Virtual synchronous machine-based controller for multiple fast charging stations in grid stability support

Abstract

Ancillary based controller is an emerging concept for efficient power flow, voltage regulation, and frequency response stability, crucial for grid support at the point of common coupling (PCC) during EV battery charging process. This paper introduces an improved virtual synchronous machine (i-VSM) control concept using state-of-charge (SOC) voltage feedback as a key parameter to generate a virtual flux model within the fast-charging station (FCS) based rectifier converter. The i-VSM was modelled using VSM reactive power loop and the SOC-driven charging voltage as a reference input to the VSM. Through this approach, the i-VSM adjusts the virtual 's field excitation to produces the electromagnetic force fed to the pulse generator, which generates the switching signals to control the rectifier converter output to match grid response deviation during FCS operation. The i-VSM model was tested across 150 kW and 300 kW -rated multiple FCS setups. The comparison of the i-VSM with a conventional VSM-PI controller-based FCS, demonstrated the i-VSM's superior performance in accurately maintaining a steady power response flow, voltage tracking and frequency regulation at the rated values at PCC. The detailed voltage output variable response, stability analysis (Bode diagram) and current total harmonic distortion comparison are included in this paper. Conclusively, the i-VSM model showcase its advantages in plant stability, dynamic response tracking capacity and reactive power injection regulation, marking it as a robust alternative to VSM-PI based controller in grid-to-vehicle charging scenarios.