Study on Distributed Photovoltaic Penetration Rate of Local Area Distribution Networks

With the increasing penetration rate of distributed photovoltaic, the safety and stability of distribution networks faces challenges. This paper investigates the impact of distributed power penetration on local distribution networks and establishes relevant assessment indicators. The results show that a high percentage of distributed PV access to the distribution network may affect the distribution network automation and relay protection actions, leading to low power quality and the expansion of the scope of grid accidents. In addition, the stochastic and fluctuating nature of distributed PV may cause power back-feeding and return power to higher voltage level grids. To cope with these challenges, this paper proposes metrics such as voltage deviation, short-circuit current, power back-feeding assessment, and thermal stability assessment to comprehensively assess the impact of distributed power access on the distribution network. The reasonableness of the established metrics is verified through example analyses, and the changes in distribution network currents under different PV access scenarios are demonstrated to further confirm the impacts of distributed PV access on distribution network thermal stability, voltage deviation, and return-to-feed.