State-Derivative Feedback Control for Damping Low-Frequency Oscillations in Bulk Power Systems
MST Rumi Akter, Anamitra Pal, Rajasekhar Anguluri
TL;DR
Low-frequency oscillations in bulk power systems with high renewable penetration are challenging to damp. The paper introduces a state-derivative feedback (SDF) damping controller that uses both area frequency and RoCoF to enhance damping and accelerate frequency recovery, enabling HVDC and energy storage to stabilize the grid. The authors show that, under standard assumptions, SDF can replicate state-feedback performance via the transformation $K_n = K_s (A - B K_s)^{-1}$ and $N_n = (I + K_n B) N_s$, while using readily measurable derivatives. They validate SDF on two- and three-area models against a frequency-difference scheme, demonstrating improved damping of intra-area modes and comparable inter-area damping with realistic noise and disturbances, suggesting SDF as a practical PMU-based damping strategy for power-electronics-rich grids.
Abstract
Low-frequency oscillations remain a major challenge in bulk power systems with high renewable penetration, long lines, and large loads. Existing damping strategies based on power modulation of high voltage DC (HVDC) or energy storage, are often limited by fixed control architectures, leaving some modes poorly damped. This paper introduces a state-derivative feedback (SDF) damping controller that uses both frequency and its rate of change as feedback signals. Incorporating state derivatives enhances modal damping and accelerates frequency recovery, enabling HVDC and energy storage to effectively stabilize the grid. We evaluate the SDF controller on two- and three-area systems and compare performance with a frequency difference-based damping scheme. Results show that the SDF control reproduces state-feedback performance while providing good damping of both inter- and intra-area oscillations compared to the frequency-difference method, highlighting its potential as a practical solution for stabilizing power-electronics-rich grids.
