Assessment of an electrical resonance issue in a fast electronic on-load tap-changer transformer based test-bench during renewable energy source tests

The growth of renewable energy source (RES) installations in remote locations and less favourable grid sites increases the grid stability challenges in transmission and distribution systems. The use of electronic on-load tap-changer (eOLTC) on electromagnetic power transformers will allow RESs to have faster voltage ride-through (VRT) and reactive power injection responses, thereby improving the grid operability. The validation of these RESs equipped with novel eOLTC technology demands test-benches that allow fast voltage variations of the medium-voltage grid to which the power generation unit (PGU) is connected. To do so, eOLTC transformers can also be used. Thus, operating conditions of conventional field RES installations composed of a cascaded connection of a mains transformer and a…