Innovative mitigation measures for electrostatic charge build-up on surfaces of dry-type air-core reactors for HVDC application

摘要

Equipment installed in the d.c. yards of HVDC converter stations is subject to the electrostatic charge build-up phenomenon. This can result in pollution accumulation on the surfaces of the high voltage equipment operating at high d.c. potential. The charge build-up on the reactor surface may cause discharges across the surface and through the encapsulation of the winding packages. In case of dry-type air-core HVDC reactors the observed pollution build-up takes the form of an irregular pattern of varying sized black spots. In order to mitigate discharges the following precautions can be taken. A proven mitigation technique is to apply a dissipative plastic film on the outer surface of the reactor in order to drain off the charges to the winding ends of the reactor. Another innovative mitigation method is to apply a dissipative coating directly to the reactor surface by using a sprayable varnish.