Damping LFOs: Grid Following with Power Oscillation Damping vs. Grid Forming vs. PSS

TL;DR

This paper compares grid-following, grid-forming, and PSS methods for damping low-frequency oscillations in power systems, demonstrating that GFM-VSM performs comparably to PSS and better than GFL dampers.

Contribution

It introduces a GFL controller with auxiliary damping, compares GFL, GFM-VSM, and droop controls, and shows GFM-VSM's effectiveness in damping LFOs.

Findings

GFM-VSM rivals PSS in damping performance.

GFL with auxiliary damping is less effective.

GFM controls outperform traditional GFL in LFO damping.

Abstract

Low-frequency oscillations (LFOs) present a significant challenge to the stability and reliability of power systems, especially in grids with a high penetration of renewable energy sources. Traditional grid-following (GFL) inverters have proven less effective in damping such oscillations. This paper presents a GFL-power plant controller with an auxiliary power oscillation damping control for damping LFOs. This approach is compared with a traditional power system stabilizer (PSS) for a two-area power system. Next, the research is extended by deploying grid forming (GFM) controls, which by actively controlling the voltage and frequency dynamics emulate the behavior of traditional synchronous generators. The paper analyzes two GFM control strategies: virtual synchronous machine (VSM) and droop control, and demonstrates their effectiveness in damping LFOs in the test system. The simulation results reveal that the performance of the proposed GFM-VSM rivals that of the PSS and is better than the GFL-power oscillation damper.