High-voltage direct current (HVDC) and high-voltage alternating current (HVAC) cables are the most important equipment for high-voltage, large-capacity and long-distance power transmission. Electrical tree is a pre-breakdown phenomenon leading to failure of insulation materials, and it is the major issue that threatens the safe and stable operation of HVDC and HVAC cable systems. This study summarises and analyses the achievements in the research of electrical tree for HVDC and HVAC cables. The initiation mechanisms of the electrical tree, including Maxwell electro-mechanical stress, charge injection–extraction, charge trapping and electroluminescence theories, are elaborated for fully understanding the electrical degradation process in insulation materials. Then, the influences of the high electric field, high temperature and mechanical stress on electrical tree behaviours are discussed, and the relationship between charge transport and the electrical tree is analysed and illustrated. The suppression methods of the electrical tree are put forward by introducing inorganic and organic additives into insulation materials, and the suppression mechanisms are presented from the viewpoints of the structure-property and microscale–macroscale relationships. Recently, the electrical tree research studies are focused on the high-precision of initiation models, high-dependence of multi-physical fields and high-efficiency of suppression methods. The achievements provide theoretical support for improving the electrical performance of insulation materials, while it is a practical problem to explore their application feasibility in HVDC and HVAC cable.

高压直流（HVDC）和高压交流（HVAC）电缆是高压，大容量和长距离输电的最重要设备。电气树是导致绝缘材料失效的预故障现象，并且是威胁HVDC和HVAC电缆系统安全稳定运行的主要问题。本研究总结并分析了高压直流输电和暖通空调电缆电气树的研究成果。详细阐述了电气树的引发机制，包括麦克斯韦机电应力，电荷注入-萃取，电荷俘获和电致发光理论，以充分理解绝缘材料中的电降解过程。然后，高电场的影响 讨论了高温和机械应力对电气树行为的影响，并分析和说明了电荷传输与电气树之间的关系。通过将无机和有机添加剂引入绝缘材料中，提出了抑制电树的方法，并从结构性质和微观-宏观关系的角度提出了抑制机理。近来，电树的研究集中在高精度的引发模型，高度依赖于多物理场和高效的抑制方法上。这些成果为提高绝缘材料的电气性能提供了理论支持，而探索它们在HVDC和HVAC电缆中的应用可行性是一个实际问题。