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This paper sets forth a sizing optimization methodology of a surface permanent magnet machine-converter system over a torque-speed operating profile. The two optimization objectives are to minimize the cost of the machine-converter system and to minimize (or maximize) electrical energy consumption (or generation). The optimization parameters serve to describe both the machine geometry and the electrical ratings of the electronic power converter. Each operating point of the profile is treated independently, and current control is optimized at every operating point to not only minimize machine drive losses but also satisfy several constraints and then implicitly considering flux-weakening possibility. This optimization methodology is generic and is applied to a particular case: a direct-drive conversion chain for a wave energy converter (WEC). We show that taking into account both the sizing parameters of the converter and the flux-weakening control, in addition to the classical sizing parameters of the machine, has a strong impact on the machine-converter system optimal results. Moreover, the strong coupling with the WEC through damping parameters plays also a crucial role on the sizing results. [ABSTRACT FROM PUBLISHER]

This paper will begin by presenting two power takeoff (PTO) technologies for the SEAREV wave energy converter (WEC) followed by the design methodology applied to electromagnetic generator cycles for the all-electric solution. The operating principle associated with the SEAREV WEC will be described before discussing the two conversion technologies intended to transform wave energy into electricity. The types of systems are twofold: hydroelectric and all-electric. The strong coupling between the hydrodynamic, mechanical, and electrical phenomena heavily influences the behavior of the recovery (PTO) system and leads to a complex system design that requires a full-scale modeling description. A unique design methodology for the all-electric conversion chain has been developed around several distinct control modes, including one featuring power leveling. [ABSTRACT FROM AUTHOR]

Highlights • The energy conversion chain in a photovoltaic water pumping system was modelled. • Water collection by the inhabitants was included as a model input. • The model was validated by using data acquired on a system in rural Africa. • The accuracy of the model is higher than 95% when using local climatic data. • Accuracy drops of 1–3% when replacing local climatic data by satellite ones. Abstract The low electrification rate in rural sub-Saharan Africa prevents access to energy services which are essential to improve living conditions. One of these energy services is electrified water pumping, which is particularly relevant for these areas where water access continues being a significant challenge. Pumping systems powered by photovoltaic energy have emerged as an interesting solution in off-grid areas. This article presents a model of photovoltaic water pumping system (PVWPS) for providing domestic water to off-grid rural communities. The model simulates the pumped flow rate and the water level in the storage tank from the climatic data (irradiance, ambient temperature) and the profile of water collection by the users of the system. The modelling of the different stages of the energy conversion chain and a method for identifying the unknown parameters of PVWPS are presented in this article. The model is applied to a pilot PVWPS situated in a rural village of Burkina Faso. The comparison between the measurements performed on the system and the model outputs allows to validate the model experimentally. Results indicate that the model permits to accurately simulate the water height in the tank both when climatic data from local sensors and from satellite are inputted in the model. The model could therefore be applied to other off-grid areas to perform techno-economic optimization and size new PVWPS as well as to evaluate the performances of existing PVWPS. The originalities of this work include the consideration of the water collection profile as a model input and the monitoring of a PVWPS in a rural village of Sub-Saharan Africa, an area where no continuous measurements on these systems has been performed, to the best knowledge of the authors. Further, the comparison of the impact of inputting satellite climatic data instead of measured ones on the PVWPS model accuracy is also a novel contribution. [ABSTRACT FROM AUTHOR]

This paper proposes a flicker severity study for Wave Energy Converter farms. The flicker severity is introduced and the reason why it is an important constraint for a wave farm is explained. A new representation called intrinsic flicker severity is introduced which describes the flicker severity independently of the grid. The influence of device type, its control and the sea-state on average production, flicker severity and on the ratio between flicker and production are studied with three types of devices: an Oscillating Water Column and two Direct Wave Energy Converters (two point absorbers: a Heaving Buoy and the SEAREV). The influence of the size and the placement of each unit in the wave farm is presented with a farm-unit flicker ratio, compared with the square-root of unit hypothesis (noise behavior), as a function of wave direction by taking into account wave direction dispersion. Finally, solutions are presented to reduce the flicker produced to comply with grid code requirements in order to allow grid integration of wave farms. [ABSTRACT FROM AUTHOR]