Transient Response Improvement for Interconnected Linear Systems: Low-Dimensional Controller Retrofit Approach

摘要

In this paper, we propose a method of designing low-dimensional retrofitcontrollers for interconnected linear systems. In the proposed method, byretrofitting an additional low-dimensional controller to a preexisting controlsystem, we aim at improving transient responses caused by spatially local statedeflections, which can be regarded as a local fault occurring at a specificsubsystem. It is found that a type of state-space expansion, calledhierarchical state-space expansion, is the key to systematically designing alow-dimensional retrofit controller, whose action is specialized to controllingthe corresponding subsystem. Furthermore, the state-space expansion enablestheoretical clarification of the fact that the performance index of thetransient response control is improved by appropriately tuning the retrofitcontroller. The efficiency of the proposed method is shown through a motivatingexample of power system control where we clarify the trade-off relation betweenthe dimension of a retrofit controller and its control performance.