A modern look at bumpless transfer: Robust, optimal, hybrid

Reliable and well-behaved switching among controllers, or bumpless transfer, is an important element of modern advanced control settings in power plants. One of its uses is the benchmarking of the new controller against the existing one, the other use is switching among several controllers to cover the entire operating load range of the plant. This paper establishes a modern steady state bumpless transfer design paradigm - a hierarchy of optimal design techniques defined by the characteristics of controller uncertainty. Within this paradigm, the internal model based robust H_∞-optimal full information steady-state bumpless transfer synthesis handles the most general controller uncertainty; simplification of controller uncertainty structure reduces the latter technique to LQ state/output transfer, while complete elimination of uncertainty provides further reduction to LQ state transfer. The paradigm is completed by indicating that all of the above techniques admit hybrid implementation, i.e. almost instantaneous controller transfer attained through either direct calculation or computational speedup.