On applying an Enhanced Generalized Alpha Plane to shunt reactor protection

Shunt reactors are used for long and high voltage transmission lines operation. Therefore, it is necessary to use a protection logic to identify turn-to-ground and turn-to-turn faults with few turns involved or high leakage factor value. In this context, the present work evaluates the use of differential functions based on Alternative Current Alpha Plane and based on Enhanced Generalized Alpha Plane for dry-type air-core shunt reactors protection. These algorithms are independent of voltage measurement and are implemented considering the reactor's zero-sequence current and neutral current. Based on simulations implemented in the Alternative Transient Program software, different turn-to-ground and turn-to-turn faults were investigated by varying the number of short-circuited turns, the leakage factor value, and fault resistance value. The obtained results reveal that the joint use of these functions guarantees a more secure identification of internal faults in shunt reactors, even when dealing with low current faults.