Self-Secure Inverters Against Malicious Setpoints
Tareq Hossen, Fahmid Sadeque, Mehmetcan Gursoy, Behrooz Mirafzal
Abstract
The next generation of grid-interactive inverters is a cyber-physical device, which can receive setpoints in real-time from a utility operator or a third-party aggregator. This feature enhances the controllability of grid-interactive inverters to provide services beyond just pumping power to the grid. Being a cyber-physical device makes an inverter vulnerable to cyberattacks. In this paper, a model/knowledge-based technique is proposed for developing self-secure smart inverters. The reference model/knowledge is built based on the normal operating region of the inverter and its reduced-order dynamic model. The inverter can autonomously examine the incoming setpoints before engaging them to the local controller. The inverter must learn about the input and output circuits to determine its normal operating region through estimating system parameters. The estimation of the grid parameters is accomplished by injecting current at a different frequency than the power frequency. In this paper, the feasibility of realizing self-secure inverters is examined using a laboratory setup including a Powerflex 755 three-phase inverter and a 12 kW NHR 9410 power grid emulator. The results confirm that inverters can be programmed to autonomously accept or reject the incoming commands and protect themselves from malicious setpoints.