A Novel Electric Spring With Improved Range of Operation for Isolated Microgrid Systems

Abstract

The smart load phenomenon of electric spring has been proven to be an important aid to the distribution network in terms of voltage stability. While the performance of ES is commendable, its operational range presents a significant challenge. The effectiveness of an ES depends on various factors, including the choice of control structure, smart load ratio, ES placement, and non-critical load power factor. To address the challenges regarding the noncritical load power factor, this study proposes a novel hybrid control structure that combines two well-established schemes: quadrature voltage injection and in-phase voltage injection. The performance of the proposed scheme is evaluated under variable non-critical load resistance, inductance, and power factors, with the results presented in this paper. Additionally, the sensitivity of the proposed scheme is analyzed for different scenarios, such as varying non-critical load power factors, resistances, and inductances using MATLAB/Simulink environment. A comparative sensitivity analysis is conducted between the proposed scheme and the quadrature and in-phase voltage injection schemes, and the findings are also documented. Further a real-time validation of the proposed control scheme, as well as the other schemes, is conducted using the OPAL-RT 4510 real-time simulator. At last, THD analysis along with a competitive study is done with other pre-published control structures to showcase the superiority of the proposed control scheme.

Keywords

• Self-excited induction generator (SEIG)
• wind energy conversation system (WECS)
• electric Spring (ES)
• sliding mode control (SMC)
• critical load (CL)
• non-critical load (NCL)