Maximum power point tracking for tidal turbine generator

Abstract

Tidal energy is a clean and environment-friendly energy source. It has many advantages such as sustainability, low initial cost, abundant and highly predictable due to its regular pattern. The working principle of tidal energy conversion system (TECS) is to use the potential and kinetic energy of the ocean waves caused by the celestial gravitation to drive the turbine that is coupled with a generator to produce electricity. However, due to the physical structure of the generator, the power output is closely related with water speed, direction, load amount, etc., which show highly non-linear characteristics. The water speed and direction of the tidal stream are closely related to the moon phase, which can be considered as deterministic factor. However, there are non-deterministic factors such as sea habitat migration, seaweed entanglement, bio-foiling, etc. that can make the power output sub-optimal. In order to extract the maximum potential of tidal power in terms of electricity, the maximum power point (MPP) needs to be monitored and tracked in real time. In this paper, we will review state-of-the-art MPP tracking (MPPT) of TECS such as optimal tip speed ratio (TSR) method, optimum relation based (ORB) method, and perturb and observe (P&O) method. Based on the reviewed methods, we summarize the principles, advantages and limitations of the methods, and show the performance of MPPT based on P&O in TECS with simulated results.