Variable-step photovoltaic MPPT (Maximum Power Point Tracking) control method based on angle of contingence

Abstract

The invention discloses a variable-step photovoltaic MPPT (Maximum Power Point Tracking) control method based on an angle of contingence. The variable-step photovoltaic MPPT control method based on the angle of contingence comprises the following steps: (1), obtaining the power-voltage characteristic curve of a photovoltaic cell; (2), obtaining a speed factor NL=1-costheta by the power-voltage characteristic curve, wherein theta=arctan(dP / du) is the angle of contingence of the power-voltage characteristic curve, P is the output power of the photovoltaic cell, and u is the output voltage of the photovoltaic cell; (3), obtaining the step Di by the speed factor NL; (4), according to the basal principle of a perturbation and observation method, obtaining the reference voltage of a proportional-integral controller Uref(i+1)=Uref(i)+ / -Di, and thus achieving the maximum power point tracking. According to the method, the problems of difficulty to select the maximum step and of appearance of dead regions or misconvergence of MPP right tracking caused by improper parameter design in current variable-step control method are solved, the maximum power point tracking speed and accuracy can be simultaneously considered, and the maximum power point output by a photovoltaic array can be accurately and rapidly tracked.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and more specifically relates to a variable step-length photovoltaic MPPT control method based on a tangent angle. Background technique [0002] As a renewable clean energy, photovoltaic power generation has been highly valued and developed rapidly in the world. In the photovoltaic power generation system, photovoltaic cells use the photovoltaic effect to convert light energy into DC power, and then convert the DC power into various forms of electrical energy required by the load through a power electronic converter. However, the power delivered by the photovoltaic power generation system to the grid changes with changes in light intensity, ambient temperature, output impedance, and load, and its output characteristics show strong nonlinearity. Therefore, it is very necessary to control the interface converter so that the photovoltaic power generation system can continuousl...

AI Technical Summary

Problems solved by technology

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a variable step size photovoltaic MPPT control method based on tangent angle, which effectively solves the difficulty in selecting the maximum step size in the existing variable step size control method, and is easy to be affected by parameters Improper design leads to the problem that the tracking on the right side of the MPP does not converge or produces a dead zone. It can take into account the speed and accuracy of the maximum power point tracking at the same time, and accurately and quickly track the maximum power point of the photovoltaic array output.

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