Pseudo-Random Sequences in DQ-Domain Analysis of Feedforward Control in Grid-Connected Inverters

Abstract Grid-parallel inverters are typically used to connect renewable energy sources to a power grid. The impedance mismatch between the grid and the interfacing circuit can generate harmonic resonances which may lead to reduced power quality. The impedance mismatch can be mitigated by applying an inverter that employs feedforward control. This paper presents a novel DQ-domain technique, based on pseudo-random sequences, for acquiring the impedance information and verifying the effectiveness of the feedforward control. The results can be used for tuning the feedforward control and as a method to perform fast on-line stability analysis of grid-connected systems in the DQ domain.