Method for controlling dynamic direct voltage of parallel connection type active electric filter

Abstract

The invention relates to a method for controlling dynamic direct voltage of a parallel connection type active electric filter, comprising the following steps: 1. charging current from the power grid pre-charges a capacitor at the direct current side; 2. a lower bridge arm switch of an uncontrolled rectifier bridge is switched on due to control of switching pulse signals transmitted by a controller, the duty cycle of the switching pulse signals increases to a fixed value from zero in a linear manner; 3. the switch of an upper bridge arm and the switch of a lower bridge arm are both simultaneously cut off; 4. a PI controller in an electric ring is placed under a d-q synchronization coordinate system and PI controller initial output value is set; 5. Gn(s) calculation is carried out on sampling value of the power grid voltage and then the sampling value is added to output value of the PI controller in a PI control inner ring in the electric current ring; 6. a repetitive controller is arranged in a repetitive control outer ring of the electric current ring. The invention ensures high stability of DC bus capacitor voltage in dynamic processes such as start, synchronization and load switching of a high-capacity active filter.

Description

technical field [0001] The invention relates to a method for controlling dynamic DC voltage of a parallel active power filter, in particular to a large-capacity parallel active filter device. The patented technology of the present invention is mainly used in the occasions that require high DC bus voltage stability during dynamic processes such as large-capacity active filter device start-up, grid connection, and load switching. The invention belongs to the technical field of active power filters. Background technique [0002] In recent years, with the rapid development of modern power electronics technology and the surge of nonlinear loads in the power grid, the voltage and current waveforms of the power grid are seriously distorted, resulting in the continuous increase of harmonic levels in the power grid. Since the shunt active power filter is very suitable for compensating the harmonic and reactive current in the grid, it has been widely researched and used in recent yea...

AI Technical Summary

Problems solved by technology

A DC-side voltage control method disclosed in a Chinese invention patent (Patent No. 02153872.7, titled "Converter DC-side Voltage Closed-loop Control Method and System for Active Power Filter") can overcome the delay caused by digital controllers. The impact of DC voltage control, but does not solve some core issues of DC voltage control in dynamic processes

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