Transient Stability Assessment of Cascade Tripping of Renewable Sources Using SOS

TL;DR

This paper analyzes the stability risks of cascade tripping in renewable energy systems using Lyapunov methods and SOS programming, providing a probabilistic framework to assess and mitigate instability risks.

Contribution

It introduces a Lyapunov-based approach with SOS programming to estimate stability regions and assess cascade tripping risks in renewable-rich power systems.

Findings

Proposes a conservative stability region definition using SOS programming.

Visualizes instability risk through a probabilistic stability region.

Demonstrates the approach on a 3-machine system with high renewable penetration.

Abstract

There has been significant increase in penetration of renewable generation (RG) sources all over the world. Localized concentration of many such generators could initiate a cascade tripping sequence that might threaten the stability of the entire system. Understanding the impact of cascade tripping process would help the system planner identify trip sequences that must be blocked in order to increase stability. In this work, we attempt to understand the consequences of cascade tripping mechanism through a Lyapunov approach. A conservative definition for the stability region (SR) along with its estimation for a given cascading sequence using sum of squares (SOS) programming is proposed. Finally, a simple probabilistic definition of the SR is used to visualize the risk of instability and understand the impact of blocking trip sequences. A 3-machine system with significant RG penetration is used to demonstrate the idea.