A grid-side current balance control method for a unified power quality conditioner

Abstract

The invention relates to a grid-side current balancing control method of a unified power quality conditioner. The method comprises: a three-phase grid voltage, a load voltage, a load current are converted from a three-phase ABC alternating-current coordinate system to a two-phase dq rotation coordinate system and phase information needed by coordinate conversion is obtained by phase locking of a grid voltage; after coordinate conversion, alternating-current components and direct-current components of the grid voltage, the load voltage, and the load current are obtained, and after processing by a low-pass filter, alternating-current components in variables are filtered; according to the filtered direct-current components, a grid-side current fundamental current amplitude is calculated; and the grid-side current fundamental current amplitude and a direct-current bus voltage adjustment result are superposed to obtain a three-phase grid-side reference current amplitude. With the method provided by the invention, the grid-side three-phase current balancing degree can be reduced; the direct-current bus voltage fluctuation can be reduced; the dynamic response speed of the system can be increased; and defects of poor steady-state control effect and slow dynamic response speed of the direct-current bus voltage loop can be overcome.

Description

technical field [0001] The invention relates to the fields of power electronics and power systems, in particular to a grid-side current balance control method of a unified power quality regulator, which is used to control the power quality of a power grid. Background technique [0002] At present, three-phase four-wire system is widely used in domestic low-voltage power distribution system, and the three-phase system can operate independently of each other. When the three-phase circuit has an unbalanced load, the three-phase current on the grid side will also appear unbalanced, resulting in a current flowing through the neutral line on the grid side. The greater the load imbalance, the greater the neutral current on the grid side. In the three-phase four-wire system, the grid-side neutral line is generally selected as the reference ground for the main circuit and the control circuit. When there is current flowing through the grid-side neutral line, the neutral line potential...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problems of poor control effect of the DC bus voltage loop on the grid side three-phase current balance degree, large DC bus voltage fluctuation and slow dynamic response speed in the existing control technology of UPQC, and provide a unified power quality regulator grid side Current balance control method, especially under unbalanced load conditions, the advantages of the method of the present invention are more obvious

Images