Grid-connected inverter control method under unbalanced and harmonic wave power grids

Abstract

The invention discloses a grid-connected inverter control method under unbalanced and harmonic wave power grids. The grid-connected inverter control method adopts a VPI regulator to directly control frequency doubling harmonic wave frequency doubling component fluctuation of active power and reactive power, does not need to decompose positive sequences and negative sequences under multiple synchronous rotating coordinate systems to calculate power reference of frequency doubling components, therefore, reduces calculating delay and strengthens the dynamic response capacity. Meanwhile, due to the fact that the grid-connected inverter control method adopts the SVM-DPC strategy, the problem that the opening-closing frequency is changed is solved, and convenience is brought to selection of an alternating current filtering device. Therefore, the grid-connected inverter control method is suitable for single-phase or three-phase inverting devices, controlled by various PWMs, formed by other various high-frequency switch self-turn-off components under the unbalanced and harmonic wave power grids, and the one-phase or the three-phase inverting devices include grid-connected devices of power generation systems such as a wind energy power generation system, a solar energy power generation system and a fuel battery power generation system, a power electronic device of a flexible alternating current power transmission system and an inverter device in motor control.

Description

technical field [0001] The invention belongs to the technical field of converter control, and in particular relates to a control method for a grid-connected inverter under an unbalanced and harmonic grid. Background technique [0002] As a branch of VSC (three-phase voltage source converter), grid-connected inverters have been widely used in industrial production, especially in distributed energy grid-connected, high-voltage direct current transmission, servo motor drives, smart grids, etc. Field application is very common. At present, the control of grid-connected inverters mostly stays under ideal grid conditions, but because various symmetrical or asymmetrical faults often occur in the actual grid, and there are 5th and 7th harmonic components, for such sudden Under fault conditions or weak grid operation conditions, traditional grid-connected inverter control methods have great defects, and large current and power oscillations occur. Therefore, it is necessary to carry ...

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Problems solved by technology

The above situation is only for the unbalanced grid voltage. If there are harmonic components in the grid at the same time, it is necessary to separate the positive and negative sequence components of the harmonic components of the three-phase voltage and current of the converter, requiring more traps and introducing longer delays. ; At the same time, when calculating the voltage reference signal, it is necessary to separate the power DC signal and other frequency multiplied signals, which makes the calculation of the reference voltage more complicated; at the same time, this method does not make the current output by the converter symmetrical and sinusoidal, and the control target is single , can not meet the requirements of operation under weak grid

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