Mark J. Balas

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The standard region 2 control scheme for a variable-speed wind turbine, tc5Kv , has several shortcomings that can result in significant power loss. The first of these is that there is no accurate way to determine the gain K; modeling programs are not accurate enough to represent all of the complex aerodynamics, and these aerodynamics change over time.(More)
This paper introduces a methodology for the synthesis of nonlinear finite-dimensional output feedback controllers for systems of quasi-linear parabolic partial Ž . differential equations PDEs , for which the eigenspectrum of the spatial differential operator can be partitioned into a finite-dimensional slow one and an infinitedimensional stable fast(More)
This paper proposes a methodology for the synthesis of nonlinear finite-dimensional time-varying output feedback controllers for systems of quasi-linear parabolic Ž . partial differential equations PDEs with time-dependent spatial domains, whose dynamics can be partitioned into slow and fast ones. Initially, a nonlinear model reduction scheme, similar to(More)
Using a singular perturbation formulation of the linear time-invariant distributed parameter system, we develop a method to design finite-dimensional feedback compensators of any fixed order which will stabilize the infinite-dimensional distributed parameter system. The synthesis conditions are given entirely in terms of a finite-dimensional reduced-order(More)
Variable speed wind turbines are designed to follow wind speed variations in low winds in order to maximize aerodynamic efficiency. Unfortunately, uncertainty in the aerodynamic parameters may lead to sub-optimal power capture in variable speed turbines. Adaptive generator torque control is one method of eliminating this suboptimality; however, before(More)
In this paper we develop a very general projection approach to obtain and unify necessary and sufficient conditions for making a linear timeinvariant system positive real using static output feedback. Such systems are called “Almost positive Real”. These conditions are that the open-loop system must be weakly minimum phase, have positive definite high(More)
A new control problem called Disturbance Tracking Control (DTC), which arises in active control of variable speed horizontal axis wind turbines for electric power generation, was developed previously. Feedback control of a linear plant, which is persistently disturbed, must cause the plant output to track a linear function of the disturbance. This control(More)
Many systems must operate in the presence of delays both internal to the system and in its inputs and outputs. In this paper we present a new robustness result for nonlinear systems. We use this result to show that for small unknown input delays, a simple adaptive controller with leakage can produce output regulation to a neighborhood with radius dependent(More)
A new control problem called Disturbance Tracking Control (DTC), which arises in active control of variable speed horizontal axis wind turbines for electric power generation, was developed previously. Feedback control of a linear plant, which is persistently disturbed, must cause the plant output to track a linear function of the disturbance. This control(More)