Voltage-Based Current-Compensation Converter Control for Power Electronic Interfaced Distribution Networks in Future Aircraft

Abstract

Superconductors have a potential application in future turbo-electric distributed propulsion (TeDP) aircraft and present sig-nificant new challenges for protection system design. Electrical faults and cooling system failures can lead to temperature rises within a superconducting distribution network which necessitate a reduction or temporary curtailment of current to loads to prevent thermal runaway occurring within the cables. This scenario is undesirable in TeDP aircraft applications where the loads may be flight-critical propulsion motors. This paper proposes a power management and control method which exploits the fast acting measurement and response capabilities of the power electronic interfaces within the distribution network to maximise current supply to critical loads, reducing the impact of a temperature rise event in the superconducting distribution network. This new algorithm uses the detection of a resistive voltage in combination with a model-based controller that estimates the operating temperature of the affected superconducting cable to adapt the output current limit of the associated power electronic converter. To demonstrate the effectiveness of this method and its impact on wider system stability, the algorithm is applied to a simulated voltage-source converter supplied aircraft DC superconducting distribution network with representative propulsion motor loads.

Sizing of Superconducting Cables for Turbo-ElectricDistributed Propulsion Aircraft Using a Particle Swarm Optimization Approach

“…To maximise the benefits of electrical propulsion, optimization of cable design is required to minimize the lifetime cost of the network in terms of initial capital expenditure and ongoing fuel costs due to network mass. However, given the thermal limits of superconducting components and the safety criticality of flight systems, the optimization method adopted must consider protection system operating speed and the impact of an electrical fault on the transient heating of un-faulted superconducting components in the fault path [8]. This is to prevent these components requiring isolation due to being unable to maintain the superconducting state once normal loading conditions resume.…”

“…One solution to this problem is presented in [8] which uses a control method that allows for cables that have exceeded the critical temperature for normal full load conditions to continue to operate in a reduced power mode. However, this is reliant on a back-up energy source or load shedding to be available to support network voltage stability [8]. This may not be possible in all architectures.…”

“…The interdependent nature of the critical parameters results in any increase in superconducting cable temperature leading to a temporary reduced maximum current that the cable is able to carry while maintaining the superconducting state [6]. Hence, if a component rides through the initial fault, it may still require removal from service due to it being unable to support the required load current without generating excessive heat as the increased temperature has reduced its maximum loading capacity [8]. In order for superconducting cables to provide safety margins that allow for fault ride-through capability, they must be sized appropriately with respect to four key variables: the size of the superconducting layer which affects the maximum value of the critical current; the size of the conventional cable former that provides an alternate path for current to flow through, the power rating of the cooling system to remove heat from the cable, and the speed at which the protection system can operate to interrupt the fault current.…”

“…Under-sizing superconducting components could lead to a damaging temperature rise during faults alongside limiting the power delivered to key network loads following a fault ride-through [8]. Conversely, over-sizing superconducting components causes an increase in weight and volume as well as capital cost.…”

A Modelling Framework for Efficient Design of Electrical Power Systems for Electrical Propulsion Aircraft

“…[2][5][7] [9]], and transient levels, e.g. [18][19] [20][21] is very widely reported in the literature. However, an EPS Modelling Framework to co-ordinate these modelling approaches, optimize and de-risk the design process, and to translate between performance and functionality requirements is needed.…”