In order to optimise a tidal energy conversion system operation, maintenance and power generation aspects have to be taken into account. As a result the key focus of this paper is to propose and investigate an alternative method of implementing a tidal energy conversion system using a pitch-regulated turbine and a variable-speed squirrel cage induction generator with long distance converters. The generator power output can be optimised by utilising variable-speed control strategies allowing the system to operate at maximum power coefficient while availability can be increased by reducing the components installed offshore by using long three-phase cables between the generator and onshore voltage source converters. The tidal current energy conversion system is investigated by developing a full resource-to-grid model in MATLAB/Simulink and by performing system analysis regarding the effects of harmonics. Simulation results show that by manipulating the harmonic components, by adding passive filters, the problems associated with the harmonics and the reflecting voltage waves in the cables can be minimised.