Unstable Equilibrium Points in Standalone Synchronous Generator

We have found that the synchronous generator in standalone operation can have unstable equilibrium points in the open loop at realistic operating conditions, a finding which has not been shared before to the best of our knowledge. In contrast, a grid-tied generator with the same parameters will be open loop stable for the same operating points. Starting from a 7th order two-axis (dq) model of the machine, we have employed a combination of techniques such as: small signal analysis, time domain simulation, large signal trajectory analysis and model order reduction to study this phenomenon. Knowledge of the system dynamics, in particular the plant stability, is important for controls and systems engineers to design more suitable control mechanisms.