Efficient aggregation of distributed generations and Interruptible loads: A new tool for market integration of distributed recourses

Because Distributed Generations (DGs) grow under non-market mechanisms (i.e. supporting mechanism and economic incentives), they will lead to market distortions as their capacity level in electric power system increases. Therefore it is necessary to integrate DGs in market mechanism. Some difficulties emerge so as to complicate direct integration of DGs into the market competitions. Such intricacies can be accounted for by intrinsic and technical aspects. From an intrinsic point of view, DGs that have grown under supporting mechanisms cannot be self-supporting units in a competitive market environment, owing to their small size to be neglected in the market operator´s eye. From technical-wise, DGs dispersed in distribution level have no direct access to the markets usually existing in the transmission level. To solve these difficulties, this paper proposes a new method for aggregating DGs and Interruptible loads (ILs), thus forming an equivalent unit at the junction point of distribution and transmission systems. The proposed method uses the security-constrained economic dispatch (SCED) technique to take the characteristics of distribution network (constraints, impedances and losses) into account. The method is applied to a primary distribution system and the results are discussed.