A Model for SSTDR Signal Propagation Through Photovoltaic Strings

The ability of spread spectrum time domain reflectometry (SSTDR) to detect and locate faults in photovoltaic (PV) systems is considered in this article. This article provides a simulation that could be used for studying how faults and other parameters affect the reflectometry response and evaluating fault detection algorithms, for providing comparison simulations in iterative inversion algorithms used to detect and locate faults, or it could potentially be used to replace the measured baseline for these algorithms. The simulation uses an enhanced systematic solution procedure to find the reflection signature of the PV system, and is capable of modeling elements with complex impedance in both series and parallel separated by transmission lines. This article is an expansion of previous work to be capable of simulating systems containing n number of elements (such as PV panels and transmission lines) in series or parallel. The simulation was tested for 20 systems containing up to four resistors, capacitors, and PV cells, and was compared to the measured data.