Second Derivative Zero-crossing of Current Protection for VSC-HVDC with Renewable Energy Integration

To ensure the steady access of renewable energy and isolate its impact on the AC system, an accurate and reliable protection with high-speed action based on the second derivative zero-crossing of current for DC transmission lines is proposed. First of all, classification of protection area of the renewable energy integration system is determined, and the protection requirements for the transmission line with renewable energy integration are defined; Secondly, the different characteristics of fault current traveling wave initial rise rate under different type of faults are summarized through modeling and analysis; Then, according to the characteristics of fault current, the second derivative zero-crossing of current can be calculated to construct the fault detection criteria; Finally, the accuracy, reliability and quickness of the protection is verified on the PSCAD/EMTDC simulation platform.