Single-phase photovoltaic grid-connected generating system power decoupling circuit and control method thereof

Abstract

The invention belongs to the field of single-phase photovoltaic power generation, and discloses a single-phase photovoltaic grid-connected generating system power decoupling circuit and a control method thereof. The circuit comprises a photovoltaic power supply, a BOOST unit, a full-bridge inverting unit, a power decoupling unit, an LC filtering unit and a power grid, which are sequentially connected from left to right. The method comprises the following steps of: (1) boosting the voltage of the photovoltaic power supply through the BOOST unit; (2) inverting the direct-current voltage boosted in the step (1) into an alternating-current voltage through the full-bridge inverting unit; (3) generating a power vector on an inductor Lc by controlling the switch-on / off time sequences of MOSFET (Metal-Oxide -Semiconductor Field Effect Transistor) switching tubes Sc1and Sc2 in the power decoupling unit by using the power decoupling unit; and (4) filtering an alternating-current grid connected voltage signal output from the step (3) through the LC filtering unit, and connecting the signal into the power grid. Due to the adoption of the circuit and the control method thereof, a low-capacity film capacitor is adopted instead of a high-capacity electrolytic capacitor, so that the generating efficiency of a photovoltaic system in increased, the service life of the photovoltaic system is prolonged, and generating cost is effectively lowered.

Description

technical field [0001] The invention belongs to the field of single-phase photovoltaic power generation, and more specifically relates to a power decoupling circuit of a single-phase photovoltaic grid-connected power generation system and a control method thereof. Background technique [0002] As a kind of renewable energy, solar energy currently has three main forms of utilization, namely photothermal utilization, photochemical utilization and photovoltaic power generation. Among them, photovoltaic power generation is the most important application field in the development and utilization of solar energy. Photovoltaic power generation is the use of solar cell technology to directly convert the sun's light energy into electrical energy. Using solar power to generate electricity has obvious advantages, such as renewable, clean and pollution-free, rich in resources and flexible in mobility. With the development of the times, people have gradually shifted their attention to t...

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Problems solved by technology

[0007] Aiming at problems such as large fluctuations in the bus voltage and distortion of the grid-connected current caused by the double grid frequency harmonic component existing on the DC side in the photovoltaic grid-connected system of the prior art, the present invention proposes a single-phase photovoltaic grid-connected Power generation system power decoupling circuit and its control method. The circuit and method of the present invention can not only effectively ensure the normal operation of the photovoltaic grid-connected system, but also realize power decoupling on the basis of replacing large-capacity electrolytic capacitors with small-capacity film capacitors, improving the The power generation efficiency and service life of the photovoltaic system effectively reduce the cost of power generation

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