ISLANDING DETECTION USING RATE OF CHANGE OF ZERO SEQUENCE COMPONENT OF SECOND HARMONIC VOLTAGE

Abstract

Disconnecting the Distributed Generator (DG) in case of the grid outage (islanding operation) is one of the most important requirements of the protection system of power network. The DG relay should sense the variation of islanding situation and trips the DG quickly within two seconds from islanding occurrence according to IEEE STD 1547. The main problem addressed in this thesis is to detect the islanding condition, and thus a comprehensive study of several islanding detection techniques (IDTs) is carried out and introduced. The thesis presents an IDT achieving the goals of minimizing the islanding detection time and avoiding the presence of Non Detection Zone (NDZ). The rate of change of zero sequence component of second harmonic voltage signal at the Point of Common Coupling (PCC) is used for design the proposed IDT. The proposed technique is extensively tested for inverter-based DG includes wind turbines with double-fed induction generator. It is clear from the achieved results of extensive simulations for several scenarios that the proposed technique could distinguish the islanding operation within only one cycle from the islanding occurrence without any NDZ. These scenarios have covered different cases such as normal operation, load variation, unbalance loading, voltage sags and swells, capacitor switching, faults, and DG outage.