Fault-tolerant strategy without redundant switches for PV systems based on differential power processing converters

Abstract

Considering the failure risk and cost-effectiveness of photovoltaic (PV) systems with high granularity maximum power point tracking (MPPT), a fault-tolerant strategy without redundant switches is proposed for the PV system based on differential power processing (DPP) converters. This fault-tolerant strategy optimizes the output power of the PV system under different converter fault conditions by adjusting the coordinated operation of the DPP converter and the centralized converter. Compared to previous methods, in the case of hardware cost advantage, the proposed fault-tolerant strategy achieves the stable operation of the PV system after the converter failure and completes the targeted power optimization of all PV modules. The PV system with the proposed fault-tolerant strategy operates in three modes: distributed MPPT (DMPPT) mode, the coexistence of DMPPT and centralized MPPT (CMPPT) mode, and CMPPT mode. The PV system operates in the DMPPT mode when no switch failure occurs in the DPP converter. In the latter two post-fault operating modes, this paper proposes a simple fault-tolerant method to remove the faulty DPP converter and adjust the MPPT coverage of the centralized converter to recover the power loss caused by the fault. The experimental results validate the proposed fault-tolerant strategy.