By Duotong Yang, Dominion Energy
Utilities today are experiencing large-scale retirement of existing traditional generation and a switch to more renewable generation sources, such as solar and wind. As a result of these widespread changes, the North American grid is becoming much more complex, both in planning and operation.
Power grids all over the world are seeing similar trends. With the increase in inverter-based renewable generation and a decrease in traditional rotating synchronous generators, new issues are arising. Two of these are the reduction in fault current, which is of utmost importance for distribution protection, and reduction in system inertia to help bound frequency and angular excursions during disturbances. Furthermore, the variability in output from renewable sources is changing the way we plan for and operate the grid.
In the past decade, there have been major advancements in semiconductor technology. The most relevant advancements for the power grid include IGBT and GTO, that allow for faster switching and four-quadrant operation. Downward trends in pricing for these technologies are encouraging widespread adoption in power grids. Flexible AC Transmission System (FACTS) devices based on IGBTs and GTOs offer increased controllability and transfer capacity, which is needed to support the changing electric grid. Another positive development is the advent of advanced smart inverters for interfacing renewable resources to the grid.
According to Hesen Liu, an engineer with Dominion Energy, “With the help of smart inverters, the challenges introduced by renewable energy sources may be alleviated.”
“A more recent issue that has emerged is the loss of large amounts of megawatts from distributed generation during bulk electric system disturbances,” said ISGT Industrial Co-Chair Chetan Mishra, also from Dominion Energy. “Germany’s 50.2 Hz is one such example.
“Today, some distributed energy resources are intended to offline during islanding situations to ensure safety to customers and utility workers. The current practice is to rely on ride-through curves, which are limits on voltage on frequency at the point of interconnection, in order to distinguish between an islanding and non-islanding situation. But these ride-through curves and the changes they represent are a technical challenge that is under much discussion in the industry.”
Please plan to join us at ISGT NA in Washington D.C., on February 17-20, 2019. It will be a great opportunity to have engaging discussions with colleagues from industry and academia on the development and adoption of smart grid technologies in our power system networks