High Impedance Fault Detection and Classification Based on Pattern Recognition

High-impedance faults (HIFs) occur in distribution networks due to contact between an electrified conductor and objects such as trees or conductor falling to the ground. In these cases, a small current flows in the conductor due to the low voltage in the network and the high impedance between the ground and the conductor. According to the conducted tests, the fault current amplitude can take a value between less than 1 A and 100 A. Protective devices are generally used to protect grid equipment, such as transformers or overhead and underground power lines, against fault currents exceeding the permissible values for this equipment. However, an HIF falls within these values; hence, conventional protections in distribution networks, such as overcurrent protection or ground fault protection, cannot detect this fault and do not damage this equipment. The main reason for detecting HIFs in traditional power grids is to prevent harm to persons as a result of electrocution. Moreover, the electric arc occurring due to the fault, especially when the conductor breaks and falls onto a tree, can result in fire. Early detection of this fault can prevent potential outages and reduce outage duration in distribution networks. Since the nature of an HIF depends on numerous parameters, such as feeder structure, ground structure, and humidity, the disturbance in the current and voltage waves of the feeder are diverse and unpredictable. This has prompted many researchers to propose various solutions for detecting HIFs and has resulted in the production of relays for this purpose. The present chapter book involves a thorough investigation of HIF detection schemes along with their advantages and disadvantages.