Maloperation analysis and suggested countermeasures for inter-turn protection of high-voltage shunt reactors in offshore wind power transmission

Abstract

Misoperation of the inter-turn protection of high voltage shunt reactors （HVSRs） frequently occurs in submarine cables for offshore wind power transmission during conventional opening and closing operations. The misoperation scenarios are analyzed， and corresponding countermeasures are put forward. Firstly， the inter-turn protection principles of different manufacturers are compared， and the misoperation processes under different operation scenarios are examined. Secondly， it is concluded that the core saturation generates a zero-sequence source during closing. The decreased measured impedance due to the increased current amplitude during resonance results in protection misoperation. Thirdly， the waveforms recorded in the field operation scenario are reproduced via simulation to verify the correctness of the theoretical analysis. Finally， it is suggested to adopt misoperation countermeasures， such as increasing the zero-sequence inrush current harmonic blocking criteria， resonant frequency identification criteria， and opening the switch on the high-reactance side and closing it afterward during operation.

Keywords

• high-voltage shunt reactor
• inter-turn protection
• core saturation
• lc resonance