Fault Location in HVDC Grids Equipped With Quick-Action Protections and Circuit Breakers Based on Voltage Transient Response

A novel fault-location scheme is designed for transmission lines of high-voltage dc (HVdc) grids equipped with quick-action protections and circuit breakers using very few milliseconds of postfault signals, measurable before the ultrafast fault-isolation stage. A simplified equivalent circuit analysis shows that the first negative overshoot time and average derivative of voltage in the early postfault moments are directly related to the fault location. However, due to HVdc grids' characteristics and several factors involved in reality, the analytical use of these features may not be feasible or may not result in an acceptable accuracy. Hence, a soft computing strategy is adopted to overcome this problem. Based on this strategy, machine-learning-based locators are trained for both line terminals, each responsible for locating faults in the half-line of its side using the two introduced features extracted from the locally captured voltage signals. The statistical evaluations of the performance on a four-terminal grid for various fault cases not considered in the training stage confirm the designed scheme's satisfactory accuracy, generalization ability, tolerance to noisy measurements, and tolerance to changes in the line parameters.