Contingency Based Power System Security

Abstract

A contingency in the electric power system is termed as a disturbance resulting from single or multiple equipment outages. This disturbance is a sudden change in the system configuration causing severe violations on the operating constraints such as branch overloads and bus voltage limits violation. These violations may result in successive interruptions leading to the occurrence of a partial or a total blackout phenomenon. This means that the resulting effects of contingency cases are investigated on the operating constraints of the system to prevent the occurrence of this phenomenon and hence to maintain the power system security that aims to keep the system operation in normal condition and especially in the event of a contingency. The purpose of this thesis is to study the effect of power system component outages in terms of their severity on the system operating constraints to select and rank all severe contingencies, and then to apply the Remedial Action Schemes (RASs) that are necessary to withstand these contingencies and return the system into a secure state. The N-1 Contingency Analysis (CA) technique using Newton Raphson Load Flow (NRLF) method in a DIGSILENT Power Factory environment is applied for each outage to investigate the resulting effects on the operating constraints of the remaining system. This thesis uses a hybrid of contingency screening method and the contingency Performance Index (PI) ranking method to select and rank all severe contingencies. The contingency screening method is used to reduce the numerous calculations by eliminating the outages having no effect on the system operating constraints and selecting only the contingencies those lead to violations on the operating constraints.