This paper presents a simulation model of DC traction system which is based on bilateral power supply mode. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of short circuit current and the train starting current, more effective algorithms such as DDL protection has been proposed. The paper presents the principle and analysis of DDL protection scheme, which shows effectiveness of DDL protection for fault detection and discrimination against train starting currents in the DC transit system.
Negative-sequence pilot protection (NSPP) is one of the most widely used protective principles for high-voltage/extra high-voltage transmission lines due to its excellent properties. Properties, such as immunity to system oscillation and the fact that it is not influenced by shunt capacitance, make it especially valuable for the protection of long-distances ultra-high voltage lines, which transfer large amounts of energy. However, negative-sequence pilot protection (NSPP) is not suitable for applications when a system operates with one phase open, which inevitably limits its overall application. To solve this problem and to achieve the selectivity and sensitivity for the NSPP algorithm, a novel algorithm for NSPP is proposed in this paper, which takes the load-phase voltage into the calculation of the negative-sequence voltage with a fault in the open-phase condition, and compensates the negative-sequence current in the open-phase operations for phase-ground faults. Simulation studies show that the proposed algorithm is able to produce excellent performance.
Index Terms-Negative-sequence pilot protection, open-phase line, ultra-high voltage (UHV).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.