Experimental assessment and model validation of power quality parameters for vehicle-to-grid systems

摘要

Vehicle-to-grid (V2G) and dynamic charging have been pointed out as potential assets to provide grid ancillary services and enable higher levels of renewable generation. However, such strategies may require that EV chargers operate below their nominal power, which can raise power quality (PQ) concerns. This work aims to propose a PQ characterization procedure for V2G systems, as well as to assess their PQ performance. Experimental tests were carried out for a 10-kW V2G charger connected to a Nissan Leaf, operating at different relative power levels in charging and discharging modes. Power factor (PF), harmonic distortion, and voltage unbalance were assessed as PQ metrics. Results show that although the V2G system complies with the limits established in international standards when operating at nominal power, the PQ metrics degrade for lower power values; discharging mode perform worse in terms of electricity pollution. For phase 3, lowering the relative power from 85% to 10% increased total harmonic distortion in current (THDi) from 3.1% to 19% and from 4.6% to 33% when in charge and discharge mode, respectively. Additionally, mathematical models used to describe the PQ behavior of grid connected PV systems proved to accurately describe the behavior of the system under analysis.