Challenges of overcurrent protection devices in photovoltaic arrays brought by maximum power point tracker

Abstract

This paper discusses the challenges of overcurrent protection devices (OCPD) brought by the maximum power point tracker (MPPT) of the centralized grid-connected inverter in a photovoltaic (PV) array. Since PV arrays have non-linear output characteristics, MPPT algorithms of PV inverters are often used to harvest the maximum output power from PV arrays. Most MPPTs are designed to respond to unexpected environmental variations, such as the change of solar irradiance on PV arrays. For this reason, instead of remaining constant, the fault current in the PV array may be reduced by the MPPT. Sometimes the fault current might evolve to an undetectable level for overcurrent protection devices. As a result, the fault might be hidden in the PV array and become a potential hazard for system efficiency and reliability.