Improving power system stability: a 3-level UPFC with PI control for enhanced power quality and dynamic performance

The global demand for electricity is steadily increasing, driven by industrialization, population growth, and the increasing adoption of electric vehicles and other energy-intensive technologies [1,2].Meeting this demand while ensuring reliable and high-quality power supply is a major challenge for power system operators [3].Traditional power grids, often designed for centralized generation and unidirectional power flow, are struggling to cope with the increasing complexity and variability of modern power systems [4].One of the primary challenges is the integration of renewable energy sources (RES), such as solar and wind power, into the grid [5,6]. *Author for correspondenceWhile RES offer significant environmental benefits, their intermittent nature poses challenges for grid stability and power quality [7,8].Furthermore, the increasing demand for power necessitates efficient and reliable transmission of electricity over long distances, often through aging infrastructure [9,10].To address these challenges, flexible alternating current (AC) transmission systems (FACTS) devices have emerged as a crucial technology for enhancing power system controllability and reliability [11,12].FACTS devices utilize power electronics to dynamically control power flow, voltage, and other critical parameters, enabling improved power quality, stability, and overall grid performance [13,14].Among various FACTS devices, the unified power flow controller (UPFC) stands out as a highly versatile and powerful solution [15,16].The UPFC,