LVDC and Harmonic Currents
NEMA, UL and NFPA sponsored a very successful workshop in Crystal City, VA during April on the topic of Low-Voltage Direct Current. There were 17 presenters and over 140 attendees at this state-of-the-industry event. LVDC is of interest because establishing a direct connection between distributed power generators (especially photovoltaics) plus energy storage devices (mostly batteries) and the many electronic products that operate on LVDC allows elminiation of the power supplies that eat up energy making the conversion from AC to DC and continue consuming power even when the connected device is off (vampire currents). Manufacturers presented information about products that can facilitate the implementation of LVDC circuits and systems. Professors described research into the mechanisms that can be used to enhance the efficiency of LVDC "Microgrids" and "Nanogrids". Association and certification body representatives discussed challenges, opportunities and standards considerations.
What else can LVDC do? It could be a means to solve a growing concern, particularly in the electric utility community, with Harmonic Currents that are generated by all of the electronic products that can be connected to LVDC grids. Harmonic currents tend to be additive to eachother where the power company lines connect to big buildings and communities, and are blamed for overheating and damage to utility equipment and negative impacts on power quality. In the economics of business, many electronic devices are considered near commodities where the small price increases necessary to cover the cost of preventing each of the small harmonic currents could create a competitive disadvantage for the device manufacturers vs. those who just carry on as usual. With the implementation of LVDC grids, replacing the multitude of small power supplies with larger ones, which are less impacted by the cost to minimize harmonic current emissions, would significantly reduce the harmonic currents the utilities have to fight. Making these LVDC grids available could require the installation of parallel electric systems in existing buildings and residences but could be part of the design for new construction.
This could be a win-win-win situation: improved energy efficiency, utilization of renewable resources, and minimizing a power quality issue for the utilities. Comments are of course welcome!!
06-02-2011 11:33 AM