Model for impact of storage on spinning reserve requirements and distributed generation

In power system scheduling reserve margins are kept in order to maintain the security of the system if a nonforecasted event occurs. This security is maintained by re-dispatch of the generators in the system. The maximal increase of the generation during this time when excess energy is required is called the spinning reserve. The energy storage provides a dual remedy of providing immediate backup for the shortfall in the power supply as well as the retention of excess power that was generated but left unutilized. In this paper we incorporate the impact of such energy storage on the spinning reserve in an electric system. The mathematical model discussed is based on the load curve of a typical power utility and clearly indicates that the introduction of storage energy in the system reduces the need for excessive generation to meet peak load demand. The Lagrangian relaxation method is used for determining the spinning reserve requirements, and to achieve the objective of minimizing the total generation cost.