基于电流模分量特性的多端柔性直流配电网线路纵联保护

Pilot Protection for Multi-Terminal Flexible DC Distribution Network Based on Current Mode Component Characteristics

多端柔性直流配电网因在供电可靠性方面极具优势而受到广泛的关注,然而对于直流线路保护中故障的快速、可靠识别成为其急速发展所需解决的关键问题之一。因此,设计了一种利用电流模分量特性的直流线路纵联保护方法。该方法利用故障时正极电流线模分量方向来判别区内外故障,以不同故障条件下故障点正极电流零模分量平均值的差异来构造保护判据,从而判别故障类型,形成保护策略。最后,在PSCAD/EMTDC4.5上搭建了多端柔性直流配电网模型,对保护判据及关键影响要素进行了仿真分析。结果表明,该保护方法能够有选择性地快速、可靠识别区内外故障及故障类型,且具有较好的耐过渡电阻与抗噪声能力。

The multi-terminal flexible DC distribution network has drawn a lot of attention due to its major advantages in terms of power delivery dependability.However,the rapid and accurate detection of faults in DC line protection has become one of the key issues that need to be addressed in its rapid development.For that reason,a DC line pilot protection method utilizing the characteristics of current mode components was designed.This method uses the direction of the positive current aerial mode component during a fault to distinguish between internal and external faults,constructs the protection criteria,which distinguish the type of fault,and forms a protection strategy based on the difference in the average value of the pos-itive current zero-mode component at the fault point under different fault conditions.Finally,a multi-terminal flexible DC distribution network model was built on PSCAD/EMTDC4.5,and simulation analysis was conducted on the protection criteria and key influencing factors.The results show that this protection method can selectively,quickly,and reliably identify faults and fault types inside and outside the zone,and has good resistance to transition resistance and noise.