MPPT method based on optimal model prediction algorithm combined with variable step size disturbance control

Abstract

The invention provides an MPPT method based on an optimization model prediction algorithm combined with variable step size disturbance control, and belongs to the technical field of new energy power generation. Firstly, a photovoltaic cell model is constructed, and the output current of the photovoltaic cell is obtained according to the photovoltaic cell model. Then the Z-source network model is constructed and the boosting factor of Z-source network is calculated. Then the function relationship between the output power P and the output voltage U of the photovoltaic cell and the duty cycle D of the switching device of the Z-source network is determined. The topological state space equation of Z-source network is established. Finally, the optimal model prediction algorithm combined with variable step duty cycle disturbance control method is used to achieve the maximum power point tracking of photovoltaic system. The MPPT method based on the optimization model prediction algorithm combined with the variable step size disturbance control ensures the stability of the maximum power point tracking of the photovoltaic system, ensures the stability of the tracking when the external conditions (illumination and temperature) change suddenly, avoids the misjudgment phenomenon, and thus ensures the long-term stable power output of the photovoltaic system.

Description

technical field [0001] The invention relates to the technical field of new energy power generation, in particular to an MPPT method based on an optimization model prediction algorithm combined with variable step size disturbance control. Background technique [0002] With the depletion of conventional energy such as oil and coal, the energy crisis has attracted widespread attention from all over the world. As one of the effective means to deal with the energy crisis and protect the environment, the development and application of new energy (renewable energy) has become an inevitable choice for the future sustainable development of all countries. Photovoltaic system grid-connected power generation (using solar energy to generate electricity and grid-connecting the electric energy) has become one of the main application forms. [0003] However, the biggest problem at present is the response rate of the maximum power point tracking (Max Power Point Trackin, or MPPT) of the pho...

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Problems solved by technology

[0004] The model predictive control method is a special control method. Its current control action is obtained by calculating the minimum value of the evaluation function in each sampling period. It has the advantages of steady-state optimization and multi-variable integrated control, but it is vulnerable to The limitation of switching frequency and switching loss reduces the speed and accuracy of algorithm tracking

[0005] Duty cycle disturbance control is carried out through the functional relationship determined between the output power of the photovoltaic system P main output voltage U main and the switching element duty cycle D, but the disturbance control will cause the system to slow down the convergence speed

At the same time, it will make the photovoltaic system fluctuate greatly near the maximum power point. When the external conditions change suddenly, it is easy to misjudgment, causing the photovoltaic system to stop running.

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