Research On High-power Active Power Filter Based On Mutilevel Inverter

In the management of harmonic pollution in power system, reactive and harmoniccompensation in power system using active power filter becomes people to solve powerpollution preferred scheme. At present, the active power filter in low voltage power distrib utionlevel power supply network has been widely applied, and plays an important role in the powersystem harmonic control and reactive power compensation. However, the active power filter inhigh voltage, high power conditions is still not mature, mainly because of two factors: first,largepower semiconductor switching devices working at lower frequency, PWM excellent modulationtechnique not on these devices application; and second, the voltage bearing capacity of Powersemiconductor device limit the active power filter in high voltage applications. If the activepower filter applied to high voltage, high power applications, firstly should solve the above twoproblems. In order to solve the conflict between power and switching frequency, high voltageapplications and the voltage bearing capacity of power electronic devices. At the present stageof the power device level objective constraints, the topology structure of main circuit and itscontrol method has become the same strategy choice.In this article, active power filter and multi-levels technology development are firstlyintroduced, then detailed description of the H cascaded bridge inverter structure workingprinciple. The cascaded H bridge inverter modulation of carrier phase shift technique(CPS-SPWM) were also studied, by experimental analysis of two phase in different groups ofinverter unit under the condition of cascade equivalent relation.The basis for parameter design and method of cascade APF are discussed, and cascadeAPF simulation model is built in the MATLAB/Simulink simulation platform, the cascadedactive power filter current output and the filtering effect are validated by simulation. Cascadedactive power filter mathematical model is also constructed in this paper. The difference betweenAPF cascade based on three-phase full bridge APF reference current generation were alsopointed out from the harmonic compensation and DC voltage control two aspects.DC side voltage stability and the inverter module DC voltage balance are the key problemsof cascaded active power filters. In this paper the DC voltage fluctuation and instability phenomenon is analyzed theoretically from the DC and AC energy exchange perspective also.