Maximizing power-system loadability in the presence of multiple binding complementarity constraints

In this paper, the problem of maximizing power-system loadability with multiple complementarity constraints representing generator limits is examined. The structure of the loadability surface is investigated, the various type of limits are classified and a general algorithm to optimize settings of control variables, in order to maximize loadability margin is developed. The importance of nonsmooth corner points (CPs) of the loadability surface that are due to the simultaneous occurrence of several loadability conditions is discussed. At such limits, maximization of loadability margin is performed based on techniques provided by nonlinear optimization theory. For this purpose an algorithm to identify multiple binding constraints on a CP is developed. Illustrative examples on small, but realistic systems are included.