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This paper compares the sizing of distributed energy storage systems (ESS) with two control types in order to smooth a direct wave energy converter farm production, namely a centralized one that deals with the point of common coupling (PCC) power with aggregated information and a decentralized one that deals with each unit with only local information. The main objective is to compare the two controls on the basis of their life cycle cost. The ESS is necessary for grid integration in the case considered here due to the flicker constraint. The co-optimization strategies for both the sizing and the management of an ESS are based on a rule-based energy management and a sequential approach to deal with the power quality constraint. This management strategy has been optimized for each size in order to reduce aging speed while respecting the flicker criterion. The final design is expected to minimize total system cost. The centralized control clearly allowed smaller capacity. However, it may lead to an increase in cables losses compared with the decentralized case, although it is expected to be negligible under the conditions considered in this paper. The confirmation of this hypothesis will be the objective of future work. [ABSTRACT FROM PUBLISHER]

We usually find applications of rotary induction generator, direct-drive tubular linear permanent-magnet generator, etc. for the mechanoelectrical conversion process within Stirling microcogenerator systems. This paper presents the design optimization investigation for a direct-drive tubular linear induction generator for a dual free-piston Stirling microcogenerator system. On the one hand, a high oscillating frequency and a relatively long piston's travel bring about a very high acceleration of the generator's moving part, up to 1018 m/s 2. On the other hand, the tubular linear induction generator offers many interesting assets in this application: low weight mover, appearance of levitation force, no mechanical spring, low mechanical losses, no cogging force, easy manufacture, very low investment and maintenance cost, and so on. However, the tubular linear induction generator is sparsely used, because of its a priori relatively low energetic efficiency. This paper presents a sizing optimization approach for maximizing the performance and demonstrates that, with an astute arrangement of electrical devices, the tubular linear induction generator can constitute a well adapted solution for free-piston Stirling microcogenerator systems. [ABSTRACT FROM PUBLISHER]

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]