H-infinity loop-shaping

About: H-infinity loop-shaping is a research topic. Over the lifetime, 57 publications have been published within this topic receiving 1524 citations.

A loop-shaping design procedure using H/sub infinity / synthesis

Abstract: A design procedure is introduced which incorporates loop shaping methods to obtain performance/robust stability tradeoffs, and a particular H/sub infinity / optimization problem to guarantee closed-loop stability and a level of robust stability at all frequencies. Theoretical justification of this technique is given, and the effect of loop shaping on closed-loop behavior is examined. The procedure is illustrated in a controller design for a flexible space platform. >

Model-Based $\hbox{H}_{\infty}$ Control of a Unified Power Quality Conditioner

Abstract: This paper presents a solution to the control of a unified power quality (PQ) conditioner (UPQC) for PQ improvement in power distribution systems. The problem formulation allows not only harmonic compensation but also voltage sags/swells, load demand changes, and power factor correction to be tackled in a unified framework. The proposed controller combines the multivariable regulator theory with H infin loop shaping, so that zero steady-state error, robustness to modeling uncertainties, and insensitivity to supply frequency variations can be accomplished simultaneously, thus providing a complete theoretical solution to all the aforementioned PQ problems. The effectiveness of the proposed controller is, in practice, verified by experimental studies on a single-phase power distribution system.

Sensitivity considerations in optimal system design

Abstract: The sensitivity of a control system is usually taken to be the normalized variation of some desired characteristic with the variation of plant or controller parameters. Rather than the usual absolute sensitivity described above, a new definition of relative sensitivity is introduced for the optimal control problem, wherein the system performance is always compared with its optimum under the given circumstances. The implications of the relative sensitivity and its relevance to optimal system design are discussed in detail. Moreover, a theoretical approach to the problem of system optimization when plant parameters are subject to change or are incompletely specified is presented.

On the Mixed H2/H-infinity Loop Shaping Trade-offs in Fractional Order Control of the AVR System

Abstract: This paper looks at frequency domain design of a fractional-order (FO) proportional-integral differential (PID) controller for an automatic voltage regulator (AVR) system. Various performance criteria of the AVR system are formulated as system norms and are then coupled with an evolutionary multiobjective optimization (MOO) algorithm to yield Pareto optimal design tradeoffs. The performance measures consist of mixed H 2 /H ∞ design objectives, such as the set-point tracking, load disturbance, and noise rejection controller effort, which are an exhaustive set of conflicting control objectives. A fuzzy logic-based mechanism is used to identify the best compromise solution on the Pareto fronts. The advantages and disadvantages of using an FOPID controller over the conventional PID controller, which are popular for industrial use, are enunciated from the presented simulations. The relevance and impact of FO controller design from the perspective of the dynamics of AVR control loop is also discussed.