Research Of The Detection And Control Algorithms For Three Phase Four Wire SVG

Three phase four wire static var generator can solve the reactive power and harmonic problems of low voltage power grid,improve power supply system stability.Mainly to research the three part key technologies for SVG,that is the problem of phase-locked for DQO detection,the problem of real-time for traditional PI double closed control and the problem of resonance peaks for LCL filter,in order to meet the real-time,accuracy and stability of the reactive power harmonic compensation of the power grid of the three phase four wire SVG.In this paper mainly to do the work of analysis、improvement and implementation with respect to the detection technology、control technology and grid-connected inverter technology. In terms of the phase detection problem for DQO detection method,proposed a phase-locked loop EPLL with robustness, that phase detection results are not affected by grid voltage unbalance and flicker,which has a good adaptability to grid;For defects of traditional PI double closed loop control method of the slow tracking response speed,the big overshoot and the low static difference and stability accuracy,an adaptive PI double closed loop control method is proposed,the voltage square outer loop controller is realized based on the dqO coordinates transformation,achieved the DC capacitor voltage regulation and balance control,the design of current loop controller is completed based on the Parke transformation,and introduced the adaptive PI control;In terms of the resonance peaks problem for LCL filter,proposed a RC series LCL method with the characteristics of high damping, low loss, low cost, good filter characteristics etc,in order to improve the waveform quality and system efficiency for grid-connected SVG.At the same time proposed the research key technologies in this paper.conduct the MATLAB simulation,DSP programming, prototype testing,In order to make sure the feasibility of each improved program and the actual effect of the SVG for dynamic harmonic and reactive power suppression.Research findings of this paper,provide a theory basis for realizing harmonic and reactive power dynamic compensation of three phase four wire grid effectively,also has a certain practical value and important research significance for cleansing distortion grid as well as improving system quality.