Observability Analysis for Dynamic State Estimation of Synchronous Machines

This paper is concerned about the observability analysis of time-varying nonlinear dynamic model of a synchronous generator with its associated control systems. A byproduct of observability study is a set of guidelines to choose the appropriate set of measurements or sensors to be used to ensure strong observability for the dynamic states. The proposed analysis is developed using a Lie derivative based observability matrix and its singular values. A two-axis synchronous generator model and an associated IEEE-Type1 exciter are used to validate the results of observability analysis with dynamic simulations of disturbance scenarios using different types of measurements. It is shown that the dynamic state estimates will converge to the true trajectory faster and smoother if appropriate measurements that provide higher level of observability based on the proposed analysis are chosen. Results can be extended to other dynamic elements such as loads or time-varying parameters of machines.