Method and system for controlling three-phase four-wire inverter

Abstract

The invention provides a method and system for controlling a three-phase four-wire inverter. The method comprises the steps of 1, acquiring all on-off states of a three-phase four-wire inverter to be predicted, and building a variable relation model of the three-phase four-wire inverter at a load disturbance state; 2, acquiring a voltage change pattern of a DC-side capacitor of the three-phase four-wire inverter, and acquiring predicted values of inductor current and capacitor voltage of an output side of the three-phase four-wire inverter in the next sampling period; and 3, selecting an on-off state, which enables a cost function result value to be the minimum, from all of the on-off states in each sampling period of the three-phase four-wire inverter to act as the on-off state of the three-phase four-wire inverter in the next sampling period. According to the invention, the distortion in voltage of an output filtering capacitor under load disturbance can be effectively suppressed, the inverter is enabled to output sinusoidal asymmetric three-phase voltage, and the voltage-sharing effect at the DC side is good; and meanwhile, the DC side can be enabled to acquire a good voltage-sharing effect under the condition that capacitance values of the capacitor are inconsistent.

Description

technical field [0001] The present invention relates to the technical field of inverter control, and more specifically, to a control method and system for a three-phase four-wire inverter. Background technique [0002] At present, with the development of power electronics technology, three-phase inverters are widely used in smart grids, renewable energy systems, distributed power generation systems and other systems. When the three-phase inverter has an unbalanced load, or the inverter is connected in parallel to the unbalanced grid; usually a three-phase four-wire inverter is required, and the three-phase four-wire inverter is generally divided into two types: split capacitor type, four-arm type. In the split capacitor three-phase four-wire inverter, the midpoint of the split capacitor serves as the neutral point of the load, the neutral wire provides a channel for the zero-sequence current, and finally the neutral wire current flows into the midpoint of the split capacito...

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Problems solved by technology

[0004] However, in the traditional technology, the output voltage closed-loop control is realized by designing a suitable PI controller, repetitive controller, etc. The disadvantage of this method is that the controller design process is more complicated

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