A flexible perturb & observe MPPT method to prevent surplus energy for grid-failure conditions of fuel cells

Abstract

Energy management is a critical issue for the economical and optimum operation of grid integrated renewable energy systems. In conventional grid integrated systems, the control methods are operated according to the design criteria for grid connection modes and cause surplus energy for low-loading conditions under grid-failure situations. For this purpose, in this paper, a flexible control strategy is improved basis on perturb & observe MPPT, and it is purposed to improve the system efficiency under grid-connection and grid-failure modes of renewable energy systems. In this way, it is aimed to ensure optimized power delivering capability with optimum load voltages/currents at desired values, and it also prevents overloading under grid-failure mode. To show the proposed method's validity, the algorithm of control method is embedded in a function block and performed for grid connection & grid-failure modes under different load conditions. The performance results show that the flexible control strategy prevents surplus energy under the grid-failure mode and reduces the power losses compared to the conventional method. Also, the proposed method increases the load-side power quality. The results show that THD values are significantly reduced to fewer than the conventional perturb & observe method.