Dynamic hysteresis current control method for active power filter

Abstract

The invention discloses a dynamic hysteresis current control method for an active power filter, relates to a dynamic hysteresis current control method for an active power filter under the condition of asymmetric power grid voltage, and aims to overcome the defect that under the condition of normal power grid voltage imbalance, the adoption of an existing hysteresis current control method has the problems of large switching loss, high average switching frequency and incapability of ensuring the current quality of a power grid in the prior art. The method comprises the specific steps of 1, calculating to obtain voltages at two ends of all interface inductors in all switch combination states in the active power filter; 2, dividing a plurality of sectors according to the on-off states of the a phase, the b phase and the c phase; and 3, detecting the validity of the sector, judging whether the sector in which the switch switching operation exists is valid or not, and if the sector in which the switch switching operation exists is valid, keeping the switch switching operation in the sector; otherwise, transferring the switching operation to other sectors until the the switching operation is transferred to the closest effective sector.

Description

technical field [0001] The invention relates to a dynamic hysteresis current control method of an active power filter under the condition of asymmetric grid voltage. Background technique [0002] At present, the control strategies for active power filters are all based on the ideal grid voltage. At this time, the amplitude of the three-phase grid voltage is the same, and the phase difference is 120°. However, there are a large number of single-phase loads in the actual power system, which will cause the amplitude and phase of the three-phase grid voltage to be different, that is, the voltage of the three-phase grid is unbalanced. [0003] Generally speaking, there are two main reasons for the unbalanced voltage of the three-phase grid: accident and normality. Accidents are caused by system faults, including one-phase, two-phase disconnection, single-phase grounding, etc. For such faults, the power grid generally has a protection function. When an accident occurs, the power...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the problems that the existing hysteresis current control method has large switching loss and high average switching frequency and cannot guarantee the current quality of the power grid under the condition of normal grid voltage unbalance, and provides an effective A Dynamic Hysteresis Current Control Method for Source Power Filter

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