Sammendrag
Switching transient as one of the main transient phenomena in power systems
have been simulated and measured in many studies. Since offshore wind farms have
been integrated to power system only in recent years, the consequences of switching
phenomena in offshore wind farms have not yet been thoroughly analyzed. This paper
contributes to the topic by a study on overvoltages using a high-frequency model of the
wind turbine transformers (WTTs).
The WTTs are represented by a black-box high-frequency model obtained from
measurements and represented by an equivalent RLC network for inclusion in ATPEMTP.
The model represents a 300 kVA 11.0/0.230 kV transformer.
The resonance frequencies observed at the Low Voltage (LV) and High Voltage (HV)
terminals of the transformer are found by voltage ratio and impedance matrix simulations
using the derived high frequency transformer model. The simulation results indicate that
the dominant resonance frequency of this transformer in terms of voltage ratio from the
HV side to the LV side appears at 2 MHz.
In energization of a wind turbine, the critical cable length leading to transformer
resonance overvoltages and the impact of surge arresters on LV and HV are investigated.
The simulation results indicate that the LV surge arrester have prominent role in limiting
the resonance overvoltages although the ground lead inductances some how decrease
the effect of surge arresters.
have been simulated and measured in many studies. Since offshore wind farms have
been integrated to power system only in recent years, the consequences of switching
phenomena in offshore wind farms have not yet been thoroughly analyzed. This paper
contributes to the topic by a study on overvoltages using a high-frequency model of the
wind turbine transformers (WTTs).
The WTTs are represented by a black-box high-frequency model obtained from
measurements and represented by an equivalent RLC network for inclusion in ATPEMTP.
The model represents a 300 kVA 11.0/0.230 kV transformer.
The resonance frequencies observed at the Low Voltage (LV) and High Voltage (HV)
terminals of the transformer are found by voltage ratio and impedance matrix simulations
using the derived high frequency transformer model. The simulation results indicate that
the dominant resonance frequency of this transformer in terms of voltage ratio from the
HV side to the LV side appears at 2 MHz.
In energization of a wind turbine, the critical cable length leading to transformer
resonance overvoltages and the impact of surge arresters on LV and HV are investigated.
The simulation results indicate that the LV surge arrester have prominent role in limiting
the resonance overvoltages although the ground lead inductances some how decrease
the effect of surge arresters.