Strategy Study Of HVDC Line Protection

Along with the prompt development of HVDC in China, how to guarantee the security and reliability of HVDC systems has become very important. Compared with HVAC, HVDC has larger transmission capacity, better economic returns, more flexible control and higher reliability. HVDC often plays an important role in the regional power grid contact, thus the protection of HVDC system is very important. HVDC protection is very different from AC transmission protection. It is very flexible because valve control can be used in protection system. First common faults and their mechanisms are studied, including commutation failure, converter fault, filter fault and DC transmission line fault. And measures are proposed to reduce the probability of failure and the impact of failure. With PSCAD/EMTDC, typical transient responses of CIGRE HVDC Model at different faults are studied. The response characteristics of HVDC transmission system and its controllers are analyzed. Finally, the failure process and mechanism of HVDC transmission lines are studied and fault traveling wave propagation characteristics of DC transmission line is revealed. Traveling wave protection features, advantages, disadvantages and possible situations are analyzed and new traveling wave protection strategy is proposed to overcome the shortcomings of traditional traveling wave protection.