Grid-connected current control method for combined single-phase two-stage photovoltaic generation system

Abstract

The invention discloses a grid-connected current control method for a combined single-phase two-stage photovoltaic generation system. The single-phase photovoltaic generation system is of a two-stage structure and comprises a first-stage BOOST up circuit link and a second-stage single-phase full-bridge inverter circuit link. The single-phase full-bridge inverter circuit link adopts a double-closed-loop control strategy and comprises an outer loop which is a direct-current bus voltage loop and an inner loop which is a grid-connected current loop and further utilizes voltage forward feed control of a power grid. The BOOST up circuit link is used for realizing boosting voltage of a photovoltaic battery module to a direct-current bus voltage reference value while realizing maximum power point tracking. Besides, the single-phase full-bridge inverter circuit link is used for realizing stabilization of the direct-current bus voltage and synchronization of frequency and phase of system output current and voltage of the power grid. The grid-connected current control method for the combined single-phase two-stage photovoltaic generation system has the advantages of excellent stability, flexibility in dynamic response, low content of low-order harmonics, high interference resistance, good robustness, high reliability and the like.

Description

technical field [0001] The invention relates to a control technology of grid-connected current in a single-phase two-stage photovoltaic power generation system, belonging to the field of photovoltaic power generation control. Background technique [0002] In today's society, the increasing shortage of non-renewable energy and the increasing environmental pollution have made the use of renewable energy such as solar energy a strong concern of the government and all walks of life, and photovoltaic power generation technology has also developed rapidly. Grid-connected current control technology is one of the main technologies involved in photovoltaic power generation. [0003] Currently commonly used current control technologies include: PI control, hysteresis control, deadbeat control, proportional resonance (Proportional resonant, referred to as PR) control, repetitive (Repetitive control, referred to as RC) control and harmonic compensation (Harmonic compensation, referred t...

AI Technical Summary

Problems solved by technology

Repetitive control technology has a simple control algorithm, and only needs to sample the output voltage, so that the inverter can obtain a steady-state output waveform with lower THD under periodic disturbances, and the steady-state performance is excellent; however, due to the existence of In the fundamental cycle delay link, the output is adjusted cycle by cycle; in the first fundamental cycle of the load step change, the repetitive controller does not produce any adjustment effect, and is almost in an open-loop state, with poor dynamic response; in addition, If the disturbance is non-periodic, repetitive control will increase the error in the output voltage

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