Assessing the Provision of Ancillary Services by PV-BES Systems Considering BES Capacity Degradation

The ever-increasing penetration of distributed renewable energy sources, e.g., photovoltaics (PVs), poses new technical challenges, jeopardizing the reliable operation of power systems. For this reason, battery energy storage (BES) are situated alongside PV systems to provide ancillary services (ASs) to system operators. However, BES operation is often limited due to the restricted number of operating cycles. In this paper, a methodology for the assessment of the provision of voltage regulation and power smoothing services by PV-BES systems is presented, taking into account the capacity degradation of BES. The proposed framework involves quasi-static simulations incorporating the operating conditions of the distribution network. A battery aging model is used to estimate the BES capacity loss caused by both the calendar and the cyclic aging mechanisms. The updated BES capacity sets new constraints on its operation and consequently influences the efficiency of the provided ASs. A parametric analysis is conducted to investigate the impact of the most critical parameters on the BES capacity degradation.