A line-current measurement based state estimator

The authors present a method for state estimation when the measurement set consists basically of node voltages and line currents. The key idea is that P-θ observability can be reached provided inequality constraints are added to the estimation process. These constraints simply state that P⩾0 for a generator bus and P⩽0, for a load bus. Simulation results confirm that the method may be applicable to medium-sized subtransmission networks, the only major exception being radial networks with more than one feeder bus