Method and device for controlling photovoltaic inverter circuit

Abstract

The embodiment of the invention discloses a method for controlling a photovoltaic inverter circuit. The method includes the steps that after a starting command is received, a positive total bus capacitor and a negative total bus capacitor are charged; after a first preset condition is met, charging operation is stopped, and a phase-locking loop of a power grid is controlled to conduct phase-locking operation; after the phase-locking loop finishes the phase-locking operation, a five-level inverter is started in a three-level mode, and voltage loop control and current loop control are conducted on the five-level inverter; when a second preset condition is met, a first Boost converter and a second Boost converter are controlled to be started without loads, and voltage loop control is conducted on the two Boost converters; after input voltage and input current of the first Boost converter and the second Boost converter are stable, the five-level inverter is controlled to run in a five-level mode. According to the method for controlling the photovoltaic inverter circuit, fluctuation of input voltage and input power of a solar cell array can be reduced when the photovoltaic inverter circuit is started, and the starting process is smoother. The invention further 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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