Determination of protection system requirements for DC UAV electrical power networks for enhanced capability and survivability

A growing number of designs of future Unmanned Aerial Vehicle (UAV) applications utilise dc for the primary power distribution method. Such systems typically employ large numbers of power electronic converters as interfaces for novel loads and generators. The characteristic behaviour of these systems under electrical fault conditions, and in particular their natural response, can produce particularly demanding protection requirements. Whilst a number of protection methods for multi-terminal dc networks have been proposed in literature, these are not universally applicable and will not meet the specific protection challenges associated with the aerospace domain. Through extensive analysis, this paper seeks to determine the operating requirements of protection systems for compact dc networks proposed for future UAV applications, with particular emphasis on dealing with the issues of capacitive discharge in these compact networks. The capability of existing multi-terminal dc network protection methods and technologies are then assessed against these criteria in order to determine their suitability for UAV applications. Recommendations for best protection practice are then proposed and key inhibiting research challenges are discussed.