Small defects on the rails develop fast under the continuous load of passing trains, and this may lead to train derailment and other disasters. In recent years, many types of wireless sensor systems have been developed for rail defect detection. However, there has been a lack of comprehensive reviews on the working principles, functions, and trade-offs of these wireless sensor systems. Therefore, we provide in this paper a systematic review of recent studies on wireless sensor-based rail defect detection systems from three different perspectives: sensing principles, wireless networks, and power supply. We analyzed and compared six sensing methods to discuss their detection accuracy, detectable types of defects, and their detection efficiency. For wireless networks, we analyzed and compared their application scenarios, the advantages and disadvantages of different network topologies, and the capabilities of different transmission media. From the perspective of power supply, we analyzed and compared different power supply modules in terms of installation and energy harvesting methods, and the amount of energy they can supply. Finally, we offered three suggestions that may inspire the future development of wireless sensor-based rail defect detection systems.

Due to the wind farm 35kV system single-phase grounding fault capacitance current is relatively large, Therefore, the wind farm 35kV system adopts the bus configuration Z-type grounding transformer and the neutral point is grounded by small resistance, Zero sequence protection are used to quickly remove the single phase ground fault.In this paper, the single-phase ground fault of wind power plant collection wire in Eastern Inner Mongoliais is taken as an example. introduces the working principle of zero sequence current transformer,Clarify the setting and matching principles of zero sequence protection,,Comparing the different wiring modes of several cable shielding layers will be cause how Influence on the secondary measurement current of zero-sequence transformer, Analyze the zero sequence protection rejection of the set wire,The cause of the grounding tripping event. Summarizes the cable shield connection mode correctly,And propose rectification measures on site.