Increasing energy yield of PV Parks by controlling On-Load Tap Changers to optimize inverter utilization

Large PV Parks usually span several voltage levels, separated by stationary transformers. In such parks, inverters face restrictions and losses that originate from varying voltage levels on the AC and DC side. In this paper, the option to equip transformers with on-load tap changers and control them with the aim of regulating voltage levels on the AC output side of inverters in order to increase their effectiveness across several operation points and to lift restrictions in power feed-in is explored. Based on a model of a 105 MVA-Park, the operation principle is explained and annual increase in energy yield is simulated for a specific setup. A concluding economic analysis gives insight into whether the investment into additional tap-changers can be economically justified for a PV Park operator for this setup.