Frequency domain investigation of switching transients in Offshore Wind Farms

Soloot, Amir Hayati; Høidalen, Hans Kristian; Gustavsen, Bjørn

doi:10.1109/ptc.2011.6019358

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…RC filters and arresters are applied to protect the transformers from overvoltages. The critical cable length for the 300 kVA transformer is 23 m with α = 1, corresponding to f s = f dr = 2 MHz.…”

Section: Simulation Resultsmentioning

confidence: 99%

Resonant overvoltage assessment in offshore wind farms via a parametric black-box wind turbine transformer model

2014

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The protection of offshore wind farms (OWFs) against overvoltages, especially resonant overvoltage, is of paramount importance because of poor accessibility and high repair costs. In this paper, we study how switching overvoltages at the wind turbine transformer (WTT) medium voltage (MV) side can lead to high overvoltages on the low voltage (LV) side. The effect of overvoltage protective devices is analyzed. A detailed model of an OWF row is developed in electromagnetic transients program–alternative transients program (EMTP‐ATP), including interconnecting cables, WTT, surge arresters and resistive–capacitive filters. A parameterized black‐box WTT model is obtained from measurements and is used for investigating the transfer of resonant overvoltages from the MV to the LV side. The model is capable of shifting systematically the frequencies and adjusting the transformer input impedance. Simulation results show that wind turbine energization in an OWF can lead to overvoltages on the LV terminals. The rate of rise of overvoltages (du/dt) is in the range of 300–500 pu/µs. It is found that resistive–capacitive filters should be installed on both MV and LV terminals of WTTs to decrease both resonant overvoltages and du/dt, which is unachievable by surge arrester alone. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Simulation Resultsmentioning

confidence: 99%

Resonant overvoltage assessment in offshore wind farms via a parametric black-box wind turbine transformer model

2014

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“…For example, tap 2 ,which is close to top yoke, has high transferred voltage at resonant frequencies; 97, 161, 213, 276, 361 and 393 kHz compared to the transferred voltages at f < 97 kHz. The energization of the transformer with short cables, e. g. wind turbine energizations, can lead to internal resonant overvoltages at this weak point, located near to LV terminal, if the quarter wave frequency of the cable matches with 680 kHz [17]. The overvoltage can also occur during earth fault [18] at short cable distance.…”

Section: Transferred Voltage To the LV Windingmentioning

confidence: 99%

“…Resonant overvoltage at the LV terminal of offshore wind farms can occur both due to energization transients [15][16][17] and close-up short circuits [18]. They can be mitigated by Resistive-Capacitive (RC) filters.…”

Section: Introductionmentioning

confidence: 99%

Influence of the winding design of wind turbine transformers for resonant overvoltage vulnerability

Soloot

Høidalen

Gustavsen

2015

IEEE Trans. Dielect. Electr. Insul.

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Switching transients and earth faults may lead to resonant overvoltages at wind turbine transformer terminals as well as inside High Voltage (HV) and Low Voltage (LV) windings. The winding design in a transformer could strongly influence the internal voltage distribution as function of frequency, and this has a great impact on risk of insulation failure. In this paper, resonant overvoltages in three winding designs; layer, disc and pancake, are investigated and analyzed for the application in offshore wind farm. To achieve this, a prototype 500 kVA transformer with the three winding types on the HV side and taps for voltage measurements is designed and produced. The measurements show that a HV winding of layer type gives the highest transferred voltage to the LV terminal and that this happens at 1.6 MHz which could be excited for close-up earth faults. Although disc winding seems the least vulnerable when measuring the transferred voltage to the LV terminal, it has higher potential of internal resonances in the HV winding compared to the two other types both voltage-to-ground and voltage drops. Pancake and layer windings have less vulnerability in the case of internal resonances. Pancake windings have modular design characteristic. This advantage eases the repair for offshore wind applications.

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The Assessment of Overvoltage Protection Within Energization of Offshore Wind Farms

2012

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Frequency domain investigation of switching transients in Offshore Wind Farms

Cited by 5 publications

References 11 publications

Resonant overvoltage assessment in offshore wind farms via a parametric black-box wind turbine transformer model

Resonant overvoltage assessment in offshore wind farms via a parametric black-box wind turbine transformer model

Influence of the winding design of wind turbine transformers for resonant overvoltage vulnerability

The Assessment of Overvoltage Protection Within Energization of Offshore Wind Farms

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