Overcurrent Protection Assessment with high PV Penetration in a Distribution Network

Abstract

The utilization of DGs has revolutionized power utility and has recently promoted renewable energy technology with considerable positive impacts such as loss-reduction, reliability improvement of grids, economic benefits and ecological preservation progress. Solar energy, considered as one of the cleanest energy in the energy industry, is becoming an indispensable and strategic need in Power Supply. PV integration to grid brings new challenges, thus technical issues influencing the entire Network. To guarantee a stable and safe grid energy supply, some aspects have to be taken into consideration preventing partial or total unnecessary outage. This can be done only through the implementation of an efficient and effective control and protection mechanism as DGs are known to have impacts on distribution over current protection system. This paper investigated the potential protection issues associated to high PV penetration. The impact of different penetration level (20%, 40% and 60%) on two different network configurations (centralized and distributed) which have been modeled and analyzed using PSCAD/EMTDC software. The inverter controller response was assessed under grid faults integrating LVRT capabilities. The presence of PVs in the grid has led to identify nuisance tripping or false tripping in high penetration condition of Solar PV. Moreover, and most important presented in this research is the operational impacts study of PVs on the protection coordination which has been done for a satisfied backup and selectivity protection with a reliable and effective relay setting suggestion. Some measures have been recommended as well to mitigate the PV impacts with an acceptable penetration level.