International Journal of Power Electronics and Drive System (IJPEDS) Vol. 16, No. 2, June 2025, pp. 1368∼1375 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v16.i2.pp1368-1375 ❒ 1368 Design a novel SSSC based FOPID controller for the hybrid PV-DFIG-based system to enhance transient stability and dampen power oscillations Chethan Hiremarali Ramalingegowda 1 , Mageshvaran Rudramoorthy 2 , K. M. Mahesh Kumar 1 1 Department of Electrical and Electronics Engineering, PES College of Engineering, Mandya, India 2 School of Electrical Engineering, Vellore Institute of Technology, Vellore, India Article Info Article history: Received Jul 3, 2024 Revised Apr 5, 2025 Accepted May 6, 2025 Keywords: Doubly fed induction generator Fractional order proportional integral derivative Proportional integral controller Static synchronous series compensator Wind energy conversion system ABSTRACT The integration of photovoltaic (PV) and wind energy systems is becoming in- creasingly significant in the modern energy sector. Among various technologies, doubly fed induction generator (DFIG)-based wind power systems are exten- sively utilized due to their superior power control capabilities. Conventional control strategies, such as proportional-integral (PI) controllers, are commonly implemented to stabilize system waveforms. However, recent advancements highlight the potential for improved oscillation damping through optimized con- troller designs. This paper introduces an optimal fractional-order proportional- integral-derivative (FOPID) controller integrated with a static synchronous se- ries compensator (SSSC) to enhance power system stability. The proposed ap- proach incorporates the dynamic characteristics of a wind energy conversion system (WECS) connected to an infinite grid. A detailed WECS model is de- veloped to assess the effectiveness and robustness of the proposed controller in mitigating power oscillations, particularly under varying wind conditions. The proposed FOPID controller offers enhanced flexibility for parameter tun- ing, enabling precise damping of power oscillations, and presents a significant advancement over traditional wind turbine systems based on permanent magnet synchronous machines (PMSM). This is an open access article under the CC BY-SA license. Corresponding Author: Mageshvaran Rudramoorthy School of Electrical Engineering, Vellore Institute of Technology, VIT Vellore Campus Thiruvalam Road, Vellore 632014, India Email: rmageshvaran@vit.ac.in 1. INTRODUCTION Voltage injection through static synchronous series compensators (SSSC) is a widely adopted method for enhancing reactive power flow and improving power transmission performance [1], [2]. As part of FACTS devices, SSSCs enhance voltage stability, system stability, and oscillation damping by regulating voltage, cur- rent, and impedance [3]-[5]. Advanced control strategies, including modified differential evolution, improved PID, and fuzzy lead-lag controllers, have been explored for stability improvement [6]-[10]. Traditional PID controllers are common in power system stabilizers (PSSs) to mitigate low-frequency oscillations (LFOs), but their fixed gains limit adaptability to dynamic conditions [11]-[13]. Fractional order PID (FO-PID) controllers address these limitations using fractional calculus; however, their complexity and lack of standardized tuning methods remain challenging [14], [15]. Decentralized PID-PSS designs using linear Journal homepage: http://ijpeds.iaescore.com