Simplified Stability Assessment of Power Systems with Variable-Delay Wide-Area Damping Control

TL;DR

This paper introduces a simplified method for assessing the stability of large power systems with variable communication delays, improving prediction accuracy and computational efficiency over existing techniques.

Contribution

It proposes a delay-processing strategy that simplifies the stability analysis of switched linear systems in power systems with wide-area damping control.

Findings

The method accurately predicts stability and damping performance.

Validation on a 2-area 4-machine system confirms effectiveness.

Simplifies analysis compared to traditional LMI-based approaches.

Abstract

Power electronic devices such as HVDC and FACTS can be used to improve the damping of poorly damped inter-area modes in large power systems. This involves the use of wide-area feedback signals, which are transmitted via communication networks. The performance of the closed-loop system is strongly influenced by the delay associated with wide-area signals. The random nature of this delay introduces a switched linear system model. The stability assessment of such a system requires linear matrix inequality based approaches. This makes the stability analysis more complicated as the system size increases. To address this challenge, this paper proposes a delay-processing strategy that simplifies the modelling and analysis in discrete-domain. In contrast to the existing stability assessment techniques, the proposed approach is advantageous because the stability, as well as damping performance, can be accurately predicted by a simplified analysis. The proposed methodology is verified with a case study on the 2-area 4-machine power system with a series compensated tie-line. The results are found to be in accordance with the predictions of the proposed simplified analysis.