极限温度范围内特高压换流变压器典型绝缘结构在复合电场下的击穿及沿面闪络特性研究

The converter Transformer is the key equipment in HVDC power transmission system, and its reliability will directly effect the safe operation of power system.Due to the particular working conditions,the walve side windings of the converter transformer subjects the complex electrical field(such as AC,DC & AC and polarity reversal electrical field), which makes the breakdown characteristics of oil-paper insulation in converter transformer are very different from those in the traditional AC transformer.The issued research results show that the space charge and physical parameter changes in oil-paper instulation structure are very important effect factors for insulation breakdown in the converter transformer, and the temperature has the great influence on above factors. According to the operation conditions of converter transformer, this project will firtly carry out the research work on the influencs of temperature on space charge accumulation(oil-paper interface polarization, oil flowing electrifation) and physic parameter changes in oil-paper insulation, and then carry out research work on breakdown and flashover characteristics of oil-paper insulation under complex electrical field with extreme temperature scopes from -35℃~105℃. The rules of the temperature inflence on breakdown and flashover characteristics will be explored, and the physical and mathematics models will be built to explain the phenomenons of charge accumulation, flowing electrifation and breakdown or flashover under complex electrical field. The results of the above research works can complete the mechanism of breakdown and space charge accumulation in oil-paper insution structure, and can also be used to instruct the design and manufacture of the converter transformer to improve the safe operation of power system.

换流变压器是特高压直流输电系统中的重要设备，其运行可靠性直接影响系统的安全运行。由于运行工况的特殊性，换流变压器阀侧绕组绝缘承受着交流、交直流叠加和极性反转等复合电场的作用，使其绝缘结构内部的电场分布和击穿特性与普通交流变压器存在很大差异。已有研究结果表明空间电荷和油纸绝缘物理参数是影响换流变压器内部击穿及沿面闪络的重要因素，而温度对上述因素有着极大影响。本项目结合换流变压器实际运行工况，从温度对空间电荷积聚（界面极化、油流带电）及油、纸物理参数的影响入手，开展极限温度范围内（-35℃~105℃）换流变压器典型绝缘结构在复合电场作用下击穿与沿面闪络特性的研究，探索温度和油流速度对复合电场作用下油纸绝缘击穿及沿面闪络特性的影响规律，建立用以解释试验现象的物理与数学模型。项目成果可填补该领域的研究空白，对指导特高压换流变压器及相关产品的设计与制造，保障特高压直流输电系统安全运行具有重要的意义。

换流变压器是特高压直流输电系统中的重要设备，其运行可靠性直接影响系统的安全运行。由于运行工况的特殊性，换流变压器阀侧绕组绝缘承受着交流、交直流叠加和极性反转等复合电场的作用，使其绝缘结构内部的电场分布和击穿特性与普通交流变压器存在很大差异。已有研究结果表明空间电荷和油纸绝缘物理参数是影响换流变压器内部击穿及沿面闪络的重要因素，而温度对上述因素有着极大影响。本项目结合换流变压器实际运行工况，从温度对空间电荷积聚（界面极化、油流带电）及油、纸物理参数的影响入手，开展不同温度下油纸绝缘在复合电场作用下的油流带电和空间电荷积聚特性，以及油纸绝缘电场分布及击穿特性。通过上述理论与试验研究，得出了温度对换流变压器典型绝缘在复合电场作用下空间电荷积聚和油流带电的影响规律；探索出温度所引起空间电荷积聚、流油带电及油纸物理参数变化对换流变压器典型绝缘结构在复合电场作用下的击穿特性的影响规律，建立了用于描述不同温度和不同电场类型下油纸绝缘击穿的物理与数学模型，用以指导特高压换流变压器及相关产品的设计与制造，保障特高压输电系统安全运行。