An electric spring with an extended range of operation and current filtering capability for SEIG-based isolated system

This work proposes an electric spring (ES) based on a back-to-back converter. The proposed electric spring is used for voltage control in a self-excited induction generator (SEIG)-based isolated system. This work focuses on extending the operating range of the ES as well as providing current filtering capabilities to the ES. For that, a back-to-back configuration-based ES is proposed in this work. This article provides a comparative study of the proposed electric spring with its widely used battery-operated counterpart. Unlike most battery-operated electric springs, the proposed one does not need a battery. The active power requirement of the electric spring is fulfilled through a back-to-back converter configuration. Using a back-to-back configuration not only improves the operating range of the electric spring but also reduces total harmonic distortion (THD) in various system currents and voltages through the active filter capabilities of its shunt side converter. The work shows that the proposed electric spring can handle 83.3% more power variation than its battery-operated counterpart. With a non-linear load, the proposed electric spring successfully filters out the current harmonics, thus keeping the current and voltage THD at 2.76% and 0.55%, respectively. In contrast, battery-operated electric springs are incapable of doing so. The performance of the proposed ES is also verified with computational delays of 1.8 and 2.5 μs, to show the effectiveness of the control structure. The proposed ES is also evaluated under dynamic load switching, both on the CL and NCL side, to show its response to suddenly changing loads. Apart from that, the real-time validation of the proposed system is carried out using an OPAL-RT 4510 platform, and the obtained results are presented in this article.