Unified Dynamic Equivalent Model for Distributed Photovoltaic Generation Systems With Different Fault-Ride-Through Strategies
Zhe Zhang, Siyang Liao, Yuanzhang Sun, Jian Xu, Deping Ke, Bo Wang, Rui Chen
Abstract
The grid penetration of distributed photovoltaic (DPV) energy is increasing; therefore producing equivalent models of DPV systems is critical for the dynamic analysis of power systems. In this article, a DPV system aggregation model based on interconnection point voltages and inverter types with a novel cluster and aggregation method is proposed. This model can obtain a similar power output to that obtained through simulation with a detailed model. Dynamic voltages of interconnection points and an equivalent admittance matrix were used as clustering indices in this study. These indices were weighted using an analytic hierarchy process model. Photovoltaic systems with different inverters, control strategies and fault-ride-through dynamics; grid connection points with varying electrical distances and voltage dynamics were unified in the developed model by ensuring that the power characteristics before and after aggregation were equivalent. The results of this study imply that the DPV systems in an area differ substantially in terms of output dynamics, and these dynamic features should be quantified during equivalent modeling. The proposed method obtained superior results to relevant previous methods that do not consider the fault ride throughs and voltage dynamics.