Power harmonic suppression device

Abstract

The invention relates to a power harmonic suppression device. A harmonic calculation circuit receives a power line harmonic distortion rate signal detected in real time; the power line harmonic distortion rate signal and a total current signal are subjected to product operation when a sampling period arrives,so that harmonic current is output; the harmonic current enters a pulse width modulation circuit; and when the harmonic current is small, the harmonic current is converted into a PWM signal through a first voltage frequency conversion circuit, and the PWM signal is subjected to buffering and sampling maintaining, a driving pulse is outputted to a first power module so as to be subjected to harmonic current compensation; when the harmonic current is large, the harmonic current drives the first power module and a second power module through the first voltage frequency conversion circuit and a second voltage frequency conversion circuit to carry out balance compensation on the harmonic current; when the change rate of the harmonic distortion rate signal is small, on one hand, a pulse width compensation circuit directly compensates the harmonic current by adjusting the pulse width of the first voltage frequency conversion circuit and the second voltage frequency conversion circuit, judges whether pulses before and after sampling maintaining are consistent or not through an exclusive-OR gate, adjusts the pulse width of the second voltage frequency conversion circuit when the pulses are consistent, and adjusts the second power module to compensate the harmonic current.

Description

technical field [0001] The invention belongs to the technical field of power control, in particular to a power harmonic suppression device. Background technique [0002] Harmonics reduce the production, transmission and use efficiency of electric energy, and even cause problems such as local overheating of transformers, mechanical vibration, noise and overvoltage, and malfunction of relay protection and automatic devices, which seriously threaten the safety and stable operation of power systems. . [0003] At present, the method of eliminating harmonics in the power system mainly uses active power filters to detect the current in the line in real time. After DSP processing, the power module is driven by pulse width modulation signals to generate harmonics with opposite directions and equal magnitudes. wave current to offset or compensate the harmonics in the system and actively eliminate power harmonics. Its filtering effect is good, but the structure is complex and the cos...

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Problems solved by technology

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a power harmonic suppression device, which effectively solves the problem that the existing active power filter has complex structure, high cost, and will cause failure of the power module

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