An innovative generic platform to simulate real-time PTO damping forces for ocean energy converters based on SIL method

Abstract

This paper proposes a generic PTO (power-take-off) simulation platform which can be used to predict how devices perform in wave conditions when a simulated real-time linear or non-linear PTO damping forces is employed. The experimental platform could be used to investigate the maximum power output of wave converters(WECs) without constructing a physical PTO system and complex control strategies at the design stage of a WEC, thus making it efficient and inexpensive to explore different PTO solutions. For this purpose, a software-in-the-loop (SIL) simulation method is adopted which uses an innovative control loop running on an inexpensive real-time controller coupled to a DC motor which simulates the PTO damping torque. To calibrate the proposed PTO simulation platform, 1349 drop tests are carried out. A series of relationship curves and corresponding equations are drawn for both the linear and non-linear PTO cases. Moreover, correlation curves for input gains and the produced damping force coefficients are provided. The correlation indicates the PTO simulation platform's capacity of simulating linear PTO can reach 40–220 and can reach 10–70 for quadratic damping in terms of damping force coefficient. To investigate the accuracy of the platform, uncertainty analyses are also carried out in good details. The calibrating tests and uncertainty analyses indicate that the proposed experimental platform can be used to overcome many of the limitations in modelling PTO systems at laboratory scale to simulate both real-time linear and quadratic PTO damping forces.