Author
V. Jayashankar
Bio: V. Jayashankar is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Turbine & Oscillating Water Column. The author has an hindex of 13, co-authored 48 publications receiving 481 citations.
Papers
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01 Dec 2009
TL;DR: In this paper, a twin unidirectional turbine topology has been proposed as a power module for an OWC-based wave energy plant, which has no valves or moving parts.
Abstract: A twin unidirectional turbine topology has been proposed as a power module for an OWC based wave energy plant. It has no valves or moving parts and demonstrates high efficiency over a broad range of flow coefficients. Scaling laws show that a turbine of 2.6 m diameter is sufficient to achieve a power rating of 2 MW, Thirty one such modules can be used to produce an annual output of 50 GWh.
1 citations
31 Oct 2008
TL;DR: In this paper, a consistent laboratory reproduction of waveforms during impulse tests with solid insulation materials has been a difficult task, and carbon polyethylene composites can serve as benchmarks for such studies.
Abstract: A consistent laboratory reproduction of waveforms during impulse tests with solid insulation materials has been a difficult task. Carbon polyethylene composites can serve as benchmarks for such studies. Experimental results on films and a practical voltage transformer (VT) are shown that can help develop signal analysis tools.
1 citations
03 Nov 2011
TL;DR: In this paper, a twin unidirectional turbine topology has been proposed as a power module for an OWC-based wave energy plant, which has no valves or moving parts.
Abstract: A twin unidirectional turbine topology has been proposed as a power module for an OWC based wave energy plant. It has no valves or moving parts and demonstrates high efficiency over a broad range of flow coefficients. Scaling laws show that a turbine of 2.6 m diameter is sufficient to achieve a power rating of 2 MW, Thirty one such modules can be used to produce an annual output of 50 GWh.
1 citations
19 May 1997
TL;DR: In this article, a novel probe, comprising miniature pressure transducers, was designed and developed for the measurement of air velocity variations into and out of the turbine, which was first calibrated and tested at the laboratory before shifting to site for actual measurements.
Abstract: Measurement of air velocity when flow is oscillating is required in ocean wave energy studies. A special type of self-rectifying air turbine called "Wells turbine", coupled with induction generator is used for converting the air column movement in a wave energy basin to electrical energy. So far no attempts have been made to study the air velocity variations into and out of the turbine at site. Some efforts for measurement of oscillating air column at laboratory using hot-wire anemometer have been reported. A novel probe, comprising miniature pressure transducers, for the measurement of air velocity variations into and out of the turbine, was designed and developed. The probe was first calibrated and tested at the laboratory before shifting to site for actual measurements. An unidirectional oscillating air flow facility was initially setup at the existing air flow laboratory, which has a variable speed blower as the prime mover. Oscillating flow was generated by a butterfly valve, operated through a function generator. Tests at a nominal frequency of 0.1 Hz and flow velocities upto 35 m/s were conducted. Accuracies of the order of /spl plusmn/2% were estimated for the probe.
1 citations
01 Jan 2003
TL;DR: An instrumentation system for the measurement of harmonic emission to IEC 61000-3-2 is a subset of the general problem of harmonic measurements and a virtual instrument is suggested to improve the measurement accuracy of a single stage analog front end and digitiser.
Abstract: An instrumentation system for the measurement of harmonic emission to IEC 61000-3-2 is a subset of the general problem of harmonic measurements. A condition is derived for the SNR of a signal (with monotonically decaying harmonic amplitudes) to be zero due to quantization errors. This is enlarged to cover Gaussian noise in the analog front end of the measuring system. A virtual instrument, which can considerably improve the measurement accuracy of a single stage analog front end and digitiser, is then suggested.
1 citations
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TL;DR: In this paper, the progress in wave energy conversion in Europe during the past ten years is reviewed and current activities and initiatives in the wave energy sector at National and Union level are described.
Abstract: The progress in wave energy conversion in Europe during the past ten years is reviewed and current activities and initiatives in the wave energy sector at National and Union level are described. Other important activities worldwide are summarized. The technical and econ
908 citations
TL;DR: A comprehensive review of wave energy converters and air turbines can be found in this paper, together with a survey of theoretical, numerical and experimental modelling techniques of OWC converters.
594 citations
TL;DR: In this article, a review of the state of the art on self rectifying air turbines, which could be used for wave energy conversion, has been presented, and the overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of their starting and running characteristics.
221 citations
20 Jul 2008
TL;DR: In this article, the authors summarized all the advancements made and provided a composite picture of costs and trends in storage technologies, and concluded that energy storage technology has become an enabling technology for renewable energy applications and enhancing power quality in the transmission and distribution power systems.
Abstract: Overall structure of electrical power system is in the process of changing. For incremental growth, it is moving away from fossil fuel based operations to renewable energy resources that are more environmentally friendly and sustainable. At the same time it has to grow to meet the ever increasing need for more energy. These changes bring very unique opportunities and obstacles. Over the past few decades many new and innovative ideas have been explored in the broad area of energy storage. They range in size, capacity and complexity in design. Some of the systems are designed for applications in large scale power and others are performing short term energy storage ride through capabilities for critical manufacturing and technology systems. Energy storage technology has become an enabling technology for renewable energy applications and enhancing power quality in the transmission and distribution power systems. This paper summarizes all the advancements made and provide a composite picture of costs and trends in storage technologies.
180 citations
TL;DR: In this article, the authors have concentrated on issues arising while on-line transformer winding deformation diagnosis is going to be applied on transformers with various kinds of techniques, such as frequency response analysis (FRA), short circuit impedance measurement and transfer function measurement.
Abstract: On-line monitoring and diagnosis of transformers have been investigated and discussed significantly in last decade. This study has concentrated on issues arising while on-line transformer winding deformation diagnosis is going to be applied on transformers with various kinds of techniques. From technical perspective, before replacing off-line methods by on-line methods and eventually by intelligent approaches, practical challenges must be addressed and overcome. Hence, available off-line transformer winding deformation diagnosis methods are discussed precisely. Mathematical calculation in on-line short circuit impedance measurement is investigated. On-line transformer transfer function measurement setup is presented. A profound insight to the problems pertaining on-line transformer winding deformation recognition methods, characterizes existing online methods, explains the concepts behind online measurements and striving to open the discussion doors towards challenges are discussed. In the end a 400 MVA step up transformer has been taken as a case in order to clarify the capability of Frequency Response Analysis (FRA) method in fault detection while short circuit impedance could only demonstrate some rough understanding about transformer condition.
164 citations