The contemporary electricity market demands a robust mechanism that allows the integration of various sources of energy. Power produced from intermittent energy sources, such as wind energy and solar energy, fluctuates, and it is very challenging to maintain the voltage frequency of the grid (around 50 Hz). This means that other generating units need to absorb the fluctuations (known as short peaks).
Hydraulic turbines are extensively used to absorb the short peaks due to their high flexibility of power generation. The numbers of short peaks and the ramping have significantly increased in the last two decades. Such high numbers of ramping have pushed the hydraulic turbines to the endurance limit, and the turbines have started to show signs of fatigue. The HydroFlex project aims to design and develop a turbine that allows power generation in conjunction with solar and wind, i.e., more start-stop cycles and high ramping rates. Two distinct approaches will be implemented, i. e., variable speed and improved fatigue characteristics.
In the third work package (WP3) of HydroFlex, we deal with the flexibility of turbines. We aim to design a turbine, which is capable of handling up to 30 start-stop cycles per day while accommodating variable power from wind and solar energy. Turbines are expected to operate off-design loads (i.e., far away from the design point, also known as the best efficiency point) for longer time and the variable speed approach will help to improve the dynamic stability and hydraulic efficiency at off-design loads.
Under WP3, we develop new designs of the turbine blades, guide vanes, stay vanes and draft tube aiming to reduce the adverse effects on the turbine during frequent starts and stops. When turbines are operated in a flexible manner to accommodate the variable electricity demand, the loading on the turbine blades changes frequently. That means such loading is time dependent
(or varies depending on power generation/demand), and this may lead to the development of fatigue crack in the blades. Keeping this in mind, HydroFlex also aims to develop a lifetime predicting tool that will help to predict the life expectancy of a turbine. In WP3, three universities (NTNU-Norway, UKiM-Macedonia and LTU-Sweden) and two industrial partners, EDR Medeso (consultancy company –Norway) and Rainpower (turbine Manufacturing company -Norway) are working together.