High voltage capacitor ground fault

The grounding fault of high voltage capacitor has great influence on the stable operation of dc transmission system, and the protection method of dc filter high voltage capacitor grounding fault has some problems, such as poor selectivity, low sensitivity and difficulty in setting the fixed value. Learn about these questions and read on!

1) poor selectivity. On high voltage capacitor when earthing fault occurring at different position, protect the acquisition of the current difference is very big, in the same point of failure in different system operation conditions, there exist great differences in the current size, differential protection and grounding protection can not distinguish between high voltage capacitor ground fault location and severity of selectivity of protection operation cannot be guaranteed.

2) low sensitivity. In some cases, the high voltage capacitor has an earth fault, and the differential current and unbalanced current are very small, which cannot meet the protection operating conditions.

3) it is difficult to set the value. High voltage capacitor ground fault protection need to choose according to severity fault alarm or trip, uhv engineering on the use of grounding protection fixed value setting is completed by means of engineering dynamic simulation test, this approach fails to cover all system operation condition, setting the fixed value has a certain randomness, and consume a large amount of manpower.