Moving Toward Medium Voltage DC Technologies

Large centralized power plants continue to play a role in providing alternating current (AC) power to the wholesale power grid, but momentum is growing at the medium voltage (MV) level to diversify power offerings and pursue hybrid solutions that incorporate more direct current (DC). 

In an article for Energy Central, Michael Hartnack, senior research analyst with Guidehouse Insights, says as the grid becomes more decentralized, there’s room for new DC architectures, especially for grid-tied applications such as short-distance MV offshore renewables, distributed energy resources (DER) integration, and back-to-back asynchronous grid interconnections in either AC or DC grids. Remote off-grid applications, such as island-to-island power and interconnecting multiple microgrids with no high voltage power, are also gaining traction.

“DC technologies are not new, however, new applications are made possible by technological advances in energy systems that allow for more creative networking of generation, load, and storage,” Hartnack said.

In his article, Hartnack identified six technology trends converging to create promising markets for MVDC networks:

• Increasing small renewable installations, especially close-offshore
• Growing numbers of microgrid deployments, particularly in developing regions
• Declining costs and increased efficiency of solar PV and wind turbines, which are both natively DC generation sources
• Surging grid penetration of natively DC energy storage devices due to steeply declining costs
• Climbing rates of DC loads in commercial and industrial sites, ranging from electronic devices to lighting and machinery
• Intensifying grid reliability and stability technology deployments

Related applications include renewable generation interconnections, EV fast charging, microgrids, and the reinforcement of existing transmission infrastructure.

“The efficiency benefits gained from MVDC architecture often outweigh concerns about cost, installation time, and complexity,” Hartnack said.