A Visualization Tool for Real-Time Dynamic Contingency Screening and Remedial Actions

This paper proposes a real-time visual interactive transient stability screening and remedial action tool that uses an approach based on Lyapunov functions to enable the selection of appropriate remedial actions that stabilize power systems due to large disturbances and cascading failures. At present, there is no effective tool that enables making a well-informed choice from amongst a profusion of remedial action alternatives. Conventionally, transient stability analysis of power system is performed offline to assess the capability of the power system to withstand specific disturbances and to investigate the dynamic response of the power system as the network is restored to normal operation. In this paper, postfault stable and controlling unstable equilibrium points are determined using a homotopy-based approach. Subsequently, stability assessment of the system and the corresponding potential remedial actions are determined from the equilibrium points of the system dynamical model. The real-time transient stability analysis and remedial action algorithm are incorporated with the visualization tool to facilitate interactive decision making in real time. The transient stability analysis and remedial action algorithm, and the visualization tool are demonstrated on several test systems including the equivalent Western Electricity Coordinating Council system and the simplified New England 39 bus test system.

I. Introduction

Control paradigms of modern power grids have been augmented with sophisticated communication and computation technologies that enable real-time monitoring and control of possible contingencies. However, the increasing pace of integrating variable energy resources has driven power grids to operate at lower security margins due to the low inertia or lack of inertia of these resources. Consequently, transient instability has become a major concern in modern power system security despite the advances in the communication and computation technologies. In other words, power grids will grow more vulnerable to transient instability and cascading failures if real-time transient stability screening and remedial action tools are not integrated with the communication and computation technologies. Traditional online contingency analyses have only evaluated static contingencies; dynamic contingencies were deemed too computationally intensive to solve in real time. Stability scenarios were evaluated offline; safe operating zones were determined and documented; and operators were required to be familiar with these scenarios and remedial actions. Therefore, the need for better situational awareness has become evident, and triggered several ongoing efforts to develop improved methods of determining remedial action alternatives including special protection schemes, emergency action, and online contingency analyses.