Improved Robustness of Sequential Three Phase Power Flow Using Homotopic Method

Driven by environmental concerns and fluctuations of electric energy cost, the integration of distributed generators (DGs) into distribution networks close to the loads, has gained its importance and emerged as complementary to the conventional central power plants. However, the proliferation of distributed generators (DGs) has altered a distribution network from a passive system to an active one. Hence, modifications in the existing distribution power flow methods are needed to account for a DG unit, which can operate either as a PV or PQ bus. Among these methods, the Sequential Power Flow (SPF) method can readily accommodate for PV buses as long as the DG models in the sequence-component frame can be formulated. However, the convergence of SPF is heavily dependent on the choice of initial conditions. Moreover, when the resistance-to-reactance ratio (or R/X) is high, SPF will also diverge. This paper presents a new robust three-phase distribution power flow, which incorporates a homotopic method into the SPF method to overcome these problems. An IEEE benchmark system is used to test the validity and robustness of the proposed algorithm