Optimal PMU placement for topological observability of power system: Robust measurement design in the space of phasor variables

This paper presents a new mixed-integer linear programming formulation of the optimal phasor measurement units (PMUs) placement problem when considering the topological observability of the power system. Different from other formulations, decision variables are associated with phasor measurements, but not with PMUs. This approach makes it easy to take into account the availability of PMU measuring channels, effect of zero-injection bus, possible system contingencies like single PMU or branch loss, as well as gross error occurrence, and offers flexibility in specifying the objective function. Paper describes a presolve technique that makes the formulation more compact and tighter. Numerical results on IEEE standard test systems are presented and reveal the existence of the PMU placements which ensure topological observability, but fail to meet numerical observability.