A novel method of calculating current reference for shunt active power filters without hardware synchronization

A new method to calculate the source current reference and the compensating current reference for shunt active power filters (APFs) is detailed in this paper. Two parts should be obtained for the current reference. One part is the phase angle, which is obtained by calculating the fundamental-positive sequence component of the source voltage. The other part is the amplitude that is determined from the viewpoint of energy balance. Several cases are discussed to get the current reference. A new synchronization method, which is realized by performing the Fourier analysis to get the fundamental positive sequence voltage in a sliding coordinate system, is also featured in the paper, making it unnecessary for an extra synchronization circuit to the grid. Simulation and experimental results obtained from a prototype confirm the feasibility of the proposed method.