A real time sliding mode control for a wave energy converter based on a wells turbine. (1st September 2018)

• Record Type: Journal Article
• Authors: Barambones, Oscar; Cortajarena, José A.; Gonzalez de Durana, José M.; Alkorta, Patxi
• Is Part Of: Ocean engineering. Volume 163(2018)
• Page Start: 275
• Page End: 287
• Publication Date: 2018-09-01
• Subjects: Wave power -- Wave energy converters -- Sliding mode control -- Real-time control -- DFIG (doubly-fed induction generator); Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2018.05.058
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Due to the nonlinear dynamics and uncertainties usually present in wave energy conversion systems, the efficiency of these devices can be enhanced employing a robust control algorithms. Wave energy converters are constructed using electric generators of variable velocity, like double feed induction generator (DFIG) since they may improve the system efficiency to generate power when compared to fixed speed generators. The main reason is that this generators with variable speed may adapt the speed of the turbine in order to maintain the optimal flow coefficient values which improves the efficiency of the Wells turbine. However, a suitable speed controller is required in these systems first in order to avoid the stalling phenomenon and second in order to track the optimal turbine reference velocity that optimizes the power generation. In this paper a real time sliding mode control scheme for wave energy conversion systems that incorporate a Wells turbine and a DFIG is proposed. The Lyapunov stability theory is used to analyse the stability of this control scheme under parameter uncertainties and system disturbances. Next, the proposed control scheme is validated first by means of some simulation examples using the Matlab/Simulink software and second using a real-time experimental platform based on a dSPACE DS1103 control board. Highlights: A real time sliding mode control for variable speed wave power generation plants is proposed. The proposed control law improves the system efficiency compared to fixed speed generators, because turbine speed can be adjusted as a function of the flow coefficient to maximize the output power. The proposed control avoids the stalling phenomenon that usually appears in the wave power generation plants based on the wells turbines. The stability analysis of the proposed controller is provided under disturbances and parameter uncertainties by using the Lyapunov stability theory. The Real time experimental results show, on the one hand that the proposed controller provides high-performance dynamic characteristics, and on the other hand that this scheme is robust with respect to the uncertainties that usually appear in the real systems.