A Proposed Passive Islanding Detection Approach for Improving Protection Systems

Abstract

Nowadays, distributed generation (DG) is commonly used in networks. In spite of the numerous benefits of DG units in these networks, several challenges are introduced such as unintentional islanding, reverse power flow, protection concerns, etc. In this paper, a new passive islanding detection approach is proposed depends on the production of voltage sequence components at every relay location not only at the DG point of common coupling. The proposed approach uses only one threshold value for all relays in the distribution network. The performance of the proposed approach is not influenced by changes in type, capacity or location of DG. The proposed approach is evaluated under different transient conditions such as capacitor switching, load switching and DG switching. Also, the performance of the suggested islanding approach has been compared with most prevalent islanding detection techniques. The performance of the proposed algorithm is stable during balanced and unbalanced conditions. Moreover, detecting the islanding case at all relays provides the ability to improve the protective relays performance by updating the protection setting for all relays based on local measurement only without the need for fault current limiters (FCLs) or a communication network. The proposed approach is evaluated using the Canadian distribution system embedded with DG units in MATLAB/Simulink simulation. The achieved results demonstrate that the proposed approach is robust during all non-islanding events. Also, it succeeds to detect islanding condition with high confidence without non detection zone (NDZ).