Line impedance estimation using model based identification technique

The estimation of the line impedance can be used by the control of numerous grid-connected systems, such as active filters, islanding detection techniques, non-linear current controllers, detection of the on/off grid operation mode. Therefore, estimating the line impedance can add extra functions into the operation of the grid-connected power converters. This paper describes a quasi passive method for estimating the line impedance of the distribution electricity network. The method uses the model based identification technique to obtain the resistive and inductive parts of the line impedance. The quasi-passive behaviour of the proposed method comes from the combination of the non intrusive behaviour of the passive methods with a better accuracy of the active methods. The simulation results reveal the good accuracy of the proposed method.