Role of the State Estimator
Substations are equipped with different monitoring devices that can provide voltage and current samples captured through instrument transformers. These samples are then processed by the SCADA system to produce real and reactive power flow measurements in addition to voltage and current magnitude measurements. Moreover, the introduction of phasor measurements that are synchronized via the Global Positioning Satellite (GPS) system and provided by the phasor measurement units (PMUs) allows direct measurement of phase angles associated with voltage and current measurements. All of these different types of measurements are transmitted to control centers, where they are processed by the SE. State estimation is a function that takes advantage of the inherent redundancy among the available measurements in order to determine the best estimate of the system state, which is defined as the set of all the bus voltage magnitudes and phase angles in the system.