Method for tracking maximum power point of photovoltaic cell on basis of fuzzy probability

Abstract

The invention discloses a method for tracking the maximum power point of a photovoltaic cell on the basis of fuzzy probability. The tracking method comprises the steps that N sampling points [ui, P(ui)] are obtained by taking epsilon as a sampling interval, wherein i is a positive integer which is smaller than or equal to N, epsilon ranges from 0.05 UOC / Ns to 0.5 UOC / Ns, UOC represents the open-circuit voltage of the photovoltaic cell, and Ns represents the serial number of the photovoltaic cell; probability functions Pro(i) are solved by constructing a spread function fD and a subordinating degree function fM, results of the probability functions Pro(i) are ordered from large to small, and union sets of Xi corresponding to front probabilities are sequentially selected as the searching range of the maximum power point, so that the sum of the front probability functions Pro(i) is larger than or equal to a probability threshold value delta; the maximum power point[uMPP, P(uMPP)] is solved in the searching range of the maximum power point. According to the method, the defect that close sampling is needed in a global scanning method under the multi-extremum condition is overcome, and the advantages of being high in tracking speed and good in environmental adaptability are achieved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and more specifically relates to a method for tracking the maximum power point of photovoltaic cells based on fuzzy probability. Background technique [0002] As a renewable clean energy, photovoltaic power generation has been widely used due to its advantages of low pollution, low noise, and abundant reserves. However, the output energy of photovoltaic cells is unstable and the conversion efficiency is low. Therefore, it is necessary to track the maximum power point in order to control the interface converter so that the photovoltaic cell can continuously and stably output the maximum power to the grid. [0003] Since the power delivered by the photovoltaic power generation system to the grid changes with changes in light intensity, ambient temperature, output impedance, and load, its output characteristics show strong nonlinearity and multiple extreme values. It is diffi...

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Problems solved by technology

[0005] Aiming at the above defects or improvement needs of the prior art, the present invention provides a method for tracking the maximum power point of photovoltaic cells based on fuzzy probability, the purpose of which is to construct a probability function with a small number of sampling points to solve the Defects of slow tracking speed and inaccurate maximum power point acquisition

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