Validation of a Robust Cyber Shield for a Grid Connected PV Inverter System via Digital Watermarking Principle

In this paper, validation of a Robust Cyber Shield (RCS) for a grid connected inverter is presented. This paper specifically address the problem of attacks on sensor measurements. When incorrect sensor measurements are used in feedback control loops of the inverter controls, it can lead to incorrect actuation that can cause instabilities or degrade performance. The Robust Cyber Shield (RCS) approach consists of a a defense mechanism termed as dynamic watermarking to detect malicious manipulation of voltage/current sensor measurements feeding inverter control. To prove that the proposed attack detector will not be triggered when there are disturbances present in the grid, such as low-order harmonics, the detector is tested under different conditions on the grid voltage. To test the validity of the proposed approach, a testing platform is developed with a laboratory scale experiment to obtain Hardware results using a real inverter. Simulation results from a grid connected inverter system are also discussed.