1,721,032 research outputs found
Electrical and energy systems integration for maritime environment-friendly transportation
Full text linkThe policies against climate change require the reduction of greenhouse gas emissions of marine transportation. To reach the planned goals, the most promising approach is working both on ships improvement and ports redesign. The latter must enable the new green ships supply with sustainable electrical energy, by integrating shore connection systems, local renewables, and energy storage systems. In this paper, a methodology to obtain such an objective is proposed, capable of taking into account both ships’ and ports’ characteristics. The methodology workflow is explained through a case study, where two shore connection power sizes and two different operative approaches for recharging the ship onboard energy storage are considered. A discussion about the most suitable energy storage technologies is also provided. The case study shows how the methodology can be applied, as well as demonstrating that the port infrastructure has a direct effect on the ship environmental performance
Optimized Tuning for Flexible and Resilient Control of Zonal DC Microgrids on Ships
Full text linkFlexibility and resiliency are among the main features of next-generation zonal DC microgrids on ships. These paramount characteristics are enabled by the huge penetration of power electronics interfaces, whose presence is beneficial for the grid controllability. Conversely, the interactions among controlled converters and filtering stages can possibly trigger unstable behaviors, thus the ship blackout. Although DC systems are designed to ensure the stability in the operating conditions, the risk of instability is anyway not negligible, especially after faults or undesired disconnections. In this paper, an advanced Power Management System (PMS) is conceived to reconfigure the control parameters in order to avoid the instability. This control tuning is performed by integrating into the PMS an optimization procedure. The latter is able to maintain the system stability without any load shedding action, while limiting the dynamics performance worsening. The stable reconfiguration capability extends the flexible and resilient operation of zonal DC grids
Active Damping Poles Repositioning for DC Shipboard Microgrids Control
No full textMedium Voltage Direct Current will be the enabling technology in the shipboard power systems of tomorrow. In such grids, the stability assessment results of paramount importance, as the pervasive presence of power converters can lead to system instability. In presence of perturbations, dynamic interactions between high bandwidth controlled converters and LC filtering stages can indeed provoke unstable behaviors, thus the consequent ship blackout. By adopting the Eigenvalues method, the paper performs the small-signal stability analysis on a DC shipboard power system. Once recognized a system perturbation (i.e. generating converter disconnection) as destabilizing, the virtual Active Damping effect is consequently tuned to re-establish the DC grid stability. Poles repositioning in the left-half plane and dynamics simulations will justify the designed control's capability
A multi-model methodology for stability assessment of complex DC microgrids
No full textThe system stability is a paramount requirement to be attained in islanded DC microgrids. Even more crucial the obligation in MVDC shipboard power systems, where instability means ship blackout. The destabilizing interactions between high bandwidth controlled converters and LC filters are investigated to ensure the on board safe operation. Albeit the stability analysis is well-proven in case of few filtered power converters, the study becomes prohibitive in case of complex shipboard DC microgrids. To overcome this bottleneck, the paper defines a smart procedure to assess the small-signal stability in a multi-converter DC distribution, where several are the interacting controlled converters as well as the filtering stages. Basing on the Eigenvalues Based Method, the procedure can detect in advance the instability by analyzing nonlinear/linearized models, while the dynamics effect is testified on PSCAD switching simulations. A step-by-step comparison between the model's outputs can confirm the procedure validity, thus proving its capability in assessing the DC system stability
Strategies for Preserving the Battery SOC in DC Shipboard Power systems
No full textNowadays, the energy storage solutions are reaching a more prominent role when integrated in DC shipboard power systems. Among others, batteries and supercapacitors are already capable of assisting the traditional on-board energy resources, both during normal operation (e.g. fuel consumption optimization, peak shaving, pulsed loads supply) and in critical situations. When a main source of energy goes out of service, the remaining online sources and the storage are to be proficiently managed, thus ensuring enough power to the vital loads without outages. In this scenario, the power sharing between the storage systems gets a notable importance, as an accurate load subdivision can actually extend the power-on time. The paper investigates different options to manage the Battery Energy Storage Systems of a DC shipboard power system. Two batteries are onboard installed to temporarily support the loads supply if a generating system disconnection occurs. Three power sharing profiles are investigated to identify the best solution in preserving the State of Charge of batteries
All Electric Ships Integrated Power Systems: Dependable Design based on Fault Tree Analysis and Dynamic Modeling
Full text linkThe All Electric Ship concept is becoming a standard for ships with large power requirements. At present, the design of the onboard power system (i.e. the IPS – Integrated Power System) is done through a well-proven process. This process rely on historical data and trial-and-error procedures developed in nearly 30 years of design experience to address the ship’s complexity. Nowadays, the evolution in IPSs is pushed towards by the introduction of more demanding requirements, which can be complied with only by using new power system architectures and introducing onboard innovative subsystems. However, introducing innovation by means of a design process defined on the basis of past experience is inefficient. Thus, new design paradigms are needed. In this regard, concepts and tools from other technical areas can be used to achieve a “dependable design process” able to ease the introduction of innovation in ships’ IPSs. In this paper, after a brief presentation of the conventional process and the actual drivers pushing towards its revolution, the dependable design process is proposed. The latter integrates both dependability enforcing techniques and dynamic power system modeling. Insights about the process integration in the overall ship design process are given, while an application example is used to show the effectiveness of the proposed approach
Stability-oriented filter design optimization in cascade-connected MVDC shipboard power system
No full textVoltage stability is one of the issues that need to be tackled before successfully exploiting innovative Medium Voltage DC distribution systems. Focusing on a cascade-connected MVDC power system (i.e. a feeder DC-DC converter supplying a load controlled DC-DC converter), the paper presents a filter design optimization process. The proposed procedure allows minimizing the DC filtering stage capacitor size, assuring at the same time the compliancy with voltage ripple requirements and the system voltage stability for a given load-side control bandwidth
Anti-roll control for by-wire lift truck
No full textThe introduction of drive-by-wire (DbW) systems in the vehicles makes it feasible the implementation of active controls to improve the driving safety. In this paper, an anti-roll control for a lift truck is developed by exploiting the capabilities offered by a DbW system. To this aim, a suitable multi-mass model of the lift truck is formulated and the rollover condition is analyzed for both pivoting and locked rear axle. From the analysis, the longitudinal speed at which rollover begins is found as a function of the cornering and loading situations. Further to this result, the anti-roll control is arranged that substantially operates by conditioning the speed command entered by the driver. Hints on the implementation of the control are droppe
Real-time monitoring and control system for Trieste University Campus electrical distribution grid
No full textThe growing integration needs in the electrical systems are increasingly demanding more control also on the distribution network. This can be satisfied by introducing advanced control on the small and medium distribution grid sites and, in general, introducing electronic devices for voltage and power-flow control. All these concepts are commonly summarized with the Smart Grid term and putting the emphasis on system management through the Micro Grid paradigm. In this context the distribution network of a university campus, with one connection point to the distribution network, can be an interesting test bed. In this paper the status and the evolution of the Trieste University Campus distribution network is presented, showing also the adopted technical solutions
Cold Ironing Integration in City Port Distribution Grids: Sustainable electrification of port infrastructures between technical and economic constraints
No full textIn the near future, a strong development in port infrastructures is expected in response to the ecological transition. At the same time, tight environmental requirements in city ports make compulsory new actions for site decarbonization. These two aspects are forcing toward a port electrification, where renewable energy resources and storage systems can increase port sustainability in accordance with the green deal
- …
