Series-type fractional-order electric spring for energy storage reduction

The rise of renewable energy sources (RES) has highlighted the demand for energy storage. However, the high costs associated with battery energy storage systems (BESS) pose significant barriers to wider adoption of RES. Electrical springs (ESs) have the potential to reduce the dependency of RES systems on storage capacity. In conventional ES setups, power fluctuations are managed by connecting ES in series with non-critical load (NCL) to stabilize the voltage of critical load (CL). However, this approach results in considerable voltage variations for NCL and is limited by the number of available NCL. To address the challenges in distribution networks with a limited number of CL, this paper proposes a series-type fractional-order ES (S-FES) by connecting ES in series with CL directly. Leveraging the ability of fractional-order component (FOC) to absorb or dissipate active power at various orders, the S-FES maintains stable voltage for CL by adjusting the fractional order and impedance, thereby reducing the overall energy storage requirements. Under comparable conditions, the proposed S-FES can reduce the energy storage capacity by approximately 70% compared to BESS, while improving the power factor (PF) to unity.The paper then goes on to detail the topology and control strategy of the S-FES, and demonstrates its effectiveness through simulation and experimental results.