Development Of 600kV High Voltage Solid-state Switch

The 500kV cable requires 600kV voltage for Damped AC Voltage(DAC)test.However,the current maximum output voltage of the DAC device is only 400kV,which cannot meet the test requirements.The high-voltage solid-state switch is not only the core component of the DAC device,but also the basis for the development of the DAC devices.In this paper,the development of a 600kV high-voltage solid-state switch was carried out with the light-triggering thyristor as the basic component.The main work is as follows:(1)Different switch structures were designed.The COMSOL simulation software modeled the switch and performed DC steady-state electric field calculation.The advantages and disadvantages of each structure were compared,and the optimal switch structure was proposed.(2)The electrical performance of the solid-state switch that has been built was tested.Through the withstand voltage test,the insulation condition of the switch under the maximum working field strength was checked,and the possible corona discharge source was analyzed,and the suppression measures were taken;the conduction continuity test was used to verify the opening continuity of the switch under the working voltage;(3)Modeling research on switch structure and reliability was carried out.Based on the Markov model,the switch was divided into three modules,and the switch reliability model was established according to the functional relationship between each module to guide its reliability distribution and estimation.The reliability index of the switch was calculated by fuzzy hierarchy method.Through the above research work,the following main conclusions are obtained:(1)The field strength simulation calculation showed that the "spiral stacking type"was better than the "direct series type'",and the "3x4 type" structure was optimal,and the maximum field strength could be limited to 1.54×103kV/m,which was in line with the engineering.(2)The electrical performance test results showed that the single-stage structure had the highest withstand voltage of 7.5kV,and the oscillation waveform did not produce distortion during the synchronous conduction process under the maximum working field strength,and there was no disturbance that affects the partial discharge measurement;(3)The calculation results of fuzzy hierarchy method showed that the failure efficiencies assigned by the three modules of the thyristor connection body,the drive system and the control system were respectively 1.606×10-4/h?1.247×10-4/h and 1.147×10-4/h.And the average time between failures of the switch was 5659h,which met the design requirements.