This SAE Information Report establishes use cases for a Plug-in Electric Vehicle (PEV) communicating with an Energy Management System (EMS) as a Distributed Energy Resource (DER) which must be supported by SAE J2847/3. This document also provides guidance for updates to SAE J2847/2 to allow an inverter in an EVSE to use the PEV battery when operating together as either a DER or as a power source for loads which are not connected in parallel with the utility grid. Beyond these two specific communication objectives, this document is also intended to serve as a broad guide to the topic of reverse power flow.
The baseline document was first published in January 2013 and is still a valuable reference. One purpose of this revision is to update the document based on subsequent activities in the area of Distributed Energy Resources and Vehicle to Grid. Also, there are some errors and omissions that needed to be corrected.
When the inverter is located onboard the PEV, this creates an unprecedented situation for securing approval by the local utility for the interconnection of the PEV to the electric power system. SAE created J3072, Interconnection Requirements for Onboard, Utility-Interactive Inverter Systems, to deal with the some of the unique issues associated with the roaming inverter. This revision retroactively establishes the rationale for creating SAE J3072 and elaborates on many of the issues associated with the roaming inverter. The baseline document did not recognize this as a major problem.
The baseline document differentiated between the case where the inverter was onboard the PEV or externally in the EVSE but did not provide clear guidance for the communication required between the PEV and the EVSE to coordinate the DC power flows. This revision more clearly defines the purpose of the communication between the PEV and the EVSE. The actual messages needed to accomplish this will be defined by a new version of SAE J2847/2 which will add a DER mode and any new signals required by the new mode.