Analysis of test circuits for evaluating HVDC cables

The authors analyze the different test circuits suitable for producing in the laboratory the combined stresses required for testing of high-voltage cables. Although the construction of DC cables is similar to that of AC cables, their design has to meet specific requirements which are unique to their operating conditions. Of particular concern is the polarity reversal of the voltage caused either by a change in the direction of the power flow, or by a transient voltage of opposite polarity. Line-to-ground faults and converter malfunctioning can also impose an AC component on the DC voltage. Special emphasis is placed on the case of transient polarity reversal, particularly on the selection of the coupling element and its influence on the combined test voltage produced