大尺寸油纸绝缘结构空间电场非接触式测量的光学传感器

Non-contact Electro-optic Sensor for Space Electric Field in Large-scale Oil-pressboard Insulation Structure

油纸绝缘结构可靠的绝缘设计对保证电力变压器乃至电网的安全可靠运行至关重要,目前其设计可靠性主要依靠电场仿真计算及简易等效模型下的电场实测校验。对于换流变压器出线装置等大尺寸复杂结构,现有的电场测量手段无法有效应用,难以获得复杂结构内空间电场/电荷特性,对其绝缘设计和校核提出了挑战。基于Kerr电光效应,研发一种可用于大尺寸油纸绝缘结构内部空间电场测量的小型化传感器及相应的测量系统。该传感器内部采用多反射结构有效减小了器身尺寸,并显著提升了测量灵敏度,采用聚砜非金属材料降低了传感器的引入对待测电场的影响,定制化光学元件及合理的内部结构设计保证了其结构的小型化。利用平板电极,对所研制传感器的关键技术性能参数进行试验标定。利用所研发传感器,针对换流变压器阀侧出线装置大尺寸模型,进行直流电压模型内部油中空间电场特性的实验测试。测试结果表明:直流电压下,无论正负极性,随着加压时间的延长,内侧油道油中电场逐渐增加,最大增幅可达118.8%;中间油道同样逐渐增加,但达到稳态时间更短,增幅更小;外侧油道油中电场逐渐降低,最大降幅可达75.0%。该空间电场非接触式光学传感器可为进一步研究油纸绝缘空间电场和电荷分布特性提供新的方法和手段。

The design of oil-pressboard/paper insulation structure is the key to maintain the safe and reliable operation of power transformers, which mainly relies on simulation and verification test undertaken with simple or equivalent models.As for the large-scale structure such as outlet device of converter transformer, the present electric field measuring approaches could not be applied effectively, making it difficult to obtain the electric field or charge features in that complex structure, and therefore putting forward risks for the insulation design and verification. Based on Kerr electro-optic effect, a miniaturized electric field measuring sensor and the corresponding system were developed for the application test in large-scale oil-pressboard structure. The application of total reflection prism in sensor made contributions to both reduce the volume and enhance the measuring sensitivity. The polysulfone was adopted to produce the sensor body,weakening the influence of sensor on the electric field to be measured. The customized optical element and reasonable internal structure design ensure the sensor appearance to be a miniature configuration. The key technical performance parameters of sensor were obtained. The application test was conducted to capture the dynamic process of electric field in oil in large-scale outlet device model, which has three uniformlyspaced oil spacing divided by pressboards, under DC voltage.The test results indicated that under positive DC voltage, as the voltage duration prolongs, the strength of electric field in inner oil spacing and middle oil spacing increase, with a maximum growth of 118.8% to initial field strength, while that in outer oil spacing decreases to 25.0% of initial one. When it comes to negative DC voltage, the tendency of electric field is opposite to that under positive voltage. The designed sensor could provide some certain ideas and approaches for the further research in electric field and charge features in oil-pressboard/paper structure.