There are many researches on wide area fault location using bus impedance matrix. My question is as we all know, bus impedance matrix is not fix and depend on the status of power network such as line outage, fault at different locations etc. If the wide area fault location just use a very few number of measurements from PMUs (let say from 2 or 3 PMUs) and use a fix impedance bus matrix to estimate the fault, is that the practicality of the method can be accepted? For example, an outage just taken at a line near the faulted line at several cycles just before the fault happened and the outaged line is not connected to any PMU (no status of breaker position sent to the algorithm and not synchronized with gps), how can the wide area fault location method at the centre location realize the outage of the line which can make the bus impedance matrix changed and not similar to the matrix been use to locate the fault?