±1100kV特高压直流换流阀饱和电抗器样机的失效模式与加速寿命试验方法

Fault Mode Analysis and Accelerated Life Test Method of the Saturable Reactor Prototype for ±1100 kV UHVDC Converter Valves

饱和电抗器是保护晶闸管的重要设备,其失效将威胁换流阀的安全运行。为提高特高压直流换流阀的可靠性,必须研究饱和电抗器的失效模式及其平均使用寿命。首先,研究了特高压直流换流阀饱和电抗器在额定运行工况下承受的电气和热应力;然后,分析了饱和电抗器在各种应力条件下的失效模式,并且找出了决定饱和电抗器失效的主要应力形式和部件;最后,基于环氧树脂的热加速寿命试验预计了饱和电抗器的平均使用寿命。结果表明:环氧树脂是饱和电抗器的薄弱环节,铁芯发热造成环氧树脂的温升是限制饱和电抗器寿命的主要因素;±1 100 k V换流阀饱和电抗器的平均使用寿命约为48 a,满足国家电网公司对饱和电抗器产品的可靠性要求。

Saturable reactor is a key device for thyristor protection, and its fault will threaten the safe operation of the converter valves. To improve the reliability of ultra high voltage direct current （UHVDC） converter valves, it is necessary to study the fault mode analysis （FMA） and accelerated life test （ALT） of the saturable reactor. Firstly, the electrical and thermal stresses of saturable reactor were calculated under rated current operational conditions. Secondly, the fault mode of the saturable reactor was analyzed, and the main stress form and parts impacting its life time were pointed out. Finally, the average life time of the saturable reactor under high temperature stresses was evaluated based on accelerated life test. The results show that the epoxy resin is the weak point, which is caused by the temperature rise of magnetic cores. The ALT results show that the life time of the saturable reactor for converter valves is about 48 years, and the saturable reactor meets the reliability requirements of converter valves of State Grid Corporation of China （SGCC）.