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TERI Information Digest on Energy and Environment
Year : 2002, Volume : 1, Issue : 1
First page : ( 35) Last page : ( 37)
Print ISSN : 0972-6721.

Electric power engineering

 


[73]Technology solutions for improving the performance reliability of substations and T&D networks
Many utility equipments, like the power transformers in North America, are very old and show high rates of failure in terms of service. Areas of the system composed of aged equipments lend to experience a higher than average incidence of both unexpected clear-weather failures and storm related outages. The latest solutions for improving reliability and addressing maintenance issues for substations and transmission networks, is addressed with intelligent network systems that monitor and integrate the control of substations. This paper provides an overview of the current options available to utilities including application of RCM (reliability centered maintenance) programs, equipment monitoring sensors, and new expert systems for equipment diagnostics and predictive maintenance.
Electrical Review8(12):20–25
PCI Limited,
New Delhi

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[74]Controller based partitioning of power system networks
Das DB and Patvardhan C. 2001The desired features of partitions of the power networks for security control are identified in this paper. A method for partitioning based on ART-2 (adaptive resource theory) neural networks is then presented. Partitioning is done in such a way that the busbars strongly connected to a controller are placed in the same partition. Care is taken to ensure that the controllers are uniformly distributed in the partitions. An index called the PCI (partition coupling index) is defined in this paper to judge the relative independence of the partitions obtained for security control. The PCI truly reflects the extent to which the partitions are susceptible to external factors or events. The indices obtained for partitions provided by the proposed method are compared with those obtained for earlier methods for IEEE 118 bus system. The proposed method clearly provides highly independent partitions as is reflected by smaller values of PCI and the number of edges cut while retaining the partition size within manageable limits. This coupled with the high parallelization capability of ART-2 networks and their high computational speed makes the proposed method highly suitable for partitioning large power system networks.
(1 figure, 9 tables, 12 references)
Journal of the Institution of Engineers (India)82:184–188
Department of Electrical Engineers,
Dayalbagh Educational Institute, Agra - 282 005, India

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[75]Hybrid genetic algorithm solution to economic dispatch problem with multiple fuel options
Baskar S, Subbaraj P and Rao MVC. 2001This paper presents new two-phase hybrid genetic algorithm based technique to solve the economic dispatch problem with multiple fuel options. The proposed algorithm is very much useful when addressing heavily constrained optimization problem in terms of solution accuracy and computation time and it can out perform CGAs (conventional genetic algorithms). The proposed hybrid scheme is developed in such a way that a simple read coded GA (genetic algorithm) is acting as a base level search, which makes a quick decision to direct the search towards the optimal region, and local optimization by direct search and systematic reduction of the size of search region method is next employed to do fine tuning. In order to validate the effectiveness of the hybrid GAs in solving economic dispatch problems, results obtained for a system with ten-generation units are studied. The results clearly demonstrate that the proposed hybrid real coded genetic algorithm not only improve the reliability but also make the algorithm more efficient in terms of number of function evaluations to reach the global optimum point. The results show that the solution method is practical and valid for real-time applications.
(2 figures, 4 tables, 15 references)
Journal of the Institution of Engineers (India)82:177–183
Department of Electrical Engineering,
Thiagarajar College of Engineering, Madurai -625 015, India

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[76]Review of current earthing practices and recommendations
Seedher HR and Arora JK. 2001An earth electrode can vary from a single vertical rod driven into soil to a complex network of bare conductors buried in earth. Whatever be the electrode of choice it should meet the safety and other requirements. Standards are required to provide the design methodology and other necessary guidance for this purpose. Traditionally, empirical formulas are used to predict performance of electrodes; soil is often modelled to suit these formulas. There have been many developments in the analytical approach towards solving the problem. As such, the standards are being modified everywhere. In this paper, important aspects of earthing system practices prevalent in India are reviewed. Limitations of the standard IS:3043, compliance with which is mandatory for the design of earthing system in the country are discussed. Recommendations for better earthing design procedures are made.
(1 figure, 2 tables, 33 references)
Journal of the Institution of Engineers (India)82:213–218
Department of Electrical Engineering,
Punjab Engineering College, Chandigarh, India

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[77]Development of microprocessor based negative phase sequence current monitoring unit and negative phase sequence relay for an AC generator
Sengupta S and Mukhopadhyay AK. 2000The existing protection schemes for unbalance stator current in an AC generator are based on extraction of NPS (negative phase sequence) components by suitable filters from the stator current. In the present investigation, the development of NPS current in the rotor circuit during stator unbalance has been analyzed theoretically and studied experimentally. This NPS current has been sensed directly with the help of a microprocessor which measures the magnitude of the peak values and generates a trip signal according to the (I2~ t) characteristics of the generator winding. The developed scheme has been tested in the laboratory and the experimental results have been presented. The results show that since the developed system detects I2 directly from the rotor circuit of the generator, the use of current transformer and sequence filters are eliminated. The use of a microprocessor enhances the accuracy and speed of operation of the scheme and eliminates dead band of operation. However, the limitation of the present experimental set up is that since the ADC (analog to digital converter) and the microprocessor can receive a voltage up to 5 V, the signal from the rotor circuit must be limited to that range. This limitation can, of course, be eliminated by suitably choosing the ADC.
(8 figures, 4 references)
Journal of the Institution of Engineers (India)82:220–226
Department of Applied Physics,
Calcutta University, Kolkata - 700 009, India

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[78]A microprocessor based group-testing device of three phase transformers
Mukhopadhyay AK and Sengupta S. 2000The checking of vector group of a three-phase transformer is one of its essential commissioning tests. The conventional method involves a number of voltage measurement tests for identification of its vector group. In the present paper, a microprocessor-based group testing device, depending on direct comparison of primary and secondary current waveforms of the transformer, has been developed. The vector group is displayed within a very short time by this process. Necessary conceptual background and the detail hardware of the developed system have been presented in the text. The developed system has been tested in the laboratory. The developed system identifies the group of the transformer directly by the waveform comparison approach from a single set of testing. A small angular difference of 4° has been allowed to take into consideration the practical irregularities of a transformer construction.
(5 figures, 1 table, 3 references)
Journal of the Institution of Engineers (India)82:209–212
Department of Applied Physics,
Calcutta University, Kolkata - 700 009, India

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