Accurate fault location algorithm for transmission lines in the presence of shunt-connected flexible AC transmission system devices

In this study a non-iterative fault location algorithm for shunt-compensated transmission lines is proposed. Since this method does not utilise the model of the shunt compensator, the errors resulted from modelling of the shunt compensators are eliminated. In addition, the new algorithm is not an iterative one and does not require proposing a selector to determine the fault section with respect to the compensator location. In this method, synchronous data from both ends of transmission line are used and distributed parameter line model in time domain is considered. This algorithm consists of three steps. In the first and second steps, it is assumed that the fault is located on the left- and right-hand side of the compensator, respectively. Two discretised equations with respect to these steps are obtained which are used to derive an optimisation problem in the third step. The location of fault and its resistance are determined by solving this problem. This method is applicable for all transmission lines compensated by any shunt device. A 300 km/345 kV transmission line compensated by STATic synchronous COMpensator (STATCOM) simulated in PSCAD/EMTDC has been used to evaluate the performance of the algorithm. The simulation results verify the high accuracy of the method.