Study On The Fault Diagnosis And Protection Of Energy-Fed Supply System In Urban Mass Transit

The aim for fault diagnosis and protection of supply system in mass transit is to guarantee the reliability and continuity of the supply system at the most degree, and to reduce the time for repairment with power off. As a novel supply system in mass transit, the world has seen no energy-fed supply system, and the fault diagnosis and protection of it has not been widely and deeply studied. Based on the difference between the fault diagnosis and protection of energy-fed supply system and the conventional supply system, this paper features the study on the following three aspects:On the fault diagnosis of the main circuit of energy-fed supply set, this paper deals with the current and voltage characteristics of large-capacity PWM rectifier, as well as the origin of them, and critical conditions and influencing factors of the current fault characteristic. Based on the peculiarity of the fault characteristics of large-capacity PWM rectifier, this paper proposes the adoption of normalized average for the recognition of its current and voltage fault characteristics, and which is proven to be effective against a complex background from the load in mass transit.On the location of element with fault inside the supply system, this paper applies the theory of Object-oriented Colored Petri-Nets (OOCPN) into the field of topology analysis of supply system in mass transit, and builds an OOCPN model for the topology analysis thereafter. By introducing member attributes and methods into the token of OOCPN, a comprehensive representation of the node from topology analysis is achieved, which is also the case with the production of fault region. By backward reasoning of the fault region, it is made real the recognition of the fault mode in the grid, the location of the element with fault, as well as the judgment of the mis-tripping and error-tripping of DC breakers.On the DC protection configuration inside a substation, it is analyzed the difference of short-circuit characteristics between energy-fed supply system and conventional supply system, as well as the new requirements asserted by the former one on DC protection configuration. Based on the conclusion from the stage above, this paper studies on the configuration principle, the setting criteria and the action coordination and sequence of the DC protection system, and finally comes up with a detailed configuration structure of it.Finally, the integrated automation system of energy-fed supply system is designed, out of the concept of hierarchical and distributed structure, and oriented to the realization of the achievements from the three aspects above. It is also proposed a novel comprehensive monitoring and control platform in the central unit inside a substation, developed with Ethernet and virtual instrument technology.The results from the study introduced in this paper fill the gaps in the fault diagnosis and protection of energy-fed supply system, and will act as an effective promotion for the automation level of supply system in mass transit.