| Line Commutated Converter High Voltage Direct Current (LCC-HVDC) can transmit large power and long distance which has been widely used in China, but commutation failure problem still need to be solved. In recent years, Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) with full-controlled devices has developed rapidly. It can control the power flexible and connect to passive network. Voltage-Current source Hybrid-HVDC which is constituted by the LCC and VSC combines the advantages of both converters and has a wide range of applications.Firstly, the characteristics and applications of Hybrid-HVDC were described, and then the topology and wiring of it were analyzed. The parameter design and control method of both LCC and VSC are studied. Then two types of Hybrid-HVDC simulation models are established in PSCAD/EMTDC. For the Hybrid-HVDC with LCC rectifier and VSC inverter, the start and control methods are designed. To obtain the operating characteristics, Simplex algorithm is used to optimize the DC side LC and PI controller parameters. What’s more, the case of Hybrid-HVDC supply passive network is studied. For the Hybrid-HVDC with VSC rectifier and LCC inverter, the paper compares different control strategies and designs the new coordinated control method to supress the commutation failure. A Voltage Dependent Voltage Order Limiter (VDVOL) is designed based on the constant DC voltage control at the rectifier side, and constant extinction angle backup control is introduced based on the constant DC current control with Voltage Dependent Current Order Limiter (VDCOL) at the inverter side. It is concluded that, the proposed control method has the ability to effectively reduce the probability of commutation failure and improve the fault recovery performance of the Hybrid-HVDC system. |
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