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AC filter is an important part of converter station. In the actual operation of AC filter capacitors, the filter trips frequently due to the change of capacitors value, which seriously affects the safe operation of DC system. In this paper, 24 filter capacitors returned from ± 800kV Suidong converter station have been tested and analyzed for electrical parameters measurement, anatomy analysis and insulating oil analysis. The causes of capacitor failure are analyzed, and relevant operation and maintenance countermeasures are put forward. The results show that the breakdown points are all located at the edge of the electric field concentration, the internal discharge fault has a great impact on the capacitance of the capacitors, and frequent over-voltage is one of the possible causes of the internal discharge of the capacitors. In the actual operation and maintenance, the frequency of the filter tripping due to the unbalance of the capacitors bank can be reduced by means of regularly detecting and balancing the capacitance values, properly adjusting the protection setting values and strengthening the equipotential wiring of the capacitors.
Inspec keywords: power transmission faults; power capacitors; fault diagnosis; HVDC power convertors; power filters; HVDC power transmission
Subjects: d.c. transmission; Other power apparatus and electric machines; DC-AC power convertors (invertors); Power filters; AC-DC power convertors (rectifiers)