Multiagent System-Based Wide-Area Protection and Control Scheme Against Cascading Events In this paper, a multiagent system-based wide-area protection and control scheme is proposed to deal with the long-term voltage instability-induced cascading trips. Based on sensitivity analysis between the relay operation margin and power system state variables, an optimal emergency control strategy is defined to adjust the emergency states timely and prevent the unexpected relay trips. In order to supervise the control process and further minimize the load loss, an agent-based process control is adopted to monitor the states of distributed controllers and adjust the emergency control strategy. A hybrid simulation platform based on LabVIEW and real-time digital simulator is set up to simulate a blackout case in the power system of Eastern Denmark and to demonstrate the effectiveness of the proposed MAS-based protection strategy.