A novel phase-locked loop for power converters of ocean current power generation system

This paper presents a novel phase-locked loop (PLL) system suitable for ocean current power generation system. It can provide phase angle for power converters to implement Park transformation accurately and timely. The electricity coming from the ocean current generator has low and variant frequency, together with harmonics. Due to the frequency-locked loop (FLL), the proposed structure is frequency adaptive. Moreover, the system employs multiple second order generalized integrators (MSOGI) and a decoupled network to isolate the positive and negative sequence components of fundamental voltage as well as the third, fifth, seventh and eleventh harmonics from the original input voltage. Simulation and experimental results validate the effectiveness of the proposed method.