Based On Cascade Multilevel Technology Research Of Static Reactive Power Generator

With the development of industry, electrical and electronic components andnonlinear loads applied to the power grid, the power quality is reduced, seriouswhen can cause the network paralysis. As everyone knows, the electric circuitswhich are consist of electronic components and nonlinear loads are inductivenature, the inductive nature consumes reactive power. Reactive powerconsumption will bring the system losses, voltage decreases. Therefore, how tocarry out the reactive power compensation to make up for the consumption ofthe system of reactive power has become the focus of the study.This paper introduces the development of reactive power compensationdevice and the meaning of reactive power compensation, the Static VarGenerator (SVG) is widely studied at present, and a complete SVG systemconsists of the main circuit, detection circuit and control circuit. At last, thispaper research for the three parts:(1) In the main circuit, the main circuit structure using cascaded H bridges,the harmonic content of output waveform of the structure has small, electricaland electronic components are under small tension. The modulation method ofmain circuit of inverter H-Bridge cascaded using carrier phase shifting.(2) In the detection circuit, under unbalanced grid voltage, due to theexistence of phase difference, the traditional detectioni p iqalgorithm can notaccurately detect the system reactive current, so the improvement of reactivecurrent detectioni p iqalgorithm, namely A sequence voltage extracted asPLL input, the simulation results show that, the improved algorithm canaccurately detect the system reactive current when the voltage is not balance.(3) In the control circuit, The SVG is strong coupling, nonlinear system.Therefore on the basis of the differential geometry, controller is designed byusing the exact feedback linearization, the system of strongly coupled andnonlinear SVG is decoupled, therefore the active current and reactive currentare controlled respectively. For the control of DC capacitor voltage of SVG,using PI controller maintain the DC capacitor voltage stability. Finally, the simulation model of SVG is established on MATLAB, the simulation resultsverify the correctness of the algorithm.