Resonance Suppression Scheme Based On Active Power Filter

The resonance of power system usually presents as high voltage and large current or system voltage and current waveform distortion.In the light case,the protection action triggered by the power equipment or the quality of power supply will be decreased,which will affect the power consumption of users.In the serious case,the power system will be unstable and unable to operate normally.Shunt active power filter is an ideal equipment for harmonic and reactive power compensation.In order to reduce the compensation capacity of active power filter,the harmonic control and reactive power compensation can be carried out with passive filter or reactive power compensation capacitor.This kind of hybrid compensation system has good economy,but improper use will cause resonance phenomenon.Taking shunt active power filter as the research object,this thesis studies the integrated control strategy of compensating harmonic current and suppressing system resonance in order to realize harmonic compensation function and restrain resonance in hybrid compensation system at the same time.Firstly,based on the mathematical model and control technology of active power filter,the characteristics of network side current control and load current control are analyzed.Net side current control the resonant link contained within a closed loop,through reasonable design can avoid resonance.For a LCR high pass filter resonant system,based on the network side current current control,the advanced correction is designed.The simulation and experiment show that the advanced correction based on network side current control can compensate the harmonic current of the load,avoid resonance effectively,and improve the stability and filtering performance of active power filter.Secondly,at present,the cost of large-capacity active power filters is relatively high.In order to reduce the compensation capacity,reactive power compensation capacitors are often used in the distribution network to form hybrid compensation devices.The resonance phenomenon between reactive compensation capacitor and grid reactance is analyzed in detail.The capacitor current feedback resonance suppression strategy is proposed,and the selection principle of capacitor current feedback coefficient Kc and the complete selection principle of voltage current controller parameters for the control strategy are deduced.Simulation and experimental results show that the proposed control strategy can compensate the harmonic current and suppress the resonance phenomenon,and improve the performance of active filter.Finally,an active power filter experimental platform is established.LLCL output filter is designed,which has the advantages of small size,low cost and good high-frequency attenuation characteristics.An analog signal acquisition and conditioning circuit and a high reliability IGBT trigger circuit are designed.Preparation of active power filter experimental platform related applications.Finished the experiment platform of various functional test and theory research of experiment in this thesis.