Electrical and Computer Engineering professor Ryan Li explains research aimed
at enabling our century-old power grid technology to adapt to new renewable
energy sources.
The Challenge
Our existing electrical power distribution system predates new technology like electric cars, high-efficiency electrical appliances and electronic devices-and even simple things like new LED lights. The grid itself is designed to carry AC electrical power with a certain range of characteristics. However, many new high-efficiency devices and appliances operate on DC power and need to convert the AC charge; what's more, the quality of power from renewable energy generators such as wind or solar producers isn't a good match with the existing power grid. Private and public utilities need to protect this essential infrastructure and harsh restrictions on the quality of power they allow the grid to carry is a roadblock to the development of more renewable energy generation.
Learn more about how the U of A is powering new smart grid technologies.
Yunwei (Ryan) Li, a professor in the Department of Electrical and Computer Engineering, is leading research that could one day change the way power is distributed.
The U of A Faculty of Engineering is home to one of the largest such research groups in North America.
The research Li conducts deals with power electronics, focusing on circuit topologies and control techniques. This is an area that is rapidly growing in importance. Presently, about 30 per cent of power generated is processed by power electronics before it is consumed and in the next 10 - 15 years that is expected to grow to 70 or 80 per cent because of renewable energy power generation such as solar and wind, energy storage capability and the increasing use of more efficient loads like electric drives and LED lighting. Li concentrates on medium-to-high power converters. One example is the integration of renewable energy systems into the power grid through the development of power converters. This helps make the power generated by renewable energy sources more compatible with the existing power grid.
The Approach
In his research, Li's team designs circuits and control strategies for power converters in different applications; first they verify the design through computer simulation and then test it on an experimental prototype. At this stage a small micro-grid is built in the lab. These grids include photovoltaic and wind-power system emulators, a grid emulator and loads all connected together through power converters. The micro-grid also has energy storage from batteries and super-capacitors. Graduate students design the converter circuit and control boards, gaining hands-on experience and a greater depth of understanding of how the systems work.
The Impact
In the short term Li's team hopes to see new functionalities of these power converters that help the grid accommodate more power from renewable sources like wind and solar. In parallel to this, they are also working on energy management of renewable energy based micro-grid serving remote communities. Transporting diesel fuel into these remote communities for power generation can be costly. But if these communities could produce power for themselves, using wind or solar or tidal energy, you could have a great societal impact. We already have these remote communities-we need to come up with energy generation and storage solutions for them. In the long term, the team is looking at a hybrid AC/DC power system. The existing power system is an AC system developed from more than a century ago. With the increasing connection of renewable energy, energy storage, and modern loads, many of which are based on DC voltage, a hybrid AC/DC system will greatly increase the overall system efficiency in the future. Again, power electronics is the key for this.