The use of wide-area measurements for power system stabilization has recently been given a lot of attention by researchers and the power industry to avoid cascading failures and blackouts, such as the one in North America in August 2003. This paper presents the design of a nonlinear external damping controller based on wide-area measurements as inputs to a single dual-function neuron (DFN)-based controller. This DFN controller is specifically designed to enhance the damping characteristics of a power system over a wide range of operating conditions using an existing static var compensator (SVC) installation. The major advantage of the DFN controller is that it is simple in structure with less development time and hardware requirements for real-time implementation. The DFN controller presented in this paper is realized on a digital signal processor and its performance is evaluated on the 12-bus flexible ac transmission system benchmark test power system implemented on a real-time platform-the real-time digital simulator. Experimental results show that the DFN controller provides better damping than a conventional linear external controller and requires less SVC reactive power. The damping performance of the DFN controller is also illustrated using transient energy calculations