Harmonic Control And Application Research In Variable Frequency Speed Regulating System Based On Active Power Filter

As power electronics is widely used in variable-frequency speed regulating devices, electrolysis, high voltage DC transmission and electric locomotive traction, harmonic pollution in power system is becoming more and more serious due to the nonlinear and unbalanced characteristics of such loads, at the same time, insufficient reactive power and transitorily voltage rise or sag etc. problem are also caused. The higher and higher requirements for power quality makes it an urgent task to improve power quality and promote enterprise new energy saving technologies. A scheme that mainly uses shunt hybrid active power filter devices is design to realize dynamic harmonic control and reactive power compensation based on the project of comprehensive managing of variable-frequency speed regulating system harmonics and reactive power compensation. The simulation results indicate that the power quality of distribution network can be significantly enhanced with the device put into use.Firstly, harmonic analysis methods and reactive power compensation measures are introduced, and a brief description of the damage caused by harmonics and insufficient reactive power, which leads to the background of hybrid active power filter.Secondly, reactive power needs are calculated according to practical engineering information. Simulation models of electric motor variable frequency speed regulating system are built, besides the function of the built system is also verified through simulation and the gained results match previous expectations. What is more, simulation under different frequency and loads is conducted, whose results are also analyzed in detail, Current distortion is serious,5th and 7th harmonic current content as well as other high-order harmonic waves are beyond the national standard. Therefore, we propose the use of hybrid active power filter technology solutions, Passive filter are mainly applied to filter the 5th,7th harmonic waves and compensate reactive power, other higher harmonics are dynamically managed by active part. A kind of shunt hybrid active power filter is proposed in this thesis, whose topological structure and operational principles are analyzed, and simulation models are built.Finally, simulation results are analyzed, and the percentage of harmonic current is compared to the standard required and proved better under different frequencies and different loads. The managing goal is effectively reached and the social and economic benefits brought by the use of the device is also analyzed in the end.