Service operation of UHVDC systems with emphasis on switching phenomena

The presented paper is aimed at the topic of UHVDC systems with emphasis on switching and breaking techniques both for nominal and non-standard cases of service. The topic of HVDC is very actual and demanding amongst challenges being dealt with within the professional public and power engineers. The first part of the paper contains introduction, assessment and evaluation of the state-of-the-art technology of UHVDC transmission systems and the definition of the greatest challenges within the switching and breaking operations. The second part of the paper is aimed at comparison of conventional and hybrid DC circuit breakers with the detailed explanation of crucial advantages of hybrid technology. The model of hybrid DC circuit breaker is shown in the last part of the paper and its functionality is discussed within exemplary scenarios. The paper concludes with the evaluation of DC breaking techniques and their current and future demands.