中文摘要：

随着超高压大容量电力变压器不断投入运行，现场对变压器主保护的可靠性、快速性和灵敏性提出了更高的要求，完善变压器差动保护和提出新型主保护原理势在必行。首先分析了变压器差动保护中尚未很好解决的一些关键性问题，在此基础上，讨论了若干种与差动保护迥然不同的新原理。仿真和动模实验结果表明，新原理不受励磁涌流和Y/△接线方式的影响，能够灵敏、可靠地切除内部故障，在与差动保护原理进行对比后，给出了变压器主保护技术的发展路线。

英文摘要：

Recently, with the EHV large capacity transformers putting into operation continuously, reliability, rapidity and sensibility are in highly demand. It is imperative to consummate transformer differential protection and bring forward novel transformer main protection. Novel principles and algorithms are analyzed to solve some key problems still existing in power transformer main protection. Simulation and dynamic testing results verify this scheme is independent of core characteristics and transformer parameters and is suitable for the Y/A connected transformers. By comparing with the transformer differential protection, technical routes of power transformer main protection is proposed. This project is supported by National Natural Science Foundation of China（No.50777016）.