Impact of Distributed PV Penetration on Power Transmission Lines

Based on the unexploited hydro capacity of Albania, government policies have encouraged continued investment in order to build new hydropower plants (HPPs). Meanwhile, most of them are installed to the distribution system. On the other hand, the photovoltaic (PV) systems have been intensively promoted in Albania, pushed by support mechanisms frameworks, PV cost reduction and solar radiation potential. Thus, under the circumstances of a high and rapid RES penetration, it is important to analyze the power system parameters. In this context, this paper presents the impact of PV Penetration on the 110 kV Power Transmission Lines, analyzing performance indexes, such as: Voltage Profile Improvement Index (VPII), Line Transmission Apparent Power Improvement Index (LTAPII), Line Loss Reduction Index (LLRI), Line Loading, as well as Line Losses. The Kukës distribution system area is taken as a case study. This area is characterizing of the presence of 5 run-off-river HPPs, which represent 66% of actual hosting capacity (HC). Meanwhile, this value is lower, because HPPs cannot produce electricity at full capacity all the time. However, even in maximum HPPs generation case, the lines loading is below 100%. Thus, there is still available transmission capacity, for PV penetration. For this reason, the maximum PV capacity connected in various distribution busbars is identify, considering different scenarios (with/without PVs), and different PV penetration level (with a maximum of 54 MWp). A comparison between the base scenario (50% of HPPs production) and the other ones (50 % of HPPs + different PVs production) has been carried out. The results show an improvement in all of the performance indexes (according to the Albanian Transmission Code), for low PV penetration (up to 40% of PVs maximum capacity). For example, while the line losses are reduced up to 50%, the VPII in the system is improved up to 0.06%. On the other hand, the further increase of PV penetration (over 50%), leads to deterioration in the transmission lines. For maximum PV capacity (54 MWp), the total transmission apparent power increases by 2.3 times, increasing losses by 2.6 times. In this way, we conclude that, choosing the right level of PV penetration would bring benefits to the transmission power lines.