A Characterization of All Retrofit Controllers

Hampei Sasahara, Takayuki Ishizaki, Masaki Inoue, Tomonori Sadamoto, Jun Ichi Irnura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


In this paper, we give a characterization of all retrofit controllers for control of large-scale network systems. A retrofit controller is a local plug-in controller such that, rather than an entire network system model, only a model of the subsystem of interest is required for controller design. The retrofit controller guarantees the entire system stability for any (norm-unbounded) variations of neighboring subsystems, other than the subsystem of interest, as long as the network of the subsystem and neighboring subsystems is stable. Although a design procedure of a retrofit controller has been already proposed, how to characterize all retrofit controllers still remains an open question. We consider two cases where the interconnection signal is available and unavailable as a feedback signal. It is revealed that, in the case where the interconnection signal is available, all retrofit controllers are composed of a localizing compensator that cancels out the input-to-output map from the interconnection signal to the measurement signal, and a local controller that locally stabilizes the subsystem. It is also found that, in the case where the interconnection signal is unavailable, the effect from the measurement signal to the control input must be cancelled out in the controller. Finally, the effectiveness of retrofit control is verified through a numerical example of a benchmark model representing the bulk power system in the eastern half of Japan.

Original languageEnglish
Title of host publication2018 Annual American Control Conference, ACC 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages6
ISBN (Print)9781538654286
Publication statusPublished - 2018 Aug 9
Event2018 Annual American Control Conference, ACC 2018 - Milwauke, United States
Duration: 2018 Jun 272018 Jun 29

Publication series

NameProceedings of the American Control Conference
ISSN (Print)0743-1619


Other2018 Annual American Control Conference, ACC 2018
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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