With the large-scale integration of distributed photovoltaics, the morphology and characteristics of distribution networks are becoming increasingly complex. Accurate and efficient modeling of distributed photovoltaic aggregation is of significant importance for the planning and operation of new distribution networks. In this study, we first evaluated the similarity of different photovoltaic generation units by integrating the output characteristics of photovoltaic systems and the sensitivity indicators of grid connection points, proposing a distributed photovoltaic clustering method based on the K-means algorithm. Secondly, the output of the photovoltaic aggregation cluster was calculated using the capacity-weighting method. An equivalent network connecting various photovoltaic clusters was constructed based on the node elimination of the admittance matrix, and a modeling method for distributed photovoltaic aggregation was developed. Finally, the effectiveness of the method proposed in this paper was verified through the IEEE-33 test system. The results show that the distributed photovoltaics aggregation modeling method proposed in this paper can effectively simplify network topologies and improve the accuracy of the calculation results while also improving the efficiency of power flow analysis.

This paper investigates the transient stability of Grid-Forming (GFM) Permanent Magnet Synchronous Generator (PMSG) systems during grid faults. An analysis demonstrates how a fixed saturated current angle can trap the system in undesirable operating points, while reactive power coupling can degrade performance. Both factors pose a risk of turbine overspeed and instability. To overcome these vulnerabilities, a dual-mechanism control strategy is proposed, featuring an adaptive saturated current angle control that, unlike conventional fixed-angle methods, which risk creating Current Limiting Control (CLC) equilibrium points, dynamically aligns the current vector with the grid voltage to guarantee a stable post-fault trajectory. The effectiveness of the proposed strategy is validated through time-domain simulations in MATLAB/Simulink. The results show that the proposed control not only prevents overspeed trip failures seen in conventional methods but also reduces post-fault recovery time by over 60% and significantly improves system damping, ensuring robust fault ride-through and enhancing overall system stability.