A Study On Fault Analysis And Protection Principle For HVDC Converter

The power grid of China is in the period with high speed of development and now the transition from big-area network to fully-meshed national power grid has come into being. With the far-ranging application of HVDC in our country , HVDC has been the hotspot in the field of power. The design of DC Protection System which is related to the core issues of power system safe operation, received extensive attention.Converter is a critical, complex and expensive component in HVDC system, its failure forms and mechanisms is different from them in AC system. At present, the research of DC protection system has not been given due attention in our country. Therefore, we need to conduct a deep study on converter's failure mechanism, for the purpose of standardization of DC protection.In this paper, using the 12-pulse HVDC converter as the research object, we analyze a variety of failures within the range of converter protection. Focused on the interaction between two 6 pulse converter during the failure, and made a quantitative analysis and calculation on the converter failure to provide a theoretical basis for converter protection.Based on this, we studied the protection principle of the HVDC converter, focusing on comparative analysis of operation characteristics of two types of valve short-circuit protection in the HVDC project which applied widely. And then, using the fault current while converter fault inside and outside the district, made the protection setting about one type of the valve short-circuit protection.Using PSCAD / EMTDC simulation software, based on CIGRE HVDC test system, we simulate all of the converter short-circuit fault within the range of protection and related the short-circuit fault outside. The results show that theory and method on the failure of the converter analysis is correct and reasonable, and analysis and setting on the HVDC converter protection system is an effective and reliable.