This paper describes an adaptive fault location method for distribution and transmission networks based on the travelling waves' theory. The algorithm is self-adaptive to the unbalance of the electrical system and performs the transient detection through the Park's transformation application. The method is able to calculate automatically the fault location almost immediately after the fault occurrence with no need of an off-line analysis of oscillographic records. So, the proposed technique may be incorporated into Smart Grid devices to perform a real time disturbance monitoring. The algorithm is evaluated by means of EMTP simulations of distribution and transmission systems. The ATP (Alternative Transients Program) software was used for this end and the method was implemented using the MODELS language.