Wave Energy Converter’s Slack and Stiff Connection: Study of Absorbed Power in Irregular Waves

Abstract

Two different concepts of wave energy converter coupled to the novel C-GEN linear generator have been studied numerically, including the evaluation of different buoy sizes. The first concept has a slack connection between the buoy and the generator on the seabed. Another concept is based on a stiff connection between the buoy and the generator placed on an offshore platform. Three different approaches to calculate the damping force have been utilized within this study: the optimal damping coefficient, R-load, and RC-load. R-load is a model for the load applied to a grid-connected generator with passive rectification. RC-load is a model for a phase angle compensation applied to a system with active rectification. The radiation forces originating from the oscillatory motion of the buoy have been approximated using the transfer function in the frequency domain and the vector fitting algorithm. A comparison of the approximation methods is presented, and their accuracy has been evaluated. The advantage of the vector fitting method has been shown, especially for higher approximation orders which fit the transfer function with high accuracy. The study’s final results are shown in terms of the absorbed power for the sea states of March 2018 at Wave Hub, UK.

Impact of translator mass and buoy choice on a power absorption of point absorbing wave energy converter linear generator with linear generator power take off

“…The connection rope is taut when the buoy moves upwards (i.e. the buoy and translator velocity are positive) and in very low energy sea conditions when the buoy moves downwards (the buoy and translator velocity are negative for the sea conditions with the wave height less than the free stroke length, which is in the present case study is 2 × 0.75 m = 1.5 m. This relation to the buoy dynamics has been studied in [26]. Namely, two concepts of similar WECs were compared: with the slack connection between the buoy and translator, where the line was allowed to slack, and with the stiff connection, where the line was firmly fixed between the buoy and translator.…”

Multi‐mode converter control for linear generator‐based wave energy system

“…On the grid side, various grid requirements must be met by electric power producers at the PCC. Each country has its own set of grid requirement codes, determined by their FIGURE 1 Wave energy converter [18].…”

“…The forces acting on the buoy and translator can be seen in Figure 3. The reader can refer to [55] and [18] for the detailed modelling of the different forces.…”

Linear Permanent Magnet Vernier Generators for Wave Energy Applications: Analysis, Challenges, and Opportunities

“…In order to extract the energy from waves, wave energy converters are extensively employed, which can be classified into several categories based on different criteria. In this paper, wave energy conversion systems are classified based on their principles of operation [43][44][45], as follows: • oscillating water column; • overtopping converter; • oscillating body system. • Among the mentioned classifications, four types of oscillating body converters perform based on linear power take-off systems.…”