Development of Multilinear Regression Models for Online Voltage Stability Margin Estimation

This paper investigates the use of reactive power reserves (RPR) as an indicator to estimate voltage stability margin (VSM) in an online environment. The methodology relies upon the relationship between system-wide RPRs and VSM. Statistical multilinear regression models (MLRM) are utilized in order to express how variations in RPRs can be transformed into direct information about VSM. Data regarding RPRs and system VSM are obtained through an offline voltage stability assessment (VSA) and stored in a database for further MLRM development. Different load increase directions and a comprehensive list of contingencies are considered to account for uncertainty present in real-time operations. Once properly designed and validated, the MLRMs are ready to be used in the online environment. The methodology is tested on the IEEE 30-bus system and a real size test system containing 1648 buses. Preliminary results show that MLRMs can be successfully employed in online VSM estimation.