Evaluating risk indices of weak lines and buses causing static voltage instability

A set of risk indices of weak lines and buses causing static voltage instability and an assessment technique to evaluate the risk indices are proposed. The assessment technique is based on the integration of a quadratic optimization model combined with a line-based voltage stability index into Monte Carlo simulation. The proposed risk indices can be used to differentiate the risk responsibilities among the weak lines and buses and are useful information in determining locations of operational and planning measures for improving static voltage stability. The simulation results for the IEEE 30-bus system and Polish power grid system with 2383 buses demonstrate the effectiveness of the presented technique and usefulness of the proposed risk indices.