Power Flow Modelling of Dynamic Systems - Introduction to Modern Teaching Tools

As tools for dynamic system modelling both conventional methods such as transfer function or state space representation and modern power flow based methods are available. The latter methods do not depend on energy domain, are able to preserve physical system structures, visualize power conversion or coupling or split, identify power losses or storage, run on conventional software and emphasize the relevance of energy as basic principle of known physical domains. Nevertheless common control structures as well as analysis and design tools may still be applied. Furthermore the generalization of power flow methods as pseudo-power flow provides with a universal tool for any dynamic modelling. The phenomenon of power flow constitutes an up to date education methodology. Thus the paper summarizes fundamentals of selected power flow oriented modelling methods, presents a Bond Graph block library for teaching power oriented modelling as compact menu-driven freeware, introduces selected examples and discusses special features.Comment: 12 pages, 9 figures, 4 table

Generation of electrical energy using lead zirconate titanate (PZT-5A) piezoelectric material: Analytical, numerical and experimental verifications

Energy harvesting is the process of attaining energy from the external sources and transforming it into usable electrical energy. An analytical model of piezoelectric energy harvester has been developed to determine the output voltage across an electrical circuit when it is forced to undergo a base excitation. This model gives an easy approach to design and investigate the behavior of piezoelectric material. Numerical simulations have been carried out to determine the effect of frequency and loading on a Lead zirconate titanate (PZT-5A) piezoelectric material. It has been observed that the output voltage from the harvester increases when loading increases whereas its resonance frequency decreases. The analytical results were found to be in good agreement with the experimental and numerical simulation results

A wave emulator for ocean wave energy, a Froude-scaled dry power take-off test setup

A dry laboratory environment has been developed to test Power Take-O_ (PTO) systems for Wave Energy Converters. The costs accompanied by testing a wave energy converter and its PTO at sea are high due to the di_cult accessibility of (remote) test locations. Next to easy accessibility, the lab setup provides controllable waves at a relatively lower cost. The setup enables extensive analysis of the dynamics of a PTO during its mechanical towards electrical energy conversion. The scaled setup is designed such that it resembles as close as possible the real system. Froudes similarity law provides easy transformation. The oater and waves are represented by a Wave Emulator, the motion of which is determined by a time series of the wave exciting forces supplemented with the actual hydrodynamic reaction forces due to the motions of the oater. A real-time calculation method is introduced, accounting for the actual PTO actions. Furthermore, the inertia of the oater is represented in the emulators rotary inertia, and a compensation method is proposed enabling an identical normalized PTO load curve as at full scale. Comparison between experimental and simulation results have been performed and good correlation between the movement of setup and simulations has been found

Power quality disturbances assessment during unintentional islanding scenarios. A contribution to voltage sag studies

This paper presents a novel voltage sag topology that occurs during an unintentional islanding operation (IO) within a distribution network (DN) due to large induction motors (IMs). When a fault occurs, following the circuit breaker (CB) fault clearing, transiently, the IMs act as generators due to their remanent kinetic energy until the CB reclosing takes place. This paper primarily contributes to voltage sag characterization. Therefore, this novel topology is presented, analytically modelled and further validated. It is worth mentioning that this voltage sag has been identified in a real DN in which events have been recorded for two years. The model validation of the proposed voltage sag is done via digital simulations with a model of the real DN implemented in Matlab considering a wide range of scenarios. Both simulations and field measurements confirm the voltage sag analytical expression presented in this paper as well as exhibiting the high accuracy achieved in the three-phase model adopted.Postprint (published version