适用于交直流混联系统的时域全量故障模型 判别纵联保护方案

受直流系统接入的影响，交流侧出现频率偏移的故障特征以及叠加原理适应性差的问题，这都会导致基于工频故障分量的传统纵联保护存在误动或拒动的可能。在参数识别思想的基础上，对混联系统交流送出线的线路故障进行分析，提出基于阻感模型符合度的判别方法。若故障相符合阻感模型则判定为区内故障，不符合则为区外故障，并给出保护判据。该保护采用时域全量，解决了叠加原理不适用的问题，克服了频率偏移对保护带来的影响。仿真结果显示，该保护方案能够准确快速地识别故障，表明基于时域全量阻感模型相似度判别的保护方案适用于交直流混联系统。

Principle of active distribution network pilot protection based on time domain model identification

Given the effect of access of the DC system, the fault characteristics of the frequency offset on the AC side and the poor adaptability of the superposition principle may lead to the possibility of mis-operation or refusal of the conventional pilot protection based on the power frequency fault component. On the basis of the parameter identification idea, the line fault of the AC transmission line of an AC/DC hybrid system is analyzed, and a method based on the similarity of the resistance model is proposed. If the fault meets the resistance model, it is determined as an internal fault, and if it does not, it is determined as an external fault. Protection criteria are proposed. The protection scheme adopts the full time-domain, solves the problem that the superposition principle is not applicable, and overcomes the influence of frequency offset on protection. Simulation results show that the protection scheme can identify faults accurately and quickly. The protection scheme based on the similarity discrimination of the time-domain full resistance model is adapted to the AC/DC hybrid system. This work is supported by National Natural Science Foundation of China (No. 51877185).