Real-time unbalanced load flow development using direct-ZBR method and modified Lambda iteration for on-line monitoring and control

The interconnection of Distributed Generations (DG's) directly to the existing distribution systems has changed the characteristics of a distribution network from a passive network to an active one. This paper introduces a three phase load flow method that can handle both passive and active unbalanced radial distribution networks. The proposed method combines the direct-ZBR method (Forward-Backward based method) and Modified Lambda iteration. The direct ZBR load flow [1]is known as a fast and accurate method for solving passive radial three phase distribution systems. The Modified Lambda approach is chosen because of its simple algorithm that can be easily combined with direct ZBR method in handling DG'swhich are operated as voltage controlled(PV) buses.