Correlation technique investigation for islanding detection of inverter based distributed generation

Islanding detection is an important R&D topic in the area of distributed generation (DG) interconnection with utility grid. For many years, different anti-islanding protection methods were developed for inverter based distributed generation. However, most of these methods have limit capability for detecting islanding when multiple DGs have to be connected with one distribution line. This paper proposes an islanding detection method based on correlation technique. Analytical and simulation analyses of the correlation method are presented. Single and multiple DGs islanding detection schemes were investigated for different operating conditions including the most difficult one when the DG output power matches the local load power. The critical case-studies show that correlation method is effective for both single and multiple grid connected DG systems.