A Simple Open-Circuit Detection Strategy for a Single-Phase Grid-Connected PV Inverter Fed From Power Optimizers

A simple and real-time open-circuit fault (OCF) detection method is proposed for a single-phase grid-connected photovoltaic inverter fed by series-connected power optimizers (POs). To implement the proposed method, PO controllers periodically monitor POs' output voltage variations and calculate output voltage residual errors. Then, on the PO side, the OCF identification rule for the inverter is developed, which is based on the amount of voltage variation and the improved judgment criterion derived from voltage residual error and power. The proposed OCF detection method is of low cost and is real time, needing no extra hardware and no communication between the inverter and POs. Generally speaking, the method provides a reliable and fast solution to detect OCFs in the series-connected distributed dc power or energy storage systems. Its effectiveness and reliability are verified by experimental results.