Advanced Islanding Detection Scheme Based on Zero Sequence Phase Angle for AC Microgrids

This paper introduces a new, localized islanding detection method for Distributed Generation (DG) systems connected to the main power grid with a focus on applications in AC microgrids. In contrast to conventional active methods, which intentionally disturb the system, this method is completely passive, ensuring no adverse effects on power quality, stability, or reliability. This method focuses on the phase angle between two specific components, the superimposed component of zero sequence current (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta {{I}_0}$</tex-math></inline-formula>) and voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta {{V}_0}$</tex-math></inline-formula>). By continuously monitoring the cumulative sum (CumSum) of this phase angle at the DG connection point, the system can identify islanding events. The calculated values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta {{I}_0}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta {{V}_0}$</tex-math></inline-formula> exhibit inconsistencies in their magnitudes and variations due to real power imbalance, making them unsuitable for islanding detection. A key benefit of this approach is its capability to nearly eliminate the issue of large non-detection zones (NDZ), a common problem with many passive islanding detection methods. As a result, the technique can identify islanding events more reliably under a wide range of operating conditions. Simulation studies were conducted using PSCAD/EMTDC software to showcase the effectiveness of the proposed method. Testing across various system configurations verified its capability to minimize the NDZ and detect islanding events in under 10 milliseconds, far quicker than the usual response time of reclosers, which is approximately 150 ms. The proposed approach was further tested and validated using the RTDS simulator in conjunction with the dSPACE (DSP-1104) controller.