A Novel Electrothermal Combined Aging Test System for High-Power Thyristor in the Converter Valve of HVDC Power Transmission

Thyristor converter valve is the core equipment of HVDC power transmission system, and its operation reliability is directly related to the safety and stability of the HVDC power grid. Under the Operating conditions of high current and strong electromagnetism, some thyristors are prone to develop the performance degradation, device damage, breakdown or other problems, which lead to commutation failure, chain breakdown and other serious faults of converter valves. Therefore, in order to deeply understand the degradation law and aging mechanism of characteristic parameters during the aging process of the converter valve thyristor, it is first necessary to build a thyristor aging test device that simulates the operation process of the converter valve required for the test. The paper first analyzes the actual operating conditions of the thyristor of the converter valve, and designs the main circuit of the thyristor's electric and heating combined aging based on this, and then designs and builds the control units involved in the circuit, including the driving circuit of the IGBT and the trigger circuit of the thyristor, and the thyristor junction temperature control system is designed based on the actual operating conditions of the thyristor. In order to obtain the degradation law of characteristic parameters in the aging process of thyristor, an online monitoring system for thyristor leakage current and an offline measurement system for reverse recovery are designed. It's found that each module and the main circuit can maintain long-term stable operation based on the inspection and test, which has laid a good foundation for the aging test of the high-power thyristor.