Validation techniques of network harmonic models based on switching of a series linear component and measuring resultant harmonic increments

In this paper two methods of validation of transmission network harmonic models are introduced. The methods were developed as a result of the work presented in W. Wiechowski (2006). The first method allows calculating the transfer harmonic impedance between two nodes of a network. Switching a linear, series network component that links the nodes causes a variation of the background harmonic voltage distortion at the nodes. Harmonic current in the series element is measured together with the harmonic voltages at both nodes, before and after the switching. Obtained incremental values of harmonic voltages and the current are used for calculation of the transfer harmonic impedance between the nodes. The determined transfer harmonic impedance can be used to validate a computer model of the network. The second method is an extension of the first one. It allows switching a series element that contains a shunt branch, as for example a transmission line. Both methods require that harmonic measurements performed at two ends of the disconnected element are precisely synchronized.