University of California, Riverside

Department of Electrical and Computer Engineering

Control of Power Electronic Systems Using Nonparametric Models

Control of Power Electronic Systems Using Nonparametric Models

Control of Power Electronic Systems Using Nonparametric Models

March 10, 2014 - 11:00 am
Winston Chung Hall, 205/206


To take full benefits of renewable energy resources in Distributed Generation (DG) units and for the optimal operation of their interfacing power electronic circuitries, the use of robust and optimal control strategies are essential. Moreover, many other power electronic-related applications, e.g., traction systems, dc-dc converters, etc., require robust control schemes for their efficient and optimal performance. The objective of this talk is to introduce a recently developed controller design methodology and its application in various power electronic systems. 

This talk is divided into two parts. In the first part, the aforementioned robust controller design methodology in the frequency-domain is introduced. This method is based on robust loop shaping in the Nyquist diagram by convex optimization. The main interest of this approach is that almost all types of linear models (parametric with time-delay, nonparametric, and multivariable) can be treated, and almost all sorts of uncertainties (frequency-domain, parametric, and multimodel) can be straightforwardly taken into account with no conservatism. The proposed method can design simple PID controllers or high order decoupling multivariable controllers as well as gain-scheduled controllers. 

In the second part, to demonstrate the potentials of the above-mentioned controller design methodology in power electronic systems, three applications are discussed: 

1. Vector control of grid-tied VSCs with LCL-filters capable of inherently damping the filter resonance phenomenon. This is a 3rd -order Multi-Input Multi Output (MIMO) system and needs high-order controllers to provide fast dynamic response and also to damp the resonant modes of the closed-loop system. Applying the controller design approach to the nominal model of the LCL-filter-based system, a multivariable high-order controller is designed, which contrary to existing solutions for LCL-filter- based VSCs, does not require additional damping strategies.

 2. Voltage control of single-DG-unit islanded microgrids. For this application, assuming various load scenarios, a family of models is formed. Then, applying the proposed control design approach to the assumed family, two controllers are designed: (a) a cascade control strategy and (b) a single-stage control strategy capable of canceling the effect of nonlinear loads.

 3. Voltage support in weak traction networks using the active line-side converter of modern locomotives. The active line-side converter of modern locomotives is adopted to inject proper amount of reactive power to compensate for the voltage drop and overvoltage in the catenary line. The required reactive power is determined through a SISO controller.


Behrooz Bahrani received the B.Sc. degree from Sharif University of Technology, Tehran, Iran, the M.Sc. degree from the University of Toronto, Toronto, ON, Canada, and the Ph.D. degree from Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, all in electrical engineering, in 2006, 2008, and 2012, respectively. From May 2008 to November 2008, he was a Research Intern with the ABB Corporate Research Center, Dättwil-Baden, Switzerland. From September 2012 to August 2013 and from October 2013 to December 2013, he was a postdoctoral fellow at EPFL and Purdue University, respectively. He is currently a postdoctoral fellow at Georgia Institute of Technology, Atlanta, Georgia. In 2013, he was awarded the Swiss National Science Foundation Early.Postdoc.Mobility fellowship. His research interests include control of power electronic systems, applications of power electronics in power and traction systems, and grid integration of renewable energy resources.



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Electrical and Computer Engineering
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University of California, Riverside
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