Research on the characteristics of multi-infeed DC system with hybrid commutation converter suppressing successive commutation failure

• This paper addresses the problem of successive commutation failure in multi-infeed DC system. • Studies have shown that hybrid commutated converter is effective greatly for successive commutation failure. • The risk of successive commutation failure is analysed and the mechanism of HCC to suppress the risk is analysed . • Because of active turn-off, less reactive power, faster recovery, successive commutation failure can be supressed by HCC. • Solving successive commutation failure can suppress the power transmission blocking and improve security & stability. In view of the problem of successive commutation failure in multi-infeed direct current systems, this paper investigates the commutation characteristics of hybrid commutation convert technology and its application in mitigating successive commutation failure, with a case study based on the Lingbao Converter Station modification project in the Henan grid. First, the operational mode of hybrid commutated converter is proposed, and its low reactive power consumption reduced by 20% is calculated and compared with that of a line commutated converter. Then, the mechanism of successive commutation failure in Henan grid is analyzed using an equivalent grid model. The hybrid commutation convert technique is introduced as a solution to successive commutation failure due to its advantages, including complete commutation failure mitigation, fast post-fault recovery, and reduced reactive power consumption. Finally, the effectiveness of the proposed operational mode is verified through Real-Time Digital Simulator simulation tests. A simulation model of both hybrid commutation converter and line commutation converter-based high voltage direct current system is developed, and the commutation characteristics during fault and recovery are analysed. Additionally, the efficacy of hybrid commutation converter in suppressing successive commutation failure in the multi-infeed direct current system is evaluated through CloudPSS-based grid simulations.