Adaptive Output-Feedback Control with Closed-Loop Reference Models and Applications to Very Flexible Aircraft

Preprint of JGCD 2015-01-G001282 paper.This paper proposes an adaptive controller for a class of multi-input multi-output (MIMO) plants where the number of outputs is larger than the number of inputs, an example of which is very-flexible aircraft (VFA). A dominant presence of model uncertainties and actuator anomalies necessitates an adaptive approach for control of VFA. The proposed controller, denoted as the adaptive SPR/LTR controller, combines a baseline observer-based design with loop transfer recovery (LTR) properties and an adaptive design based on strictly positive real (SPR) transfer functions. In addition to accommodating the absence of full state measurements, the controller includes a reference model that also plays the role of an observer through a closed-loop component. Conditions are delineated under which this controller, can guarantee asymptotic reference tracking, and the control design is validated using a VFA model around a single equilibrium flight condition with 707 states, 12 outputs and 2 control inputs. Simulation results show that the adaptive controller not only ensures stability but also recovers a nominal performance both in time domain and in frequency domain despite the presence of varying wing shape and actuator anomalies.the Boeing Strategic University Initiativ

Frequency Control using Cooperative Demand Response through Accumulated Energy

This paper proposes a hierarchical control architecture for engaging demand into providing primary frequency response services. The proposed architecture relies on the use of information about accumulated energy for the aggregation of demand capabilities and dissagregation of demand responsibilities. Since the accumulated energy has a distinct additive property, the aggregation/disaggregation of demand becomes straightforward. Additional unique features of the proposed architecture are that it: i) includes the information of inflexible load in the aggregated demand, ii) allows for intuitive cooperation between load aggregators. Conditions for stability under cooperating load aggregators are derived. Finally, simulations are carried out on the IEEE 39-bus system to illustrate the proposed concepts of aggregation, disaggregation and cooperation.NSF initiative, Award no. EFRI-144130

A Practical Integration of Automatic Generation Control and Demand Response

For a power grid to operate properly, electrical frequency must be continuously maintained close to its nominal value. Increasing penetration of distributed generation, such as solar and wind generation, introduces fluctuations in active power while also reducing the natural inertial response of the electricity grid, creating reliability concerns. While frequency regulation has traditionally been achieved by controlling generators, the control of Demand Response resources has been recognized in recent smart grid literature as an efficient means for providing additional regulation capability. To this end, several control methodologies have been proposed recently, but various features of these proposals make their practical implementations difficult. In this paper, we propose a new control algorithm that facilitates optimal frequency regulation through direct control of both generators and Demand Response, while addressing several issues that prevent practical implementation of other proposals. In particular, i) our algorithm is ideal for control over a large, low-bandwidth network as communication and measurement is only required every 2 seconds, ii) it enables Demand Response resources to recover energy lost during system transients, and iii) it accommodates both measured disturbances and unmeasured disturbances. We demonstrate the viability of our approach through dynamic simulations on a 118-bus grid model.NSF initiative, Award no. EFRI-144130

Closed-loop Reference Models for Output-Feedback Adaptive Systems

Closed-loop reference models have recently been proposed for states accessible adaptive systems. They have been shown to have improved transient response over their open loop counter parts. The results in the states accessible case are extended to single input single output plants of arbitrary relative degree.Comment: v1 Submitted to European Control Conference 2013, v2 Typos correcte