Modeling and Assessment of Cyber Attacks Targeting Converter-Driven Stability of Power Grids With PMSG-Based Wind Farms

In a grid with PMSG-based wind farms, a lack of system strength can cause severe converter-driven instability issues, such as subsynchronous oscillation (SSO). Cyber adversaries can target the wind farm by maliciously changing the system strength observed from the power grid, triggering SSO, and further causing power outages and equipment damage. To understand the threat, this paper proposes a new model of cyber attacks targeting the system strength. Considering the common mitigations required by the operator's regulations, this paper demonstrates that the proposed attack model can trigger rapid SSO propagation by (i) simultaneously compromising the system strength provision for multiple wind farms or (ii) directly disrupting local system strength mitigation. Based on the developed attacks, this paper also presents an anomalous command verification (ACV) module incorporating a novel converter-driven stability assessment. The ACV module is designed to estimate the system strength buffer capacity in response to malicious tripping commands and indicate how close the system is to converter-driven instability. The impacts of attack-triggered SSOs are demonstrated by electromagnetic transient (EMT) simulations on the New England 39-bus system. The considered case studies validate the effectiveness of the proposed converter-driven stability assessment to detect malicious commands targeting the SSO in a timely manner.