Model prediction current control method based on NPC topology grid connected inverter under asymmetric voltage

Abstract

The invention discloses a model prediction current control method based on an NPC topology grid connected inverter under asymmetric voltage, introducing the model prediction current control technology into the NPC grid connected inverter control. The model prediction current control method disclosed by the invention comprises steps of introducing decoupling double synchronization reference coordinate system phase-locked loop (DDSRF-PLL) phase lock technology to perform tracking on a positive sequence voltage phase angle in order to accurately track the positive sequence voltage phase angle under the condition that the power system has the asymmetric fault, on the basis, utilizing the DDSRF-PLL to decouple to obtain fundamental frequency voltage positive and negative sequence components, realizing a model prediction current control with the inhibition of the negative sequence current component, the active power oscillation and the reactive power oscillation as the control goal by combining with a instantaneous power theory, and adding a weight coefficient item into a cost function in order to guarantee the capacitor voltage balance on the DC side of the NPC grid connected inverter in the control process. In the whole control process, the invention reduces the usage of the PI controller, enhances the responding speed of the system, and enables the two sides of the grid connected inverter to have higher electric energy quality and stability.

Description

technical field [0001] The invention relates to the field of grid-connected inverter control, in particular to a model prediction current control method based on an NPC topology three-phase grid-connected inverter under asymmetric voltage. Background technique [0002] Looking at the research hotspots of new energy power generation systems in recent years and the research status at home and abroad, renewable new energy power generation technologies such as wind power generation and photovoltaic power generation have achieved unprecedented development. The new energy power generation system is a network dominated by inverters, so the development of new energy also drives the rapid development of power electronic converter technology. When the power grid system is in a stable operation state or a three-phase symmetrical fault occurs, the traditional proportional-integral (PI) control strategy based on the positive-sequence synchronous coordinate system can achieve a good contr...

AI Technical Summary

Problems solved by technology

The occurrence of this type of asymmetric fault, the access of high-power single-phase loads, the unbalanced distribution of single-phase loads in the three-phase system, and the randomness of power consumption of single-phase loads will cause the three-phase voltage imbalance of the power grid.

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