However,unbalanced differential current can occur at normal conditions when traveling-wave differential protection is applied.

The traditional traveling-wave differential protection cannot be applied to ultra/extra high voltage transmission line with shunt reactor, so this paper describes a novel differential current expression.

Since the traditional traveling-wave differential protection cannot be applied to Teed transmission lines, this paper presents a novel traveling-wave differential current expression.

Traditional traveling wave differential protection needs to transmit large amount of real-time high-frequency sampling data, which is difficult for current telecommunication methods.

Research on traveling wave protection criterion on HVDC transmission line;

Discussion on several questions of the digital simulation of the traveling wave protection;

Some problems which still stay to be solved are introduced and the prospect of application of transient traveling wave protection in HV power grid of China is described.

The wavelet transform based algorithm for ultra high speed travelling wave protection and fault location;

The history of the travelling wave protection is reviewed.

Theoretical criterion and main factors influencing the performance of travelling wave protection were simulated and analyzed.

Analysis of maloperation of generator differential protection caused by transient unbalanced current;

Analysis of mal-operation of transformer differential protection;

Analysis and solution of misoperation of transformer differential protection when external ground fault occurs;