System impedance measurement for use with active filter control

This paper describes a method for on-line measurement of power system impedance to source. The method employs a power electronic circuit to inject a small current disturbance onto the energised power network, and the measurements of the disturbance current and resultant voltage transient are used to identity impedance. Simulation results demonstrate the effectiveness of the technique for identification of the impedance of transmission lines and linear loads. An alternative data processing technique is introduced in order to address the measurement problems associated with nonlinear loads. This technique is also illustrated using simulation