Hybrid power filter main circuit

Abstract

The invention discloses a hybrid power filter main circuit which comprises a passive filter circuit, an active filter circuit and a measuring circuit, wherein the passive filter circuit consists of a double-tuned filter branch circuit and a base-wave partial-pressure series double-tuned filter branch circuit; a resonance point of one double-tuned filter branch circuit is set to be three times or five times, and a resonance point of the other branch circuit is set to be five times or seven times; the passive filter circuit is directly connected with the active filter circuit by a circuit instead of a coupling transformer; and the measuring circuit comprises a voltage sensor B1 at a power grid side, a load current sensor B2 at the power grid side, a passive filter branch circuit current sensor B5 in a passive filter branch circuit, a voltage sensor B5 at an active and passive connecting point, a compensating current sensor B4 in the active filter circuit, and a direct current (DC) bus voltage sensor V1. Due to the structure without the coupling transformer, the cost and the size of a system are obviously reduced, the defect of compensating current phase delay caused by the coupling transformer can be overcome, and the compensation precision is improved.

Description

technical field [0001] The invention relates to a power filter, in particular to a main circuit of a hybrid power filter. Background technique [0002] At present, the existing hybrid power filter includes a filter branch composed of an active filter and a passive filter in series, and is equipped with a current detector and a compensation current detector for grid current detection; A hybrid power filter composed of a fundamental wave series resonant passive filter connected in parallel, and the active filter and the passive filter are coupled through an isolation transformer. Its disadvantages are: the active filter has to withstand the fundamental voltage, which is not suitable for high-voltage systems; it does not have the function of compensating the fundamental reactive power and filtering the characteristic sub-harmonic current of the passive filter, and the capacity of the system to filter harmonics is limited. limit. In order to ensure that the low-voltage active ...

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Problems solved by technology

Its disadvantages are: the active filter has to withstand the fundamental voltage, which is not suitable for high-voltage systems; it does not have the function of compensating the fundamental reactive power and filtering the characteristic sub-harmonic current of the passive filter, and the capacity of the system to filter harmonics is limited. limit

In order to ensure that the low-voltage active part can filter out the high-voltage harmonic current, the existing hybrid power filter uses a coupling transformer to connect the active filter and the passive filter, but this will lead to a decrease in the overall system economy and an increase in volume. Large, and the compensation current will cause phase delay through the coupling transformer, and the compensation accuracy will decrease

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