Parameterization of All State-Feedback Retrofit Controllers

Sasahara, Hampei; Ishizaki, Takayuki; Imura, Jun-ichi

doi:10.1109/cdc.2018.8619811

Cited by 9 publications

(17 citation statements)

References 19 publications

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“…which is more general than (7). This general parameterization, derived in [9,10], further shows that the retrofit controller in Definition 2.1 can be characterized as a controller such that the transfer matrix from v to w of the local control system isolated from the environment is kept invariant. This can be seen as follows.…”

Section: General Formulationmentioning

confidence: 93%

“…In the line of our previous work, it is shown that such a retrofit controller from the standpoint of each subsystem operator can be designed without requiring any model of its environment; see [7][8][9][10] and references therein. However, this, at the same time, implies that no information of an actual environment is used for retrofit controller design.…”

Section: Introductionmentioning

confidence: 92%

“…In the rest of this paper, as following the terminology used in [7][8][9][10], we refer to a retrofit controller K parameterized in Proposition 2.1 as an output-rectifying retrofit controller. Note that such retrofit controllers are conditioned by the transfer matrices G yu and G yv that are relevant to the subsystem G, but not to the environment G. In other words, an output-rectifying retrofit controller can be designed only with the model information of G isolated from G.…”

Section: General Formulationmentioning

confidence: 99%

“…For dynamical network systems, a modular design method of decentralized controllers has been introduced in the context of retrofit control [7][8][9][10]. The retrofit control can be applied to a general stable network system whose subsystems are supposed to be managed by their corresponding subsystem operators.…”

Section: Introductionmentioning

confidence: 99%

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Retrofit control with approximate environment modeling

et al. 2019

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In this paper, we develop a retrofit control method with approximate environment modeling. Retrofit control is a modular control approach for a general stable network system whose subsystems are supposed to be managed by their corresponding subsystem operators. From the standpoint of a single subsystem operator who performs the design of a retrofit controller, the subsystems managed by all other operators can be regarded as an environment, the complete system model of which is assumed not to be available. The proposed retrofit control with approximate environment modeling has an advantage that the stability of the resultant control system is robustly assured regardless of not only the stability of approximate environment models, but also the magnitude of modeling errors, provided that the network system before implementing retrofit control is originally stable. This robustness property is practically significant to incorporate existing identification methods of unknown environments, because the accuracy of identified models may neither be reliable nor assurable in reality. Furthermore, we conduct a control performance analysis to show that the resultant performance can be regulated by adjusting the accuracy of approximate environment modeling. The efficiency of the proposed retrofit control is shown by numerical experiments on a network of second-order oscillators.

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Section: General Formulationmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 92%

Section: General Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Retrofit control with approximate environment modeling

et al. 2019

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“…* This paper builds on its proceedings versions[25]-[27], as collecting the results on the Youla parameterization of retrofit controllers discussed in several different settings. The modular design method of decentralized controllers in this paper is developed based on those preliminary results, for which detailed mathematical proofs are also provided.…”

mentioning

confidence: 99%

Modularity in Design of Dynamical Network Systems: Retrofit Control Approach

Ishizaki

Sasahara

Inoue

et al. 2021

IEEE Trans. Automat. Contr.

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In this paper, we develop a modular design method of decentralized controllers for linear dynamical network systems, where multiple subcontroller designers aim at individually regulating their own control performance with accessibility only to respective subsystem models. First, from the standpoint of a single subcontroller designer who manages his own subsystem, we derive a constrained version of the Youla parameterization that characterizes all retrofit controllers, defined as an add-on type subcontroller such that the resultant feedback system is kept robustly stable for any variation of neighboring subsystems, other than the subsystem of interest, as long as the original system before implementing retrofit control is stable. Then, we find out a special internal structure of the retrofit controllers under the supposition that the interaction input signal coming from neighboring subsystems is measurable. We further show that the simultaneous implementation of multiple retrofit controllers, designed by individual subcontroller designers, can contribute to improving entire control performance in the sense of an upper bound. Finally, its practical significance is demonstrated by an illustrative example of frequency regulation with the IEEE 68-bus power system model.

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