Small-Signal Stability Oriented Real-Time Operation of Power Systems with a High Penetration of Inverter-Based Resources

TL;DR

The paper tackles the challenge of maintaining small-signal stability in power systems with high inverter-based resource penetration by integrating a data-driven small-signal stability constraint into Online Feedback Optimization (OFO). It develops a Small-Signal Stability Constrained OFO (SSSC-OFO) that uses a regression-based surrogate (MARS) of a damping-index stability metric to steer real-time dispatch toward stable operating points. The approach is validated on a modified IEEE 9-bus test system with grid-forming and grid-following IBRs, demonstrating improved convergence and stability compared to unconstrained OFO and traditional OPF variants. The work holds practical significance for ensuring secure operation in future grids with substantial IBR share, while maintaining computational efficiency suitable for real-time control.

Abstract

This study proposes a control strategy to ensure the safe operation of modern power systems with high penetration of inverter-based resources (IBRs) within an optimal operation framework. The objective is to obtain operating points that satisfy the optimality conditions of a predefined problem while guaranteeing small-signal stability. The methodology consists of two stages. First, an offline analysis of a set of operating points is performed to derive a data-driven regression-based expression that captures a damping-based stability index as a function of the operating conditions. Second, an Online Feedback Optimization (OFO) controller is employed to drive the system toward an optimal operating point while maintaining a secure distance from the instability region. The proposed strategy is evaluated on an academic test case based on a modified version of the IEEE 9-bus system, in which synchronous generators are replaced by IBRs operating under both grid-following and grid-forming control modes. The results demonstrate the effectiveness of the method and are discussed in detail.

Figures (7)

• Figure 1: One-line diagram of the 9-bus system.
• Figure 2: 3D scatter plot representation of dataset instances with stability classification.
• Figure 3: Modal map of the eigenvalues of the operating points in the training dataset.
• Figure 4: OPF solutions as functions of the generators active power and voltage.
• Figure 5: Voltage profiles and modal map of the solutions obtained for the operating point with a low demand level.