Industrial IIoT Edge Gateway for Smart Grid

Description

We monitor medium-voltage distribution equipment across roughly 140 substation sites, most of them unmanned, several on connections that drop for hours at a time. The build is an edge gateway on Raspberry Pi hardware: collect telemetry locally, buffer it while the link is down, and forward over MQTT when it returns without losing or duplicating readings. Node-RED is acceptable for the flow logic — our field engineers can read it, which matters more to us than elegance. Physical security is limited at these sites. Assume a gateway can be stolen and design so that a device in someone else's hands cannot be used to reach the rest of the estate.

• Build the edge collection and store-and-forward pipeline with exactly-once delivery semantics
• Configure the MQTT broker and topic structure for 140 sites with per-device credentials
• Design for device compromise: scoped credentials, revocation, and no lateral access
• Handle multi-hour outages with bounded local storage and a defined drop policy when it fills
• Provide remote update for the gateway fleet that cannot brick an unmanned site

• Edge gateway image and deployment process for the Raspberry Pi fleet
• MQTT broker configuration with per-device credentials and revocation
• Store-and-forward with tested outage recovery
• Fleet update mechanism with rollback, and a field deployment guide