Robust Coordination Design of PSS and UPFC-POD Controller for Damping Oscillations Based on PSO and DEO Techniques

Enhancing power network stability and mitigating oscillations require an effective supplementary damping controller. In this paper, a Unified Power Flow Controller (UPFC) is employed as a Power Oscillation Damping (POD) controller to improve system stability. The UPFC, a pivotal device in Flexible AC Transmission Systems (FACTS), provides multiple control input channels that can be effectively utilized for POD. This work proposes two control schemes: (i) an individual controller design, where either a traditional Power System Stabilizer (PSS) or a UPFC-POD is used independently, and (ii) a dual-coordinated controller, where the PSS and UPFC-POD operate in coordination. To optimize controller parameters, a novel Dolphin Echolocation Optimization (DEO) algorithm is employed, using an eigenvalue-based objective function to enhance dynamic stability performance in a Single Machine Infinite Bus (SMIB). Results confirm that the synchronized approach achieves a damping ratio of 0.8797 and an overshoot of 0.0074 p.u., compared to 0.8561 and 0.0105 p.u. with PSO. Additionally, DEO reduces the settling time to 3.5 s in the UPFCPOD case, while PSO requires 5s. Comparative analysis demonstrates that the dual-coordinated control strategy outperforms individual controllers by providing superior damping, faster response, reduced overshoot, and shorter settling time, effectively enhancing Low-Frequency Oscillation (LFO) damping and overall system stability. The DEO-based dualcoordinated design further enhances dynamic performance by reducing overshoot by 30 %} and achieving faster stabilization.