An adaptive differential protection scheme based on the evolution characteristics of transient frequency band energy

Transient signals contain rich fault information. However, renewable energy outgoing lines exhibit control-dominated fault characteristics, which reduces the sensitivity of conventional power-frequency protection. To address this issue, this paper proposes an adaptive time-window differential protection scheme based on the evolution characteristics of transient frequency band energy. First, the study analyses the frequency-domain energy distribution differences of transient differential currents during internal and external faults. Next, to overcome the impact of the initial fault phase angle under a fixed time window, the time-domain evolution of low- and high-frequency energies throughout the entire fault process is investigated. Based on these significant evolutionary differences, an adaptive time-window strategy is constructed to ensure high protection reliability. Finally, the proposed scheme is verified using electromagnetic transient simulations. The results indicate that the scheme reliably distinguishes internal from external faults without sacrificing operation speed. Furthermore, it exhibits strong tolerance to transition resistance and high immunity to high-frequency noise. Additionally, Real-Time Digital Simulator (RTDS) tests verify its effectiveness, demonstrating practical engineering value.