基于负序电流比的主动配电网断线故障保护方法

随着分布式电源(DG)的大规模接入和用电需求的提高,具有主动控制、协调、管理能力的主动配电网(ADN)成为电力系统的发展趋势.然而,断线故障大大降低了ADN的效益价值,严重威胁设备与人身安全.由于受DG及灵活可调拓扑影响,目前针对ADN断线故障的保护技术较为欠缺.为此,分析了 ADN的特征及其对断线故障保护的影响;解析了分布式电源上、下游单相及两相断线下故障馈线与非故障馈线序电流变化特征;在此基础上,以负序电流比作为保护特征量,提出了一种基于负序电流比的主动配电网断线故障保护方法.理论分析和仿真结果表明,该方法不受负荷分布和故障位置影响,适用于各种网络拓扑、分布式电源容量以及中性点接地方式,具有较好的适用性和灵敏度.

Break fault protection method of active distribution network based on negative sequence current ratio

With the large-scale access of distributed generation (DG) and the continuous increase in power requirements, active distribution network (ADN) with active control, coordination and management capabilities has become one of the development trends of power system. However, due to the complex structure and operating mode, the occurrence of break fault greatly reduces the value of ADN, which seriously threatens the safety of equipment and people. Due to the limited influence of break fault on the traditional distribution network, the present break fault protection technology is insufficient. Especially in ADN, due to the influence of DG and the flexible and adjustable topology, accurate identification and protection of break fault are still difficult to achieve. For this reason, this paper analyzes the characteristics of ADN and its influence on break fault protection. And the variation characteristics of sequence current of fault feeder and non-fault feeder under single - phase and two - phase break fault are analyzed. On this basis, an active distribution network fault protection method based on negative sequence current ratio is proposed, which takes the negative sequence current ratio as the protection characteristic parameter. The theoretical and simulation results show that the method is not affected by load distribution and fault location, and is suitable for various network topologies, DG capacity and neutral grounding modes, with high applicability and sensitivity.