Enhancing AC Line Emulation controls for improved inter-area oscillation damping and application to Multi-Terminal DC Grids

Abstract

The integration of High Voltage Direct Current (HVDC) systems into modern power systems offers opportunities to enhance grid resilience through advanced functionalities such as AC line emulation. By emulating AC line behavior, HVDC systems can adjust active power flows in real-time, improving system performance during contingencies. However, existing AC line emulation controllers face challenges, including impacting the damping of inter-area modes. This paper addresses these challenges with two key contributions. First, we propose a lead-lag filter to enhance oscillatory behavior by correcting the phase of active power injections, improving inter-area mode damping while preserving the steady-state behavior of the controller. Second, we extend the application of AC line emulation controllers to multi-terminal DC (MTDC) grids, enabling their deployment in complex future systems. The proposed methods are validated through time-domain simulations and eigenvalue analysis in both a simplified hybrid ACDC system and a realistic 44-bus test system with an MTDC grid. Results demonstrate significant improvements in system stability, highlighting the potential of these enhancements.