Maximum power point tracking under partial shading conditions using an embedded system

Ashraf, Ramzan (2015) Maximum power point tracking under partial shading conditions using an embedded system. Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

The effects of global warming are deteriorating the planet and have enforced strict legıslatıons for carbon footprint reductıons. One of the main causes of global warming is the use of fossil fuels for power generatıon. Renewable energy is the solution to this problem as it produces electricity in a clean way. One of the promising forms of renewable energy is photovoltaic. However, solar is intermittent source of energy and dependent upon a number of factors including solar intensity and shadowing effects. This work aims to develop an effective and inexpensive microcontroller based control scheme to track the maximum power point in standalone solar photovoltaıc power systems. In conventional photovoltaic systems, the power curve has a single peak of power. There are many algorithms to track maximum power to maximise the efficiency of the photovoltaic system. However, when the photovoltaic is partially shaded, the output power can have multiple power peaks. A unique algorithm is derived to find the largest peak out of the many peaks. The entire power curve is scanned to find the maximum peak with respect to voltage, using a microcontroller. The largest peak is known as the global peak then presented to the output. The most commonly used algorithms; “perturb and observe” and “incremental conductance” were used. The scanning process is then repeated after a certain amount of time to maintain the global peak. The algorithm has achieved this with minimal loss of power. The algorithm scans and finds the global peak in 15 minutes of intervals, this process takes one second. Therefore, one second duration of power loss occurs from the photovoltaic in every 15 minutes. The algorithms are embedded in parallax microcontroller. Compare to the numerical Simulink model of photovoltaic systems experimental tracking efficiencies are slower. Nevertheless, in principle of the algorithms, perturb and observe works better than incremental conductance technique in terms of accuracy. The concentrated photovoltaic is required to move 11 times on an average day by using 0.7 W of power each time it moves, that of which the current photovoltaic modules can provide.