The Electric Power Research Institute (EPRI) has been involved in broad collaborative industry initiative since 2009 that is working to identify set of common smart inverter functions. According to EPRI’s report, titled Common Functions for Smart Inverters, devices interface ac grid with dc energy sources, provide grid with wide array of support functions, and deliver both real and reactive power. Inverters can respond to remote commands as well as both steady-state and dynamic changes in grid frequency and voltage.
EPRI has been involved in a broad collaborative industry initiative since 2009 that is working to identify this set of common functions. The work has been carried out in contribution and coordination with standards activities, including the activities of NIST, IEC, and DNP3. EPRI’s recent report "Common Functions for Smart Inverters" summarizes the work of this initiative to-date. These common functions have been codified by the IEC in TR-61850-90-7 and mapped into various communication protocols.
The initiative has engaged a large number of individuals representing inverter manufacturers, system integrators, utilities, universities, and research organizations. The resulting work products have provided valuable input to a number of standards organizations and activities, including the National Institute of Standards and Technology (NIST) and the International Electrotechnical Commission (IEC). Participation in this activity has been, and remains, open to anyone who is interested.
This report provides a compiled summary of the function descriptions that this initiative has produced thus far. Each function is presented in the form of a proposal, which is the language used by the volunteer working group. This reflects the fact that the functions are not legal standards unless and until they are adopted by a standards development organization (SDO).
Key takeaways about this report:
Inverters are the power electronics that interface the ac grid with dc energy sources, such as solar photovoltaics and battery storage. Inverters tend to be highly intelligent, with PC-like processing capability, and because they have no mechanical inertia, can respond almost instantly to grid conditions.
Inverters are capable of providing the grid with a wide array of support functions, delivering both real and reactive power. They can respond to remote commands as well as both steady-state and dynamic changes in grid frequency and voltage.
Distribution systems of the future will likely include a combination of various sizes, brands, and types of inverter based systems. In order for the advanced functional capabilities of these systems to be exercised, it is necessary that there be a set of uniform functions and services that they provide. For example, it is not enough that a hundred different devices each have some kind of intelligent dispatchable VAR capability. In order to be useful to a distribution system operator, they must all offer this service in a consistent and uniform way.
More news and information regarding the latest developments in Smart Grid electronics can be found at Darnell’s SmartGridElectronics.Net.
