Control the active and reactive powers of three-phase grid-connected photovoltaic inverters using feedback linearization and fuzzy logic
This paper presents two techniques based on the feedback linearization (FBL) method to control the active and reactive output powers of three-phase grid-connected photovoltaic (PV) inverters. Wherein, the first suggested control scheme is an adoption of the direct FBL approach. The other is an appropriate combination of the FBL and fuzzy logic (FBL-FL), and it is also the main proposed method of this research. In detail, a unique fuzzy logic controller (FLC) is designed to enhance the effectiveness of the suggested FBL, especially in reducing fluctuations in the active and reactive output powers at the steady state. In this study, the demonstrative PV inverter uses a three-level DC-AC converter, an L-type filter and a 250V/10kV wye-wye transformer to inject the energy, obtained from PV array with a nominal power of 100kW, into the 10kV/60Hz three-phase grid. Simulations illustrate that two suggested control schemes have good performances in regulating independently active and reactive output powers to the references, even within parametric uncertainties. Furthermore, comparisons of simulation results, obtained from the traditional PI control and two the presented FBL-based structures, show salient advantages of the proposed FBL-FL technique in terms of quick response, slight overshoot, small steady-state oscillation and high robustness.