The rapid and accurate fundamental positive sequence active current detection method is very important for the protection and control for modern power system. However, many traditional methods need to use the phase locked loop (PLL), the low pass filter (LPF) or αβ and dq coordinate transforms which increase the complexity of the detection and have the large detection errors in three-phase unsymmetrical system. In view of these problems, many novel detection methods were proposed. In this paper, two detection methods based on the fan-in vector transformation will be analyzed and compared by theory and simulation under different grid conditions. The simulation results verify that both of these methods can detect the fundamental positive sequence active current accurately. But the speed of detection is different.

Fundamental positive sequence active current,fan-in vector transformation,amplitude integrator,cascaded delayed signal cancellation