Method, device, electrical equipment and photovoltaic system for preventing energy back-filling

Abstract

The application discloses a method, a device, electrical equipment and a photovoltaic system for preventing energy back-filling. The method comprises the following steps: controlling a five-level inverter to operate in a three-level operating mode in a grid-connected manner and a preceding stage Boost circuit of the five-level inverter to be maintained in an operation stop state when a potential safety hazard of back-filling of energy to a photovoltaic cell panel from a direct current side of the five-level inverter exists in the photovoltaic system, wherein the three-level operating mode refers to an operating mode of outputting a level +2, a level -2 and a level 0 by the five-level inverter. Therefore, the back-filling of energy to the photovoltaic cell panel from the direct current side of the five-level inverter is avoided.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, and more specifically, to a method, device, electrical equipment and photovoltaic system for preventing energy backfeeding. Background technique [0002] figure 1 The DC side of the shown five-level inverter 10 is connected to the photovoltaic panel 20 to receive the PV input voltage, and the PV input voltage is connected across the positive terminal of the capacitor C1 and the negative terminal of the capacitor C2, while the PV input The voltage is boosted by the Boost circuit 50 at the front stage of the five-level inverter 10 and then connected across the positive terminal of the capacitor C3 and the negative terminal of the capacitor C4. The grid-side output of the five-level inverter 10 is filtered by the filter 30 and boosted by the transformer 40, and then sent to the power grid. Under different combinations of switching tube on-states, the five-level inverter 10 alt...

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Problems solved by technology

[0003] When the five-level inverter 10 is connected to the grid in the event of grid failure, disturbance, etc., or when the five-level inverter 10 needs to be started at night when the PV input voltage is extremely low, five-level inverters may occur. If the energy on the DC side of the inverter 10 is poured back into the photovoltaic panel 20, it will not only cause damage to the photovoltaic panel 20, but also reduce the reliability of the entire photovoltaic system.

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