A new data-driven protection method for inter-pole hybrid DC line with control and protection synergy

• Uses EOF on rectifier voltage to create planes distinguishing internal from external faults. • Proactive rectifier phase shift enables rapid fault current suppression. • Adapts control based on inverter-side judgment, enhancing high-resistance fault withstand capability. A sensitive and reliable protection scheme is significant for hybrid multi-terminal HVDC transmission systems. However, the conventional single-ended protection fails to accurately identify the external and high resistance faults on the DC line. To solve this problem, this study proposes a DC line protection method. Firstly, the complex frequency domain expressions for voltage traveling waves during faults in different locations are derived. Subsequently, the judgment plane for visualizing internal and external faults is constructed using the empirical orthogonal functions. Finally, a new data-driven protection method for inter-pole hybrid DC line with control-protection synergy is proposed, which can accurately identify high-resistance(500 Ω) faults and lighting interference. The performance of the proposed protection is assessed using PSCAD and the real-time digital simulator (RTDS).