Optimal transformer allocation under single-contingency

Under the single-contingency environment where interdependencies are inherent, allocating power transformers to substations ought to take on a system approach. In this paper, the authors present a multi-year mathematical programming model which determines the optimal allocation of transformers over a planning horizon. The possibility of relocating transformers from substations with low utilizations is explicitly explored. To meet load demand, the model identifies the least-cost allocation and/or relocation of transformers. It ensures that each substation's single-contingency capacity exceeds its load forecast. The alternatives to be evaluated include combinations of: additions via purchase; relocations from a transformer storage; and relocations within the network. Fort Myers, a small district of Florida Power and Light (USA), is studied as a case example.