Photovoltaic grid-connected inverter MPPT (Maximum Power Point Tracking) system based on admittance optimization algorithm

Abstract

The invention discloses a photovoltaic grid-connected inverter MPPT (Maximum Power Point Tracking) system based on the admittance optimization algorithm. In the invention, the advantages of the conductance increment algorithm and the fuzzy control algorithm are combined, the admittance optimization algorithm is independently researched and developed, and the fuzzified transfer function and the defuzzification judgment are established. A photovoltaic array Pmax is calculated through a photovoltaic array P-U curve, the voltage level fluctuation can be fast followed, no complex algorithm is required, the maximum power of a solar battery can be fast tracked, and the requirement for MPPT control on the photovoltaic system in various occasions can be well satisfied. Test results verify that the algorithm has better effects such as compatibility with different systems, fastness and the like in comparison with the conductance increment algorithm. The results of a great deal of experiments and test show that the photovoltaic grid-connected inverter MPPT system based on the admittance optimization algorithm has excellent real-time performance and dynamic performance, and is stable in tracking without misjudgment, with tracking accuracy reaching up to 99%.

Description

1. Technical field [0001] The invention belongs to a photovoltaic grid-connected system, in particular to a photovoltaic grid-connected inverter MPPT system based on an admittance optimization method. 2. Background technology [0002] The stability, cost, and efficiency of the photovoltaic grid-connected system largely depend on the photovoltaic grid-connected inverter power supply. The quality of the power supply, such as serious pollution to the grid and waveform distortion, determines whether the grid is acceptable. Because the efficiency of solar photovoltaic modules is very low (the efficiency at home and abroad is about 15%), and the cost of materials is relatively high, this is the fundamental reason why photovoltaic power generation cannot be as popular as solar water heaters. To give an example: the load capacity of a family is 2KW, and the current price of solar photovoltaic modules is about 15 yuan per watt. In this way, solar photovoltaic modules need 30,000 yua...

AI Technical Summary

Problems solved by technology

[0004] Due to the strong nonlinearity of U-I of solar photovoltaic modules and the great influence of temperature, this makes the realization of MPPT very complicated. At present, Japan, the United States and Europe mainly use the Incremental Conductance Algorithms, and the domestic ones are mainly used. Perturbation and observation method P&O (Perturb&Observe Algorithms), others also use disturbance observation method, fuzzy logic control and optimal gradient method, "uphill method (first-order difference method)", etc., but the above methods are in control accuracy, stability and calculation difficulty. There are deficiencies. In actual use, either the hardware requirements are high, or the program is out of order, and the normal operation of the MPPT system cannot be guaranteed.

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