A Modal-Space Method for Online Power System Steady-State Stability Monitoring

TL;DR

This paper introduces a novel modal-space method for online estimation of power system steady-state angle stability limits, enabling real-time monitoring without extensive scenario setup or multiple nonlinear power flow solutions.

Contribution

The paper presents a new modal-space approach that simplifies nonlinear power system models into single-machine-like systems for online stability limit estimation.

Findings

Accurately estimates SSASL without manual scenario specification.

Demonstrates effective online stability monitoring in case studies.

Outperforms traditional power flow-based analysis in real-time environments.

Abstract

This paper proposes a novel approach to estimate the steady-state angle stability limit (SSASL) by using the nonlinear power system dynamic model in the modal space. Through two linear changes of coordinates and a simplification introduced by the steady-state condition, the nonlinear power system dynamic model is transformed into a number of single-machine-like power systems whose power-angle curves can be derived and used for estimating the SSASL. The proposed approach estimates the SSASL of angles at all machines and all buses without the need for manually specifying the scenario, i.e. setting sink and source areas, and also without the need for solving multiple nonlinear power flows. Case studies on 9-bus and 39-bus power systems demonstrate that the proposed approach is always able to capture the aperiodic instability in an online environment, showing promising performance in the online monitoring of the steady-state angle stability over the traditional power flow-based analysis.