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Islanding Detection Methods for PV Converters in DC Distribution System Based on Injected Perturbation with Feedback

With the increasing penetration level of both DC sources (distributed generators) and DC loads, DC distribution technology has been widely concerned for the improved system reliability and efficiency. However, islanding detection techniques for DC grids are still in infancy and are not incorporated into the operation principle of renewable power generation well in the existing literature. This paper presents a detailed analysis and performance comparison of two active islanding detection methods that are based on injected perturbation with feedback for PV converters in DC distribution system, combining with the MPPT operation principle of PV generation. As an indicator of both system stability and islanding detection performance, the feedback gain that causes system instability in islanding condition while still preserves stability in grid-connected mode is theoretically obtained. Furthermore, the impact of system parameters including PCC bus capacitance and DG location are analyzed. The proposed two methods are verified by system simulation.