For improving the rapidity and stability of the phase detection in a three-phase grid-connected system

we proposed a novel fast phase-locked loop（FPLL） method.Firstly

by analyzing the inherent relationship between the grid voltage and the phase angle

and through calculation and table looking-up

the real-time phase angle can be obtained by the proposed FPLL.Moreover

the harmonic and disturbance contents in phase angle can be eliminated by a digital low-pass filter.Experiments and comparisons between FPLL and SRF-PLL were performed under five conditions of gird voltage

including the conditions of three-phase grid voltages sag synchronously

frequency changes

phase jumps

with harmonics and phase loses

etc.The experimental results show that

compared with SRF-PLL

FPLL has a faster phase tracking speed and a better phase-locking performance.Therefore

the proposed FPLL can be widely applied in the occasions where a fast dynamic response performance in three-phase grid-connected systems is required.