Controlling method of improving current quality of grid-connected inverter during low-load operation

Abstract

The invention discloses a controlling method of improving current quality of a grid-connected inverter when operated in low load. The controlling method of improving the current quality of the grid-connected inverter when operated in low load achieves judgment of the operating mode of the grid-connected inverter according to the difference of the ratio of the actual output power and rated power of the inverter. When the ratio ranges from 0.6 to 1, the grid-connected inverter is in the normal working mode, and the classic voltage current double closed-loop PI controlling is adopted; when the ratio ranges from 0.3 to 0.6, the grid-connected inverter is in the mild low-load working mode, the classic voltage current double closed-loop PI controlling is adopted at the moment, and software measurements are added, wherein the software measurements comprise improving the switch frequency by one time, enabling an inner ring PI adjuster to be merged into a repetition controller and the like; when the ratio is less than 0.3, the grid-connected inverter is in the severe low load working mode, at the moment hardware measurements are added on the basis of the mild low load controlling method, the hardware measurements comprise starting a controlling relay and enabling a bridge-arm side addition inductor to be merged. The controlling method of improving the current quality of the grid-connected inverter when operated in low load ensures grid current when the grid-connected inverter runs under low load, can reduce the quantity of the added inductor, and saves cost.

Description

technical field [0001] The invention relates to a control method for improving the current quality of a grid-connected inverter under low-load operation, and belongs to the technical field of electric power industry. Background technique [0002] In today's pursuit of a low-carbon society, new energy power generation technologies, such as wind power generation, photovoltaic power generation and fuel cell power generation, have attracted more and more attention, and attention to grid-connected power generation inverter technology has also increased. As a key part of new energy power generation technology, the grid-connected inverter is usually designed according to the nominal rated capacity. These designs mainly include filter parameters, capacity selection, switching tube selection, switching frequency setting, sensor selection, control system design, etc. However, due to the volatility and randomness of solar and wind energy, grid-connected inverters often operate at non-...

AI Technical Summary

Problems solved by technology

[0003] Aiming at the inherent defect of poor grid-connected current quality when the grid-connected inverter operates at low load, the present invention provides a control method for improving the current quality of the grid-connected inverter under low-load operation, so that the grid-connected inverter When the load is running, the quality of the grid-connected current is guaranteed to meet the grid-connected requirements, and the control method combining software and hardware can reduce the amount of additional inductance and save costs

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