评价直流电缆绝缘材料电性能的有效方法

Effective Method for Evaluating the Electrical Properties of DC Cable Insulation Materials

随着输送容量的增大,电压等级的上升,超高压直流电缆的绝缘性能要求越来越高。在国产化±535kV直流电缆的开发中,如何有效评价绝缘材料的电性能成为一个难点。文中研究了几种不同绝缘材料的平板试样、模型电缆和真型电缆的电性能评估方法,发现:平板试样的电性能测试难以表征材料成缆后的电性能,与成缆后的旋切片性能测试差异较大,而模型电缆采用等场强原理设计,其性能测试最接近实际电缆,能有效反映电缆绝缘材料的介电性能、可加工性能等综合耐电性能。因此建议采用模型电缆作为平板试样与真型电缆之间过渡评价的关键一环,有效地弥补平板试样评价真型电缆电性能的不足;此外,直流电缆料的电导率温度参数与附件材料的电导率温度参数匹配性也是评价直流电缆绝缘材料性能的重要参数,是决定直流电缆与电缆附件能否通过型式试验的关键评价指标之一。

With the increase of transmission capacity and voltage level,the demand for insulation performance of EHV DC is higher and higher.In the development of domestic±535 kV DC cable,how to evaluate the electrical properties of insulating materials effectively has become a difficulty.In this paper,the electrical performance evaluation methods of flat samples,model cables and real cables of different insulating materials are studied.It is found that the electrical performance test of flat samples is difficult to characterize the electrical performance of materials after cable manufacturing,which is quite different from the performance test of cable spin slice.However,the model cable is designed based on the principle of equal field strength,and its performance test is closest to the actual cable,so it can effectively reflect the dielectric properties,processability and other comprehensive electrical resistance of cable insulation materials.Therefore,it is suggested to use model cable as a key link in the evaluation between flat sample and real cable,so as to effectively make up for the deficiency of flat sample in evaluating the electrical properties of real cable;In addition,the matching between the conductivity temperature parameter of DC cable material and accessory material is also an important parameter,which is one of the key evaluation indexes to determine whether DC cable and cable accessories can pass the type test.