Stable MPPT (Maximum Power Point Tracking) control system and method of single-stage photovoltaic inverter

Abstract

The invention provides a stable MPPT (Maximum Power Point Tracking) control system and method of a single-stage photovoltaic inverter. The stable MPPT control system comprises a solar panel, a photovoltaic inverter, a power grid and an MPPT controller, wherein the solar panel, the photovoltaic inverter and the power grid are sequentially connected with one another; and the MPPT controller is respectively connected with the solar panel and the photovoltaic inverter. According to the stable MPPT control method, a novel voltage ring controller is adopted and comprises a proportional integral (PI) control module, a pole compensation module and a notching filter module, and the voltage ring controller and a current ring controller adopt a same control period, thus ensuring the operation stability of a single-stage inversion system and guaranteeing the single-stage inversion system to output electric energy with good quality; and an MPPT (Maximum Power Point Tracking) variable-step voltage disturbance method is adopted, a proportional coefficient is regulated to guarantee better dynamic response and steady-state performance of MPPT, and thus the use efficiency of the solar panel is improved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a single-stage photovoltaic inverter stable MPPT control system and method. Background technique [0002] In a solar grid-connected power generation system, a solar cell is a semiconductor device that directly converts light energy into electrical energy. Under a certain light energy, how to effectively increase the output power of the solar cell, so as to make full use of solar energy and improve the overall solar grid-connected power generation system. The power generation efficiency of the system is of great significance. [0003] Through the research on the output power characteristics of solar cells, it is found that the output power P of solar cells is related to the light intensity W and the ambient temperature T, such as figure 1 Shown is the P-U characteristic curve under the same T and different W, wherein, U is the output voltage of t...

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Problems solved by technology

[0006] At present, the existing controller using the MPPT control strategy uses the voltage disturbance method to track the maximum output power point of the solar cell, which has a low disturbance tracking rate, and the calculated output voltage difference Δu of the solar panel between the current beat and the previous beat is easy Deviations lead to polarity errors, that is, the positive and negative errors of Δu, which cannot effectively ensure that the solar panels work stably near the maximum output power point, and cannot quickly track the rapidly changing lighting environment, thereby reducing the efficiency of solar panels

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