SAE J2847/3-2023: Smart Communication for Vehicle-Grid Integration

The 2023 revision of SAE J2847/3 marks a significant milestone in enabling plug-in electric vehicles (PEVs) to act as distributed energy resources (DERs). This recommended practice defines the communication requirements for vehicle-to-grid (V2G) and vehicle-to-home (V2H) functions, leveraging the IEEE 2030.5 Smart Energy Profile 2.0 (SEP2) application layer protocol. It provides a standardized framework for interoperability between electric vehicle supply equipment (EVSE) and PEVs, covering everything from system architecture and communication stacks to reverse power flow management, DER control events, and ride-through capabilities. The standard is essential for engineers designing EVSE, onboard chargers, and energy management systems that integrate PEVs into the grid or home energy ecosystem.

🛠️ Overview and Rationale

SAE J2847/3 was originally issued in 2013 and has been updated to reflect the growing need for bidirectional energy transfer in AC applications. The 2023 revision adds Sections 5, 6, and 7 specifically for AC V2G and AC V2H capabilities, including updated pilot signal sequences and boundary diagrams. The rationale highlights alignment with UL standards and the inclusion of new communication stages for AC power flow. The standard adopts a client-server architecture using SEP2 over TCP/IP, which provides the scalability and flexibility required for diverse grid and home scenarios.

Technical Architecture and Core Protocols

At the heart of the standard is the communication stack defined in Section 4. The architecture uses SEP2 resources implemented in XML and accessed via HTTP methods (GET, PUT, POST, DELETE). This enables standardized interactions between EVSE (as server) and PEV (as client) or vice versa, depending on the use case.

Key technical components include:

• IEEE 2030.5 SEP2: The mandatory application layer for DER information models and control.
• Flow Reservation and Reverse Power Flow: Mechanisms to manage home energy consumption and enable discharge from the vehicle battery.
• DER Control Events: Curve functions, schedules, and default controls that allow grid operators to send events to the PEV.
• Voltage and Frequency Ride-Through: Requirements that the PEV must stay connected during grid disturbances to support stability.

AC V2G/V2H and Pilot Signal Sequences

Section 5 and 6 of the standard detail the AC V2H and V2G requirements. The SAE J1772 pilot signal is extended with new stages to indicate bidirectional operation. System boundary diagrams clarify the roles of the EVSE, PEV, automatic transfer switch (ATS), and home loads. The pilot signal communication summary in Section 6.2 outlines the necessary sequences for standby battery requirements and safe disconnection.

The following table summarizes key elements from the standard:

Element	Description	SEP2 Resource Example
DER Capability	Reports the PEV’s available power, energy, and characteristics	/dcap
DER Status	Provides real-time operating state and warnings	/dstatus
Flow Reservation	Manages forward and reverse power flow at the premises	/frs, /frc
DER Control	Event-driven setpoints (e.g., charge/discharge power, reactive power)	/derg, /derc
Ride-Through	Voltage and frequency tolerance curves (e.g., trip points and time delays)	/rtv, /rtf

Implementation Considerations and Common Pitfalls

When implementing SAE J2847/3, engineers often encounter challenges that can affect interoperability and compliance. Drawing from the standard’s design insights and industry experience, here are some common mistakes to avoid:

• Incorrect SEP2 Resource Model: Mismatching client-server roles or missing mandatory resources like /derg or /dstatus can break communication.
• Pilot Signal Transitions: AC V2G/V2H require specific pilot duty cycles and sequences. Failing to properly implement the state machine (e.g., skipping the standby stage) can cause system lockout.
• Flow Reservation Misconfiguration: Reverse power flow must be properly negotiated using flow reservation resources; omitting this can lead to unsafe backfeed or nuisance trips.
• Ride-Through Compliance: The PEV must adhere to voltage and frequency ride-through curves. Ignoring these may result in disconnection during minor grid events, violating DER interconnection requirements.
• Outdated XML Schemas: Using schemas from older revisions of SEP2 can cause parsing errors. Always validate against the IEEE 2030.5-2018 (or later) schema.

Frequently Asked Questions

What is the role of IEEE 2030.5 in SAE J2847/3?

IEEE 2030.5 (Smart Energy Profile 2.0) provides the application layer protocol and information model for all DER communication. SAE J2847/3 adopts it as the mandatory method for exchanging control and status data between the EVSE and the plug-in vehicle.

How does the standard handle reverse power flow?

The standard uses flow reservation resources to negotiate and manage the direction and magnitude of power transfer. Both forward (grid to vehicle) and reverse (vehicle to grid/home) flows are controlled through SEP2 DER control events, with safety limits defined in the DER capability resource.

What ride-through requirements apply to PEVs?

Section 4.12 and 4.13 specify voltage and frequency ride-through curves. The PEV must remain connected and operational during certain disturbances (e.g., voltage sags or frequency deviations) for specified durations, similar to other grid-connected DERs. This ensures grid stability and prevents unintentional islanding.

Do I need to implement SEP2 as a client or server?

It depends on the use case. In V2G scenarios, the EVSE typically acts as the SEP2 server and the PEV as the client. However, the architecture supports both roles; refer to Section 4.1 for boundary diagrams and specific assignment in AC V2G/V2H configurations.

By understanding the core communication framework, design insights, and common pitfalls, engineers can effectively implement SAE J2847/3-2023 in their products and contribute to a more resilient and interactive grid.