Forced commutation controlled series capacitor (FCSC) circuit applied to stand-alone wave energy conversion buoys

Abstract

Stand-alone buoys are used as navigation aids and for scientific marine research, including the measurement of seismographic movements of the seabed as part of a tsunami warning system. Solar power is commonly used to power up the electronic devices of these buoys. However, due to limitations in delivering constant power from solar panels, linear electric generators have been employed as an alternative/additional power source to convert the energy of oceanic waves into electricity.The variable AC amplitude and frequency of the generated voltage waveform is usually converted to DC using a simple, low cost diode bridge rectifier resulting in a low operating power factor (PF) and low power transfer capacity because of the high inductive reactance of linear electric generators. A Forced Commutation Controlled Series Capacitor (FCSC) technique is employed in this paper to improve the PF of these variable amplitude and very low and variable frequency devices. FCSC circuits have been employed in the past in power transmission networks where the voltage and frequency are fixed, but never in a wave power application where the amplitude and frequency of the AC voltage are variable.This paper provides an analytical description of the proposed FCSC converter. The method is experimentally demonstrated and evaluated using a 2.25kVA test circuit. A comparison of the performance of the FSCS circuit with a standard uncontrolled single-phase diode bridge rectifier circuit is included.

Power electronic converter systems for direct drive renewable energy applications

“…The limitation on the power transfer due to the internal inductance of the generator can be overcome by shunt-connected AC capacitors , Such a method has also been used in direct drive wave generator investigation (Mueller, 2002 ). A Forced Commutation Controlled Series Capacitor (FCSC) technique (Pickert et al ., 2011 ) has been discussed to improve the power factor of the variable amplitude and low and variable-frequency voltage produced by linear wave generators.…”