Contents I. Introduction
Photovoltaic (PV) arrays are subject to numerous kinds of faults. These include ground faults [1], line-to-line faults [2], arc faults [3], open circuits [4], short circuits [4], and faults based on the PV materials [5], [6]. These faults reduce the efficiency of the array and can result in more devastating outcomes, such as fire. To detect these faults, protection devices such as ground fault detection and interruption, have been developed. Their primary function is to interrupt the flow of current when it is above their ratings. These devices, however, do not localize faults and can fail to detect faults due to blind spots [7], [8]. For example, if a line-to-line fault occurs under low illumination, the current through the affected string of panels will be low and will not be detected by these conventional systems [7]. Smart inverters [9] and rapid shutdown systems [10], [11] have also been introduced as a way to quickly de-energize an array in the case of a fault or fire. These also do not localize the faults. In this article, we describe a new fault detection and location method for PV systems—spread spectrum time domain reflectometry (SSTDR). We evaluate the parameters needed for accurately detecting and locating disconnections (open circuits) in commercial PV systems.
