A novel single phase grounding fault protection scheme without threshold setting for neutral ineffectively earthed power systems
A novel single phase grounding fault protection scheme without threshold setting for neutral ineffectively earthed power systems
复制标题
中性点小电流系统单相接地故障保护新方案
DOI：
10.17775/cseejpes.2016.00038
复制
发表时间：
2016-09
影响因子：
7.1
通讯作者：
Xiangjun Zeng;Yu Kun;Yuanyuan Wang;Yao Xu
中科院分区：
文献类型：
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作者：
Xiangjun Zeng;Yu Kun;Yuanyuan Wang;Yao Xu
故障特征参数门限值的整定是各种保护方案的关键。当检测到的特征参数值超过整定值时，保护跳闸。然而，传统的基于整定值的保护方案，有时不能满足中性点无效接地电力系统（NIEPS）的保护要求，由于运行条件的广泛变化和故障情况的复杂性。提出了一种新的无门限值单相接地故障保护方案。故障检测是根据运行状态而不是设定值来实现的。采用模糊c均值算法将被保护馈线的运行状态分为非故障状态和故障状态。然后通过在构造的多维故障特征空间中将在各种运行条件下提取的保护馈线的历史特征样本分类到其对应的状态中来获得每个状态的聚类中心。计算检测到的特征样本与非故障和故障状态的聚类中心之间的距离。如果到故障状态的距离短于到非故障状态的距离，则检测到故障。否则，认为馈线正常。PSCAD/EMTDC仿真器用于在各种操作条件、非线性负载和复杂故障情况下仿真35 kV NIEPS。结果表明，所提出的单相接地故障保护方案无需设定门限，在各种故障情况下都能正确保护系统。
The setting values of thresholds for fault feature parameters are critical in all kinds of protection schemes. When the detected feature parameter value exceeds the setting value, the protection will trip. However, the setting value based conventional protection schemes sometimes cannot satisfy the protection requirements of neutral ineffectively earthed power systems (NIEPS) due to wide variations in operating conditions and the complexities of fault cases. In this paper, a novel single phase grounding fault protection scheme without threshold setting is proposed. The fault detection is achieved based on operating states rather than setting values. A fuzzy c-means algorithm is used to divide the operating state of the protected feeder into non-fault states and fault states. The cluster center of each state is then obtained by classifying the historical feature samples of the protected feeder extracted under various operating conditions into their corresponding states in a constructed multi-dimensional fault feature space. The distances between the detected feature samples and the cluster centers of the non-fault and the fault states are calculated. If the distance to the fault state is shorter than that to the non-fault state, a fault is detected. Otherwise, the feeder is considered normal. A PSCAD/EMTDC simulator is used to simulate a 35 kV NIEPS under various operating conditions, non-linear loads, and complex fault cases. Results show that the proposed single phase grounding fault protection scheme without threshold setting can protect the system correctly under all kinds of faults.