Load reallocation based algorithm for state estimation in distribution networks with distributed generators

Abstract

In this paper is proposed a novel branch flow and weighted least square (WLS) based algorithm for state estimation in three phase distribution networks with distributed generation (DG) units. The basic formulation is simplified by the use of radial property of distribution network and later will be extended to meshed networks. Unmonitored (or partially monitored) loads are initially estimated from normalized daily load profiles (NDLPs) with lower weights (treated as the pseudo measurements). Also, the different types of monitored, partially monitored, or unmonitored DG units are included in state estimation. Their initial power outputs are calculated on the basis of external inputs, such as wind, sun and water inflow forecasts etc. (depending on DG unit type) or by normalized daily generation profiles (NDGPs) obtained from historical generation data. The pseudo measurements obtained by Initial Load/Generation Allocation are re-adjusted additionally by Optimal Load/Generation Reallocation procedure to fit real-time measurements inside WLS-based state estimation. The results and practical aspects of the proposed methodology are demonstrated on two real-life distribution networks. © 2011 Elsevier B.V.