Sequential Distributed Development of Multiple Retrofit Controllers: Independence of Identification, Design, and Operation

This paper is concerned with sequential distributed development of multiple retrofit controllers managed by respective local controller designers. Retrofit control is a modular control approach for stable network systems. From the standpoint of a single controller designer, the subsystems managed by all other designers can be regarded as an unknown environment, an approximate model of which is supposed to be accessible in local controller design. This paper shows that, for the identification of approximate environment models, all environments for controller designers are invariant with respective to the design parameters in all retrofit controllers. Furthermore, it is also shown that local control performance in response to a local disturbance is improved as improving the accuracy of a corresponding approximate environment model. The significance of the theoretical results is verified through an example of power systems control.