Novel Three Phase Active Power Filter

Currently,the research on active power filter is more on three-phase three-wire active power filter,and the current is normally considered under a state of balance.But in the practical power system,three phase four wire system is very common,and the existence of unbalance current is more or less.Now the compensation control method,either cannot be directly used in three phase four wire system active power filter,or cannot be used easily.And most of the existing in the study does not consider the actual unbalance current.So the research on new type of three-phase active power filter has important practical significance.This paper proposes a modified harmonic current detecting method to adapt to the unbalance current conditions.At the same time,the improvement of existing compensation control method is appropriate to used in three phase four wire system.Finally,the new type of three-phase active power filter system for experimental verification.Firstly,this paper summarizes research status of active power filter.In view of the new type of three-phase active power filter,uses the instantaneous reactive power harmonic current detection method.Harmonic compensation control method combines PI control and voltage space vector method.Then,this paper determines the overall scheme of the system and function,and make the research train of thought.Secondly,this paper determines the measurement and control method of the new type of three-phase active power filter.Under the condition of unbalance current existence,instantaneous reactive power ip-iq harmonic detection method is improved by useing symmetrical component method.Compared with the original ip-iq method,improved detection methods can accurately detect the fundamental positive sequence active current under the condition of the unbalance current.In order to convenient for application of active power filter in three-phase four-wire system,the three-phase voltage space vector and single-phase voltage space vector constitute hybrid voltage space vector control method for harmonic current compensation control.In simulink,the harmonic detection method and compensation control method are simulated respectively.And in this paper,to build a complete simulation for the new type of three-phase active power filter,the results show that the method is feasible.Then,the hardware and software design are completed for the new type of three-phase active power filter.Hardware circuits select embedded single-chip as the core,including signal conditioning circuit,power supply circuit,isolation drive circuit and main circuit.In software part,the modified ip-iq harmonic detection method,the mixed voltage space vector control method is realized as program design.Finally,the new type of three-phase active power filter experimental apparatus is set up.The harmonic current detection method and compensation control method are validated by experiments.The results show that measurement and control scheme is feasible.