Modern thyristor valves for HVDC are of high power rating and difficult to be tested in a conventional back-to-back test circuit.The application of some equivalent test circuits significantly reduces the size of test facilities

but the test equivalence of those test circuits is worth to be discussed.The core to evaluate the equivalence of those test circuits is whether it can reproduce the stress applied on the valves correctly.Three types of test circuits are introduced in this paper

periodic firing and extinction test have been carried out based on EMTP/ATP simulation.The simulation result verifies that the ABB synthetic test circuit is more flexible in setting test condition and more accurate in reproducing the stress applied on the valves.