Observing the state of a synchronous generator Part 1. Theory

The problem of observing the state in non-linear systems is presented. A new approach to the problem of non-linear observer stability is developed. This approach, thanks to the application of Massera's theorem, allows the construction of non-linear observers for a wide class of systems and the proof of their stability. The method for gain-matrix K selection are just the same as for linear observers. A new concept of non-linear proportional-integral observers is given and a simple algorithm for gain element selection is developed.