Seveal Single-phase Circuit Improved Harmonic And Reactive Current Detection Methods

In this thesis,the Active Power Filter(APF) has been used to realize the harmonic suppression is an important developmental trend of current power system. Because the electric current detect block has decided the compensation capability of the APF.Then this thesis emphasizes the research of the question about the harmonic current detection.In the same time,making the design and simulation about the main electro circuit parameter and control circuit of the APF.The article firstly narrated the three-phase instantaneous reactive power theory. Then analysis the harmonic current detection method(p,q and i_p-i_q)that based on the instantaneous reactive power theory.These methods are applied in three-phase three-wire circuit and in three-phase four-wire circuit.Analysis the veracity of these methods detects three-phase fundamental positive active currents and other current heft to meet the need of compensation,whether electric voltage is symmetrical and aberrance.How to extended the three-phase circuit instantaneous reactive power theory to the detection of harmonic and reactive current in single-phase circuit.In this article, we advance three improved detection methods:the phase-shifting structured approach,the improved single-phase i_p-i_q detection approach,the improved detection circuit i_p-i_q approach.The simulation tool MATLAB was used to study on the simulation.The method detection harmonic current using instantaneous reactive power theory in single-phase active power filter by phase-shifting structured approach,in this method,we advance three structured approaches.The simulation results verify the shifting 90~·Structured approach is the best in real-time;The improved single-phase i_p-i_q detection approach simplifies three-phase to two coordinate transformations,this method compute simplily and is easiler achieved by using DSP.The improved detection circuit i_p-i_q approach,this method,appilied in APF,simply replaced the conventional lower-pass filter(LPF) with integrals,time-delay circuits and amplifiers,thus reducing the delay-time from one cycle to 1/6 cycle,the simulation results verify the total dalay-time of the method can be reduced from 0.02 second to 0.0033second.