Power And Energy Needed For Starting A Vertical Axis Marine Current Turbine

Abstract

A marine current power station has been deployed in Söderfors, Sweden. It comprises a five bladed fixed pitch vertical axis H-rotor turbine directly connected to a permanent magnet synchronous generator. The turbine is rated for 1.3 m/s, but at lower water speeds the turbine is generally not self starting. This paper investigates the energy and power needed to at low speeds start the turbine electrically with a BrushLess DC (BLDC) motor until  he turbines gives a net positive torque to the generator. A range of startup BLDC powers have been investigated. It is shown that for three water speeds (0.98 m/s, 1.04 m/s and 1.16 m/s) the energy needed for start up is equivalent to less than 1.2 s of power production at maximum power capture of the turbine. The startup time is mostly dependent on BLDC power setting, not on water speed. A BLDC power of 1/7th of rated power of the machine is enough to start the machine within 2 seconds. The results suggest that a higher BLDC power than that will not significantly reduce the startup time nor reduce the energy needed (increase the efficiency of the startup process). The water speed has the highest impact on the time it takes to recover the energy needed for startup once the BLDC power is well above the losses in the system.Marine Current Powe