A Direct Computational Method for Photovoltaic Maximum Power Point Tracking

Abstract

A photovoltaic maximum power point tracking method with direct calculation, belonging to the technical field of solar photovoltaic power generation, adopts a realization system including a photovoltaic array, a sampling module, an MPPT calculation module, a PWM drive module, a Boost module and a load / inverter module; The method includes: the sampling module collects the output current and output voltage value of the current photovoltaic array, the MPPT calculation module and the PWM drive module calculate the maximum power point voltage value, and control the Boost module to maximize the system output power. The invention uses the ideal volt-ampere characteristic formula as the theoretical basis for calculation, and calculates the changing parameters that determine the shape of the volt-ampere characteristic curve through the parameter values ​​of the battery board in the standard state; Get the current value of short-circuit current, open-circuit voltage and temperature; by establishing a classical equation for calculating the voltage value of the maximum power point, combined with numerical algorithms such as dichotomy or genetic algorithm, the voltage value of the current maximum power point can be directly calculated; solved Problems such as misjudgment, power loss, and system oscillation in the disturbance process of traditional methods.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and in particular relates to a directly calculated photovoltaic maximum power point tracking method. Background technique [0002] Currently, due to low conversion efficiency and high cost of solar photovoltaic products, they have not been widely popularized and applied. The maximum power point tracking (MPPT) technology is an effective way to improve the efficiency of photovoltaic power generation. The commonly used MPPT methods can be divided into the following three categories: disturbance incremental method, intelligent incremental method, and derivation dp / de method. The disturbance increment method refers to the method of gradually approaching the maximum power through continuous sampling. The advantage of this method is that the algorithm is simple, but the disadvantage is that the selection of the initial value and the step size have a great impact on the track...

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Problems solved by technology

The disturbance increment method refers to the method of gradually approaching the maximum power through continuous sampling. The advantage of this method is that the algorithm is simple, but the disadvantage is that the selection of the initial value and the step size have a great impact on the tracking accuracy and speed, and cannot adapt to the amount of sunlight. Rapid changes, and may oscillate near the maximum power point of the array, resulting in partial power loss, and sometimes the program control will be out of order during operation, resulting in misjudgment; intelligent incremental methods include fuzzy control method, neural network control method, etc. The fuzzy control method establishes fuzzy rules between the sunshine change and the conduction rate, and improves the influence of the sunshine change on the system. The advantage is that the maximum power point can also be found when the sunshine changes sharply. For the oscillation phenomenon of the system, the neural network control method needs to extract a large number of samples, which cannot reach the actual application process; the derivation dp / de method is currently a more commonly used method, by calculating the derivative of power and voltage and when the tube is turned on and off The relationship between each parameter, adjust the size of the conduction rate, when the derivative of power to voltage is zero, the maximum power can be reached. The advantage of this method is that the fluctuation near the maximum power point is small, and it can achieve high accuracy. The disadvantage is that The algorithm is complex, there are many parameters to be determined, and the parameter values ​​are difficult to determine

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