Voltage and frequency profile improvement in a storage-less SEIG-PV-based isolated microgrid

This article focuses on voltage and frequency profile stabilization in a self-excited induction generator-based hybrid system without using any battery energy storage unit. Eliminating the use of storage units significantly reduces the system cost and maintenance. Although this may reduce reliability, this work proposes an electric spring-based control strategy that employs a nine-switch converter and a reactive power management scheme that can provide reliability comparable to systems with energy storage units. The proposed system's performance has been evaluated during the day and night. During daytime conditions, when both photovoltaic and self-excited induction generators contribute to generation, the electric spring stabilizes the system's voltage and frequency. At night, power is generated only by the self-excited induction generator, and the system remains mostly in a power shortage. The proposed reactive power management scheme increases the utilization of the NSC during the night and improves the non-critical load voltage profile by nearly 28 V, while reducing the reactive power burden on the self-excited induction generator, resulting in an excess of 1.75 kW. On the other hand, the frequency profile remains nearly constant with a deviation of ±3%. The system is dynamically modelled and validated in real-time using an OPAL-RT 4510 platform.