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

This paper presents a novel inductive loop sensor which detects large (e.g., bus) as well as small (e.g., bicycle) vehicles and help a traffic control management system in optimizing the best use of existing roads. To accomplish the sensing of large as well as a small vehicle, a multiple loop inductive sensor system is proposed. The proposed sensor structure not only senses and segregates the vehicle type as bicycle or motor cycle or car or bus but also enables accurate counting of the number of vehicles that too in a mixed traffic flow condition. A prototype of the multiple loop sensing system has been developed using a virtual instrumentation scheme and tested. Field tests indicate that the prototype successfully detected all types of vehicles and counted, correctly, the number of each type of vehicles. Thus the suitability of the proposed multi loop sensor system for any type of traffic has been established.

A multiple loop vehicle detection system for heterogeneous and lane-less traffic

A correlation method is proposed for the location of partial discharge within a winding. Theoretical simulations and experimental results on a lumped parameter model of a winding are shown to prove the feasibility of the method.

A correlation method for detection of partial discharges in transformers

A matched filter approach is proposed for the location of a partial discharge within a winding. The approach is very general and does not need isolation of the capacitively transferred components. Simulations are performed on a lumped parameter model of a layer winding to prove the feasibility of the method. Experiments are also performed on a layer winding in order to validate the method. It is possible to extend the method to the determination of location of PD during impulse tests.

Location of partial discharges in transformers

Oscillating water column (OWC) based wave energy plants have been designed with several types of bidirectional turbines for converting pneumatic power to shaft power. Impulse turbines with linked guide vanes and fixed guide vanes have been tested at the Indian Wave Energy plant. This was after initial experimentation with Well’s turbines. In contrast to the Well’s turbine which has a linear damping characteristic, impulse turbines have non-linear damping. This has an important effect in the overall energy conversion from wave to wire. Optimizing the wave energy plant requires a turbine with linear damping and good efficiency over a broad range of flow co-efficient. This work describes how such a design can be made using fixed guide vane impulse turbines. The Indian Wave Energy plant is used as a case study.

Performance estimation of bi-directional turbines in wave energy plants

Despite several wave energy plants based on oscillating water column concept having been tested worldwide, wave energy has not yet gained popularity as a renewable energy source because of highly intermittent nature of available wave power. Still maintaining a constant voltage and frequency at the output, requires embedding of energy storage devices of sufficient capacity into the system. As the first stage, an impulse turbine is used to convert differential air pressure due to the oscillating water column into mechanical shaft power. A permanent magnet based alternator driven by this turbine generates variable voltage variable frequency AC, which is rectified to DC by a diode bridge. At the second stage, a DC motor - alternator set converts this into fixed frequency, fixed voltage AC acceptable as a utility AC supply. Employing MATLAB-Simulink based steady-state model of the plant and assuming an adjustable load, PID control of the output load is carried out in order to estimate the energy storage requirement especially under different climatic conditions

V. Jayashankar

Papers

A multiple loop vehicle detection system for heterogeneous and lane-less traffic

A correlation method for detection of partial discharges in transformers

Location of partial discharges in transformers

Performance estimation of bi-directional turbines in wave energy plants

Energy storage considerations for a stand-alone wave energy plant