Modelling and Use of an Aircraft Electrical Network Simulation for Harmonics Consideration in Generator Design

In upcoming and future airplanes, more nonlinear electrical loads and loads behaving nonlinearly will be connected to the power distribution network. This induces advanced demands on the network to keep the power quality. The generator design also has to face the new demands and constraints. Trade offs between performance, weight, and latterly power quality have to be made and design choices have to be backed up by qualitative and quantitative measures. In a prior study a design tool chain was elaborated for an externally excited synchronous generator. In the first part of this paper this study is concluded. An outlook is given on the generator size demanded in relation to the portion of nonlinear loads in the network, in case the industrial standards are kept unchanged. The power quality criteria can be gained by time-domain simulation. This simulation can be computationally extensive, especially in case of a large ramp up time to the operating point. Therefore in the second part of this paper an approach for advanced initialization using equivalent models in frequency domain is given. Both frequency and time domain models were embedded component wise using the modelling language Modelica. Thus, simulation based studies can be performed within a single graphical and object-oriented modelling and simulation suite. A novel rectifier model in time-domain is presented, which has benefits for the harmonic initialization.