Extraction method of command current of active filter with adjustable power factor

Abstract

The invention relates to an active power filter command current extraction method with a power factor being adjustable. The method comprises the following steps: acquiring a voltage of a three-phase system, and performing phase-locking calculation to obtain a phase of the system; acquiring current of the three-phase system, and performing CLARK-PARK transformation on three-phase current by the system phase to obtain a d-axis component and a q-axis component; processing the d-axis component and the q-axis component through a low-pass filter to obtain a fundamental wave active component and a fundamental wave reactive component; determining a d-axis component and a q-axis component needing to be reserved by a network side system; and performing CLARK-PARK reverse transformation on the reserved d-axis component and the reserved q-axis component, and subtracting system current from a component obtained through the reverse transformation to obtain command current. Through adoption of the method, harmonic current and reactive power of a specified capacity are compensated at the same time by an active power filter, and the compensation performance and utilization ratio of the system are improved.

Description

technical field [0001] The invention relates to a power system power quality monitoring technology, in particular to a command current extraction method of an active filter with adjustable power factor. Background technique [0002] The active power filter (APF) can compensate the harmonics whose frequency and magnitude change at the same time, and can compensate the reactive power of a certain capacity. It is currently a research hotspot of scholars at home and abroad. Active filters are mainly used to compensate harmonic currents, reactive power compensation is only an additional function, and are affected by system parameters, the best working condition of active filters is the rated capacity. If the harmonic content in the system is lower than its compensation capacity, its compensation performance will be significantly reduced. If the active filter is used to compensate a certain capacity of reactive power, the compensation capacity can be increased to the rated capacit...

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Problems solved by technology

If the harmonic and reactive power capacity are lower than the rated capacity of the active filter compensation, the total amount of compensation required is higher than the rated capacity, and the active filter cannot work in the best state if the reactive power is fully compensated or not compensated. ; If full compensation is performed, the reactive power can be limited by the upper limit of compensation of the active filter, which can also make the system work near the rated capacity. However, this compensation method is relatively passive, that is, it cannot actively control the size of the compensated reactive power

In addition, at some nodes in the power system, it is necessary to reserve a certain amount of reactive power to improve the transmission characteristics of the power system, etc. Therefore, the compensation method of the active filter for reactive power needs to be improved

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