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A review of fault tolerant design in wave energy converters

Publication . Kamarlouei, Mojtaba; Gaspar, José F.; Guedes, Carlos; Cruz, B. F.; Mendes, Mário J. G. C.

The main objective of this pape is to presente a review on typical faults including the actual development and application of the fault tolerant design techniques in WEC systems and subsystems. Also, various WEC devices are studied and categorized in three diferente maintenance levels based on the defined criteria in maintenance standard. In this paper, the oscillating body and structure, power take-off system and transmission units, control,safety and survivability units are considered as the essencial componentes of the WEC for fault and failure study. Moreover, several faults are identified and fault tolerant design techniques are proposed for these systems. Moreover, several faults are identified and fault tolerant design techniques are proposed for these systems.

2018-09-12Book part

Restricted access

Assessment of the adequacy of safety barriers to hazards

Publication . Sobral, José; Guedes Soares, Carlos

The assessment of safety barriers performance is often achieved through tests or inspections in order to determine their availability or probability of failure on demand (PFD). The ultimate objective of these activities is to observe if the safety barrier is operational and to detect possible hidden failures. However, sometimes due to error in design or changes performed on the installation, the referred safety barrier is not adequate or no longer suitable to face the current level of risk. In the present paper is made a description of safety barriers as important means concerning risky situations and a methodology to evaluate the adequacy of a safety barrier is proposed. This methodology links the safety integrity level of an assessed safety barrier to the probability of occurrence of the hazardous event that it should protect. There is a pre-selection of the classified dangerous undetected safety function failures that will be used to determine the probability of failure on demand (PFD) and the safety barrier adequacy to a specific risk. It will be also possible to estimate the probability of occurrence of a hazardous situation corresponding to the simultaneity of the initiating hazardous event and the safety barrier fault (when a demand occurs).

2019-04Journal article

Restricted access

On the experimental study of a concentric wave energy array adapted to an offshore floating platform

Publication . Kamarlouei, Mojtaba; Gaspar, José F.; Calvário, Miguel; Hallak, Thiago S.; Mendes, Mário J. G. C.; Thiebaut, Florent; Guedes Soares, Carlos

Experimental results of the dynamics of a small scale concentric wave energy converter array adapted to a floating offshore platform are presented. A small scale prototype is tested without and with twelve conical heaving point absorbers. The free decay and regular wave tests are carried out in an ocean basin to understand the hydrodynamic interactions between various elements of the floating offshore platform and wave energy converter array. Meanwhile, the heave motions of the buoys are observed in regular waves with and without dampers for the initial estimation of power take-off damping as a pitch control module. The results show the improvements in heave, pitch, and roll performance of the platform due to the interaction between the buoys and platform.

2019Conference object

Open access

Experimental analysis of wave energy converters concentrically attached on a floating offshore platform

Publication . Kamarlouei, M.; Gaspar, José; Calvário, Miguel; Hallak, T. S.; Mendes, Mário J. G. C.; Thiebaut, F.; Soares, Carlos Guedes

This paper presents an initial experimental study of wave energy converters concentrically arranged and attached on a floating offshore platform model. The 1:27 scale model, has been designed, built and tested, in two main situations, without and with twelve cone shape wave energy converters. To simulate the power take-off system in each wave energy converter, rotational friction dampers have been installed on the joints of the floaters arms to the platform deck. The experimental results show that the interaction between buoys and platform have a positive effect on the platform heave and pitch motions. However, the reduction in heave and pitch motions of the platform, after installing the wave energy converter array, depends on the damping of the equivalent power take-off system. Thus, the effect of dampers in the motion of buoys is presented to allow an initial understanding of the required damping range of the power take-off system and related control strategies.

2020-06Journal article

Open access