1731 / 2020-09-29 17:52:02

Influence of Coupling between VSC and LCC on Commutation Failure of New LCC-VSC

commutation failure,control strategy,CFII,HVDC power transmission system

Power System and Automation > HVDC technologies and applications

Under the relatively mature development of conventional DC transmission and flexible DC transmission, hybrid cascaded multi-terminal DC transmission provides a more flexible transmission method, improves the voltage stability of the inverter AC system, and reduces the probability of commutation failure. The hybrid LCC-VSC at the receiving end of DC system is a new type of topology.In order to study the influence mechanism of the coupling between VSC and LCC on commutation failure in AC power grid at receiving end, this paper firstly elaborates the operation characteristics of the system during the fault,  Based on PSCAD / EMTDC, a hybrid LCC-VSC simulation model is built to verify the reactive power support ability of VSC to LCC, and the improvement effect of VSC on LCC-HVDC under different reactive power control modes is compared and analyzed. The simulation model of LCC-VSC verifies the reactive power support ability of VSC to LCC, and analyzes the improvement effect of VSC on LCC-HVDC under different reactive power control modes. Commutation failure immune factor (CFII) was introduced to study the influence of AC system strength on commutation failure of LCC. Finally, considering that the coupling of AC/DC on commutation failure is closely related to the degree of coupling, the electrical distance between LCC and VSC is further studied. The results show that the conclusion can provide theoretical guidance for the design and analysis of related projects.