Optimal Duty Cycle Modeling for Maximum Power Point Tracking of Photovoltaic System

摘要

Maximum Power Point Tracking (MPPT) concept is an important topic in the control and optimization of the power obtained from the Photovoltaic system (PV). It helps ensuring harvesting the maximum possible power at any change in irradiance and temperature values. As irradiance and temperature change with time, the power extracted from the PV also changes. Efficient MPPT control is thus necessary to keep the output power at its maximum value irrespective of any sudden change in such environmental conditions. This paper presents a mathematical-based MPPT control based on the optimization of the converter duty cycle values. The main idea is to build a mathematical model relating the optimal duty cycle with the irradiance and temperature. The model is built based on simulations of a grid-connected PV system incorporated with the Incremental Conductance (INC) MPPT algorithm. The simulations are carried out according to varying irradiance and temperature values while monitoring and recording the corresponding optimal duty cycle achieved by the INC algorithm. Using EUREQA software, a mathematical model relating the optimal duty cycle as a function of irradiance and temperature values has been built. The results from the proposed model are compared with the simulated results using INC method. The maximum recorded error is less than 0.76 %.