To improve the damping of a multimachine power system, a static VAR compensator (SVC) equipped with a supplementary feedback controller is proposed. In the design of the supplementary feedback controller, a fixed‐gain proportional‐integral (PI) controller is first investigated. To further improve system dynamic performance, two types of adaptive controllers, i.e., pole‐shifting self‐tuning controllers and self‐tuning PID controllers are developed. The effectiveness of the presented adaptive control schemes is demonstrated by time domain simulation of the multimachine system subject to a three‐phase fault. It is found that both self‐tuning controllers can yield much better dynamic responses than the fixed‐gain feedback controllers under disturbance conditions.