Unified controller for overvoltage prevention, Islanding detection and LVRT at high penetration of PV systems connected to a LV grid

This paper examines the issues of overvoltage prevention, islanding detection (ID) and low-voltage ride-through (LVRT) operation for high penetration of inverter-based PV systems. A unified controller based on reactive power support enhanced with active power curtailment (RPS-APC) strategy is proposed for the PV systems. The controller regulates the active and reactive power injection based on local PCC parameters. It has the following integrated features: 1) effective overvoltage prevention for feeders with low X/R; 2) accurate and fast islanding detection in multiple-PV scenario; 3) negligible non-detection-zone (NDZ) without affecting system power quality; 4) dynamic voltage regulation, power factor correction and reduction of feeder losses; 5) improved system reliability by distinguishing short voltage transients and islanding condition; and 6) smooth ride-through operation based on LVRT curve. To validate the proposed strategy, an existing LV distribution feeder under high PV penetration is simulated in EMTDC/PSCAD under different grid conditions.