Spanish Researchers use Real-Time Simulation to Improve Efficiency of Wind Turbine Control Systems

 As the world’s third-largest producer of wind power and the second-largest producer of solar power, Spain has become a global leader in the adoption of renewable energy technologies. Driven by the dual objectives of reducing both greenhouse gas emissions and the country’s dependence on foreign oil, about 30% of Spain’s electricity is now produced by renewable energy sources.

But, Spanish leadership in the area of renewable energy is not limited to production. A number of both private- and public-funded research projects are ongoing at research centers and universities across Spain.

At Universidad del Pais Vasco’s San Sebastian campus, significant research is taking place in the development of innovative control systems for wind energy production.

With over 600 active research groups and close to 49,000 registered students, Universidad del Pais Vasco (University of the Basque Country) is the largest public university in the Basque region of northern Spain, and among the nation’s largest universities.

Led by Dr. Gerardo Tapia, a professor in the university’s Department of Systems Engineering & Automation, the research team investigating innovative control systems for wind energy production has a number of objectives including making significant improvements to the efficiency of control systems, increasing the system’s mechanical strength and reducing maintenance costs.

According to Dr. Tapia, “Our project is focused on improving the regulation of power converters associated with traditional Doubly-Fed Induction Generators (DFIG), which are present in the vast majority of wind turbines currently on the market. We’re seeking to make a number of technological innovations to this aspect of the wind power generation system, including reducing the number of sensors used, optimizing control algorithms and enabling automatic adjustment of control parameters.”

Typically, a DFIG control system consists of a vector control, a PI controller and an angular position sensor. By eliminating the sensors used to measure the position of the rotor, maintenance costs can be dramatically reduced. In addition, the research team is working on ways to integrate a control system that incorporates an algorithm that enables “on-line” identification of the DFIG’s electrical parameters. This will allow an automatic adjustment of parameters associated with the control algorithm to optimize the efficiency of the system. An interesting aspect of this element of Dr. Tapia’s research is that the proposed identification process will enable configuration of the electrical generator without the need to resort to traditional off-line testing, in turn maximizing the operational availability of the turbine.

Development of algorithms and related mathematical models, as well as the use of Real-Time Simulation tools play a critical role in Dr. Tapia’s research.

“Conducting simulations in MATLAB/Simulink is an important part of our study of these new algorithms,” said Dr. Tapia. “Equally important is the Real-Time Simulation we conduct using Opal-RT’seMEGAsim simulator and an industrial 7kW prototype DFIG.”

The eMEGAsim Real-Time Simulator was deployed in Dr. Tapia’s research lab in late 2008 by Opal-RT, in partnership with the company’s Paris-based European distributor, Viveris Technologies. It is currently being used for conducting rapid prototyping of control algorithms and high-fidelity Real-Time Simulation of the complex power systems under study, with physical hardware-in-the-loop.

“What we like about the eMEGAsim simulator is its scalability,” said Dr. Tapia. “Since the platform is based on commercial-off-the-shelf PC hardware, we can easily expand the number of CPUs in the simulator as the complexity of the systems under study increases.”

The eMEGAsim simulator in use at Universidad del Pais Vasco also incorporates high-speed FPGA-based I/O that are user-programmable using Opal-RT’s RT-XSG blockset for MATLAB/Simulink.

In addition, eMEGAsim’s open architecture facilitates easy integration of models developed using a variety of tools including the SimPowerSystems blockset for MATLAB/Simulink, as well as C and Labview. Automated test scripts can also be developed using the Python scripting language.

Researchers, industry, and government in Spain have taken the lead on the world stage, demonstrating how power generation from renewable energy sources can be done safely and efficiently, while making economic sense. Through the use of tools like Opal-RT’s eMEGAsim simulator, research projects such as the one led by Dr. Tapia will build further on this success, not just for the benefit of Spain, but in wind energy projects around the world.