Control method and control device for photovoltaic inverter circuit

Abstract

The embodiment of the present invention discloses a control method for a photovoltaic inverter circuit, which includes: after receiving a power-on command, charging a positive total bus capacitor and a negative total bus capacitor; when a first preset condition is satisfied, stopping the charging operation, and controlling The phase-locked loop of the power grid performs the phase-locked operation; after the phase-locked loop completes the phase-locked operation, the five-level inverter is started in the three-level mode, and the voltage loop control and current loop control are performed on the five-level inverter; When the second preset condition is met, the first Boost converter and the second Boost converter are controlled to start without load, and the voltage loop control is performed on the two Boost converters; when the input voltage of the first Boost converter and the second Boost converter is After the input current is stabilized, the five-level inverter is controlled to operate in a five-level mode. The control method disclosed by the invention can reduce the fluctuation of the input voltage and input power of the solar cell array during the starting process of the photovoltaic inverter circuit, so that the starting process is smoother. The invention also discloses a corresponding control device.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a control method and a control device for a photovoltaic inverter circuit. Background technique [0002] Photovoltaic power generation technology has been widely used. The inverter is a very important part in the photovoltaic inverter circuit. The current five-level inverter has lower grid-connected current ripple and lower switching loss, and has lower grid-connected current harmonic distortion than traditional two-level or three-level inverters and higher efficiency. [0003] figure 1 A photovoltaic inverter circuit based on a five-level inverter, mainly including a first Boost (boost) converter 201, a second Boost converter 202 and an inverter group, wherein the inverter group includes three Five-level inverters 301 , 302 and 303 . The solar cell array 100 is connected to the positive input bus and the negative input bus, the voltage of t...

AI Technical Summary

Problems solved by technology

[0004] At present, in the process of starting the photovoltaic inverter circuit, the five-level inverter is directly started in the five-level mode, resulting in large fluctuations in the input voltage and input power of the solar cell array, and the start-up process is not stable.

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