RGO—North Dakota State University faculty will conduct research that could make wind power more widespread, reliable and efficient.

​”One of the key aspects of this study is to research the possibility of using DC (direct current) grids,” said Nilanjan Ray Chaudhuri, assistant professor with the North Dakota State University electrical and computer engineering department who will run the research project. “With that, we’ll be able to increase wind energy penetration.”

The United States is lagging when it comes to direct current power transmission technology, missing on the benefits DC provides — benefits that could one day transform how the nation gets its power, according to Ray Chaudhuri.

Most U.S. wind energy potential is in the Midwest, where less power is in demand, said Ray Chaudhuri, adding that requires longer transmission lines to get the power to more highly populated areas. In the case of long distance, he said DC transmission technology is more economical. Switching transmission will require more infrastructure to be built but, in the end, it will be more reliable and efficient than alternating current.

A DC system also can help overcome the problem of fluctuating power that plagues wind today, allowing the power to be moved longer distances when the wind is blowing one place but not another, Ray Chaudhuri said.

North Dakota is particularly well-positioned to take advantage of the industry, according to Ray Chaudhuri, adding that the state has so much wind potential that industry could shut its fossil fuel power plants nationwide and supplement it only with North Dakota wind power, according to Colorado-based National Renewable Energy Laboratory data.

Ray Chaudhuri said North Dakota also has the advantage of being home to two high-voltage DC transmission lines owned by ALLETE’s Minnesota Power. He said there are not a lot of these lines in the U.S., most of them are on the West Coast, but more are being built.

Focused research

While DC connection to offshore wind power is being studied in Europe, Ray Chaudhuri saw the opportunity to focus on integrating the U.S.’s onshore wind power. The National Science Foundation’s Division of Electrical, Community and Cyber Systems awarded the five-year, $502,810 grant for the research. He and his students will use the funding to focus on addressing four key aspects.

First, Ray Chaudhuri said there has not been computer modeling done on how a Hybrid DC grid system would work. Within that grid system, different technologies for onshore and offshore wind power will have to be integrated.

“No one has worked on any such hybrid system; that’s where we have some challenges,” he said.

Next, the study will take on power sharing. Power generated by wind turbines and the power needed to run everything, from industrial machinery to home appliances, is AC. So, conversions will need to take place from AC to DC and back to AC.

Ray Chadhuri said AC grid does not handle disturbances in power supply well when connected to the DC grid, so he and his students will have to devise a solution for if a converter goes down.

“That becomes a huge problem,” he said, so they will develop a way for other converters still online to share the burden, causing less disturbance to the AC system.

Another problem researchers will need to solve relates to generators currently used on the AC system that kick in when there are power disturbances. The conversion from DC to AC can sometimes block the generators from turning on and providing support.

Finally, because wind farms are typically in rural areas, AC generators are not nearby, making the AC system weak, something the researchers are aiming to combat.

The research for making such a DC system reality will likely take 30 years or more to perfect, Ray Chaudhuri said. Ultimately, he would like to see North Dakota become home to a Center of Excellence for HVDC research.