The Algorithm Research Of APF Harmonic Detection Based On Instantaneous Reactive Power Theory

Extend using of nonlinear loads,the pollution produced by the harmonic current in the power grid is becoming increasingly serious.As one of power facilities controlling the harmonic in power grid,active power filter(APF)has played a key role.And the performance in step of detection directly influenced the effective of the whole system.Focus on this problem,shunt active filter being the research object,the paper has deeply researched the way to bring up the characters in step of harmonic current detection.And it has made up for grid-side current through constructing control system model,verifying the feasibility and effectiveness of the discussed method.First of all,this thesis analyzed in particular about the theoretical basis of p-q and ip-iq detecting harmonic current from the phase of the instantaneous reactive power algorithm,comparing the performances of both algorithms in situation of distortion voltage in net of power.The results have implied that the algorithm of ip-iq is more suitable for detecting the harmonic in voltage of power net.Consequently it is prefer to ip-iq when encounter the above situation.In addition to,the paper has compared the influence on performance of harmonic detection by both Butterworth and average filter.Result demonstrates that average filter reduces amount of calculation,and enhances the dynamic response speed of system.Second,correctly locking on the frequency of the voltage in the power grid is the foundation whether you can correctly detect the harmonic current.Therefor,the paper analyzed the dq transform about Phase-locked loop under the synchronous rotating coordinate system.Has verified that voltage of power net including the fundamental negative sequence component will make twice the power frequency fluctuations which would impact on the performance of the whole system.In order to raise the effective of Phase-locked loop used in power net whose voltage include harmonic,the essay adopts the phase-locked loopbasing on SOGI.The article realizes to extract the fundamental sequence-component and to control about harmonic in voltage,reducing the influence about harmonic on the phase-locked loop by using SOGI.Furthermore,the paper analyzed the impacts on performance of phase-locked loop from main characters of SOGI,verified the correct and availability about this method.Finally,the article compensates the harmonic detection algorithm discussed in this paper through constructing the system model and the experimental prototype of active power filter,to verify the feasibility and effectiveness of the theory.The result of simulation and experiment indicate that voltage and current after compensation are satisfied with relevant standard.