To address the issue that current limiting degrades fault characteristics and may cause conventional pilot protection to malfunction
this paper proposes a recursive minimum error entropy pilot protection method based on model matching
which improves algorithm robustness and eliminates the adverse influence from current limiting. This paper firstly analyzes the fault characteristics of metallic return bipolar DC grids with CFC under current limiting conditions and explains the drawbacks of traditional current differential protection. An accurate line equivalent model is then established to derive system measurement equations
which are discretized by “quadratic integration” into algebraic equations. Finally
the recursive minimum error entropy algorithm is introduced to solve the state estimation model: the internal and external faults are identified according to the model matching degree
and a fault pole selection strategy is proposed according to the fault current mode component. The simulation results show that the method can quickly and accurately recognize the internal and external faults and correctly select poles within 2 ms after fault inception
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