A METHOD TO COMPUTE REACTIVE POWER MARGINS WITH RESPECT TO VOLTAGE COLLAPSE

This paper proposes a method to compute the reactive power margin - i.e. the difference between the maximum reactive load and the corresponding base case value - at a given set of load buses of a power system. This margin is aimed at assessing the system robustness with respect to voltage collapse. The corresponding collapse point is directly obtained as the solution of an optimization problem with the load increase as the objective, the non-optimized loads as equality constraints and the generator reactive limits as inequality constraints. The CRIC electrical decoupling yields a "voltage-only" problem. The latter is solved using the Newton approach and a procedure is given to efficiently deal with the inequality constraints. A simple illustrative example is given as well as simulation results obtained on the Belgian 520-bus 41-generator system.