Study On DC Protection Functions And Typical Fault Of Yun-guang UHVDC Project

Since the CPC Central Committee and the State Council put forward the westerndevelopment strategy, China power grid construction has entered a new stage, which takes“Power Transmitted from West to East”as the carrier and UHV construction as the core.UHVDC has characteristics of ultra-long-distance, large-capacity, low-loss and flexibleadjustment, also has a significant advantage in the line corridors savings, saving investment,reducing the grid construction costs and improving transmission efficiency. UHVDC issuitable for large-scale hydropower and thermal power base sending electricity to distant loadcenters and undoubtedly brings significant economic and social benefits.Yunnan-Guangdong UHVDC Project, which put into operation in June2010, is the first±800kV UHVDC Project in the world. Till now±800kV UHVDC Project has no maturedoperation experience in the world, and relevant research has just started. Foreignmanufacturers have not completely opened the core technical details of the UHVDCprotection function, and only a few domestic manufacturers and research institutions havecarried out study on the DC control and protection equipment relative to UHVDC, which leadhard to analysis in DC transmission system fault.Hence, this paper deeply studies DC protection system of Yunguang UHVDC Projectand the main work is as follows.Firstly, Yunguang UHVDC DC pole protection and valve protection are deeply studied，as well as hardware and software loops of pole protection and valve protection and realizationprinciples of all kinds DC protection function from protection logic and protectioncoordination. Protection exports are also studied completely.Secondly, Yunguang UHVDC EMTDC model is established by EMTDC simulation toolto analysis the DC system response after fault of different regions and to study the protectionresponse situations and the coordination between different DC protections, the operationcharacteristics of the DC protection by failure, the operation law of both DC pole protectionand valve protection are all summed up.Finally, according to monopole and bipolar outage, based on DC pole protection and valveprotection research achievement, various typical fault problems are analyzed, and what’s moremeasures for improvement are proposed.To sum up, this paper studies Yunguang UHVDC protection configuration, protectionfunction, action law and typical failure, and will contribute an important practical significanceto the safe and stable operation of Yunguang UHVDC Project, as well as an important theoretical significance to the development of UHVDC technology.