Online tracking of power system impedance parameters and field experiences

The Thevenin impedance seen at a load bus is an important parameter for power system planning and operation. This paper presents a new algorithm to track the impedance parameters online. The algorithm uses the natural variations of loads connected to substations for impedance estimation. It neither depends on the load model nor requires synchronized measurements. The input data are several seconds of voltage and current waveform data. Such data are readily available from substation power monitors. Simulations, experiments and field test results show that the proposed algorithm can be used for online monitoring of power system impedance parameters.