A novel single-ended fault identification algorithm for full selective protection strategy

Abstract

While more and more HVDC point-to-point connections are initiated worldwide, the emergence of multi-terminal grids still faces important hurdles among which the protection is seen as particularly challenging. We propose a parametric single-ended fault identification algorithm to be used in fullyselective fault-clearing strategies. Such strategies are preferential for meshed grids as they limit the impact of the fault. The method is able to determine whether the line monitored by a relay is faulty or not using very few local measurements, making ultra-fast fault identification possible. Contrary to most existing approaches, extra inductances are not required to distinguish between faults occurring on the protected line and elsewhere. When a fault is suspected, the proposed algorithm estimates the parameters that characterize the fault, namely the fault distance and impedance. The estimation process uses a parametric model describing the voltage and current evolution just after the fault occurrence based on the fault parameters.The identification of the faulty line is then based on the size of the confidence region of the estimated fault parameters. Use-cases and performances of the algorithm for a fournode meshed grid are studied using Electro-Magnetic Transient (EMT) simulations.