IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

<a href="https://www.sciencedirect.com/topics/engineering/nonlinear-feedback">Nonlinear feedback</a> linearization techniques are being used for transforming nonlinear power system dynamics into <a href="https://www.sciencedirect.com/topics/engineering/feedback-control-systems">closed loop systems</a>, whose dynamics are linear over wide range of operating conditions. This facilitates use of <a href="https://www.sciencedirect.com/topics/engineering/linear-technique">linear techniques</a> for designing <a href="https://www.sciencedirect.com/topics/engineering/feedback-controller">feedback controllers</a> to damp out oscillations. The advantage of using such feedback controllers is that they do not depend on the system operating conditions unlike the conventional controllers, for example a conventional power system stabilizer. A nonlinear feedback law is proposed in this work, which converts a nonlinear power system into closed loop decentralized linear time varying systems. A feedback controller has been designed using linear quadratic regulator with prescribed degree of stability to stabilize the decentralized linear time varying systems. The performance of the proposed method has been tested on a 16-machine, 68-bus system representing interconnected New England Test system (NETS) and New York Power System (NYPS).

Department of Electrical Engineering

World University root node

Electric Power Systems Research

A decentralized nonlinear feedback controller with prescribed degree of stability for damping power system oscillations

Static Var compensator (SVC) provides reactive power support at a bus to maintaining bus voltage. When provided with a supplementary feedback controller SVC can improve system dynamic performance by damping out inter area oscillations. The conventional supplementary controller of SVC is designed by linearizing the system around an operating point. Since, it is designed at a single operating condition its performance in different operating conditions is not guaranteed. In recent years direct feedback linearization techniques (DFL) are used for designing feedback controllers. The advantage with DFL is that linearizing the system around an operating point is not required thereby making the controller independent of operating conditions. In this paper, a nonlinear supplementary controller to SVC has been proposed which utilizes DFL with prescribed degree of stability. The proposed nonlinear supplementary controller does not depend on system operating condition and is a decentralized controller. The proposed method has been implemented on 16 machines, 68 bus system representing interconnected New England Test system (NETS)-New York Power System (NYPS).

IET Conference Publications

A decentralized nonlinear feedback controller for SVC with prescribed degree of stability for damping power system oscillations

Line power flow control can be effectively achieved through series compensator. Thyristor controlled series compensator (TCSC), in addition to its primary task of controlling the power flow in the transmission line, can also be used for damping inter-area oscillations. The effectiveness of a TCSC in damping inter-area oscillations depends on its location in the system. A method is proposed in this paper which suggests suitable location for TCSC placement to damp inter-area oscillations using a modal controllability index termed as line index. The effectiveness of the proposed method is demonstrated on New England 39-bus system. © 2005 IEEE.

2005 IEEE Power Engineering Society General Meeting

A modal controllability index for optimal placement of TCSC to damp inter-area oscillations

The spreading resistance between two parallel contacts, the smaller of which is located arbitrarily over the area of the larger, is of wide interest in electrical/thermal design of devices and ICs. We propose a simple, continuous, and asymptotically correct closed-form expression to predict the accurate but involved calculations of this resistance for all contact conditions. The contacts may be rectangular or circular, and the boundary condition on these may either be equipotential/isothermal or uniform current density/uniform heat flux. The validity of the model is established by comparisons with accurate numerical calculations of spreading resistances having aspect ratios in the range zero to 1000 and with experimental observations. © 2005 IEEE.

IEEE Electron Device Letters

A unified compact model of electrical and thermal 3-D spreading resistance between eccentric rectangular and circular contacts

The power system stabilizers (PSS) are widely used for damping out the oscillations in a large power system. The interactions of multiple PSS may adversely affect the system stability, hence, they must be properly coordinated. An optimal control strategy with pseudo-decentralization is proposed for the coordination of multiple PSS. FACTS controllers such as static Var compensator (SVC) and thyristor controlled series compensator (TCSC) are used mostly for improving voltage/reactive power and power flow control. These along with supplementary controllers can also be used for damping out the oscillations in the system. The strategy for coordination of the multiple PSS has also been extended for the coordination of supplementary controllers of SVC and TCSC with PSS. The proposed technique has been tested on 39-bus New England system.

International Energy Journal

Optimal control strategy using pseudo-decentralization for coordination of power system stabilizer and FACTS in a multi-machine system

This paper describes an efficient methodology for testing dedicated clock lines in Field Programmable Gate Arrays (FPGAs). A H-tree based clocking architecture is proposed along with a test scheme. The H-tree architecture provides optimal clock skew characteristics. The H-tree architecture consumes at least 25% less of the routing resources when compared to conventional clock routing schemes. A testing scheme, which utilizes the partial reconfiguration capabilities of FPGAs through selective re-programming of the Complex Logic Blocks, to detect and locate faults in the clock lines is proposed

Department of Computer Science and Engineering

Field Programmable Logic and Application

Testable Clock Routing Architecture for Field Programmable Gate Arrays

Case-based reasoning is an area of artificial intelligence which deals with using past cases for solving new problems. Representation of design cases is an important issue in the development of case based design systems. The requirements of a representation scheme for design cases are discussed in this paper. A representation scheme has been proposed that enables not only browsing through past design cases, but also enables reasoning about the designs. The representation is based on an object oriented approach, upon which a reasoning mechanism called complementary view model is built. The components of the case base are described in order to bring out the use of the above mechanisms in their representation. © 1997 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved.

Department Of Civil Engineering

Computers and Structures

Object oriented representation of design cases

This paper proposes an approach for reusing design methods from past designs for solving new problems. This is an application of case-based reasoning to design. The proposed approach is implemented as a prototype system called CADREM. CADREM has been tried in the domain of conceptual structural design of buildings. First, a description of case-based reasoning is given followed by its application in design. Then follows a description of the proposed approach and CADREM. Sample outputs from CADREM are also included.

Engineering with Computers

CADREM: A case-based system for conceptual structural design

This paper discusses the issues related to retrieval of cases in a case-based design system. The limitations of the conventional approaches are brought out, and this is followed by a description of a new approach to indexing and retrieval. This approach aims at capturing control knowledge required for retrieval from individual retrieval examples. Since this approach is based on past retrieval examples, we call it RBEX (Retrieval Based on EXamples). The proposed approach is implemented in a prototype system called CADREM. CADREM uses design methods used in solving past design problems to solve new problems. This is closer to the derivational analogy approach rather than the more common transformational analogy. CADREM has been tried in the domain of conceptual structural design of buildings. Sample outputs from CADREM are also included.

Indexing and retrieval of cases in a case-based design system

This paper discusses an approach to representing design cases using the methods used in solving specific design problems. This differs from the conventional representation of design cases in that they are not based simply on attribute-value pairs. It is argued that this approach offers a more powerful representation for reuse in future designs.