The effect of branch parameter errors to voltage stability indices

Abstract

Errors in the values of network parameters stored in the control center may affect the important application of voltage stability monitoring. This paper investigates the effect of branch parameters errors to voltage stability monitoring, using the state vector obtained by the state estimator. In particular, the state vector is used for calculating a voltage stability index that indicates the most critical branch (the one that first reaches its active power transfer limit). The states of the power system are estimated under various scenarios of possible errors in the reactance of the critical branch and then are used for the calculation of the voltage stability index. The case studies are performed using the IEEE systems with 14 and 39 buses and it is shown that the calculated value of the stability index depends on the error in the branch parameters, the power system structure and the contingency leading to voltage instability.