Auto-Disturbance-Rejection Controller And Its Application In HVDC Control System

High voltage direct current (HVDC) transmission system is verysuitablefor the high power long distance transmission and plays an important role intheWest toEast Power TransmissionProject. The securityandstabilityof theHVDC system is ensured bythe well influence of its controller. However, theHVDC system is a strongly nonlinear, uncertain system. The study onimprovingtherobustnessofthecontrollerofHVDCsystemisimportant.Auto-disturbance-rejection controller (ADRC) has the adaptability fortime-varyinganduncertaindisturbance. But it is complex anddifficult totunetheparameteroftheADRC.Animprovedgeneticalgorithm is usedtotuneofthe parameter of the ADRC in this dissertation. And the ADRC is used in therectifier and the inverter control of the HVDC system to improve therobustness of the HVDC system. Firstly, an evaluation function to tune theparameters of ADRC is established. Both the controller's dynamicperformanceandcontrolconstraintsaretakenintoaccountinthetuningoftheADRC. The penalty function is added into the fitness function to punish thehuge output of the controller. Adaptive crossover mutation andchaos-migration operators are used in the genetic algorithm to prevent the premature convergence of genetic algorithm and speed up the convergenceprocesses. Secondly, the constant current controller of the rectifier and theconstant voltages controller are designed with the proposed approach. Theresults of the simulation of the ADRC and HVDC with the Matlab/Simulinksoftware suggest that the method of tuning the parameter of the ADRC waseffective and the controllers have a good adaptability to the externaldisturbanceandthemodelchanges.