Modelling arcing high impedances faults in relation to the physical processes in the electric arc

There is an increasing demand for more detailed and accurate modelling techniques for predicting transient response of power systems caused in particular by high impedance arcing faults (HIF). This is particularly so in relation to the design and development of improved equipment and new protection techniques. Accurate prediction of fault transients requires detailed and comprehensive representation of all components in a system, while the transient studies need to be conducted into the frequency range well above the normal power frequency. The HIF is a very complex phenomenon and exhibits very high nonlinear behaviour. The most distinctive characteristics are nonlinearity and asymmetry. The nonlinearity arises from the fact that the voltage-current characteristic curve of the HIF is itself nonlinear. It is observed that the fault current has different waveforms for positive and negative half cycles which is called asymmetry. The nonlinearity and asymmetry exist in every cycle after HIF. In order to obtain a model for a HIF, it is necessary to develop a model that gives the above mentioned characteristics, as well as the harmonic content of the HIF