Study On Low Voltage Operational Performance And Its Test Method For Hvdc Thyristor Valve

High Voltage Direct Current (HVDC) has been used widely in the field of long distance bulk capacitance transmission, submarine cable transmission and asynchronous interconnection of power system. Presently, our country is the largest one at HVDC and plan to further construct 25 projects including 15 Ultra HVDC (UHVDC) projects until 2020Thyristor valve is one of the heart equipments of HVDC. Its operational performance, which must be checked by rigorous test, must be studied thoroughly in order to ensure safe reliable and stable operation. Based on the project "study on the equivalency principle of HVDC thyristor valve operational test method" supported by National Natural Science Foundation of China, the study was done from the following aspects:1) By analyzing the operational conditions of HVDC valve, this thesis classifies the operation into two categories: one is high voltage operation; the other is low voltage operation. And accordingly the operational test is also classified into two categories: high voltage operational test and low voltage operational test. The necessity of the study on low voltage operational performance and its test method is pointed.2) Low voltage operational performance is studied. The turn on transient and the energy storage performance of the valve electronic circuit under low voltage operation is analyzed. The influence on the low voltage operational performance induced by the stored charge spreading is analyzed, deducing the relation between stored charge spreading and valve minimum firing voltage and minimum extinction angle, getting significant results for valve design. The forward recovery process of thyristor is illustrated in mechanism.3) On the basis of low voltage operational performance study, the test method for low voltage operational test is studied according to the test requirement. The requirement for low voltage operational test circuit is put forward; Evaluation of the synthetic test circuits is made by analyzing the low voltage operational test of existing circuits. A new topology used for the low voltage operational test is advanced and simulations are done to validate this topology.