Showing papers presented at "American Control Conference in 2012"

Tutorial of Wind Turbine Control for Supporting Grid Frequency through Active Power Control: Preprint

Abstract: As wind energy becomes a larger portion of the world's energy portfolio and wind turbines become larger and more expensive, wind turbine control systems play an ever more prominent role in the design and deployment of wind turbines. The goals of traditional wind turbine control systems are maximizing energy production while protecting the wind turbine components. As more wind generation is installed there is an increasing interest in wind turbines actively controlling their power output in order to meet power setpoints and to participate in frequency regulation for the utility grid. This capability will be beneficial for grid operators, as it seems possible that wind turbines can be more effective at providing some of these services than traditional power plants. Furthermore, establishing an ancillary market for such regulation can be beneficial for wind plant owner/operators and manufacturers that provide such services. In this tutorial paper we provide an overview of basic wind turbine control systems and highlight recent industry trends and research in wind turbine control systems for grid integration and frequency stability.

Battery Wear from Disparate Duty-Cycles: Opportunities for Electric-Drive Vehicle Battery Health Management

Abstract: Electric-drive vehicles utilizing lithium-ion batteries experience wholly different degradation patterns than do conventional vehicles, depending on geographic ambient conditions and consumer driving and charging patterns. A semi-empirical life-predictive model for the lithium-ion graphite/nickel-cobalt-aluminum chemistry is presented that accounts for physically justified calendar and cycling fade mechanisms. An analysis of battery life for plug-in hybrid electric vehicles considers 782 duty-cycles from travel survey data superimposed with climate data from multiple geographic locations around the United States. Based on predicted wear distributions, opportunities for extending battery life including modification of battery operating limits, thermal and charge control are discussed.

Optimal periodic control of power harvesting tethered airplanes

Abstract: This paper proposes reversed pumping as a strategy to keep tethered kites airborne in a wind-free condition without any on-board propulsion. In the context of kite power, it is shown to be a necessary addition to a rotational startup scheme. The enhanced scheme ultimately allows for injection into power harvesting orbits at high altitude, in case no wind is present near ground level. The need for reversed pumping is advocated with scaling laws, and is demonstrated in simulation by solving a proposed open-loop periodic optimal control problem. The obtained periodic orbits can be used as reference for feedback control.

Autonomous Calibration Algorithms for Planar Networks of Cameras

Abstract: We deal with the important applicative problem of distributed cameras calibration. We model a network of N cameras as an undirected graph in which communicating cameras can measure their relative orientation in a noisy way. These measures can be used in order to minimize a suitable cost function. The shape of this cost function depends on a vector of integers K. We propose two algorithms which in a distributive way estimate such K, comparing advantages and disadvantages of both. Simulations are run on a grid network to prove effectiveness of the algorithms.