Despite the abundance of wave power on Germany’s Baltic coast, the potential of this vast renewable energy source remains largely unexploited. Aside from the substantial costs of constructing and operating large mechanical devices at sea, there’s also the complexity of how to feed the constantly fluctuating current into the grid.

Nevertheless, a team of electrical engineers led by Professor Christoph Hackl from the Munich University of Applied Sciences has been working with the local start-up Sinn Power to develop intelligent control systems that can be used in wave and tidal plants. The most common type of wave plant is based on a simple, mechanical principle: rows of vertical rods are anchored to the seabed and at the end of each rod is a float that moves up and down with the waves. This drives rollers that are connected to an electrical generator; as the rollers rise and fall, the direction of rotation changes, which is how a three-phase current is produced.

The complicated part is how to feed this wildly fluctuating current into the electricity grid, which requires a constant frequency of 50 hertz. While this is technically possible, the biggest challenge for Hackl was “to achieve the highest possible efficiency and reliability in all operating areas with this conversion," he says in an interview with SolarServer.

Hackl's software minimises energy losses that happen along the various current conversion steps by controlling the interaction of all the components and increasing their resilience to the harsh maritime environment; so if one part fails, the entire system doesn’t shut down. The power electronics used in Hackl’s prototype plant were tested for a year in stormy seas off Heraklion and succeeded in continuously feeding compatible electricity from the generator into the grid with a surprisingly high energy yield of 93 percent.

Aside from making wave plants run more efficiently, Hackl hopes his smart grid conversion software can be used to improve yields in other renewable plants, be they solar, wind, hydro or geothermal.