Enabling Large-Scale PV Integration into the Grid

The intermittent nature of photovoltaic (PV) systems poses stability challenges to the distribution grid. The integration of ancillary services into distributed generation (DG) inverters is an effective approach to mitigate challenges related to intermittency. Petra Solar´s Generator Emulation Controls (GEC) technology equips DG inverters with voltage support through Volt/VAr droop, low-voltage ride-through (LVRT), and microgrid forming capabilities. This paper is focused on demonstrating the value of these features in stabilizing voltage and minimizing flicker due to PV intermittency and nuisance tripping using a laboratory-scale test-bed. A typical simplified 12kV/10MVA feeder was scaled down to its single-phase 120V/5kVA on a per-unit basis. The effectiveness of Volt/VAr support and LVRT is demonstrated by simulating cloud cover and a transient fault event. This is followed by a microgrid test where the circuit is shown to separate and continue operation as an intentional island when faced with a long-term disturbance on grid.