New strategies for estimating the coupling inductance in grid-connected direct power control-based three-phase active rectifiers

The coupling filter connected between the grid and three-phase voltage source active rectifiers (VSRs) is essential to the operation of these devices. In converters based on Direct Power Control (DPC) methods, inductors are the typical filtering option. The value of the filter inductance is needed in those methods to estimate instantaneous power and grid voltage or virtual-flux (VF). Errors when considering such a magnitude affect the system negatively. Incorporation of algorithms for online estimation of the inductance value into DPC-based methods is advisable. In this paper, new analytic algorithms aimed to achieve an accurate estimation of that value in DPC and VF-DPC methods are proposed. Furthermore, the sensitivity of the latter method to errors in the consideration of the inductance value is discussed.