Revisiting Power System Stabilizers with Increased Inverter-Based Generation: A Case Study

TL;DR

This paper tackles small-signal stability in grids with high inverter-based resource penetration by testing two model-based PSS tuning methods, Residues and P-Vref, on the Kundur Two-Area benchmark with grid-following converters. It demonstrates that the effectiveness of these tuning approaches depends on coordination and system conditions; Residues can falter under uncoordinated retuning, while P-Vref is more amenable to sequential coordination but not universally robust. The findings motivate developing local, adaptive online PSS tuning to maintain damping as grid dynamics evolve with increasing IBR share. The work highlights the need for re-thinking PSS operation in modern grids and provides insights into when coordination is essential for effective damping restoration.

Abstract

As power systems evolve with increasing production from Inverter-Based Resources (IBRs), their underlying dynamics are undergoing significant changes that can jeopardize system operation, leading to poorly damped oscillations or small-signal rotor angle instability. In this work, we investigate whether Power System Stabilizer (PSS) setting adjustments can effectively restore system stability and provide adequate damping in systems with increased IBR penetration, using the benchmark Kundur Two-Area System as a case study. Specifically, we evaluate the model-based Residues and P-Vref PSS tuning methods to examine their effectiveness under evolving grid conditions. Our findings indicate that the effectiveness of these tuning methods is not guaranteed, particularly when coordination is limited. Consequently, our case study motivates local and adaptive online PSS tuning methods.

Figures (4)

• Figure 1: Block diagram of the Excitation system (AVR) and PSS control loops.
• Figure 2: Two-area system used in simulations: 0% IBR system (only SGs connected) and 50% IBR system (SG at Buses 1 and 3 replaced with GFLs).
• Figure 3: Comparison of SG $G_4$ active power output trajectories for the different analyzed parameter sets and PSS re-tuning methods.
• Figure 4: Movement of the critical poles $\lambda_j, j \in \{1, \dots, 5\}$ in the root-locus plots for the initial PSS Parameter Set B under different re-tuning scenarios: (a) and (b) show the re-tuning of just $PSS_4$; (c) and (d) illustrate the sequential re-tuning of $PSS_4$ and $PSS_2$. The gray dotted lines indicate the damping ratio of the modes $\xi=-\frac{\sigma}{\sqrt{\sigma^2+\omega^2}}$. The stars indicate the open-loop pole positions (with $K_\text{PSS}=0$), whereas circles mark the zeros towards which the closed-loop poles migrate along the plotted trajectories as the gain increases$^1$. The line styles correspond to those used in Fig. \ref{['fig:results_trajectories']} for the respective PSS re-tuning scenario.