INVESTIGATION OF THE VOLTAGE STABILITY REGION INVOLVING ON-LOAD TAP CHANGERS

A new approach for estimating the voltage stability region of power sy stems is presented in this paper. This voltage stability region is con servative because it is based on ten sufficient conditions. The power flow solutions are utilized to estimate the voltage stability region o f the taps of on-load tap changers (OLTCs), voltage magnitudes, and ph ase angles. The coupling relation between the real and reactive powers is taken into account. The computation time is reasonable because onl y matrix and vector computation is involved. Two practical power syste ms were employed in demonstrating the capability of the proposed appro ach. The test results confirm that it is applicable to large power sys tems.