Maximum power point tracking method for photovoltaic power generation system under non-uniform illumination

Abstract

The invention discloses a maximum power point tracking method for a photovoltaic power generation system under non-uniform illumination. The method comprises the following steps of: detecting the output voltage U[k] and current I[k] of a photovoltaic array at the current moment, judging whether non-uniform illumination exists in the photovoltaic array through a maximum power point tracker, performing a variable step size perturbation and observation method to obtain the maximum power point if the illumination is uniform, and calculating the first reference voltage V0 if the illumination is non-uniform; obtaining the first local maximum power point by the variable step size perturbation and observation method, and recording corresponding voltage V1 and power P1; obtaining the second local maximum power point by the variable step size perturbation and observation method, and recording corresponding voltage V2 and power P2; by parity of reasoning, obtaining the voltage Vn and Vp, comparing n local maximum power points, extracting the maximum local maximum power point and taking the corresponding voltage as reference voltage Vnf+ output by the maximum power point tracker; and finally, calculating to obtain a duty ratio through a controller according to the Vnf+, and tracking the local maximum power point. The maximum power point tracking method has the advantages that the power loss brought by non-uniform illumination in the photovoltaic array in the system is reduced.

Description

technical field The invention relates to the technical field of photovoltaic power generation control, in particular to a method for tracking the maximum power point of a photovoltaic power generation system under uneven illumination, which is suitable for independent or grid-connected photovoltaic power generation systems. Background technique At present, the development and utilization of renewable energy are increasingly valued by governments of various countries, and photovoltaic power generation is an important part of renewable energy, and photovoltaic power generation has great potential for development in the future. According to the European Photovoltaic Industry Association (EPIA) forecast in 2011, by 2050, 100% of the energy in Europe will be provided by photovoltaic power generation. With the development of the photovoltaic industry, building integrated photovoltaics (Building Integrated Photovoltaics, BIPV), which is mainly small and medium-sized, will b...

AI Technical Summary

Problems solved by technology

Existing photovoltaic power generation technologies, such as constant voltage method, perturbation and observation method, incremental conductance method, etc., mainly study the maximum power point tracking under the condition of no shading, and fail to consider the serious power loss caused by shading

At present, a few foreign articles have proposed the tracking method of the Maximum Power Point (MPP) under uneven illumination, while few domestic articles have proposed, and the proposed methods have the following problems: increased investment in hardware equipment, low accuracy High, low efficiency, too complex algorithm, poor adaptability, poor practicability, etc.

When some photovoltaic components in the photovoltaic array are shaded (the photovoltaic array receives uneven illumination), the output current capability of the entire parallel photovoltaic array will be limited, but the output current capability of the parallel photovoltaic array that is not shaded at all will not be reduced. If the two are connected in series and the traditional maximum power point tracking algorithm is used to control the power generation of the entire system, the output power of the system will be greatly reduced, and this power loss can reach more than 30% or even more serious

Therefore, a maximum power point tracking method for photovoltaic power generation systems under uneven lighting is proposed, which can greatly reduce the serious drop in output power of the entire system caused by shading