Quantifying the Impact of Grid-Forming Photovoltaic Control Strategies on Distribution Network Line Loss Dynamics

To address the uncertain impact of grid-forming converter-interfaced photovoltaics (GFM-PV) on power losses, this paper proposes a method to quantifying the impact of gridforming photovoltaic control strategies on distribution network line loss dynamics. First, leveraging the voltage support capability intrinsic to GFM converters, a PV-bus model for photovoltaic-storage systems is established. This model reflects the dual functionality of PV nodes in power flow analysis: active power injection and voltage regulation. Second, an improved theoretical loss calculation model is developed using time-sliced daily loss integration. This model incorporates power flow directionality to enhance accuracy under bidirectional power conditions. Furthermore, correlation and sensitivity indices are introduced to quantitatively evaluate GFM-PV's loss impact, considering both metric interdependencies and loss sensitivity trends while satisfying power balance equality constraints and node voltage inequality constraints. Finally, validation is performed on a practical 0.4 kV distribution system in Shanxi, China.