Load Flow Analysis Considering Polynomial ZIP Load Model in Droop-Controlled Islanded Microgrids via BFS Algorithm

This study presents a load flow analysis for islanded microgrids regulated by droop control, incorporating a polynomial constant impedance Z– constant current I– constant power P (ZIP) load model to improve simulation accuracy. The extended ZIP formulation captures voltage-dependent load behavior through empirical expressions combining impedance, current, constant power, and higher-order voltage terms. The IEEE ۳۳-bus radial distribution system is modeled in MATLAB, where the backward/forward sweep (BFS) algorithm is employed as the load flow solution method and adapted to handle voltage-sensitive loads. Results show that the ZIP model significantly affects voltage profiles, especially at buses distant from distributed generators (DGs), and provides a more realistic representation than the constant power model. The proposed framework supports reliable evaluation of droop-controlled islanded microgrids and emphasizes the importance of realistic load modeling in system planning.

کلیدواژه ها:

Backward/Forward Sweep (BFS) ، Load Flow ، Droop Control ، Islanded Microgrid ، constant impedance Z– constant current I– constant power P (ZIP) Load Model ، IEEE ۳۳-Bus System ، Distributed Generators (DGs)