Arc Fault Detection Methods in DC MEA Distribution Systems 2018-01-1934
The replacement of non-propulsive loads with electrical equivalents on more-electric aircraft (MEA) will require higher-capacity electrical power distribution systems, integrated with advanced power electronic conversion and protection technologies, arranged to form highly-resilient network architectures. Direct current (DC) distribution is a promising solution that is being explored by aircraft system integrators as it enables the paralleling of non-synchronised engine off-take generators and reduces the number of energy conversion stages required to supply electronically actuated loads However, significant challenges in reliably detecting arc fault conditions within high-power DC systems still exist and need to be addressed to ensure high levels of safety and reliability.
Arc faults present a significant fire risk to aircraft and their presence can result in critical system damage and even potentially fatal conditions. Arc faults are typically intermittent in nature and may arise due to the vibration of loose terminal connections, or as degraded wires contact metal structures. Series arc faults in DC systems are particularly aggressive as there is no natural zero-crossing in the current profile, and so can remain exposed for prolonged periods of time if not rapidly detected and isolated. They are also particularly challenging to detect as the reduction in fault current eliminates the use of conventional overcurrent and current differential methods for detection.
This paper will provide an overview of series arc faults in DC systems, presenting both simulation and hardware results to illustrate key trends and characteristics. It will also offer a comprehensive review of arc fault detection and diagnosis techniques that have been proposed for a wide range of aerospace and other applications. The paper provides a particular focus on electrical detection methods which utilise feature extraction techniques. These are further categorised in to time-domain, frequency domain and the time-frequency domain. The paper concludes with a discussion on the potential challenge of certifying non-deterministic arc fault detection methods for aircraft applications and discusses the merit and feasibility of achieving a purely deterministic arc fault detection system for future DC aircraft power systems.