Decentralized Nonlinear Control Method of Components in Power Systems Based on Differential-Algebraic Sub-System Models

Complete nonlinear differential-algebraic equation (DAE) sub-system models are considered in the paper when designing controllers of components in power systems. First-principle models are nonlinear DAE sub-system models, but they use non-local measurable variables to describe the mutual relation (interconnection) between component and the AC grid, and thus they are not suitable for designing decentralized controllers. In the paper, component structural models are constructed, in which the localmeasurable interface variables are used to describe the mutual relation between component and the AC grid. Thus, the proposed models are equivalent to the first-principle models in essence, and have two characteristics: with local measurable interconnections and index 1. These two characteristics make it possible to transform the component structural models to nonlinear ordinary differential equation (ODE) sub-system models with measurable interconnections. Thus, traditional nonlinear control methods which are suitable for nonlinear ODE systems could be developed and expanded to be suitable for designing component controllers.