A wide bandwidth, on-line impedance measurement method for power systems, based On PLC techniques

On-line impedance measurement is a useful tool to monitor the state, health and characteristics of electrical networks in power systems. This paper proposes a method for on-line, wide-bandwidth, impedance analysis of devices used in power networks. This method uses a signal generator to inject other than mains frequency signals on-line and then measuring current and voltages to determine the impedance at the injected frequencies. Two measurement circuits based on different types of current and voltage measurement methods are discussed. Their experimental results of impedance measurement are shown. This paper also suggested some possible applications of this on-line impedance analysis method in condition monitoring of power distribution transformers and electrical machines.