Determining maximum regulating capability of UPFC based on predicting feasibility limit of power systems

This paper presents a novel procedure to determine the maximum regulating capability of a unified power flow controller (UPFC) by using optimal multiplier power flow. The capabilities of flexible ac transmission systems (FACTS) equipment are not only constrained by their thermal limits and the steady-state security limits, but also limited by their feasibility limits. After the detailed analyses have been made on the use of optimal multiplier mu as a new predictor to estimate the boundary point of the feasibility region, an algorithm for determining the UPFC regulating capability is proposed. The approach is then compared with minimum singular value decomposition on the IEEE 30 bus system. The results clearly demonstrate the effectiveness of the proposed approach.