A Linear Power Flow Solution for Distribution Power System Including PV Bus and ZIP Load

The modern power distribution system (DPS) needs most urgently a robust and fast linear power flow (LPF) solution. The voltage controlled (PV) bus is much common in DPS with the high penetration of distributed generators (DGs) into DPS. Moreover, the conventional constant P type load should be converted into ZIP load in order to get closer to the practical load level. Thus, in this paper, with the several approximations on the voltage drop, link powers, voltage controlled bus and ZIP load, a loop-theory based linear power flow (LPLPF) was proposed with respect to voltage magnitude and phase angle under a polar coordinate system. The proposed method can account for ZIP loads, transformers, and PV type DGs in a balanced distribution network. The approximations have been tested in several distribution systems including radial, meshed and ill-conditioned (much heavy-loaded) large-scale systems. The effectiveness and advantages of the proposed LPLPF method were validated with the results of test systems and the proposed method was accurate enough and robust even in the bad voltage levels.