Sensitivity factor for power system security analysis using LabVIEW

In this paper we present a calculation method for sensitivity factor for power system security based on dc power flow using the graphical programming environment of LabVIEW. The dc power flow simplifies the power flow by making a number of approximations including 1) completely ignoring the reactive power balance equations, 2) assuming all voltage magnitudes are identically one per unit, 3) ignoring line losses and 4) ignoring tap dependence in the transformer reactance. Hence the dc power flow reduces the power flow problem to a set of linear equations. For this purpose we have developed a virtual instrument (VI) suitable for contingency analysis for both line outage distribution factor (LODF) and Generation Shift Distribution Factor (GSDF). To validate the proposed VI, the dc solution load value has been increased to match the total ac load plus losses, a manner to make comparison between the ac and dc solution results possible. The effectiveness of the method developed is identified through its application to a 6 buses test system. The calculation results show excellent performance of the proposed method, in regard to computation time and quality of results.

I. Introduction

The most accurate approach for modeling the steady state behavior of balanced, three phase, electric power systems is through the solution of the power flow [1]–[5]. With modern computers the power flow (PF) for even a fairly large system, such as the NERC 43,000 bus model of the North American Eastern Interconnect, can often be solved in seconds.