A branch and bound algorithm for high-granularity PV simulations with power limited SubMICs

Differential power processing (DPP) architectures employ low power rated dc-dc converters to mitigate, without insertion losses, mismatches in series strings of photovoltaic (PV) cells. This paper presents tools for simulation of PV systems based on the isolated-port submodule integrated converter (subMIC) DPP architecture. While the ideal operation with full power rated subMICs is relatively easy to solve using a combination of numerical and analytical methods, the solution with partial power rated (current limited) subMICs is more challenging. A heuristic branch and bound algorithm is proposed as an effective method to deal with nonlinearities introduced by current limited subMICs. The approach is well suited for high-granularity simulations of large PV systems over long periods of time, as illustrated by experimental and simulations results.