The city of Hamburg has decided to electrify its bus fleets. The two public transportation companies in this city expect to operate up to 1500 buses by 2030. In order to accomplish this ambitious goal, both companies need to build an appropriate charging infrastructure. They have both decided to implement the centralized depot charging concept. Buses can therefore charge only at the depot and do not have the possibility for opportunity charging at intermediate stations. The load profile of such a bus depot is highly dependent on the charging schedule of buses. Without an intelligent scheduling system, the buses charge on demand as soon as they arrive to the depot. This can lead to an unevenly distributed load profile with high load peaks, which is problematic for the local grid as well as for the equipment dimensioning at the depot. Charging scheduling on large-scale bus depots is a relatively new and poorly researched topic. This paper addresses the issue and proposes two algorithms for charging scheduling on large-scale bus depots with the goal to minimize the peak load. The schedules created with the proposed algorithms were both tested and validated in the Bus Depot Simulator, a cosimulation platform used for bus depot simulations.

This paper deals with an integration of High Voltage DC (HVDC ¹ ) in the onboard power supply system. Conventional aircraft grids have a main voltage of 115 V AC (star voltage) with a variable frequency of 360...800 Hz. Newer aircraft try to integrate 230 V AC generators in the grid to save cable weight. With the “More Electric Aircraft”- concept HVDC grids could be integrated in future airplanes. In all concepts the airport infrastructure has to be considered. The ground power supply is based on mobile Ground Power Units (GPUs) or an inverter supplied by the airport grid (Fig. 1). The ground supply allocates 115 V AC with a fixed frequency of 400 Hz and a maximum power of 90 kVA per unit. Changing to an HVDC-grid has a lot of advantages. Higher voltage means lower cable weight. Furthermore, the electrical converter architecture can be optimized. Especially the converters inside the loads can be built much lighter when using a DC supply. This paper compares different possibilities of HVDC integration. Ancillary conditions like carbon fiber reinforced plastic fuselages and a possible ground power supply with conventional technology are taken into consideration. The attention is focused on an efficient cabin power supply. But to make a global assessment, the entire onboard power supply system is analyzed.

The evolving technologies regarding Unmanned Aerial Vehicles (UAVs) have led to their extended applicability in diverse domains, including surveillance, commerce, military, and smart electric grid monitoring. Modern UAV avionics enable precise aircraft operations through autonomous navigation, obstacle identification, and collision prevention. The structures of avionics are generally complex, and thorough hierarchies and intricate connections exist in between. For a comprehensive understanding of a UAV design, this paper aims to assess and critically review the purpose-classified electronics hardware inside UAVs, each with the corresponding performance metrics thoroughly analyzed. This review includes an exploration of different algorithms used for data processing, flight control, surveillance, navigation, protection, and communication. Consequently, this paper enriches the knowledge base of UAVs, offering an informative background on various UAV design processes, particularly those related to electric smart grid applications. As a future work recommendation, an actual relevant project is openly discussed.

In new aircraft architectures the electrical power is in perpetual growth, because the present hydraulic and pneumatic systems are being eliminated and replace by electrical systems. Therefore the increase of electrical power has to be managed. With the constantly increasing electrical power demand onboard of aircraft, new electrical voltage levels are actually alluded, in order to respond to these challenges. Many advantages of high voltage alternating current (HVAC) and high voltage direct current (HVDC) in the aircraft electrical power system (EPS), in compliance with the aviation's jargon, namely 230V AC constant or variable frequency and +/- 270V DC (or 540V DC between positive and negative potentials), are presented in comparison with the conventional 115V AC with constant or variable frequency and 28V DC ESP. The adoption of higher voltage levels must comply with the system requirements. Power quality, weight comparison as well as applicability are exhibited at power generation, distribution and load level. Issues regarding the simultaneous supply with HVAC and HVDC are discussed. Current technological research for these changes will be overviewed.