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

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Wave energy in Europe: current status and perspectives

Oscillating-water-column wave energy converters and air turbines: A review

Current status of self rectifying air turbines for wave energy conversion

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.

Advancement of energy storage devices and applications in electrical power system

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.

Advanced transformer winding deformation diagnosis: moving from off-line to on-line

The near shore oscillating water column (OWC) wave energy plant at Vizhinjam, India had twin 1 m Well’s turbines and 1 m linked guide vane impulse turbines as power modules. Performance analysis of the observed records during operation yield significant insight on the dimensioning of the turbine with respect to the caisson. A cycle by cycle analysis of energy capture clearly identifies stalling behavior of the Well’s turbine. Similarly, the performance degradation of the linked guide vane due to mechanical problems could be identified. Such analysis is possible as the electrical machine is an induction generator and the moment of inertia of the system is relatively small. It is clear that optimum dimensioning of the turbine is a must with an OWC based wave energy plant.

Performance Comparison of Power Modules In the Indian Wave Energy Plant

The mechanical strength and integrity of the transformer windings is established by short circuit test. Reactance comparison method and frequency response analysis methods are conventionally used to assess the failures. Concurrent application of various high frequency excitations has also been tested. We show that optimized multisine excitation has the potential of high sensitivity towards displacement identification.

Sensitive method for detection of winding deformation during short circuit test

A fuzzy logic approach is proposed for identification and classification of faults based on records obtained during impulse tests on transformers. The outputs of three filters form the basis of identification. Experiments are performed on a physical lumped parameter model of a winding to identify breakdown, partial discharge and the presence of non-linear element within the winding. The location of breakdown can also be estimated.

Fuzzy Logic based Fault Classification of Impulse Test Records

Results from near-shore bottom standing Oscillating Water Column (OWC) based wave energy plants in Japan and India have now been available for about a decade. The most complete and detailed experimental results with near shore OWC plants are possibly from the one at Sakata port, Japan. Experience in Europe is mostly with shoreline devices as evidenced in the LIMPET and other similar plants. The plant in India is the longest standing device since its commissioning in 1991. It is unique in that several power modules with different turbines have been tested. Recently a proposal has been made to use twin unidirectional turbines in lieu of traditional bidirectional turbines promising very significant improvements in the power module efficiency. However, as experience has shown, the overall efficiency is also dependent on matching the power module to the OWC. In this work we review the principal design features that were initially considered for the Indian wave energy plant in the light of recent developments. We suggest methods for optimizing the overall performance in order to design the next generation OWC plant. The work will also be useful for planning newer installations. The influence of the power module on the overall efficiency will be clearly highlighted. As an example we estimate the performance of the Sakata port design with proposed twin unidirectional impulse turbines instead of twin 1.337 m Wells turbines using the experimentally observed hydrodynamic efficiencies. We show the performance of a wave energy plant designed for Indian conditions based on a comparison of the two designs for a plant with an overall width of 10m. The calculation is done for both monsoon and non monsoon conditions and the significant conclusions are highlighted. Cost estimates for two different plant sites, one island and one mainland, are also provided.

Techno-Commercial Study of Twin Unidirectional Turbine Based Wave Energy Plants

Many lesions remain undetected in normal ultrasound B mode imaging of cancerous tissues because of their isoechoic nature and poor contrast. Imaging of the elastic properties of tissue provides new information which is correlated with tissue pathology. A quantitative analysis of the improvement in the diagnosis of the tumor by combining the ultrasound B mode imaging and elastography is carried out. Quantification is based on the textural parameters measured from the ultrasound B mode image and strain measured from the elastogram. Polyacrylamide gel based tissue mimicking phantoms were used for the analysis.

V. Jayashankar

Papers

Performance Comparison of Power Modules In the Indian Wave Energy Plant

Sensitive method for detection of winding deformation during short circuit test

Fuzzy Logic based Fault Classification of Impulse Test Records

Techno-Commercial Study of Twin Unidirectional Turbine Based Wave Energy Plants

Improved Diagnosis of Breast Tumor by Combining Ultrasound Elastography and Tissue Characterization — Phantom Based Analysis