Optimization of Operational Energy Cost in a Hybrid Distributed Generation System

In a hybrid distributed generation system (HDGS), electric power is derived from more than one energy sources. These sources are, in general, a mix of non-conventional (e.g. wind, photovoltaic etc.) and/or conventional sources. An HDGS can either be grid connected or stand alone system. In what proportion should the energy be drawn from each source of the HDGS is a critical issue which affects the per unit cost of the generated electric power. This paper presents an optimization algorithm, suitable for use by the utility, for economical and optimal use of energy from different sources. An example HDGS with wind and PV sources is considered. But the algorithm can be extended to any number of sources. An HDGS is normally supported by a backup (storage) medium like battery or a fuel cell stack. The proposed algorithm considers the levelised unit cost of electricity (LUCE) and also takes into account the backup source(s). LUCE of the example hybrid system has been estimated and its sensitivity to factors such as the energy produced by the system, battery life, optimal sharing of excess energy storage between the battery and the fuel cell stack etc. is analyzed in detail. All the results of this study are presented.