ZnO压敏电阻是电力系统中用于过电压保护的避雷器的最核心元件，阀片的性能直接决定避雷器的过电压保护水平，而特高压输电系统对ZnO避雷器及其阀片的性能参数提出了更高的要求。为了研制适用于特高压避雷器的高电压梯度ZnO阀片，目前面临的最大困难在于阀片各项性能参数的综合平衡。解决目前面临困难的最理想可行的途径是从材料设计的角度出发，引入合理有效的数值计算模拟模型，并应用数值计算模拟成果来指导相关的试验研究过程，提出优化的试验研究策略和步骤。材料设计的最基本特征是围绕材料实际应用所需的性能要求开展针对性的研究工作。针对特高压避雷器的实际应用需求，高电压梯度的ZnO阀片能够降低避雷器总体高度，减小避雷器的体积和重量，降低生产制造难度和成本，并改善避雷器整体电位分布。同时，ZnO阀片的压敏电压梯度也受制于特高压避雷器绝缘间隙距离以及通流容量的限制，不宜无限制地提高。对于采用传统组装方式的特高压瓷套型、复合型、GIS罐式避雷器，最合适的压敏电压梯度分别为213 V/mm、300 V/mm和426 V/mm，相应的阀片能量吸收密度至少需要达到150 J/cm3、226 J/cm3、301 J/cm3的要求。材料设计的最基本工具是能够真实反映材料特性变化规律的计算模拟模型和算法。论文提出了以ZnO晶粒微结构模型、晶界分区模型以及双肖特基势垒导电机理模型为核心的ZnO压敏电阻计算模拟模型，并采用创新的快速分段线性化算法求解模型中的大规模、超复杂的非线性电阻网络问题。基于新型ZnO压敏电阻计算模拟模型和算法，论文详细分析了ZnO压敏电阻内在微结构及晶界固有的各种物理特性参数对于ZnO阀片宏观电气性能的影响效果和规律。应用ZnO压敏电阻计算模拟研究的成果，对稀土配方ZnO阀片各种原料成分和工艺条件的作用机理进行了更加深入、合理的分析，并在优化原理理论的框架下，提出了ZnO阀片优化试验研究的策略和步骤，试验研究过程比以往更有针对性和目的性，能够更快速地获得实际应用需求的试品性能。基于优化的策略和步骤，论文研制出压敏电压梯度接近2000 V/mm、非线性系数达到80左右、泄漏电流小于1 mA的高电压梯度ZnO阀片实验室试品。
ZnO varistor is the core component of the arrester applied in power systems for protection against over voltages. The performance of an arrester is directly decided by the capabilities of ZnO varistor. According to ultra-high voltage power systems, the required capabilities of ZnO varistor are also extra high. However, during the research process of ZnO varistor with high voltage gradient applied in ultra-high voltage arresters, the most difficult issue is the balance of all capability parameters of ZnO varistor. It seems that the method of material design is the most feasible solution for current problem.The basic objects of the material design method are the actual requirements of material capabilities based on practical application. According to the requirement of the ultra-high voltage arrester, ZnO varistor with higher voltage gradient can lower the height of the arrester, reduce its volume and weight, which results in lower difficulty and cost of manufacture, besides the improved uniformity of voltage distribution of the arrester. In addition, the voltage gradient of ZnO varistor is also restricted by the insulation and current requirements of the ultra-high voltage arrester. Assembled with traditional modes, the perfect voltage gradients of ZnO varistors applied in the porcelain, polymer and GIS arresters should be 213, 300 and 426 V/mm respectively, with the energy absorbabilities of 150, 226 and 301 J/cm3 at least.The basic tools of the material design method are the reasonable numerical simulation models which can describe the real characters of material capabilities. A novel simulation model has been proposed, consisted of ZnO grain microstructure, grain boundary division and double Schottky barriers. In addition, a novel arithmetic was also given to solve the large scale and extra complicated simulation model. Then, the relationships between the microstructural charaters and the macroscopical electrical capabilities of ZnO varistor were researched completedly.The simulation results have been well used for analysing the mechanism of additives and process conditions of ZnO varsitor toward its macroscopical capabilities. Later, the optimal strategy and process of ZnO varistor experimentation were proposed, and ZnO varistor samples with high voltage gradients were successfully made under instruction of above optimal experimentation process.
