Optimal Tuning of Virtual Inertia-Integrated Railway Power Conditioner With Phase Correction for Renewable-Dominated Supplies With V/V Transformers

The transition to renewable energy-dominated power generation heightens the vulnerability of frequency stability, impacting various modern power systems, including railways. While recent studies have investigated the role of railway systems in supporting frequency and inertia through methods such as traction motors, regenerative braking, and air conditioning, these approaches predominantly address frequency stability in isolation. The integration of virtual inertia control into Railway Power Conditioners (RPCs) has received limited attention. The existing Virtual Inertia-Integrating Railway Power Conditioner (VIIRPC) is designed for Scott transformers with 90-degree secondary-side phasor angles but encounters compatibility challenges with V/V transformers, exacerbating the imbalance issue at the Point of Common Coupling (PCC). This paper proposes an enhancement to the VIIRPC by incorporating a phase correction technique, allowing it to perform comparably with both Scott and V/V transformers. A comparative analysis is conducted under both unbalanced and balanced loading conditions on the secondary sides of the traction transformer, including the load characteristics of a 4-minute headway train schedule. The results from this train-running simulation demonstrate substantial enhancements in grid strength, including a 99.03% reduction in the Rate of Change of Frequency (RoCoF), a 0.34% decrease in the frequency nadir, a significant reduction in the Voltage Unbalance Factor (VUF) from 7.44% to 0.28%, and an optimized power factor of 1. Additionally, the study explores energy storage sizing and provides a comparative analysis of converter sizing for both Scott and V/V transformer configurations, further contributing to grid stability and resilience.