Cost-Effective Size of HESS Incorporated in VSG With Enhanced Performance of Battery Providing Implicit Inertia

Virtual synchronous generator (VSG) incorporates hybrid energy storage system (HESS) comprising supercapacitor (SC) and battery energy storage system (BESS) for frequency support services (FSS). In this work, new aspects namely implicit contribution of BESS in inertia and subjection of higher magnitude stress factors (SFs) on BESS during FSS are observed, while HESS is sized by existing methodology. Least square estimation and novel performance evaluation model are used to quantify the BESS implicit contribution in inertia and decrease in its desirable performance due to higher SFs, respectively. The resulting computations are utilized in reducing the SC size and marginally increasing the BESS size that leads to reduction in SFs on it. The estimated HESS size also demonstrates lower investment cost (INVC). Further, the implicit contribution by BESS in inertia and reduction in SFs with its estimated size is validated at Power Hardware-In-Loop (PHIL) level.