The concepts behind automating wind turbines have hardly advanced in the last 20 years and no longer reflect the state of the art. At WindEnergy (September 25 to 28, 2018 in Hamburg), the world’s leading trade show in this domain, IAV showcased for the first time a demonstrator illustrating what is possible with modern open-loop and closed-loop control systems. The model-based approach permits real-time supervisory control which either leads to a higher amount of energy produced for the same load or higher turbine life at identical energy production.
The automation solution IAV has developed involves no new sensors and actuators. As hitherto, the measurement variables used are rotor speed, generator output, the rotor blade pitch angle and the acceleration which the tower of the wind turbine undergoes during current wind conditions. They feed a model of the wind turbine which can use the predicted wind speed to calculate the state of the system in real time up to 20 seconds into the future. An optimization algorithm then determines control action for the pitch drives of the rotor blades and the generator which are best suited for operating the system.
Better yield or life-time extension
The aim of the wind park operators is to get the maximum return from their investments. This can mean producing more electricity for the same level of wind turbine loading. Here, the new automation solution promises to increase yield by up to 1.5 percent. Conversely, a wind park operator may wish to reduce load for the same return. In this case, major mechanical loads acting on wind turbine components can be reduced by up to ten percent, significantly extending their useful life.
“Generally speaking, our new automation solution could be used for all wind turbine systems”, says Dr. Axel Schild, Senior Technical Consultant in the Powertrain and Power Engineering division at IAV. “As a retrofit solution, it makes existing wind turbines more efficient. In turn, new ones could be produced at far lower cost because the lower load would lead to significant material savings.” In the meantime, IAV’s solution has advanced to such an extent that field testing is to begin before the end of the year. The market potential is immense: worldwide, some 20,000 new wind turbines are installed every year, and IAV’s experts estimate that a large proportion of new systems will be equipped with such an automation solution.
Experiencing automation solution first hand
IAV presented the idea and an initial concept at WindEnergy 2016. This year, show visitors saw a well-advanced technology demonstrator. To make the abstract subject something to experience first hand, a test rig environment was set up at IAV’s show booth in Hamburg that visualized the operation of the automation solution. Visitors could stand on a triangular platform and, by shifting their body weight, quite literally “weight” the three different basic goals (producing electricity, minimizing component strain, minimizing actuator load). The distribution of current weighting could be seen on a screen and provided input for the control system. The response of the control system was also shown on the monitor, providing first-hand experience of how the automation solution works. Graphs showed in real time how electricity production as well as strain on components and actuators changed. A video completed the show experience. It portrayed the controller as a split personality and had the purpose of illustrating the subject in a way that appealed to viewers’ emotions.
From a technical perspective, the new automation solution is already so advanced that IAV is looking for partners to market it. “This could be, for instance, manufacturers of industrial control systems who can combine their hardware with our software and offer this as a package”, Schild says. “For us, this makes WindEnergy precisely the right trade show for presenting our solution to the public because it attracts so many OEMs and component suppliers from the wind energy sector.”
Permanent advances in research project
IAV is continuously advancing the new wind turbine automation solution in cooperation with academic partners in the eco4wind research project which is constantly benefiting from the latest research results. “To define control intervention, today’s control solutions only focus on the past to the present. Our new, model-based approach, in contrast, predicts and optimizes future events”, Schild says, summarizing. “This innovative approach maximizes the potentialof wind turbine generator systems and is a radically innovative step.”