Reduction and aggregation for critical and emergency operation of distribution network in presence of distributed generators

A new type of network namely “Active Network” is foreseen as a relevant evolution of the current passive distribution networks and might be a technically and economically feasible solution to facilitate Decentralized Energy Resources (DERs) interconnections in a deregulated energy market. But one of the difficulties of related studies consists in the small size of Distributed Generator (DGs) and the quantities of algebraic and differential equations resulting from the large number of buses and state variables attached with their control systems. These factors, added to the limited state estimation in distribution networks make it difficult for the Distribution System Operator (DSO) to have online security assessment. This paper presents a hybrid reduction method, which enables the DSO to decrease the number of computed elements and, consequently, the simulation time for distribution network. This reduction should enable also DSOs to facilitate the real time critical and emergency analysis of distribution network in presence of DGs.