Enhancing Grid Stability Using a Virtual Inertia-Integrated Railway Power Conditioner in Railway Power Supplies With High Renewable Energy Penetration

Abstract

As electric power systems increasingly integrate Renewable Energy Sources (RESs), the consequent reduction in system inertia has heightened their sensitivity to disturbances, such as sudden load changes. This issue is especially relevant in railway power supply systems, which are evolving to be dominated by RESs. Traditional solutions, including Railway Power Conditioners (RPCs), primarily address unbalanced loads and reactive power compensation but offer limited frequency support. This paper introduces a Virtual Inertia-Integrated Railway Power Conditioner (VIIRPC), a novel solution that enhances traditional RPCs with Energy Storage Systems (ESS) to provide critical virtual inertia support, thereby addressing the critical gap in frequency stability amidst the evolving energy landscape of railway systems. Utilizing a current source-based model, the VIIRPC effectively extends inertia support from two-phase systems to balanced three-phase systems at the Point of Common Coupling (PCC). This achievement is realized by dividing a virtual inertia signal and integrating it into both sides of the RPC control loop, while respecting each side’s signal orientation. Simulations have been conducted to verify the operation under different loading conditions, including a 4-minute headway train schedule, under both conventional and low-inertia grid conditions. These results demonstrate that the VIIRPC outperforms traditional RPCs by enhancing frequency stability and maintaining conventional functionalities. This advancement is particularly significant for modern, RES-dominated railway power supplies, especially in remote areas with RES-based power sources and low short-circuit levels at the PCC.

Keywords

• Virtual inertia control
• railway power conditioners
• unbalanced power systems
• Scott transformers
• renewable energy sources