Online supervisor synthesis for partially observed discrete-eventsystems

A partial information supervisor that generates a class of closed controllable and observable sublanguages of a specified “legal” language is presented. This supervisor has the following features: 1) it can be implemented online (i.e., the disabled event set need only be computed once upon each event observation); 2) the computations of the disabled event set can be performed in O(mn) worst case complexity, where a is the number of states in the legal language generator and m is the number of events; 3) an online supervisor presented previously by Heymann and Lin (1993) is a special case of the new supervisor; and 4) all the languages generated by the new supervisor contain the supremal closed controllable and normal (supCCN) sublanguage of the legal language (in fact, they contain a language developed by Fa et al. (1993) that was shown to contain the supCCN sublanguage)     

On alternative methodologies for the design of robust linear multivariable regulators

This paper presents two synthesis algorithms which embody the two major variants of the numerous methodologies which have been proposed for the design of multivariable linear regulators which exhibit the property of disturbance rejection with or without additional robustness qualities. It is shown that these two procedures generally lead to substantively different compensator structures.     

An eigenvalue characterization of multivariable system zeros

A characterization of multivariable system zeros as the common eigenvalues of certain matrices is obtained. Major differences are noted between this and other approaches, including implementation and interpretation of results. In addition, a useful determinantal identity is proven.     

Computation of singular and singularity induced bifurcation points of differential-algebraic power system model

In this paper, we present an efficient algorithm to compute singular points and singularity-induced bifurcation points of differential-algebraic equations for a multimachine power-system model. Power systems are often modeled as a set of differential-algebraic equations (DAE) whose algebraic part brings singularity issues into dynamic stability assessment of power systems. Roughly speaking, the singular points are points that satisfy the algebraic equations, but at which the vector field is not defined. In terms of power-system dynamics, around singular points, the generator angles (the natural states variables) are not defined as a graph of the load bus variables (the algebraic variables). Thus, the causal requirement of the DAE model breaks down and it cannot predict system behavior. Singular points constitute important organizing elements of power-system DAE models. This paper proposes an iterative method to compute singular points at any given parameter value. With a lemma presented in this paper, we are also able to locate singularity induced bifurcation points upon identifying the singular points. The proposed method is implemented into voltage stability toolbox and simulations results are presented for a 5-bus and IEEE 118-bus systems.     

An Application of Signal Processing Techniques to the Study of Myoelectric Signals

This paper describes the use of power spectral density and cumulative power functions in the examination of the electromyogram (EMG). The EMG signals were obtained with surface electrodes from two muscles, the flexor pollicis brevis and the extensor digitorum, in four subjects. Each muscle was studied at two levels of contraction, both before and during fatigue. The power spectral density functions are compared, using a cumulative power difference function and the mean frequency of the spectrum, to determine differences between loading conditions in an individual muscle, before and during fatigue, between different muscles, between individuals (same muscle), and combinations of these conditions.     

ROBUST NONLINEAR CONTROLLER DESIGN FOR A LONGITUDINAL FLIGHT CONTROL PROBLEM

In this paper, the H_∞ approximate I/O linearization formulation and μ‐synthesis are employed to design a nonlinear controller for an aircraft longitudinal flight control problem. We propose modified nonlinear H_∞ controller formulas to approximately linearize the system and use μ‐synthesis to address tracking, regulation, and robustness issues.     

Turbine-generator system control for a HTGR power plant

Dual turbine-generator systems offer several operating advantages for large electric power generating plants. In order that these benefits be fully realized, it is necessary that the twin turbine-generator system, including its associated control systems, perform satisfactorily in a variety of normal and energy operating modes. This paper combines nonlinear simulation and linear multivariable systems analysis techniques to investigate system dynamic behavior and governor design. Specific results are reported for load following operation in which one turbine-generator is shut down.     

Local bifurcation in power systems: theory, computation, andapplication

This paper provides an of overview of local bifurcation theory and its application to power system voltage stability analysis. The qualitative behavior of power system dynamics as modeled by differential-algebraic equations is discussed, followed by a summary of the concepts and tools for the analysis of local bifurcation from equilibria. Computational methods for locating and classifying bifurcation points as they have been applied in power system analysis are reviewed. Several examples are given     

Variable structure servomechanism design and applications to overspeed protection control

A new class of variable structure feedback systems capable of rejecting a persistent disturbance is developed. This type of system which is called the VS servo is structurally similar to linear multivariable servomechanisms. Its behavior on the switching manifold and its internal stability and output regulation properties are examined using the theory of variable structure systems and sliding modes and existing results on high gain feedback.The concepts of the VS servo are particularly well suited for the study of ‘emergency’ control system design. The design of the VS servo is applied to the problem of overspeed protection control for large steam turbines. This study leads to an understanding of the generic difficulty associated with the application of overspeed protection control to large coal fired power plants and provides a feedback control structure with considerable promise for such applications. In addition, the paper serves as a useful illustration of the flexibility and potential applicability of variable structure designs. The effect of actuator parasitic dynamics is considered.