A Novel Synchronous DGs Islanding Detection Method based on Online Dynamic Features Extraction

Reliable and fast state discrimination are among the most important requirements in islanding detection methods (IDMs) to avoid islanded operation problems of distributed generation (DG) systems. This paper proposes a novel, IDM based on the dynamic response characteristics of synchronous DGs. The proposed method is based on four features of the dynamic behavior of synchronous DGs, namely, participation matrix; zero mode; oscillation frequency; and damping factor. This allows to distinguish between islanding conditions and grid-connected disturbances, even when demand and generation are closely matched. These features are extracted in practice from local measurements using Hilbert-Huang transform (HHT) technique. Moreover, a new method for online observation of the participation matrix based on online power system measurements is proposed. The impacts of synchronous DG controllers and motor loads are considered in the proposed method. Different scenarios such as load shedding, load restoration, capacitor switching, and short circuit faults have been simulated to assess the performance of the proposed method. Simulations are performed on a typical distribution system with real data for different scenarios to verify the high speed performance, reliability, robustness, and applicability of the proposed islanding detection algorithm. Comparison with alternative islanding detection methods prove the superiority of the proposed approach.