A Supercapacitor-Enhanced Grid-Forming SVG with Fault Ride-Through Strategy for Symmetrical Fault

The increasing integration of renewable energy sources into power grids has led to a steady decline in system inertia and a continuous reduction in damping capability. These changes contribute to recurring stability issues such as voltage fluctuations and frequency deviations. To address these challenges, this paper proposes an enhanced static var generator (ESVG) system incorporating supercapacitor-based energy storage. Unlike conventional static var generator (SVG), the proposed ESVG not only performs voltage regulation but also offers rapid inertial support and four-quadrant operation capability, significantly enhancing power system operational stability. This study demonstrates that through properly designed grid-forming control strategies, the ESVG can utilize active power exchange between its DC-link capacitor and the AC grid to emulate the inertial behavior of synchronous generators. This mechanism provides millisecond-level inertial response, effectively suppressing frequency fluctuations. Moreover, during short-duration voltage sags, the ESVG delivers rapid reactive power support, thereby enhancing voltage stability and preventing renewable generation units from tripping due to sudden voltage drops. This functionality also contributes to improved fault ride-through capability. In light of the global energy transition, the ESVG represents a solution with substantial theoretical and practical value, offering key technical support for building future power systems with high penetration of inverter-based renewable resources.