Research On New Seven-level Reactive Power Compensation Device And Control Technology

With the advent of industry 4.0 era,a large number of power equipment have been applied to industrial manufacturing and production,which has brought huge reactive power impact and high-frequency harmonic current to the power grid,seriously affecting the normal operation of the power grid and reducing the power quality of users.Reactive power compensation and harmonic suppression have become two urgent problems in the field of power quality control.Static Var Generator(SVG),as the latest reactive power compensation device,has become a hot topic for domestic and foreign scholars due to its good dynamic performance,flexible compensation method,small volume and low cost.The development direction of SVG is gradually towards multi-level and multiple technology.Firstly,this dissertation introduces the importance and necessity of reactive power compensation device,and analyzes the research status of multi-level SVG topology and control technology at home and abroad.In order to improve the shortcomings of the traditional multi-level topology with many switching devices and complex control,this dissertation proposes a new topology that uses only 6switching devices and 2 capacitors to achieve seven-level output,analyzes its working principle,and gives a method to expand the new topology to more output levels.Then this article introduces the working principle of SVG based on the new seven-level topology,and derives its mathematical model.Secondly,this dissertation studies the control technology of the new-seven level SVG,and designs the overall control scheme of the system.The ip-iq detection method based on instantaneous reactive power theory is selected to extract reactive and harmonic command currents.This dissertation studies the phase-locked technology in the case of unbalanced power grid and harmonic distortion,and proposes an improved phase-locked loop design based on Multiple Variable Filter combined with Adaptive Notch Filter(MVF-ANF).The command current tracking technology chooses the control technology of quasi-Proportional Resonance and repetitive control;the Carrier in-Phase Disposition Pulse Width Modulation technology is used to generate PWM.For the problem of capacitor voltage regulation,a two-stage voltage regulation control strategy combining overall control and independent control is proposed.Based on this,the MATLAB/Simulink platform is used to carry out the simulation verification of the new seven-level SVG,and the simulation model and simulation result analysis of each part are given.The dynamic performance,compensation effect and control technology of SVG are comprehensively verified and analyzed under the two working conditions of grid balance and grid unbalance.Finally,this dissertation designs the hardware and software circuit of the system,and builds an experimental platform with DSP+FPGA as the control core and the system capacity is 10 k VA.The experimental results also verify the correctness and feasibility of the proposed new seven-level SVG topology and control technology.