Voltage stability constrained VAr planning-a case study for New Zealand

This paper discusses a VAr planning optimisation model that takes into account voltage stability constraint, and proposes an efficient solution algorithm to solve it. A contingency constrained optimal power flow (OPF) based model incorporating (static) voltage stability constraints is developed to analyse optimal VAr support decisions. Given a set of contingencies, the model performs the contingency ranking, decides optimal location and quantity of VAr support to simultaneously cover all the contingencies. DICOPT++, a state-of-the-art mixed integer nonlinear programming (MINLP) algorithm, is proposed to solve the model efficiently. The model is implemented for a 17 bus reduced New Zealand North Island system. The modal analysis is also conducted and the result is discussed.