中文摘要：

从分析传统变压器差动保护抗电流互感器（currenttransformer，CT）饱和性能和灵敏度入手，提出一种幅值相位分别反映的新型变压器差动保护算法。新算法通过幅值和相角2个比较式共同作用，突破了单一比较式难以兼顾灵敏性和安全性的局限，其中相角比较式采用类似于标积制动原理的形式，在其高灵敏度的基础上，进一步提高了算法对内部轻微故障的灵敏度。算法引入了分段的思想，可以兼顾严重故障时的抗CT饱和能力。分别在差动电流一制动电流平面和复平面上从理论上分析新算法的特性，并用仿真工具对比验证了新算法和三折线比例制动算法在区内外各种故障时的性能。理论分析及仿真结果表明，新算法具有更好的内部故障灵敏度和外部故障抗CT饱和能力。

英文摘要：

With analyzing the anti current transformer （CT） saturation performance of traditional transformer differential- protection and its algorithm sensitivity, the paper proposes a novel transformer differential-protection algorithm reflecting amplitude and phase angle respectively. The new algorithm adopts two comparison formulas according to amplitude and phase angle respectively, to overcome the limitation of each comparison formula. The phase angle restraint takes a form of similar scalar product restraint, and based on the sensitivity, the paper further improves the criterion sensitivity for slight internal faults. The idea of subsection is also introduced to the algorithm to enhance its anti CT saturation performance during serious faults. The criterion characteristic is analyzed both in differential current vs. restraint current plane and complex plane, and the performance of the novel criterion during different internal and external faults is compared with that of triple-bias differential-protection in the simulation. Theoretical analysis and simulation results indicate that the novel criterion has higher sensitivity during internal faults and better anti CT saturation performance during external faults.