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ABSTRACT: In this paper two possible design alternatives are investigated for a high-power synchronous motor propulsion drive employing two voltage-source inverters for motor supply. The two arrangements are compared based on their steady-state behavior in both normal and faulty conditions (i.e. with one out-of-service inverter), predicted by time-stepping finite-element simulations. Simulation results found consistent with the results expected theoretically and based on previous studies. Pros and contras of the two design alternatives are highlighted together with the possible design strategies that could help mitigate their drawbacks.
Electrical Systems for Aircraft, Railway and Ship Propulsion (ESARS), 2010; 11/2010
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ABSTRACT: The use of General Purpose Processors (GPP) in conjunction with Real Time Operating Systems (RTOS) derived from non real time operating systems gives new solutions to the industrial control designer. Several factors work towards this direction and bring advantages in terms of reduced time for development and low cost of deployment. In particular, the Real Time Application Interface (RTAI) is a real time extension for the Linux kernel with a real time interface available in high-level simulation tools and in user space programs. In this work, an experimental implementation of a single-axis motion control based on RTAI will be presented, along with an assessment of its real time performance. Feasibility of proposed solutions to implement multi-axes controls using a large number of I/O channels will be exploited as well.
Power Electronics Electrical Drives Automation and Motion (SPEEDAM), 2010 International Symposium on; 07/2010
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ABSTRACT: Linux operative system, extended with the real time application interface (RTAI), makes it possible to realize industrial motion controls. This requires general purpose processors (GPPs) instead of dedicated DSPs or microcontrollers. RTAI offers the possibility of designing and developing motion controls using high level object languages (i.e., Simulink). The main advantages brought using Linux-RTAI and a PC as a controller platform are: very reduced time for development, diagnostics, design of controls; cost reduction offered by the open-source status of the operating system; high availability of the hardware. This paper shows that such a system offers adequate digital programming and signal processing capabilities to make real time motion control applications. An industrial-PC based acceleration control is presented and points of strength of RTAI solution are shown.
Power Electronics and Applications, 2009. EPE '09. 13th European Conference on; 10/2009
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ABSTRACT: This work presents the design and development of an innovative system aimed at detecting, recording and transmitting electrical and climate data from a PV field. Data are to be taken both from the PV modules and from the power conditioning system of a given PV field, through appropriate sensors, to monitor: climate data (irradiance, temperature), electrical quantities (voltage, current, power), performance of the PV generator as a function of climate parameters, performance of the power conditioning system over different working conditions. The system will exchange data through a communication network (i.e. Ethernet/TCP-IP) to download data, visualize quantities and operative states. The proposed system is designed to be integrated into any PV field, independently from the plant layout, the inverter type, the presence of preexisting data loggers, sensors, etc. Such a result is achieved using an open architecture, which assures an extremely high flexibility of utilization.
Clean Electrical Power, 2009 International Conference on; 07/2009
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ABSTRACT: Ensuring system stability in medium-voltage DC (MVDC) integrated power systems (IPS) is a key issue, due to the presence of many shipboard electric users fed by constant power load (CPL) converters. This paper presents an innovative control system aimed at utilizing alternators, connected to the IPS through controlled AC-DC interface converters, to improve MVDC stable voltage control. Such system is designed to control, for each shipboard generator, the AC machine voltage, the prime mover speed and the interface converter, in an integrated way. Technological aspects and control principle scheme of this system will be presented in the paper, with particular reference to the issue of DC-link voltage stability. This system is expected to bring advantages in terms of MVDC IPS integration, stable parallel operation of generators and loads, safe exploitation of alternators capability as a source of stabilizing power.
Electric Ship Technologies Symposium, 2009. ESTS 2009. IEEE; 05/2009
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ABSTRACT: The paper points out innovative design issues of the shipboard power stations for all electric ships (AESs). Alternators and voltage control system operations are reviewed under an approach which emphasizes the impact of design choices on power generation and availability. The work moves from an in-deep analysis of modern cruise ship integrated electric power systems (IEPSs), in order to assess points that permit to improve and optimize the power station design. Different operative conditions are taken into account, both for navigation and port calls, and related active and reactive power demands are considered. The objectives of the study are to improve cost-effectiveness in power generation management, including both design aspects that have an impact on initial (i.e. alternator power factor rating) and cruise costs (i.e. diesel-generator efficiency, optimal selection of running generators, generator active and reactive loading).
Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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ABSTRACT: The paper presents a small-signal stability analysis of voltage control systems employed onboard all-electric cruise liners. To realize the stability analysis, a model of shipboard power station voltage control system has been determined, moving from dynamic models of alternators, voltage regulators and loads. Reduced order models of alternators have been utilized, to simplify at best the analysis. Analysis results have been validated through numerical simulations, using a simulator of power station electromechanic quantities developed at the University of Trieste. Such simulator includes alternators, voltage and frequency regulators, breakers, protections and R-L loads. Numerical results obtained from simulations of both complete and reduced order models fully validate the analytical findings, while computation times are in the order of real-time simulations.
Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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ABSTRACT: In todaypsilas high-power electrical drives using synchronous machines, voltage source inverters (VSI) based on multilevel PWM technology and current source inverters (CSI) based on load commutated operation are the most important alternatives for motor supply (cyclo-converters being confined to very low speed applications). In this paper a comparative performance analysis of the two drive typologies in various multi-phase design configurations is presented. It is highlighted how the performance of the CSI drive could be remarkably improved resorting to motor windings with more than six phases.
Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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ABSTRACT: The world total photovoltaic (PV) installed capacity is growing very quickly, due to both government incentives and increased environmental concerns. This situation calls for the realization of large, grid-connected ldquoindustrialrdquo PV plants, aimed at delivering energy to the grid. However, the cost/kWh of PV energy is still quite high. This paper reports some of the most promising research approaches currently in progress on new PV materials and devices, focusing on the reduction of PV generation cost expected from the technological implementation of such research. Because of their large size, industrial PV plants could have different characteristics compared to the small ones that, with few exceptions, have been realised until now. This problem is analyzed with the aim of providing a set of recommendations and guidelines for proper design of industrial PV plants, mainly concerning the choice of the power electronic conditioning systems and the use of simulation-aided design tools.
Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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ABSTRACT: RTAI extension to Linux operating system makes it possible to perform Hard Real-Time (HRT) controls using a commercial PC and utilizing open-source code. This paper details a software installation process, along with the suitable hardware chosen for realizing motion controls using Linux-RTAI. Advantages offered by the possibility of designing and developing motion controls using the powerful tools of high level object-languages (i.e. Simulink) are described. It is proven that the combination of Simulink as a development environment and Linux-RTAI PC as a controller platform brings advantages that can be greatly appreciated in industrial motion control applications, such as: very reduced time for development, diagnostics, design of controls; adequate control performance; cost reductions offered by the open-source status of the operating system.
Power Electronics, Electrical Drives, Automation and Motion, 2008. SPEEDAM 2008. International Symposium on; 07/2008
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ABSTRACT: Power quality is a key issue in island, shipboard integrated electric power systems (IEPS). However, it is not of easy accomplishment, due to the complexity of shipboard power station (generators are many and differ by sizes, prime movers, control systems, etc.) and to the intrinsic weakness of the shipboard grid. This paper presents a new approach for controlling voltage and reactive power generated in the power station of an all electric ship (AES). A shipboard voltage and VAr integrated regulator (WIRE) is proposed. The WIRE is aimed at controlling alternators voltage, main busbar voltage and jointly optimizing the reactive power generated by each alternator. WIRE project reunions into an integrated device the most advanced control functions presently implemented in smartest land power stations. WIRE is also endowed with an embedded power-station/IEPS real-time simulator, suitable for performing factory functional, diagnostic and hardware-in-the-loop (HIL) tests. The paper will show how WIRE can improve power quality into an AES, while respecting marine constraints like: reduced room availability, redundancy, reliability, optimal and safe utilization of generators, fast commissioning, diagnostics.
Electric Ship Technologies Symposium, 2007. ESTS '07. IEEE; 06/2007
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ABSTRACT: Electric propulsion for cruise liners has now become a standard owing to its several advantages. However propulsion drives have a large impact on the ship power system. This gives rise to the requirement for designers to understand in depth the effects of propulsion drives on the ship network in different operating conditions. For this purpose computer simulations have proved to be a very useful tool. In the paper a typical propulsion drive for an all-electric cruise liner is described and simulation results are shown. Owing to the model complexity, simulations turn out to be computationally quite heavy. For this reason a simplified model has been developed. Simulation results, from the ship network viewpoint, proved to be close to the detailed model ones.
Electric Ship Technologies Symposium, 2007. ESTS '07. IEEE; 06/2007
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ABSTRACT: Photovoltaic (PV) plants in Italy are presently subject to a rapid increase due to recent government incentives dedicated to grid connected PV plants. Incentives are given on the basis of the energy actually delivered to the grid, so that it becomes fundamental for the owner to produce as much energy as possible in order to reduce the payback time. In this framework, PV system efficiency plays a fundamental role. This paper focuses on medium and large size PV power systems, for which plant efficiency becomes a key design issue. In particular, the choice between centralized or distributed ("string") architecture is analyzed in terms of plant efficiency, considering the following basic issues: (1) losses in the power electronic conditioning system; (2) losses due to cable dissipation; (3) losses due to possible maximum power point mismatch.
Clean Electrical Power, 2007. ICCEP '07. International Conference on; 06/2007
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ABSTRACT: All electric ship alternators are connected to a main busbar which feeds all shipboard electric loads. To fulfill power quality requirements of the resulting electrical system, high-performance control of busbar voltage and frequency is needed. Such a task is not of easy accomplishment, due to the complexity of shipboard power station (generators are many and differ by sizes, prime movers, control systems, etc.) and to the intrinsic weakness of the shipboard grid. In this frame, a key power quality issue is voltage control. This paper presents an innovative shipboard voltage and VAR integrated regulator (WIRE). The WIRE controls main busbar voltage and jointly optimizes the reactive power generated by each alternator. It is designed to be interfaced with onboard automation and to realize the integrated management of all reactive power sources (rotating, capacitive, static). Furthermore it satisfies naval requirements as redundancy and fast commissioning
Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006. International Symposium on; 06/2006
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ABSTRACT: More and more commercial and pleasure modern ships are equipped with electric propulsion system, which is the most important and power-consuming electric apparatus onboard. The significant increase in the power required onboard by the adoption of electric propulsion causes a great evolution in onboard power systems and poses the need for a proper development of design techniques and tools. At the same time, the traditional approach for onboard power system design based on experience and rules of thumb is becoming no longer adequate. This paper deals with this evolving scenery, and mainly concerns power system design and power quality aspects. Real data and measurements are provided with reference to a new-built mega-yacht. The work, in progress, aims to set up a complete electric model of the all-electric ship to allow simulation of different operating conditions and to predict the main power quality issues and the fulfillment of the relevant technical rules
Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006. International Symposium on; 06/2006
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ABSTRACT: Steer-by-wire (SbW) systems are candidate to substitute the conventional (mechanical or hydraulic) steering systems in the new generation of vehicles. The task of a SbW system is twofold: turning the road wheels tracking the handwheel rotation and providing the driver with a feeling of the steering effort. In this paper, the issue of designing a SbW system is faced. An approach is proposed, based on three steps. Firstly, the model of a conventional steering system is formulated. Then the SbW system is developed with the same structure as the conventional ones. Finally, performance indexes for the steering maneuver are defined and utilized to set up the parameters of the SbW system. As a case of study, the SbW system of a lift truck is designed according to the proposed approach. Diagrams are given to demonstrate the effectiveness of the resultant SbW system
Industrial Technology, 2005. ICIT 2005. IEEE International Conference on; 01/2006
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ABSTRACT: The 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 dropped
Computer as a Tool, 2005. EUROCON 2005.The International Conference on; 02/2005
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ABSTRACT: The paper is concerned with the acceleration control used by the servo systems to make their behavior robust against load torque and parameter variations. After demonstrating that the Torque Disturbance Observer (TDO) is equivalent to a particular acceleration control, the robustness of a servo system endowed with TDO is analyzed. Then it is shown that the deliberate set-up of a Feedback Acceleration Control (FAC) offers the designer more chances and theoretically brings the robustness of a servo system up to infinite. In practice, the physical constraint on the peak value of the servo current limits the achievable robustness. Taking into account such a constraint, it is proved that, compared to TDO, a suitable design of FAC improves the robustness of a servo system of the ratio between the rated values of peak and dc servo current. Simulation results illustrating the torque disturbance rejection and the current response for the two schemes are reported.
EUROCON 2003. Computer as a Tool. The IEEE Region 8; 10/2003
