An Edge Intelligent Device for Advanced Monitoring and Control of DER Inverters in a High Penetration Distribution System

As the electric power grid is brought up to date with state-of-the-art devices connected to the internet, pertinent information needs to reliably make its way from the edge to the cloud for system operators to visualize grid health. Conversely, control commands also need to be sent from the cloud to individual devices on the grid in order to maintain grid stability and safety, especially during unbalanced cases. This paper presents an affordable, brand-agnostic solution to grid data aggregation and communication using off-the-shelf products pieced together with IEC 61131–3 open source language for Programmable Logic Controllers (PLCs). A Phoenix Contact PLC along with some ancillary devices used to provide wireless communication capabilities were used to build an Edge Intelligent Device (EID) which interfaces with edge devices like solar inverters using Modbus protocol and the cloud using MQTT with an LTE backend for internet connection. The advantage of the EID over other similar devices is affordability and it is highly customizable. The EID was tested in both simulated and real-world applications: over 750 solar inverters were simulated in OPAL-RT and their data were transmitted to the cloud and visualized with Grafana in intervals under 30 seconds; data from a field testbed generating real data from solar panels and inverters, as well as another inverter built in-house powered by a grid simulator, was also transmitted through the EID. The paper will describe how the EID was built and coded, how the test beds were created, and show the results in Grafana.