A complementary tool to simulation and actual offshore testing is in-house or laboratory physical testing utilizing scaled experimental rotary emulators, that incorporates similar equipment to that being used in the offshore system. These systems include a motor which emulates the rotational mechanical power of the prime mover device based on real-time simulation models of the prime mover. The motor is then coupled to an electrical generator and power electronics, which prepare the power for grid connection. This has the advantage of being significantly less costly than offshore testing, and being a controlled environment for baseline testing of the equipment or control system being utilized in the offshore environment. Moreover, the on-shore equipment can be tested in combination with offshore, but over a wider range of conditions, and thus yield a fuller picture of the system characteristics. The inhouse microgrid provides extra flexibility to these emulators.
Lir NOTF offers a scaled rotational test rig for generator type selection, control strategy design and optimisation, and power quality analysis rated at 22 kW and 1500 rpm. The flexible design of the test rig facilitates islanded, direct and indirect connection to the grid of many different types of generator (Permanent Magnet synchronous generator, Wound Rotor induction generator (IG), Squirrel Cage IG). For significantly lower costs than at-sea testing, results from the test rig can inform device developers’ decision-making through all stages of the development and testing processes. Flexible system control options are available, from simple fixed speed or torque modes to more complex hardware in the loop system modelling modes (utilising a Matlab/Simulink model interfacing a SpeedGoat and Mitsibushi PLC).
Related publications and projects
FP7 CORES. Further information available at http://www.fp7-cores.eu/
Horizon 2020 OPERA Further information available at http://opera-h2020.eu/
Duquette, J., D. O’Sullivan, S. Ceballos, and R. Alcorn. “Design and construction of an experimental wave energy device emulator test rig.” In Proceedings of European wave and tidal energy conference. 2009. Paper available here
Rea, J., J. Kelly, R. Alcorn, and D. O’Sullivan. “Development and operation of a power take off rig for ocean energy research and testing.” In Proceedings from the 9th European Wave and Tidal Energy Conference, Southampton, UK. 2011. (http://www.lir-notf.com/wp-content/uploads/2015/12/ReaRayKelly.pdf)
Ceballos, Salvador, Judy Rea, Iraide Lopez, Josep Pou, Eider Robles, and Dara L. O’Sullivan. “Efficiency optimization in low inertia wells turbine-oscillating water column devices.” IEEE Transactions on Energy Conversion28, no. 3 (2013): 553-564. (http://ieeexplore.ieee.org/document/6544582/?arnumber=6544582)
Cavagnaro, Robert J. “Impact of Turbulence on the Control of a Hydrokinetic Turbine.” In International Conference on Ocean Energy, Halifax, Canada. 2014. (http://www.icoe2014canada.org/wp-content/uploads/2014/11/2-CavagnaroRob_2-3.pdf)
Armstrong, S., J. Rea, F. X. Faÿ, and E. Robles. “Lessons learned using electrical research test infrastructures to address the electrical challenges faced by ocean energy developers.” International Journal of Marine Energy12 (2015): 46-62. (http://www.sciencedirect.com/science/article/pii/S2214166915000314)
Cavagnaro, Robert J., Jason C. Neely, Franois-Xavier Fa, Joseba Lopez Mendia, and Judith A. Rea. “Evaluation of Electromechanical Systems Dynamically Emulating a Candidate Hydrokinetic Turbine.” IEEE Transactions on Sustainable Energy 7, no. 1 (2016): 390-399. (http://ieeexplore.ieee.org/document/7321812/?arnumber=7321812)
The high speed dynamometer test rig consists of a PM (Permanent Magnet) machine with resolver feedback directly coupled to an induction machine with encoder feedback. High speed operation is achievable with ratings of 9,000 rpm and power ratings of 11 kW.
Various advanced electrical control options are available with the Vacon and Parker drive panels both with full regenerative capability and Ethernet connectivity, as well as the HBM torque sensor. A Sorrensen 10 kW dc power supply allows flexibility of power flows.
The Microgrid consists of a dual-bus three phase system. Generation, storage and load elements can be added to the Microgrid to build up a wide variety of test configurations. The Microgrid can operate in parallel with the local grid or as an islanded system. Sources of power include a 33 kVA diesel generator, a wind/ocean energy emulator, and fully controllable Triphase back-to-back 90 kW and 15 kW converters can exchange power between the grid and microgrid and offer a huge flexibility option. Storage is provided by a 5 kWhr lithium ion battery with 10 kW peak power flows. Fully controllable and adjustable loads with leading and lagging power factors are available including a 50 kVA Crestchic loadbank. Robust system control is provided by industry standard PLCs, while high speed data acquisition is offered by National Instruments cRIO system. An Opal-RT power hardware in the loop system provides advanced grid specific grid emulation capabilities.
Murray, Dónal Brendan. “Energy storage systems for wave energy converters and microgrids.” (2013). (https://cora.ucc.ie/handle/10468/1137)
Messinis, George, Fran Gonzalez-Espin, Virgilio Valdivia, Judy Rea, Darren Mollaghan, and Nikos Hatziargyriou. “Application of rapid prototyping tools for a hierarchical microgrid control implementation.” In 2014 IEEE 5th International Symposium on Power Electronics for Distributed Generation Systems (PEDG), pp. 1-5. IEEE, 2014. (http://ieeexplore.ieee.org/document/6878688/?arnumber=6878688&tag=1)
Hogan, Diarmaid J., Michael G. Egan, John G. Hayes, Gordon Lightbody, and Fran Gonzalez-Espin. “A rapid prototyping tool for load and source emulation in a microgrid test laboratory.” In 2014 IEEE Applied Power Electronics Conference and Exposition-APEC 2014, pp. 2245-2252. IEEE, 2014. (http://ieeexplore.ieee.org/document/6803616/?arnumber=6803616)
Hogan, Diarmaid J., Fran Gonzalez-Espin, John G. Hayes, Raymond Foley, Gordon Lightbody, and Michael G. Egan. “Load and source electronic emulation using resonant current control for testing in a microgrid laboratory.” In 2014 IEEE 5th international symposium on power electronics for distributed generation systems (PEDG), pp. 1-7. IEEE, 2014. (http://ieeexplore.ieee.org/document/6878633/?arnumber=6878633)
Hogan, Diarmaid J., Fran Gonzalez-Espin, John G. Hayes, Gordon Lightbody, and Michael G. Egan. “Adaptive resonant current-control for active power filtering within a microgrid.” In 2014 IEEE Energy Conversion Congress and Exposition (ECCE), pp. 3468-3475. IEEE, 2014. (http://ieeexplore.ieee.org/document/6953872/?arnumber=6953872)
Hogan, D. J., F. Gonzalez-Espin, J. G. Hayes, G. Lightbody, L. Albiol-Tendillo, and R. Foley. “Virtual synchronous-machine control of voltage-source converters in a low-voltage microgrid.” In Power Electronics and Applications (EPE’16 ECCE Europe), 2016 18th European Conference on, pp. 1-10. IEEE, 2016. (http://ieeexplore.ieee.org/abstract/document/7695503/)