A Primary and Backup Protection Algorithm based on Voltage and Current Measurements for HVDC Grids

摘要

DC grids are susceptible to DC side faults, which lead to a rapid rise of the DC side currents. DC side faults should be detected in a very short time before fault currents cause damage to the system or equipment, e.g., exceed the maximum interruptible limits of DC circuit breaker. This paper presents a primary and backup protective data-based algorithm. The proposed algorithm depends on the local voltage and current measurements to detect and identify various kinds of faults in the HVDC grid, both in the forward and backward direction. Linear Discriminant analysis (LDA) is used to derive the thresholds and the operational time frames of the primary and backup protection zones of the algorithm. A sensitivity analysis is performed to investigate the influence of the line inductor value on the decision thresholds and on the operational time frame of the algorithm. Furthermore, two statistical approaches utilizing LDA and quadratic discriminant analysis (QDA) methods are proposed to extend the operational time frame of the algorithm.