A two-level iterative model of power flow calculation for multi-slack-bus power system

Renewable energy sources with droop control characteristics actively participate in system frequency and voltage support, introducing multiple slack buses that degrade the convergence of Newton-Raphson-based power flow calculation. To address this, this paper proposes a two-level iterative model of power flow calculation. The method decouples the slack bus calculation process by constructing upper and lower models, and introduces a novel virtual bus definition to interconnect upper and lower models. Validation on the modified IEEE 39-bus system demonstrates the effectiveness of the proposed method.