Determination of Maximum Photovoltaic Penetration Level in Extended Medium-Voltage Distribution Feeders Considering the Impact of Tap-Changers and Critical Hour

This paper delves into the examination of challenges and advantages associated with the integration of photovoltaic (PV) systems into extended medium-voltage (MV) distribution feeders. With the increasing popularity of PV systems, issues such as reverse power flow, voltage elevation, and the overloading of network elements become more prominent. Consequently, in order to harness the benefits of PVs, it becomes crucial to ascertain an optimal PV penetration level that maximizes advantages while minimizing challenges. In this context, this paper concentrates on the determination of the maximum allowable PV penetration levels, by introducing the concept of critical hour. This concept is defined based on the load and PV generation profiles depending on the feeder type. Furthermore, this paper considers different load profiles and investigates the impact of tap-changers in extended feeders on the penetration level. Real-world validation on an extended distribution feeder in South Khorasan, Iran, serves to validate the efficacy of the proposed methodology, offering practical insights into feasible operating conditions and the adaptability of the network. Results demonstrate a 25% variation in the maximum allowable PV penetration level across different load profiles when static tap-changers are utilized, which increases to 40% with the implementation of dynamic tap-changers.