Secondary ripple reduction control system and control method for photovoltaic grid-connected currents and direct current voltage

Abstract

The invention discloses a secondary ripple reduction control system for photovoltaic grid-connected currents and direct current voltage. The secondary ripple reduction control system comprises a photovoltaic array, a PI controller, a grid-connected current controller, a secondary ripple controller and a single-phase photovoltaic grid-connected inverter, the grid-connected current controller comprises a low-pass filter used for integral control, a wave trap used for compensative regulation, and a PI+ repetitive controller, and the low-pass filter, the wave trap and the PI+ repetitive controller are connected in parallel; the secondary ripple controller comprises a proportion resonance controller. By the combination of a control method, secondary power disturbance in the photovoltaic grid-connected currents can be effectively eliminated, effective reduction of secondary ripple components in direct current side voltage and substantial improving of the grid-connected currents are achieved, needed direct current filter capacitance is greatly reduced, therefore the size of the system is reduced, cost is lowered, and meanwhile the service life of the photovoltaic array is prolonged.

Description

technical field The invention belongs to the technical field of photovoltaic grid-connected power generation, and relates to a photovoltaic grid-connected current and DC voltage secondary ripple suppression control system and control method for improving the quality of grid-connected current. Background technique The photovoltaic grid-connected power generation system consists of two parts: a photovoltaic array and an inverter. The photovoltaic array converts solar energy into electrical energy, and the inverter injects electrical energy into the AC grid. Single-phase single-stage photovoltaic grid-connected inverter adopts single-stage energy conversion link, which has the advantages of simple structure, low cost and high system efficiency. Therefore, it has good application and research prospects in household photovoltaic power generation systems. Traditional single-phase single-stage photovoltaic grid-connected inverters, when the grid-connected current is controlled to h...

AI Technical Summary

Problems solved by technology

This disturbance will cause a large number of secondary ripple components in the DC side voltage. On the one hand, the secondary ripple component in the DC side voltage will cause a large amount of tertiary ripple current in the grid-connected current, thereby reducing the quality of the grid-connected current; On the other hand, it will affect the accuracy of the photovoltaic array MPPT output reference voltage and the service life of the photovoltaic array

Aiming at the shortcomings of single-phase single-stage photovoltaic grid-connected systems, the currently widely used solution is to suppress secondary power disturbances by designing appropriate power decoupling capacitors. This method requires a very large DC filter capacitor, which makes the system volume and cost greatly increase

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