Dynamic performance of Controllable Line-Commutated Converter (CLCC) in HVDC systems with weak sending end AC network

Abstract

Both the sending end and the receiving end AC network of long distance HVDC systems are getting weaker and weaker, with fast growing renewable energy penetration under “dual carbon” scenario. The inherent defect of HVDC-commutation failure has become a more prominent problem. The Controllable Line-Commutated Converter (CLCC) raised recently has been proved to be effective to eliminate commutation failure. This paper aims to discuss the dynamic performance of CLCC in HVDC systems with weak sending end AC network. Firstly, the circuit topology and operation principle of CLCC are introduced. Then the dynamic performance of CLCC is theoretically analyzed. Finally, the dynamic performance of the proposed method is validated by simulation on the developed 500kV/1.2kA CLCC HVDC model in PSCAD/EMTDC. And the result shows that compared with LCC-HVDC system, CLCC-HVDC can significantly reduce the impact of active power and reactive power fluctuation imposed on the sending end AC network during the AC fault at the receiving end and greatly improve the stability of the electric power system.