Active harmonic filter is a type of electronic device that is used to eliminate harmonic distortions in electrical power systems. Harmonic distortion refers to the presence of unwanted frequency wave in the power system that could lead to issue of increasing heating of equipment, reducing system efficiency, and even making the equipment failure in work.
Active harmonic filter operates by detecting the harmonic current in the system and generating a counter-current of the same magnitude an opposite phase. This counter-current cancels out the harmonic current and prevent it from being fed back into the power system. Active harmonic filters are designed to be fast and accurate in their response to changing harmonic condition in the power system.
The load current is detected by the current transformer and calculated by the internal DSP to extract the harmonic components of the load current, and then sent to the internal IGBT through PWM signal to control the inverter to generate a phase with the load harmonic current size, and the harmonic current in the opposite direction is injected into the power grid to achieve the purpose of filtering.
The function of the command current detection circuit is mainly to separate the harmonic current component and the fundamental reactive current from the load current, and then the reverse polarity effect of the compensation current after the command signal. The function of the current tracking control circuit is to calculate the trigger pulse of each switch device in the main circuit according to the compensation current generated by the main circuit. The pulse is acted on the main circuit after the driving circuit. In this way, the power supply current only contains the active component of the fundamental wave, so as to achieve the purpose of harmonic elimination and reactive power compensation.
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Post time: Apr-21-2023