Capacitor Commutation Technology And Its Stable Control Strategy In HVDC

Firstly this thesis introduces the research status and engineering advantages of the capacitor commutated technology. Secondly analysis the operational principle of capacitor commutated converter by using mathematical model. Furthermore the two simulation models of CCC-HVDC and CSCC-HVDC are built in the PSCAD software. Research on the step response and critical SCR of these two models respectively, compares the results with the traditional LCC-HVDC model. Through the steady state analysis of these two new HVDC systems to verify their response characteristics meets the simulation requirements. Research on the dynamic performance and stability analysis capacitor commutated converter which connect with the weak AC system. This thesis emphatically discusses the transient features of CCC-HVDC and CSCC-HVDC simulation models, as well as the comparison of these two new models.The simulation results show that the steady state characteristics of the two new models are better than the LCC-HVDC model, which concluded from the analysis of critical SCR. Through the transient simulation concluded that the capacitor commutated converter can inhibit the commutation failure and disturbance effectively. When compared the CCC-HVDC to CSCC-HVDC, we find that the fault location will affect the model’s response characteristics and operation characteristics. While the failure is located near the grid side of the transformers, the response characteristics of CSCC-HVDC are better than CCC-HVDC, while the fault is located near the valve side of transformers, the CCC-HVDC response characteristics are better than CSCC-HVDC.