A Fast and Robust Load Flow Method for Distribution Systems with Distributed Generations

This paper proposes a fast and robust load flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in PQ decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and resistances are fully modeled without any simplifications. The impacts of zero-impedance branches are explicitly modeled through reconfiguring of the adjacent branches with impedances. Typical distribution generation models and distribution load models are included. A hybrid direct and indirect solution technique is used to achieve efficiency and robustness of the algorithm. Active power correction is solved by means of a sparse LU decomposition algorithm with partial pivoting, and the reactive power correction is solved by means of restarted Generalized Minimal Residual algorithm with incomplete LU preconditioner. The numerical examples on a sample distribution system with widespread Photovoltaic installations are given to demonstrate the effectiveness of the proposed method.