Damping capacitor is a key element in HVDC converter valve

which can realize dynamic and static voltage sharing of thyristors in such different states as on and off

absorb over-voltage at valve end

reduce the requirement of parameter consistency of thyristors and make series application of different thyristors with different parameters possible. The damping capacitor adopts self-healing capacitor

the self-healing phenomenon occurs continuously

and the tangent of loss angle increases continuously while the capacitance value decreases continuously. With the increase of service life

the damping capacitor ages until failure

which leads to such serious consequences as uneven voltage sharing of valve string

overload of elements and even damage of valve body. In this paper

by studying the aging mechanism of resistive-capacitive capacitor of the converter valve

the accelerated aging test scheme of damping capacitor of converter valve and suggestions for processing test data are proposed. Under the premise of not changing the failure mechanism and not adding new failure factors

the test stress（voltage and temperature）is increased to accelerate the failure process of the sample. Then

the undetermined parameters to be determined in the life model is determined in accordance with the test data

and thereby the expected service life of the sample under the actual service stress is estimated.