Long term performance verification of high voltage DC GIS

Abstract

In order to determine feasibility of SF/sub 6/ gas insulated equipment for HVDC substation technology, a testpole was built and subjected to a long term test of 2 years. The test pole consisted of slightly modified commercially available 550 kV AC and 800 kV AC gas insulated components. The components were SF/sub 6/-air bushings, an air insulated arrester, a SF/sub 6/ insulated arrester, a SF/sub 6/ oil bushing, disconnecters, bus ducts and conical spacers. Testing involved continuous DC stress (500 kV and 600 kV) lightning and switching impulse tests, polarity reversal tests and ultrasonic partial discharge measurements. Thermal cycling was performed during de load and went uninterrupted for more than 1 year. No internal breakdowns occurred during any tests. Visual inspection of the spacers at various times during tests and final disassembly revealed no visible flashover traces. The testing has demonstrated that the gas insulated technology is well suited for commercial HVDC applications.