Dynamic Analysis of a Grid-Connected Marine-Current Power Generation System Connected to a Distribution System

This paper presents dynamic-performance enhancement of a grid-connected marine-current power-generation system consisting of an induction generator (IG) driven by a marine-current turbine (MCT) through a gearbox. The studied 1.5-MW MCT-IG set is connected to an onshore 23-kV distribution system through an undersea cable, two onshore back-to-back power-electronics converters (PECs), and an onshore step-up transformer. The mathematical models of the studied marine-current power-generation system including marine-current speed, three-blade mechanical system, gearbox, IG, PECs, undersea cable, step-up transformer, etc. are established and combined together. The DC-link voltage between the two PECs and the generated active power of the IG are controlled by the PECs using the designed fuzzy logic controller (FLC). Time-domain simulations based on the developed nonlinear model of the studied marine-current power-generation system subject to various torque-disturbance conditions are performed. It can be concluded from the simulated results that the generated power of the studied marine-current power generation system can be effectively controlled to deliver to the grid by the proposed control scheme under the selected operating conditions.