Condition Number-based Contingency Ranking in a Power Transmission System Using Zip Load Modeling

Abstract

A Static load model is a relation between measured voltage at a bus, active and reactive power consumed by the load connected at an instant. Load model composition plays a crucial role in the effect of particular contingencies and this can change the ranked lists used by the system. These models have an exponential or polynomial representation of load. In this paper, the load modeling is considered for constant impedance (Z), constant current (I), constant power (P) and ZIP. Newton-Raphson (N-R) power flow technique is used for analyzing various load models on the transmission system. This paper deals with the contingency ranking based on the voltage stability of the system for single line outage with constant impedance (Z), constant current (I), constant power (P) and ZIP. The Condition number of the load flow has been computed for selected single line outage condition. Among different outage condition, the highest value of condition number will be considered most unstable. The proposed algorithm is tested on IEEE-14 and IEEE-30 bus system using MATLAB.

Keywords: Load modeling, Constant Z, Constant I, Constant P, ZIP load modeling, Load flow studies.