Investigation of ferroresonance in a high voltage network - measurement and numerical simulation

Summary

The operation of high voltage distribution and transmission systems is disturbed through the well-known disturbances of internal and external failures. Depending on the network structure and in case of switching operations or failures, resonance phenomena can occur and furthermore a ferroresonance condition may be triggered. To investigate this behaviour of ferroresonance, the described scientific investigations were divided into two parts. In the first part, field measurements were carried out in an Austrian 380 kV / 110 kV substation. For the measurement of switching operations suitable high voltage dividers were installed next to the power transformer. The line-to-ground voltage during the switching operations was recorded with a digital transient recorder. Basically the transformer energisation is controlled by point-on-wave switching device to avoid high inrush currents. During the field experiments, measurements with and without point-on-wave switching device were performed. The deactivated point-on-wave switching device leads to the expected ferroresonance oscillations in the system with high inrush currents, which could be measured in high quality. The second part of these investigations are focused on the modelling and on numerical calculations of the ferroresonance phenomena in general and in detail based on the substation configuration. Based on the field measurements and the numerical investigations, the behaviour of ferroresonance in the given network structure has been investigated during the switching operation of the power transformer. A large number of numerical simulations by varying parameters of the system had to be performed to trigger resonance circuits and to identify critical situations. With the results of this work it will be possible to find boundary conditions for the numerical simulation to trigger ferroresonance oscillations and to investigate countermeasures to avoid them in networks. Finally, these work leads to a better understanding of the occurrence of the ferroresonance phenomena in the 380 kV / 110 kV substation and adds recommendations for the operation team of substations.

Additional informations

Authors

HAN, ZHOU, KUMM

Keywords

Field measurements, numerical simulations, ferroresonance, switching operation