Gustavo Navarro

Wave energy converter dimensioning constrained by location, power take-off and control strategy

The paper analyses the performance of a wave energy converter (WEC) employing a direct-drive linear switched-reluctance machine, providing a detailed method for optimal dimensioning of a WEC. The method derives the dimensions of a particular point absorber to reach objectives such as the maximization of energy extracted, or the minimization of volume. The characteristics of a particular location, the chosen power take-off (PTO) and the control strategy chosen define the restrictions of an optimization problem whose solutions are the dimensions of the most suitable WEC. The given generator parameters (maximum stroke, velocity and force) determine an optimal WEC design. Laboratory testing of the generator will validate the force and calculate efficiency, to be used as inputs for the optimization process. Aside from the preliminary WEC dimensions design, this method can be used for an energetic analysis of a particular PTO on various locations.

Power smoothing system for wave energy converters by means of a supercapacitor-based energy storage system

One of the main issues of wave energy nowadays is the oscillation of the generated power, which is due to the oscillating nature of the waves. These power fluctuations may have an important undesired impact on the electrical grid. This paper proposes a system that compensates power oscillations in wave energy applications by means of a supercapacitor-based energy storage system. A laboratory test bench is used to emulate wave power oscillations and to partially suppress them. The paper describes the control strategy implemented in the test bench and includes experimental results for regular waves.

Design methodology of a high speed switched reluctance generator drive for aircrafts

The paper proposes a high speed switched reluctance (SR) drive for aircraft applications, covering the demand of more electric aircrafts (MEA) and defending the particular benefits of this machine technology against others, such as permanent magnet synchronous generators. An appropriate topology of electrical machine and power converter for a high speed DC distribution grid is selected. Firstly, the electromagnetic design of the generator, by means of FEM, is described in detail, paying attention to the problem of the torque ripple and pointing out some solutions to improve it, based on an iterative optimisation of both stator and rotor geometries and phases activation and deactivation angles. Then, the design of power electronics is also analysed, obtaining the required modules and cooling system from a simulation model, using the maximum and average current levels as well as the duty cycles. The model has been developed from the generator electromagnetic design and integrates the control strategy, in charge of controlling the DC-link voltage. An iterative procedure using FEM analysis and the simulation model is also used to validate the thermal and mechanical behaviour of the system. Finally, the integration of the complete electric drive is discussed with the criteria of maintaining the system within the available room and keeping the temperature under the maximum limits. The application of aircraft equipment is specially demanding in terms of robustness, low maintenance, fault tolerance, high temperature and harsh environment, and those are the reasons why the SR generator is a reliable alternative.

Multifunctional test bench for the emulation and testing of electric vehicle fast-charging from urban railway power lines

This paper describes the development and operation of a laboratory test bench specifically designed to emulate an electric vehicle charging platform in which the energy is supplied from an urban railway power line. This platform was developed in order to prove the technical feasibility of the proposed charging method and to assess its performance. Further research includes the development and comparison of control strategies from the energy management point of view.

Technology description and characterization of a low-cost flywheel for energy management in microgrids

This paper describes a modular, integrated and low-cost kinetic energy storage system (KESS), its electrical characterization as well as its future integration and operation in a microgrid within the scope of a project called MIRED-CON (Microgeneration with Renewable Sources and its control). This project aims to develop, using the power microgrid installed in the CEDER (Soria, Spain), an advanced metering and control infrastructure to improve the operation performance and efficiency of the distribution grid. Metallic flywheel and switched reluctance machine are chosen as energy storage device to provide stability to the microgrid, frequency regulation and power peak limitation, achieving a high performance in the grid operation. The KEES is integrated with a grid side converter (GSC) to connect to the A mains, providing extra functionality to the system. The combined operation of the proposed KESS together with photovoltaic (PV) panels, wind power generation and micro-pumped hydro energy storage (PHES) in the real application is analyzed by means of different simulations using MATLAB/Simulink software. Two operation modes are considered regarding the KESS: grid-connected mode (smoothing the power generation with renewables) and islanded mode (controlling the frequency and the voltage of the microgrid). Electrical characterization from experimental results are used by the central control unit to have information about the available power and energy in the device, thus improving the energy management in the real facility.

Laboratory tests before sea trials of a wave energy converter

The paper analyses the actions needed to be taken before the sea trials of a wave energy converter. In particular, the mechanical and electrical tests of the complete Power Take-Off are described, mainly these tests related toh the electric linear generator, the power electronics and its control. This work is developed in the frame of an application project consisting of sea trials of a Wave Energy Converter, carried out between the industry and some research centers. The paper describes the technologies involved in the project, including design and fabrication issues. After some successful tests to ensure the proper operation of the full scale equipment at the lab, it would be ready to be placed inside a point absorber and, after some final verification, to be deployed at sea site within a few months, thereby reducing the unnecessary risks.