Application Of Auto-Disturbance-Rejection Technique In VSC-HVDC

VSC-HVDC transmission technology possesses the advantages of high controllability and gets more and more widely used in electric power system. Compared with the traditional dc transmission, it is able to achieve the independent regulation of active power and reactive power.In this paper, on the basis of the Auto Disturbance Rejection technique, the VSC-HVDC and the VSC-MTDC converter control strategies have been analysised and researched.(1) Introduced the development Auto Disturbance Rejection technique and its advantages,on the basis of the multi-order and second-order Auto Disturbance Rejection Controller,designed a more useful ADRC of one-order.(2) Based on voltage source rectifier working principle and mathematical model research, constructted the model of double terminal VSC-HVDC. For reduce the dependence of the controller on the system mathematical model,designed a direct current controller of outer loop controller with the constant dc voltage,the active power controller and the reactive power controller, of the inner loop controller using optimal control function.Finally realizes the fast dynamic response, strong robustness and external disturbance not sensitive control objectives.(3) Three terminal VSC-MTDC model is set up, including two terminals connected to active networks and one terminal to passive network.Together with voltage margin control methods,ADRC is used on the system.The first-order ADRC have the advantages of simplely design process,fastly speed and highly reliability.Based on the result of digital simulation for double terminal VSC-HVDC and three terminal VSC-MTDC,verifyed the effectiveness of ADRC in power flow reversal step,active power step,reactive power step,ac system fault and dc voltage drop.