DC Voltage Sensor Fault Toleration for Cascaded Photovoltaic Systems Based on Coupled-dc-module

The Cascaded H-bridge-based photovoltaic system (CHB-PV) offers an alternative for existing utility-scale solar power conversion. It has advantages in modularity, scalability, distributed maximum power point tracking (MPPT), and direct high-voltage access capability. However, the large number of power supplies, semiconductor switches, and monitoring components in the circuit makes the CHB-PV less reliable than previous schemes. This paper aims to improve the system reliability by addressing DC-link voltage sensor faults that can cause current/voltage mis-tracking, power mismatch, unbalanced DC-link voltages, and even system instability. A novel fault toleration strategy is proposed based on DC-coupling links. This strategy leverages DC voltage self-balancing modes and selects suitable switching combinations to trigger the coupling between the faulty DC link and its adjacent links, thereby enabling the rebalancing of the DC voltage. Simulation results are provided to verify that the proposed method has excellent voltage sensor fault toleration capability, enabling fast recovery of DC voltages at all failure points.