed to deal with the ELD problem such as teaching and learning based algorithm (TLBA) [1], cuckoo search algorithm (CSA) [2][3][11][12], hybrid real coded genetic algorithm (HRCGA) [4], differential evolution (DE) [5], genetic Algorithm (GA) [5], particel swarm optimization (PSO) [5], improved evolutionary programming (IEP) [6], clonal algorithm (CA) [7], hybrid integer coded differential evolution (HICDE) [8], bee colony optimization (BCO) [13], biogeography-based optimization (BBO) [14], chaotic jaya algorithm (CJA) [15], firefly algorithm (FA) [16],memetic firefly algorithm (MFA) [16], FA with adaptive parameter α (ASPFA) [16], modified firefly algorithm (α-MFA) [17], seeker optimization algorithm (SOA) [18], krill herd algorithm (KHA) without using genetic operation (KHA1) [19], KHA using crossover operation (KHA2) [19], KHA using mutation operation (KHA3) [19] and KHA using crossover operation and mutation operation (KHA4) [19]. These methods have shown their powerful search ability via testing on different problems with different conditions such as different constraints related to thermal units and different constraints associate with power systems.…”