Heuristic methods Optimization 12 Integer programming 5 Particle swarm optimization (PSO) 5 Heuristic algorithms 4 Controllers 3 Feature extraction 3 Optimisations 3 AC-DC hybrid grid 2 AC-DC hybrid grids 2 Algorithms 2 Antennas 2 Binary particle swarm optimization 2 Bioluminescence 2 Classification (of information) 2 Complex dynamic characteristics 2 Conventional methods 2 Costs 2 Digital storage 2 Electric power system protection 2 Evaluation indicators 2 Evaluation methods 2 Extraction 2 Features extraction 2 Firefly algorithms 2 High quality 2 Integer linear programming 2 Iterative methods 2 K-means clustering 2 Meta-heuristic techniques 2