Nonlinear control for AC/DC power system with nonlinear loads

In view of the nonlinearity of loads and HVDC in power systems, the M derivative, M bracket and MIMO feedback linearization based on nonlinear differential algebraic system (NDAS) are introduced into the design of nonlinear controller for parallel AC/DC power system. Bronovsky normal form for NDAS is derived when the M relative degree of NDAS is less than its dimension and certain designated conditions are satisfied. The control laws of both the excitation system and the rectifier current control for AC/DC system are studied in depth, which combine the input-output linearization technique and zero dynamics design theory for NDAS. The simulation for a single-machine infinite bus system (SMIBs) with parallel AC/DC transmission lines shows that the nonlinear control strategy is able to improve system dynamic performance for a variety of system operating conditions.