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.
The roller electrical motor (REM) consists of non-magnetic stainless steel cylinders rolling on parallel stainless steel rails of the same diameter with an electrical current passing from rail to rail through the rolling cylinders. The REM is found to be capable of carrying heavy loads, the electrical driving force increasing as the current and loading are raised. When the REM carries a 50 kg load the driving force increases at the rate of 80 mN A −1 . At 30 A the REM is capable of driving external frictional loads of 1.7 and 2.2 N while carrying loads of 50 and 100 kg respectively. This paper describes the characteristics of the REM and discusses the origin of the driving force. A thermal expansion theory is developed to explain the experimental results.
Turbo-electric distributed propulsion (TeDP) for aircraft allows for the complete redesign of the airframe so that greater overall fuel burn and emissions benefits can be achieved. Whilst conventional electrical power systems may be used for smaller aircraft, large aircraft (~300 pax) are likely to require the use of superconducting electrical power systems to enable the required whole system power density and efficiency levels to be achieved. The TeDP concept requires an effective electrical fault management and protection system. However, the fault response of a superconducting TeDP power system and its components has not been well studied to date, limiting the effective capture of associated protection requirements. For example, with superconducting systems it is possible that a hotspot is formed on one of the components, such as a cable. This can result in one subsection, rather than all, of a cable quenching. The quench transition to normal conduction leads to a temperature rise which is not uniformly distributed along the cable length. Due to the high current density and low cable mass of a TeDP system, this damaging failure mode can occur over a short timescale. To improve the understanding of the formation of this failure mode and its impact on a TeDP distribution cable, this paper presents a transient thermal-electrical model based on numerical methods. Using this approach, the model is then used to provide new information supporting the capture of speed and sensitivity requirements for TeDP protection systems.
1.2 billion people, predominantly living in remote rural regions in countries of the Global South, currently live without access to any modern source of energy. Options for electrification of these communities include extending existing national grid infrastructure, deploying mini-grids, and installing standalone home systems (SHS). Deriving the most cost effective means of delivering energy to these consumers is a complex, multidimensional problem that normally requires determination on a case-by-case basis. However, optimization of the network planning may help to maximize the socio-economic return of the installed energy system. This paper presents an optimization process that minimizes the installation cost of a mix of generation sources for a rural mini-grid using a multi-objective particle swarm optimization (MOPSO) technique. Minimizing the cost of distribution layout is first formulated as a capacitated minimum spanning tree (CMST) problem and solved using the Esau-Williams method. Multiple cable sizes and source locations are then added to create a multi-level capacitated minimum spanning tree (MLCMST) problem, solved via a Genetic Algorithm (GA) employing Prim-Pred encoding. The method is applied to a case study village in India
The turbo-electric distributed propulsion (TeDP) concept has been proposed to enable future aircraft to meet ambitious, environmental targets as demand for air travel increases. In order to maximize the benefits of TeDP, the use of high temperature superconductors (HTS) has been proposed. Despite being an enabling technology for many future concepts, the use of superconductors in electrical power systems is still in the early stages of development. Hence their impact on system performance, in particular system transients, such as electrical faults or load changes, is poorly understood. Such an understanding is critical for the development of an appropriate electrical protection system for TeDP. Therefore, in order to enable appropriate protection strategies to be developed for TeDP electrical networks an understanding of how electrical faults will propagate in superconducting materials is required. An understanding of how technologies that utilize these materials may experience failure modes in ways that are uncharacteristic of their conventional counterparts is also needed. This paper presents a dynamic electrical-thermal model of a superconducting cable, at an appropriate level of fidelity for electrical power system studies, which enables the investigation of failure modes of cables. This includes the impact of designing fault tolerant cables on the electrical power system as a whole to be considered.
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