基于特征气体能量的油纸绝缘放电缺陷识别方法

Identification Method of Oil-Paper Insulation Discharge Defects Based on Characteristic Gas Energy

油中溶解气体分析法(DGA)因其包含的信息丰富、准确度高而广泛应用于现场变压器故障诊断。在传统DGA测试的基础上,结合热力学中的焓变理论,提出一种特征气体能量的计算方法,通过对比特征气体能量和放电能量的变化,发现二者发展趋势具有良好的一致性。设计了3种油纸绝缘典型放电缺陷模型:球板、柱板和针板,根据得到的特征气体能量发展情况,可将放电过程划分为前期、中期和后期3个阶段。结果表明:球板模型下气体能量发展趋势呈"S"型,而柱板和针板下气体能量的发展趋势类似。进一步提出能量密度比值R=c(C_2H_2)/c(CO)来识别柱板和针板放电。柱板模型下R值呈现出前期增长、中期停滞、后期再增长的变化趋势,而针板模型下R值持续增长。基于本研究结果,可实现对上述3种不同放电类型的识别。

Dissolved gas analysis（DGA） is widely used in on-site transformer fault diagnosis due to its abundant information and high accuracy. Based on the traditional DGA test, and combining with the enthalpy theory in thermodynamics, a method to calculate the characteristic gas energy was proposed. By comparing the variation of characteristic gas energy and discharge energy, it is found that their develop trends have good consistency. Three typical discharge defect models of oil-paper insulation, including ball-plate, column-plate, and needle-plate, were designed. According to the develop situation of the obtained characteristic gas energy, the discharge develop process could be divided into three stages including pre-stage, mid-stage, and post-stage. The results show that the gas energy develop trend under the ball-plate model shows ＂S＂ shape, and the gas energy develop trend under the column-plate and needle-plate are similar. Then the energy density ratio（R=c（C_2 H_2）/c（CO）） is further proposed to identify the discharge of column-plate and needle-plate. The R value under the needle-plate model shows a change trend of growing in pre-stage, stagnating in mid-stage, and growing again in post-stage, while the R value under the needle-plate model increases continuously. Basing on the research results, the above three discharge types can be identified.