中文摘要：

分析了变压器发生区内外故障时差流和制动电流的异步变化规律，提出了变压器差动保护新算法。以端电压序分量的大小和变化趋势作为比率差动的闭锁条件，选取小于1个周波的数据窗计算相关电压值。仿真试验表明新算法不受励磁涌流、和应涌流的影响，当发生区内略微严重故障时可在10—15ms内快速动作，发生区外故障时不会误动，对大型高压／超高压变压器能够起到快速保护作用，具有较高的实用价值。

英文摘要：

The asynchronous varying rules of differential current and breaking current are analyzed while internal or external fault of transformer occurs, and a new algorithm, i.e., the high-speed ratio differential protection algorithm, for transformer current differential protection is proposed. Taking the magnitudes and varying trends of sequential components of terminal voltage as restraint condition of ratio differential protection, the asynchronous rule of the differential current and breaking current, which are the basis of the proposed algorithm, are found out while faults occur, and a data window narrower than one cycle is chosen for the calculation of relevant values of voltages. Simulation results show that the proposed algorithm is not affected by inrush current or sympathetic current; by use of this algorithm the protection can quickly act within the time duration from 10ms to 15ms under a little serious internal fault of transformer as well as it will not misoperate under external fault, thus the high-speed protection for high capacity HV/UHV transformers can be implemented.