Superimposed Voltage Testing of HVDC Equipment with Oscillating Impulse Voltage

Superimposed voltage testing with oscillating impulse voltage offers many advantages for long-term testing of large test assemblies. The contribution will show how superimposed voltage testing with OLI/OSI voltages can be realized in high voltage laboratories and discuss superimposed OLI/OSI testing using spark gaps as coupling elements. Laboratory results have shown that with the help of spark gaps superposition of OLI/OSI voltage can be realized more easily than it is the case for conventional standard LI and SI voltage. Certain effects are observed at superimposed OLI/OSI testing. They influence amplitude and shape of the test voltage and thus have to be considered for generator design and during testing. Experimental laboratory results as well as simulations elaborate the effects.