Grid-side current balancing control method of 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, the domestic low-voltage power distribution system widely adopts the three-phase four-wire system, and the three phases of this 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 in an unbalanced state, causing current to flow through the neutral line of the grid side. The greater the load imbalance, the greater the current in the neutral line of the grid side. In a three-phase four-wire system, the grid-side neutral line is generally selected as the reference ground of the main circuit and the control circuit. When the grid-side neutral line has a current flowing through it,...

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

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