Unified Power Quality Conditioner Harmonic Detection And Control Strategy Of The Simulation

With the development of power electronics technology，a variety of powerquality problems are produced because of the increasing use of a wide range ofprecision instruments，such as voltage drop，voltage rise，over-voltage，undervoltage，harmonic pollution，voltage fluctuations，voltage unbalance，powerfrequency change．At present，the practice has proved that the active filtertechnology can effectively improve the power quality，the unified power qualityconditioner has become a research hotspot because of solving various powerquality problems．UPQC not only can compensate for the distortion waveform，but also can achieve the function of the dynamic voltage restorer．Firstly, the thesis describes researching background and significance of theUPQC．Secondly it elaborates the type and characteristic of topology．Finally, itexpounds union control which is watched by researcher for the moment．Thepaper adopts the thought of independent control because of the theory is toocomplex of union control．The effect can meet the requirements．The systemutilizes the detection methods of command signal suitable for UPQC on thebasis of the understanding of system structure and work principle．The article focuses on the control method．After comparing several widelyused tracking PWM control methods， a double-direction compensationinstantaneous comparison method is selected for the value of the compensationfor harmonic current，which overcomes the disadvantages of the local stabilityof traditional instantaneous comparison method．The space voltage vector isutilized as control method in the Unified Power Quality Conditioner seriesunit,which is more easier and faster．This method improves the accuracy of thecompensation of system. Finally，when the grid voltage, under voltage, voltagedrop, load mutation emerged in the power environment, the Unified PowerQuality Conditioner、series APF and shunt APF compensate for the problems.The simulation results proved UPQC combines the advantages of the shunt APFand series APF, has good compensation characteristic, while addressing a varietyof power quality problems in the power distribution system. The simulation results show that the UPQC can solve multiple power quality problems in powersystems, and its compensation function is better than other compensationequipments．...