PMU Impact on State Estimation Reliability for Improved Grid Security

State estimation plays a key role in real-time power system operations. It determines a best estimate of the current actual power system based on available SCADA measurements and power system model data. One of the key state variables in state estimation is the bus voltage phase angle. This was not available as a measurement before. Presently PMUs can provide the direct measurement of voltage and current phase angles. Initial research has shown that PMU data provides valuable, ´instantaneous´ information about system security and has the potential to improve the reliability and robustness of state estimation. The beneficial impacts of PMU data on state estimation depend on PMU measurement accuracy and calibration, the number of PMUs, PMU locations and related SCADA data accuracy. Practical implementation issues include: the synchronization of PMU data to a global reference, calibration of PMU data from different vendors and utilities, preparation of the PMU data for use in SE and tuning of the PMU data weights for optimal online performance