Enhancing OpenFMB Security Through a Gatekeeper for Smart Microgrids

Abstract

Open Field Message Bus (OpenFMB) provides interoperability, communication, and control among heterogeneous devices in microgrids. However, interoperability and message validity do not guarantee operationally safe control, since a correctly formatted, legitimate command may still violate safety constraints imposed by the microgrid’s current operating state. This paper presents an OpenFMB Gatekeeper that acts as an operational safety layer between control applications and physical devices. The Gatekeeper intercepts control messages, validates their structure and operational parameters against configurable safety policies, dynamically resolves target identifiers, and forwards only validated commands to the corresponding OpenFMB adapters. The architecture follows a default-deny principle, such that control commands cannot reach the physical actuation path when validation is unavailable. The proposed solution was implemented and experimentally evaluated in the Universidad de Antioquia’s photovoltaic-based smart microgrid. Functional experiments showed that the Gatekeeper rejected 100% of the evaluated malformed, incomplete, unsupported, and out-of-policy commands while allowing valid control commands to proceed. Performance experiments under manual operation and using synthetic loads showed that Gatekeeper processing remained within accepted intervals, while end-to-end median latency remained stable across the evaluated scenarios. These results show that a mandatory operational safety checkpoint can prevent unsafe control actions from reaching physical assets while remaining within microgrid control timing requirements.