A Comparative Analysis of Linear and Nonlinear Control of Wave Energy Converter for a Force Control Application

  • Arvind Parwal Uppsala University https://orcid.org/0000-0002-5711-8961
  • Martin Fregelius Department of Engineering sciences, Uppsala University, Sweden
  • Pedro Almeida Department of Electrical Energy, Universidade Federal de Juiz de Fora, Brazil
  • Olle Svensson Department of Engineering sciences, Uppsala University, Sweden
  • Irina Temiz Department of Engineering sciences, Uppsala University, Sweden
  • Janaina G. Oliveira Department of Electrical Energy, Universidade Federal de Juiz de Fora, Brazil
  • Cecilia Boström Department of Engineering sciences, Uppsala University, Sweden
  • Mats Leijon Department of Engineering sciences, Uppsala University, Sweden and Department of Electrical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
Keywords: current control, force control, neural NARMAX, permanent magnet linear generator (PMLG), wave energy converter.

Abstract

The aim of wave energy converters (WECs) is to harvest the energy from the ocean waves and convert into electricity. Optimizing the generator output is a vital point of research. A WEC behaves as a nonlinear system in real ocean waves and a control that approximates the behaviour of the system is required. In order to predict the behaviour of WEC, a controller is implemented with an aim to track the referenced trajectory for a force control application of the WEC. A neural model is implemented for the system identification and control of the nonlinear process with a neural nonlinear autoregressive moving average exogenous (NARMAX) model. The neural model updates the weights
to reduce the error by using the Levenberg-Marquardt back-propagation algorithm for a single-input-single-output (SISO) nonlinear system. The performance of the system under the proposed scheme is compared to the same system
under a PI-controller scheme, where the PI gains have been tuned accordingly, to verify the control capacity of the proposed controller. The results show a good tracking of dq (direct-quadrature) axes currents by regulating the stator
currents, and hence a force control is achieved at different positions of the translator. The dynamic performance of the control is verified in a time domain analysis for the displacement of the translator.

Published
2020-06-26
How to Cite
Parwal, A., Fregelius, M., Almeida, P., Svensson, O., Temiz, I., Oliveira, J., Boström, C., & Leijon, M. (2020). A Comparative Analysis of Linear and Nonlinear Control of Wave Energy Converter for a Force Control Application. International Marine Energy Journal, 2(1 (Nov), 39-50. https://doi.org/10.36688/imej.2.39-50
Section
Directly submitted articles