配电网单相接地故障柔性消弧与保护协调控制方法研究

架空线路为主的配电网存在固有的线路参数不平衡问题，在发生单相断线等高阻接地故障时，故障相难于判断。同时，谐振接地系统单相接地故障时零序电流特征量微弱，使保护装置难以准确判断故障馈线，导致永久性接地故障无法可靠切除，威胁电网和人身安全。为解决配电网长期存在的单相接地故障消弧与馈线保护协调配合难题，项目计划：1）研究线路参数不对称条件下，单相接地故障时零序电压和三相对地电压随过渡电阻的变化规律，得到单相接地故障电压幅值相位变化区间分布；2）研究不同相接地故障时零序电压变化轨迹，提出基于零序电压幅相特征的单相接地故障相辨识方法；3）研究柔性接地装置变阻抗控制方法，以实现单相接地故障馈线的准确判断和永久性接地故障的可靠识别，从而为保护装置的可靠动作提供准确依据。项目将完善配电网单相接地故障分析理论，弥补单相接地故障可靠消弧和故障馈线准确判断的技术空白，将有望提高配电网故障处理水平，提升供电可靠性。

Due to the inherent unbalanced line parameters existing in the aerial cable distribution system, the fault phase is difficult to be recognized when high resistance grounding such as single-phase disconnection happens. Meanwhile, the resonant grounding method attenuates zero-sequence current while suppressing the faulty current in single-phase-to-ground fault, which makes it difficult to recognize the faulty feeder and thus the protection devices are unable to clear the faulty feeder. This threatens the safety of both the power system and its neighboring human being. In order to solve the unsettled issue of coordination between arc-suppression and feeder protection, this project plans to work on the following aspects. Firstly, the trajectory of zero-sequence and three phase-to-ground voltages with different faulty resistance under the unbalanced distribution network condition will be studied, aiming to obtain the distribution of magnitude and phase of the single-phase-to-ground voltages. Secondly, a faulty phase recognition method is planned to be proposed by integrating the trajectories of three zero-sequence voltages when single-phase-to-ground fault happens in each phases. Thirdly, a variable impedance control method for flexible grounding device is planned to be proposed, aiming to realize precisely recognition of faulty phase and permanent fault. By studying the above aspects, it is probable to optimize the theory of single-phase-to-ground analysis, fill the gap of reliable arc-suppression and faulty feeder recognition. The technology of dealing with faults in distribution network and the reliability of applying electricity are both to be improved.