  Conventional state estimation routines of electrical grids are mainly reliant
on dynamic models of fossil fuel-based resources. These models commonly contain
differential equations describing synchronous generator models and algebraic
equations modeling power flow/balance equations. Fuel-free power systems that
are driven by inertia-less renewable energy resources will hence require new
models and upgraded estimation routines. To that end, in this paper we propose
a robust estimator for an interconnected model of power networks comprised of a
comprehensive ninth order synchronous generator model, advanced power
electronics-based models for photovoltaic (PV) power plants, constant power
loads, constant impedance loads, and motor loads. The presented state estimator
design is based on Lyapunov stability criteria for nonlinear differential
algebraic equation (DAE) models and is posed as a convex semi-definite
optimization problem. Thorough simulations studies have been carried out on
IEEE-39 bus test system to showcase the robustness of the proposed estimator
against unknown uncertainty from load demand and solar irradiance.
