Active power filter direct current control method suitable for condition of weak power grid

Abstract

The invention discloses an active power filter direct current control method suitable for the condition of a weak power grid. The method is implemented according to the following steps: Step 1. voltage of a PCC point of a weak power grid system, inverter direct current side voltage, an instantaneous value of load current and an instantaneous value of current emitted by the inverter are collected; Step 2.the collected instantaneous values and the instantaneous value of current emitted by the inverter are processed through a conditioning circuit and is input to a DSP to be converted to digital signals; Step 3. the DSP processes the digital signals to obtain instruction current signals of the active power filter; Step 4. the DSP performs hysteresis comparison on the instruction current signals and the digital signals, and is controlled to emit PWM waves; and Step 5. the emitted PWM waves are sent to a drive circuit of an IGBT module of the inverter, the inverter is controlled to emit current according to the instruction current signals, and harmonic waves and reactive power in a power grid system are compensated according to the emitted current. The active power filter direct current control method suitable for the condition of the weak power grid effectively and accurately compensates reactive current and harmonic current of a load.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and relates to a direct current control method of an active power filter suitable for a weak power grid. Background technique [0002] With the increasing scarcity of fossil energy and the seriousness of environmental problems, more and more attention has been paid to clean and renewable energy. Therefore, as one of the main application methods of renewable energy, the distributed power generation system has continuously increased its proportion in the power grid. According to the grid structure, the impedance of the grid is mainly determined by the low power converter and the impedance of the distribution line. The increase of distributed power makes the grid impedance not negligible and changes in a wide range under different operating conditions, and the grid presents the characteristics of a weak grid. At the same time, the wide application of power electronic devices will bring i...

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Problems solved by technology

[0005] The purpose of the present invention is to provide an active power filter direct current control method suitable for weak grid conditions, which solves the problem that traditional direct current control cannot accurately compensate harmonics and reactive power under weak grid conditions

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