Electrical Engineering

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A method to determine suboptimal control law for large scale dynamic systems using more than one reduced order aggregated models has been proposed in this paper. The suboptimal control law derived using this method yields better performance than the one obtained by a single subsystem or a simple combination of more than one subsystems and it is less sensitive to the selection of the eigenvalues. For large-scale systems (n greater than 8) the method is computationally very attractive.

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(SoE) School of Engineering

IETE Journal of Research

SUBOPTIMAL CONTROL OF LARGE-SCALE DYNAMIC SYSTEMS.

The authors consider the application of a method based on control law reduction using Davison's model order reduction technique for multi-area load-frequency control systems. A decentralized suboptimal controller is obtained for a two-area power system. The results show that the method based on control law is computationally simpler and the performance of the controller obtained by this method compares well with those obtained by other available methods of design.

Journal of the Institution of Engineers (India): Electrical Engineering Division

DECENTRALIZED CONTROL OF LOAD-FREQUENCY CONTROL SYSTEM USING CONTROL LAW REDUCTION.

Application of Marshall's and Davison's model order reduction methods to approximate a large dynamic system requires determination of the order up to which the model can tolerably be reduced and selection of eigen values and state variables to be retained in the model. This paper establishes the integral square error and the integral absolute error criteria for the selection of eigen values and determination of the order of the Marshall's reduced model. A suitable criterion for the Davison's reduced order model has also been derived.

SELECTION OF EIGEN VALUES FOR REDUCED ORDER MODELS.

— This note points out that the model order selection criteria proposed earlier for Davison's and Marshall’s reduced order models are not applicable in many of the practical cases. A new criterion is proposed to overcome the deficiencies of the earlier methods. © 1982 IEEE

IEEE Transactions on Automatic Control

On the Selection of the Eigenvalues to be Retained in the Reduced Order Models

The transient stability of a turboalternator, connected to an infinite busbar through a reactive tieline, is investigated through Liapunov's direct method. The machine is fitted with an automatic voltage regulator (AVR) sensing the machine terminal voltage and its first time derivative. The AVR time lag is ignored and it feeds the machine directly. The governor is actuated by the load-angle deviation and its first two derivatives, and is represented by a differential equation involving one or two time lags only. The variation in the rotor direct, and quadrature-axis flux linkages has been included in the system model. Under different approximations, mathematical models for the AVR are suggested. Liapunov functions are proposed and the effect of variation in parameters of the AVR and governor on the critical fault clearing time, for a three-phase fault, is studied.

TRANSIENT STABILITY OF TURBOALTERNATOR THROUGH LIAPUNOV'S DIRECT METHOD.

The paper presents 0-1 integer programming models for the control of maintenance expenditure on thermal generating units. Choosing a sound and effective maintenance policy reduces the system down-time and thus increases the revenue to the utility. The objective is aimed at selecting that sot of proposals which will maximize the not present value of its total expected return. The alternative proposals, the forecasts of the net present value of the returns associated with the alternatives, the number of repairmen required for each alternative, and cash outflow required over the next 5 years are available for the analysis. The problem is discussed both under conditions of certainty and uncertainty. A new, simple and efficient tree search method is developed for the solution of the problems. A computer algorithm is developed and results of computation are presented for sample applications. © 1976 Taylor and Francis Group, LLC.

International Journal of Systems Science

Optimal maintenance budgetary control in generating systems

In a recent letter by Phan and Kim,A a new definition of the multiple-root sensitivity is given. However, it may be pointed out that exactly the same definition was given some time agoB and is also included in some text books,Cand is used for the same reasons as advanced by the authors. © 1973, The Institution of Electrical Engineers. All rights reserved.

Electronics Letters

Comment on new definition of multiple-root sensitivity

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Children’s Right to Play and Its Implementation: A Comparative, International Perspective

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Photoconductive Antennas (PCA) are widely used for terahertz (THz) generation and detection. These PCAs build the basis for future 6G communication as they provide a high data rate and broad bandwidth. In this work, interdigitated photoconductive antenna (IPCA) has been designed and optimized for better performance in terms of THz radiation. The proposed IPCA is made of LT-GaAs substrate material deposited on SI-GaAs. Silver material has been assumed for the IPCA electrode structure. Moreover, the dependence of IPCA on the incident laser parameters such as its wavelength (λ&nbsp;=&nbsp;800, 1060, and 1550 nm) and pulse duration (100–500 fs) has been investigated theoretically for different teeth widths (We&nbsp;=&nbsp;500, 100, 50, and 20 nm). The performance of the IPCA with various parameters such as average carrier density, conductance, total photocurrent, THz radiated power, and electric field strength, has been analyzed. The results show maximum THz electric field strength of 20.85 V/m for a photo-generated current of 1.887 A and enormous bandwidth beyond 14.9 THz with 20 nm teeth-width-based IPCA when illuminated with 100 fs 800 nm laser pulses. The proposed IPCA structure provides enhanced THz radiation compared to conventional PCA. This investigation helps the researchers to develop and integrate IPCA for future wireless communications as well as for a variety of applications, such as time-domain spectroscopy (THz-TDS), medical imaging, sensing, and security-related applications.