A Resilient Protection Scheme for Active Distribution with Renewables

Ragab A. El Sehiemy

Electrical Engineering Department,

Electrical Engineering Department,

Benha University,

Kafrelsheikh University,

Egypt

Egypt mohamed.zaki@bhit.bu.edu.eg elsehiemy@eng.kfs.edu.eg

This paper proposes a generic grid-resilient protection scheme specifically developed for active distribution systems with high penetration of renewable energy technologies. The primary functions of the proposed scheme include fault detection, classification, and isolation under divers power system stress conditions, such as bidirectional power flows, voltage instability, and variations in fault impedance. The scheme employs a hybrid Spearman’s rank correlation coefficient based on the instantaneous power computation and Fuzzy Logic-based decision concept to develop a fault signature. Under normal operating conditions, the deviation between the current window of instantaneous power and the previous window is minimal. Conversely, during system stress conditions or faults, the variation in instantaneous power between successive time windows becomes significant, indicating abnormal conditions. Spearman’s rank correlation coefficient is used to quantify the degree of variation between two consecutive windows of data, and the resulting value is then fed into a Mamdani fuzzy logic system to compute the fault index. An adaptive soft computing-based threshold setting process is developed and used in conjunction with the computed fault index to accurately detect and discriminate between healthy operating conditions, system disturbances, and actual faults. Once a fault is detected, the proposed scheme is capable of classifying the fault type and promptly initiating a tripping signal to the circuit breaker for swift isolation. Simulation studies are conducted on a modified IEEE 9 bus system incorporating with photovoltaic systems under different grid conditions. The system is evaluated under a wide range of fault scenarios, including single-line-to-ground, double-line, and three-phase faults, as well as high-impedance and evolving faults, in addition to normal operational transients. The findings demonstrate that the proposed protection scheme has high accuracy, speed, and robustness, which makes it outperforming conventional protection methods in terms of fault identification time and resilience to uncertainty measurement.