Research On Adrc Control System Of Modular Multilevel Converter

A modular multilevel converter is one of the most popular voltage source converters in power electronics at present,which has many advantages,namely step voltage reduction,strong ability of fault handling,low content of harmonic.It is widely used in the flexible alternative current transmission systems now and has high utility value and good application prospects.In the field of transmission control,PID control occupies a dominant position,though it has its own shortcomings such as the method of getting error,the side effects of integral feedback.Thus,this paper proposes a novel control method,a high quality ADRC is adopted,to deal with the above problems and the original advantages of the PID are retained as well.The controller only has simple algorithm but also is easy to adjust the parameters of each link and it has no overshoot and strong robustness.This paper has high practical value by combining the ADRC algorithm with PID control,which is applied to the three-phase PWM and MMC rectification system to achieve the purpose of optimizing the control effect.First,for the MMC part,the mathematical model under the dq coordinate system is built through the analysis of its topology and working principle,followed by focusing on its modulation strategy,control strategy and other content.Last,nearest-level approximation and other modulation methods are analyzed with 5-level MMC simulated by Matlab/Simulink2017 b and theoretical knowledge.As for the ADRC design of three-phase MMC rectifier system double loop,this paper focuses on the differential tracker,the state observer,and the error feedback control rate of the internal components.And then the rapidity of the ADRC's system control,strong robustness and other features are analyzed by ADRC simulation.The simulation uses ADRC algorithm as the main control method and applies it to the three-phase PWM and MMC rectification simulation double loop system.Through the analysis and comparison of the results of the double closed-loop simulation,which uses PID as the controller,that the ADRC controller is superior to PID control whether in rapidity of the system regulation or the stability of robustness is proved.