Impacts of PMU uncertainty on voltage stability assessment in power systems
Synchronized Phasor Measurement Units (PMUs) are becoming a key element of monitoring, protection, control applications in power systems and are the basis for the implementation of Wide Area Monitoring Systems (WAMSs). Synchrophasors obtained from PMUs can provide useful and early information regarding arising stability issues in the power system.
On the ground of the existing synchrophasor standard and practical experience, a variety of PMU uncertainties are modeled and different combinations such as only magnitude error, only phase angle error and the mixed type consisting of both errors, in the form of Gaussian distribution and approximate U-distribution separately, are designed for test to find the worst impact.
To obtain a comprehensive and reliable conclusion, both global and local indexes of voltage stability are considered. Selections of IEEE standard networks are adopted as case studies. The impact of PMU accuracy in voltage stability assessment is analyzed. Such analysis constitutes the first step to developing the background for defining the required performance characteristics for synchrophasor measurements used for instability detection. The stability methods are also considered with respect to the robustness to PMUs' uncertainty as a criterion for choosing the most suitable method for stability monitoring.
The power system for test is modeled in Real Time Digital Simulation (RTDS) platform. The simulated instantaneous voltage and current signals can be recorded on PC, and then the saved data is sent to MATLAB platform for the off-line applications including synchrophasor calculation, uncertainty modeling and different voltage stability assessment testing with and without considering the uncertainty.
This research work was initiated and is carried out in cooperation with Prof. Carlo Muscas, University of Cagliari, Italy.