A method for maximum power point tracking of photovoltaic modules connected in series

Abstract

The invention discloses a tracking method for a maximum power point (MPP) of tandem photovoltaic modules. The tracking method comprises the following steps of globally scanning by taking open-circuit voltage as starting voltage; dividing a multi-peak P-U curve into single-peak P-U intervals according to output voltage of the tandem photovoltaic modules when bypass diodes are conducted; taking the P-U curve as a single-peak interval when no bypass diodes are conducted; introducing a formula delta U(n)=N*ln-dI(n+1) / dU(n+1) / [I(n+1) / U(n+1)] in absolute terms, calculating at 0.4 to 0.8 time of P-U intervals of all the single peaks to obtain a voltage value U0 when a linear equation value of delta U (n) about the output voltage U of the tandem photovoltaic modules is 0, and adopting an incremental conductance method to track the MPP by taking the U0 as starting voltage and the delta U (n) as a step length voltage value; comparing to obtain global MPP and working voltage. According to the tracking method disclosed by the invention, the quickness and the accuracy of tracking the MPP by the tandem photovoltaic modules can be guaranteed, and the effect of reducing power oscillation and loss of a circuit can be guaranteed.

Description

Technical field: [0001] The invention relates to a method for tracking the maximum power point of a series photovoltaic module. Background technique: [0002] In recent years, with the increasingly prominent environmental and ecological problems, the development of clean energy has become an inevitable trend of economic and social development. Favored by countries all over the world, my country's investment in the photovoltaic industry is also increasing. Although the scale of the photovoltaic power generation industry is getting larger and larger, the utilization efficiency of photovoltaic power generation is not too high. The main problem is how to reasonably configure the output power of the photovoltaic array to maximize the maximum power point tracking (MPPT) technology of photovoltaic power generation. [0003] In the process of photovoltaic power generation, some photovoltaic modules may be partially blocked by buildings, trees, clouds, etc., which will cause some of ...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the existing MPPT algorithm cannot quickly and accurately find the maximum power point of the series photovoltaic module, especially in the case of local shading, the output power-voltage curve of the series photovoltaic module has multiple peak intervals, which is prone to local optimization and the MPP. Problems such as energy loss caused by power oscillations occur, and a method is proposed to divide the multi-peak output power-voltage curve into multiple single-peak output power-voltage (P-U) intervals, and quickly locate the voltage value near the maximum power point in each single-peak interval. The method of obtaining the global MPP through the final tracking of MPPT by the incremental conductance method with adaptive variable step size

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