Converter and control design for very low-frequency high-voltage test systems

With the rapid growth in energy generation supplied by regenerative and decentralized sources the supplying cabling grid is increasing. Therefore, a large demand on mobile high-voltage cable test systems results in the coming years. This paper deals with the development of a LCC resonant converter-based power supply scheme and the control strategy for generating an 85 kV (RMS) sinusoidal test voltage at very low frequency of 0.1 Hz. The resonant converter is designed based on steady state AC analysis and verified through simulation and experiments based on a prototyping system. In order to substitute voluminous and costly sensors in high-voltage circuitry a novel cascaded control strategy using an observer is developed. The control strategy is implemented and verified by experimental tests.