sexta-feira, 21 de novembro de 2014
Study on voltage sensorless maximum power point tracking method using photovoltaic AC module flyback inverter KIM YOUNG HO - SCHOOL GRADUATE SUNGKYUNKWAN UNIVERSITY
Study on voltage sensorless maximum power point tracking method using photovoltaic AC module flyback inverter In recent years, interest in natural energy has grown in response to increased concern for the environment. Many kinds of inverter circuits and their control schemes for photovoltaic power generation systems have been studied. A conventional system employs a PV array in which many PV modules are connected in series to obtain sufficient dc input voltage for generating ac utility line voltage from an inverter circuit. However, the total power generated from the PV array is sometimes decreased when only a few modules are partially covered by shadows, thereby decreasing inherent current generation, and preventing the generation current from attaining its maximum value on the array . To overcome this defect, a low-power ac utility interactive inverter is mounted on each individual PV module and the inverter operates so as to generate the maximum power from the corresponding PV module. In these ac module systems, each output terminal of the individual inverter is connected to the utility line, and the generation on current of each inverter is injected into the utility line. So, these systems lied in the number of the parallel connected inverters, which is equal to the number of PV modules, can be selected in consideration of the dimensions of the roof on which PV modules are installed. This improves the flexibility of the PV generation system. . In these ac module systems, the MPPT is used to ensure optimal utilization of solar cells. The implementation essentially involves sensing input current and voltage. An MPPT algorithm uses this information to maximize power drawn from the solar cells. Various MPPT control methods have been discussed in detail in . The conventional MPPT would usually require at least a couple of current and voltage sensors and a relatively complex control strategy. With a view to minimize the overall cost and control complexity, this paper presents a novel MPPT scheme with reduced number of sensors . The proposed system is operated with P&O MPPT using current sensor and calculated quantity of electric charge. In this paper, the theoretical explanation and the detailed operational principles are explained, along with informative simulation and experimental results.