Fast tracking method of maximum power point for independent photovoltaic power generation system

Abstract

The invention relates to a fast tracking method of the maximum power point for an independent photovoltaic power generation system. The fast tracking method of the maximum power point comprises the following steps of: pre-locating the voltage of a photovoltaic battery component, and starting a perturbation observation algorithm; collecting a perturbation starting output voltage and current to obtain perturbation starting output power, changing disturbance pulse width modulation duty ratio, collecting a disturbance output voltage and current to obtain disturbance output power, and judging whether the disturbance output power is the same as the power of a disturbance starting point or not; if the disturbance output power is the same as the power of the disturbance starting point, determining to be the maximum power point, stopping the disturbance observation algorithm, and recording, locking and updating the voltage and duty ratio of the disturbance starting point; if the disturbance output power is different from the power of the disturbance starting point, tracking the new maximum power point again after the duty ratio is changed; and obtaining the interval output power, the relative change rate of the power and the relative change precision of temperature according to a time interval cycle, and determining whether the output voltage of the updated disturbance starting point is continuously locked or not. According to the fast tracking method of the maximum power point for the independent photovoltaic power generation system disclosed by the invention, the starting is fast, the operation is convenient and reliable, the intermittent disturbance characteristic exists, the conversion efficiency of the photovoltaic power generation system can be effectively improved, and the power consumption and error probability of the system control can be reduced.

Description

technical field [0001] The invention relates to a maximum power point fast tracking method for an independent photovoltaic power generation system, belonging to the technical field of photovoltaic power generation systems. Background technique [0002] Solar energy is a renewable, non-polluting green energy source. Among the effective use of solar energy, photovoltaic power generation is the most flexible, fastest-growing and most dynamic research field in recent years, and it is one of the most eye-catching projects. one. Since the output of solar cells has obvious nonlinear characteristics, and its output is affected by light intensity, ambient temperature and load conditions, under certain light intensity and ambient temperature, solar cells can work at different output voltages, but only At a certain output voltage value, the output power of the solar cell can reach the maximum value, which is the apex of the output power voltage curve (Maximum Power Point, MPP). In or...

AI Technical Summary

Problems solved by technology

[0004] These algorithms basically adjust the equivalent load of the component output by changing the duty cycle of the switching tube of the DC-DC circuit, so that the component works at the maximum power point, thereby realizing the real-time tracking of the maximum power point, but they coexist One of the shortcomings is that in order to accurately track the maximum power of the solar cell under any temperature and sunshine conditions and achieve a better tracking effect, the complexity of the algorithm and the complexity of the hardware structure are continuously increased while improving the control accuracy. As a result, the production cost has increased, and most importantly, the tracking of the maximum power point they use is real-time, and the real-time tracking process is actually a process of power optimization.

Since the reference voltage is constantly adjusted during the optimization process, the operating point of the solar cell is always oscillating near the maximum power point, and cannot work stably at the maximum power point, and the continuous oscillation disturbance to the output power of the system is bound to increase Additional energy loss caused by voltage and current fluctuations greatly increases the probability of control errors

At the same time, when the sunshine intensity changes rapidly, the reference voltage adjustment direction is likely to be wrong, resulting in deviation errors in the control algorithm

This is also a fatal flaw in the algorithm stability of the perturbation and observation method currently used.

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