Design of Harmonic Compensators in PV Systems with Large Number of Micro-Inverters

In this paper, it is shown that by increasing the number of Micro-Inverters (MIs), the performance of their harmonic compensators, may be deteriorated. Therfore, to design harmonic compensators for a large number of parallel MIs, it is not enough to consider the performance of only one MI. The analysis show that, in the design of harmonic compensators, presence of filter capacitor, can cause the MIs to have capacitive behaviors. On the other hand, by increasing the number of MIs, the probable interaction frequency between the MIs and the grid, drifts down to the lower frequency range and close to the harmonic frequencies. In this situation, the interaction among the inductive grid and the capacitive MIs, at harmonic frequencies, is inevitable. As a solution, in this paper, the modified design of harmonic compensators is proposed. A complete set of simulations is also provided to evaluate the effectiveness of the proposed analysis.