Fault-Tolerant Control of Current Measurement Circuits for Three-Phase Grid-Connected Inverters

Abstract

Three-phase grid-connected inverters (GCIs) are essential components in distributed generation systems, where the accuracy of current measurement circuits is fundamental for reliable closed-loop operation. Nevertheless, the presence of a DC offset in the measured current can disrupt the regulation of grid currents and significantly degrade system performance. In this work, a fault-tolerant control approach is introduced to counteract the impact of such offset faults through a dedicated current compensation mechanism. The proposed solution is built around two main stages: (i) detecting and isolating DC offset faults that may appear in one or multiple phases of the measured grid currents, and (ii) estimating the fault magnitude and reconstructing the corrected current signal. The offset magnitude is obtained analytically by examining the grid current projected onto the synchronous d-axis at the grid angular frequency, eliminating the need for any additional sensing hardware. Simulation and experimental investigations conducted under several fault scenarios confirm the robustness of the proposed strategy and highlight significant improvements in detection speed and diagnostic accuracy.

Conflict of Interest Statement

The authors declare no conflicts of interest.