101,875 research outputs found
More Electric Vehicles DC Power Systems: a Large Signal Stability Analysis in presence of CPLs fed by Floating Supply Voltage
No full textThis paper deals with voltage stability of DC power systems in More Electric Vehicles (MEVs) in presence of Constant Power Loads (CPLs). Large signal voltage stability is studied according to Lyapunov theory. Original analytical developments are presented to evaluate a Region of Asymptotic Stability (RAS) around a system’s stable equilibrium point. Analytical forms are found, which show how the RAS boundaries vary as a function of the system’s supply voltage, when the latter is floating. The validation has been carried out by means of the numerical continuation analysis. This result makes it possible to point out how supply voltage fluctuations can decrease the RAS, up to impairing voltage stability not only for large, but even in case of small perturbations
Transient simulation on power network including deep-bar induction motors and series capacitors
No full textOn the costs of products in multi-task systems: theoretical development and application to a cogeneration engine
No full textWeighted Bandwidth Method for Stability Assessment of Complex DC Power Systems on Ships
No full textIn shipboard DC grids, tightly controlled load converters can impair the system stability, thus provoking the ship blackout. Conversely, load converters regulated by low control bandwidths are capable of inducing a stabilizing action. This compensation is verifiable if the loads are few. On the contrary, the balancing of control dynamics is hardly evaluated if the bus feeds multiple (i.e., hundreds or more) DC controlled loads. In this paper, the weighted bandwidth method (WBM) is presented to assess the small-signal stability of a complex shipboard power system by aggregating the multiple converters into two sets of controlled loads. Once the validity of the aggregation is proven, a stability study is performed on the two-loads system. As the last system is more inclined to instability than the initial multiple-loads system, the verification of the two-loads stability criterion guarantees that the shipboard DC grid also remains stable. Finally, emulations on HIL verify the proposed stability assessment thus providing the first unique verification of WBM
Considerations on the design of voltage control for multi-machine MVDC power systems on large ships
No full textMedium Voltage Direct Current (MVDC) distribution is an enabling technology for future large ships, e.g. cruise liners or military vessels. In MVDC systems, shipboard loads are normally fed through power-converters directly connected to the MVDC bus. For such systems a key design goal is voltage stability, impaired by the presence of high-bandwidth controlled loads (Constant Power Loads, CPLs). The paper proposes an approach to stabilize the MVDC bus using the generating systems as sources of stabilizing power. Fast controlled DC/DC converters, interfacing generators to MVDC bus, are employed to control it in a stable way and to provide power sharing among the generators. To this aim, an Active Damping method is exploited. A supplementary Linearization via State Feedback control is utilized to stabilize DC/DC load converters feeding particularly impacting CPLs. Proposed controls are verified by means of time-domain numerical simulations. Shipboard feasibility and performance of the proposed control systems are most considered in the work as conclusions
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