Comparison of Fixed and Variable Step Maximum Power Point Tracking Methods Using Gradient Ascent Algorithm

Depletion of resources and adverse effects to the environment has propelled the shift of energy procurement to renewable and its long term potentials. Solar Energy is the third most widely used form of renewable energy and its working is dependent on the climactic conditions in which it exists. This offers fluctuations in the power output according to changing parameters such as temperature and irradiance. For optimal working of photovoltaic cells or solar cells, Maximum Power Point Tracking (MPPT) is used. Ensuring that under all climates, the solar cell is able to provide the maximum output allows reduction in wastage of energy and this done by tracking the maximum power at specific input parameter values. This paper implements a system, of a Photovoltaic array and buck converter utilizing the Perturb and Observe algorithm at various temperatures and irradiances. Further a MPPT method that utilizes variable step is implemented to arrive at the maximum power point, without fluctuation at the peak as in P&O method. Gradient Ascent method is utilized to realize the variable step as a function of the gradient at the point on the Power vs Voltage curve. Simulation proved better performance in realizing the maximum Dower noint using the latter method.