Theoretical Mismatch Degree Calculation of PV Array by Traversal Cell-Based Short-Circuit Characteristic Fault Topologies

Photovoltaic array consists of three levels, i.e., cell, module and array. Cell and its topology are the essential characteristics of array. For permanent cell-based faults, it is a scientific problem for academic and engineering applications whether PV arrays can be diagnosed by the degree of array power mismatch, that is, the deviation between actual output and theoretical output. Based on the generic fault cell model and the cell-based characteristic fault topology model which we proposed earlier, the simplest battery cell short-circuit fault scenario is discussed. Firstly, a power mismatch degree traversal calculation method based on the generic fault cell model and the cell-based characteristic fault topology model is proposed. Then, a theoretical power calculation model based on 2C cell model and short-circuit cell characteristic topology is proposed to quickly realize the total power output and array power mismatch degree of each topology. Finally, the theoretical calculation results are analyzed in detail, and some rules are found, which is convenient for topology diagnosis of short-circuit fault based on array power mismatch degree.