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Texas A&M University

1. Mohsenizadeh, Daniel N. Control Systems: New Approaches to Analysis and Design.

Degree: 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/152775

This dissertation deals with two open problems in control theory. The first problem concerns the synthesis of fixed structure controllers for Linear Time Invariant (LTI) systems. The problem of synthesizing fixed structure/order controllers has practical importance when simplicity, hardware limitations, or reliability in the implementation of a controller dictates a low order of stabilization. A new method is proposed to simplify the calculation of the set of fixed structure stabilizing controllers
for any given plant. The method makes use of computational algebraic geometry techniques and sign-definite decomposition method. Although designing a stabilizing controller of a fixed structure is important, in many practical applications it is also desirable to control the transient response of the closed loop system. This dissertation proposes a novel approach to approximate the set of stabilizing Proportional-Integral-Derivative (PID) controllers guaranteeing transient response
specifications. Such desirable set of PID controllers can be constructed upon an application of Widder's theorem and Markov-Lukacs representation of non-negative polynomials.
The second problem explored in this dissertation handles the design and control of linear systems without requiring the knowledge of the mathematical model of the system and directly from a small set of measurements, processed appropriately. The traditional approach to deal with the analysis and control of complex systems has been to describe them mathematically with sets of algebraic or differential equations. The objective of the proposed approach is to determine the design variables directly from a small set of measurements. In particular, it will be shown that the functional dependency of any system variable on any set of system design parameters can be determined by a small number of measurements. Once the functional dependency is obtained, it can be used to extract the values of the design parameters.
*Advisors/Committee Members: Bhattacharyya, Shankar P (advisor), Darbha, Swaroop (advisor), Rasmussen, Bryan P (committee member), Rathinam, Sivakumar (committee member).*

Subjects/Keywords: Control systems; fixed structure controller; optimization; measurement based approach

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^{th} Edition):

Mohsenizadeh, D. N. (2014). Control Systems: New Approaches to Analysis and Design. (Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/152775

Note: this citation may be lacking information needed for this citation format:

Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^{th} Edition):

Mohsenizadeh, Daniel N. “Control Systems: New Approaches to Analysis and Design.” 2014. Thesis, Texas A&M University. Accessed March 20, 2019. http://hdl.handle.net/1969.1/152775.

Note: this citation may be lacking information needed for this citation format:

Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^{th} Edition):

Mohsenizadeh, Daniel N. “Control Systems: New Approaches to Analysis and Design.” 2014. Web. 20 Mar 2019.

Vancouver:

Mohsenizadeh DN. Control Systems: New Approaches to Analysis and Design. [Internet] [Thesis]. Texas A&M University; 2014. [cited 2019 Mar 20]. Available from: http://hdl.handle.net/1969.1/152775.

Note: this citation may be lacking information needed for this citation format:

Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mohsenizadeh DN. Control Systems: New Approaches to Analysis and Design. [Thesis]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/152775

Not specified: Masters Thesis or Doctoral Dissertation

EPFL

2.
Sad Abadi, Mahdieh Sadat.
Fixed-*structure* Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids.

Degree: 2016, EPFL

URL: http://infoscience.epfl.ch/record/215861

This thesis focuses on the development of robust control solutions for linear time-invariant interconnected systems affected by polytopic-type uncertainty. The main issues involved in the control of such systems, e.g. sensor and actuator placement, control configuration selection, and robust fixed-structure control design are included. The problem of fixed-structure control is intrinsically nonconvex and hence computationally intractable. Nevertheless, the problem has attracted considerable attention due to the great importance of fixed-structure controllers in practice. In this thesis, necessary and sufficient conditions for fixed-structure H_inf control of polytopic systems with a single uncertain parameter in terms of a finite number of bilinear matrix inequalities (BMIs) are developed. Increasing the number of uncertain parameters leads to sufficient BMI conditions, where the number of decision variables grows polynomially. Convex approximations of robust fixed-order and fixed-structure controller design which rely on the concept of strictly positive realness (SPRness) of transfer functions in state space setting are presented. Such approximations are based on the use of slack matrices whose duty is to decouple the product of unknown matrices. Several algorithms for determination and update of the slack matrices are given. It is shown that the problem of sensor and actuator placement in the polytopic interconnected systems can be formulated as an optimization problem by minimizing cardinality of some pattern matrices, while satisfying a guaranteed level of H_inf performance. The control configuration design is achieved by solving a convex optimization problem whose solution delivers a trade-off curve that starts with a centralized controller and ends with a decentralized or a distributed controller. The proposed approaches are applied to inverter-interfaced microgrids which consist of distributed generation (DG) units. To this end, two important control problems associated with the microgrids are considered: (i) Current control of grid-connected voltage-source converters with L/LCL filters and (ii) Voltage control of islanded microgrids. The proposed control strategies are able to independently regulate the direct and quadrature (dq) components of the converter currents and voltages at the point of common couplings (PCC) in a fully decoupled manner and provide satisfactory dynamic responses. The important problem of plug-and-play (PnP) capability of DGs in the microgrids is also studied. It is shown that an inverter-interfaced microgrid consisting of multi DGs under PnP functionality can be cast as a system with polytopic-type uncertainty. By virtue of this novel description and use of the results from theory of robust control, the stability of the microgrid system under PnP operation of DGs is preserved. Extensive case studies, based on time-domain simulations in MATLAB/SimPowerSystems Toolbox, are carried out to evaluate the performance of the proposed controllers under various test scenarios, e.g.,…
*Advisors/Committee Members: Karimi, Alireza.*

Subjects/Keywords: Fixed-structure control; fixed-order controller design; polytopic uncertainty; convex optimization; decentralized and distributed control; control structure design; inverter-interfaced microgrids.

Record Details Similar Records

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^{th} Edition):

Sad Abadi, M. S. (2016). Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids. (Thesis). EPFL. Retrieved from http://infoscience.epfl.ch/record/215861

Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^{th} Edition):

Sad Abadi, Mahdieh Sadat. “Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids.” 2016. Thesis, EPFL. Accessed March 20, 2019. http://infoscience.epfl.ch/record/215861.

Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^{th} Edition):

Sad Abadi, Mahdieh Sadat. “Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids.” 2016. Web. 20 Mar 2019.

Vancouver:

Sad Abadi MS. Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids. [Internet] [Thesis]. EPFL; 2016. [cited 2019 Mar 20]. Available from: http://infoscience.epfl.ch/record/215861.

Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Sad Abadi MS. Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids. [Thesis]. EPFL; 2016. Available from: http://infoscience.epfl.ch/record/215861

Not specified: Masters Thesis or Doctoral Dissertation

3.
Van der Marel, C.
* Controller*-

Degree: 2014, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:38d7c6a3-9cb6-4354-9d67-b15bd911c2db

Although it is still common in the field of motion control systems to first design the structure and then the controller, integrated design approaches are becoming more popular. The problem of finding optimal parameters for a parameterized structure and controller by solving an optimization problem will be referred to as it{controller-structure optimization} (CSO). These types of problems are often characterized as multi-objective and non-convex and therefore hard to solve. Especially if the parameterized structure is modelled in a finite-element (FE) environment.
This MSc thesis report presents a design approach for solving a CSO problem by using an approximate model of the parameterized structure in the form of a it{parameter-dependent state-space} (PDSS) model. The PDSS model is obtained by taking a few samples of the original structure. Each of these samples represents a it{linear time-invariant} (LTI) modal reduced state-space model. The main emphasis of this MSc thesis is to investigate whether this approach is able to approximate the solution of the original (comprehensive) CSO problem in an efficient way.
*Advisors/Committee Members: Van Wingerden, J.W., Langelaar, M., Van der Veen, G..*

Subjects/Keywords: Controller-structure optimization; parameter-dependent state-space; Mode switching; Integral optimization; Simultaneaus optimization

…iv
Table of Contents
5 *Controller*-*structure* *optimization* (CSO)
35
5-1… …subject ’Integral *Controller*-*Structure* *Optimization*’. The
initial idea was that I would carry… …*controller*-*structure*
*optimization* (CSO). In many practical cases, a sequential design… …*controller*-*structure* *optimization* (CSO) already indicates that there are
three main items… …the *controller*, the *structure* and some criteria for *optimization* purposes.
The third item…

Record Details Similar Records

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^{th} Edition):

Van der Marel, C. (2014). Controller-structure optimization using parameter-dependent modal reduced state-space models:. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:38d7c6a3-9cb6-4354-9d67-b15bd911c2db

Chicago Manual of Style (16^{th} Edition):

Van der Marel, C. “Controller-structure optimization using parameter-dependent modal reduced state-space models:.” 2014. Masters Thesis, Delft University of Technology. Accessed March 20, 2019. http://resolver.tudelft.nl/uuid:38d7c6a3-9cb6-4354-9d67-b15bd911c2db.

MLA Handbook (7^{th} Edition):

Van der Marel, C. “Controller-structure optimization using parameter-dependent modal reduced state-space models:.” 2014. Web. 20 Mar 2019.

Vancouver:

Van der Marel C. Controller-structure optimization using parameter-dependent modal reduced state-space models:. [Internet] [Masters thesis]. Delft University of Technology; 2014. [cited 2019 Mar 20]. Available from: http://resolver.tudelft.nl/uuid:38d7c6a3-9cb6-4354-9d67-b15bd911c2db.

Council of Science Editors:

Van der Marel C. Controller-structure optimization using parameter-dependent modal reduced state-space models:. [Masters Thesis]. Delft University of Technology; 2014. Available from: http://resolver.tudelft.nl/uuid:38d7c6a3-9cb6-4354-9d67-b15bd911c2db