Three-phase AC system impedance measurement unit (IMU) using chirp signal injection

Impedance defined in synchronous coordinates is a useful tool to predict and evaluate stability of three-phase AC systems. For online impedance measurement in AC systems, the widely used frequency sweep method takes a long time and may not be practical in systems where the operating point cannot be maintained for a long time. A wide bandwidth signal could be used to significantly reduce the measurement time. This paper suggests a chirp signal and describes its advantages over other signals. Experimental results demonstrate the effectiveness of this approach.