Lecture Notes in Electrical Engineering
The controllers of three-phase grid-connected inverters usually need improvements to allow distributed generations to meet the stringent grid codes with high power quality and the fault ride through ability. Therefore, the performance of the grid-connected inverter depends on the response of the selected synchronization method. This paper proposes a method with high accuracy and good dynamics under the unbalanced and highly distorted voltage. The proposed method bases on the least squares technique using the Levenberg-Marquardt algorithm to rapidly converge the solution, thus requiring less hardware and associated cost for real-time implementation. The technique does not base on interdependent loops offering stability and easy estimating process. The robustness and accuracy of the proposed technique are better than the techniques basing on the dual second-order generalized integrator (DSOGI) and the conventional PLL. The simulation results in MATLAB/Simulink under the unbalanced and harmonic voltage conditions validated the performance of the proposed method.