Sunspec Modbus Based Smart Inverter Cyber-Attack Modeling and Mitigation Scheme

The recent amendment to the IEEE 1547 standard enables smart inverters to support grid functions like Volt-VAR/Watt and frequency Watt control, which necessitates communication between smart inverters and a microgrid central communication controller. The IEEE 1547 standard recommends this communication through Sunspec Modbus protocol. However, this standardization of communication protocol increases vulnerability to cyber-attacks. Sunspec Modbus, lacking built-in security measures, exacerbates this risk by further expanding the potential attack surface within microgrids. To determine the cyber-attack path in smart inverters, a comprehensive cyber-attack model for exploiting the cybersecurity limitations in Sunspec Modbus protocol is developed. A real-time high-fidelity cyber-physical energy system (CPES) testbed is developed to assess the impact of cyber-attacks on smart inverter control. Finally, to mitigate these cyber-attacks, a novel lightweight cybersecurity scheme based on Blake-2 s and AES-256 algorithm for the Sunspec Modbus protocol is proposed. The effectiveness of the proposed security scheme to mitigate the cyber-attacks is evaluated on the developed CPES testbed. Due to the lightweight feature of both algorithms, the proposed scheme is found to be suitable for low computation platforms, such as smart inverters.