A MPPT algorithm based on extremum seeking with variable gain for microinverters in microgrid

摘要

In this paper, a MPPT algorithm for photovoltaic microinverter in microgrid based on proposed modified Extremum Seeking is presented. Proposed MPPT algorithm possesses characteristics of faster response and smaller oscillation compares with Perturb and Observe MPPT and it is also suitable for various kinds of solar panels either. In order to acquire MPPT with higher quality, a practical interleaved boost converter topology must be employed as the DC section of the microinverter. Then, a MPPT algorithm based on Extremum Seeking with an extra accelerating coefficient can be achieved by taking advantage of high-accuracy detectable power character of interleaved converter. Besides, system modeling of whole closed-loop system is deduced and Lyapunov stability analysis of photovoltaic microinverter system is demonstrated. Therefore it can be summarized that an additional variable coefficient which is determined by the gradient information of the photovoltaic operating curve can be introduced as the accelerating coefficient. For the purpose of verifying the correctness of proposed MPPT, simulations are established on the platform of Matlab/Simulink. In short, both theoretical analysis and simulation results manifest the validity of proposed modified MPPT algorithm.