Operational Risk Assessment of Power Systems with Distributed Energy Resources Using Minimal Cut Sets

Abstract

Electric power system networks are facing major challenges because of the rapid increase in penetration of distributed energy resources (DERs). Reliability evaluation plays an important role in system analysis, design, upgrades, and operations, especially in bulk power systems. The research presented in this thesis focuses on the evaluation of the composite system reliability under steady state conditions, and also goes a step further towards assessing operational risks in real-time system operations using direct probabilistic analysis techniques. The thesis also examines the reliability and risk improvements that are accrued from penetration of DERs into the power system.

The challenge of using analytical methods in reliability evaluation of composite power systems is the large computational burden involved, to examine all the possible outage events. This thesis presents the mathematical foundations, evaluation procedures, and reliability indices associated with composite power system reliability evaluation using the minimal cut set calculations. The objective of this approach is to evaluate reliability and risk indices for the system and for every load bus in the system. The performance of the system under outage condition of generators, transmission lines, or both, is examined by conducting an appropriate power flow study. An optimal power flow (OPF) is solved to find the system minimal cut sets which are then used to evaluate reliability and operational risk. DER units are incorporated to investigate the enhancement in system reliability and operational risk. The concepts and developed model are illustrated by application to the 24-bus IEEE Reliability Test System.