what is phase shift how to tackle with problem?
There is a phase shift between the current and voltage dependant on the power factor. In a fault, this power factor moves very rapidly. This rapid change can be detected by modern IEDs (Intellegent Electronic Devices). They react to this change in a set manner according to the setting put into the protection relay (IED). These settings are calculated from the network values and dynamics. These are from resistive, inductane and capacitance values from the condutors as well as the gernerating equipment and what happens as they disconnect under switching be it planned or fault conditions. The phase shift, or in this case it is called a vector shift, forms part of a protection library of tools that can be used in protection to disconnect one generating source from another. It is called Vector Shift. I find it tends to be a little variable in its results so our protection team couple it with a voltage dip and a current value to make it more stable. The old ROCOF, Rate Of Change Of Frequency is a more accepted method where the angular phase shift is represented by a change in frequency as the current cross over moves related to the voltage cross over as the power factor changes