This paper presents the technical design and test requirements of the gas-insulated voltage dividers as an integral part of HVDC gas-insulated systems. In developing and executing these dielectric tests for gas-insulated HVDC systems, a major focus has been on the electric withstand of all related equipment, especially considering the perspective of the intrinsic difference between AC and DC. This paper describes the test procedure for superimposing DC voltages with lightning and switching impulse voltages, designated as composite voltages. The standard IEC 61869-15, relevant for HVDC voltage dividers, does not cover this new composite voltage test procedure. The impact on the divider is pointed out and described. Besides the standard DC voltage measurement, the measurement results show high precision performance on harmonic voltage signals from 15 Hz up to 30 kHz. Through the use of step response testing, it is shown that RC-dividers can perform transient voltage measurements with good precision. In the case of fast transient voltages with lightning impulse characteristics in substations or test laboratories, the so-called standard RC-divider has its limitations. An alternative, and more precise measuring solution, is to use a multipurpose divider, known as an RCR-divider. Such dividers provide application bandwidths from DC to 30 kHz up to transient voltages with high accuracy performance. We discuss the technical, electrical, and mechanical design solutions of the RCR-divider build for the same HVDC GIS system. In the paper, we present test results and corresponding voltage curves from a research project at the Universität Dresden in Germany. For this, a special GIS test bay was installed and adapted to the main research topic. Results and experience gained with lightning impulse, and switching impulse voltages superimposed on the DC voltage, are shown.
Besides the standard measurement and protection applications, various monitoring applications can be performed in parallel. This monitoring aspect is becoming increasingly important. Due to the ongoing trends in substation digitalization, together with the increasing complexity of the grid topology, a
wideband measurement capability with a holistic view has deep value, not only for the purpose of protection and equipment supervision but also for control and maintenance actions.