Graphical observer design suitable for large-scale DAE power systems

In this paper we discuss an intuitive observer design approach that is suitable for large-scale systems, such as power systems. In arriving at this approach we drew inspiration from the field of linear structured systems, where qualitative statements (e.g., solvability of the fault detection and identification (FDI) problem, controllability) about the system are made by analyzing the structure of the system. Our emphasis is design and we use information regarding the structure of the system as well as the actual values of specific entries in the system matrices to design observer-based monitors. These monitors can estimate the state of the system or detect and identify specific occurrences of faults in the system, all in the presence of disturbances and uncertainty. In this paper we demonstrate our design approach by designing observer-based monitors for electromechanical dynamics on a small 3-bus and an intermediate-sized 179-bus power system model.