Observability of nonlinear power system dynamics using synchrophasor data

Abstract

The increasing availability of high-resolution, synchronized measurements from phasor measurement units (PMUs) presents an opportunity to monitor power system dynamics in real time. However, the degree of observability of power system dynamics depends upon the power system states monitored by the PMUs. This paper presents a new algorithm to assess the observability level of rotor angle dynamics, based on PMU locations and monitored states. An observability index is proposed, which can be tracked along the trajectory of system states over time. To overcome the difficulty in calculation of high-order derivatives, an automatic differentiation technique is applied for observability calculation of large-scale systems. The proposed observability algorithms and techniques are validated on a 179-bus system. The proposed method is also helpful in identifying locations where PMUs should be installed for effective observability of nonlinear power system dynamics. This synchrophasor based observability monitoring method serves as a basis for control schemes that require knowledge of power system dynamics. Copyright © 2015 John Wiley & Sons, Ltd.