恒压下油楔放电发展全过程的状态转换特征研究

通过局部放电检测来准确诊断电气设备绝缘状态和对危险缺陷进行及时预警,是电力部门实施状态运维的重要目标,也是当前局放状态检测领域的关键技术难题。文中以油楔放电模型来模拟电力变压器绕组匝间、饼间的局放缺陷,在施加恒定交流电压下采用高频、特高频两种手段对放电缺陷信号进行了全实时的检测;研究了油楔放电发展到击穿全过程中高频和特高频局放信号幅值、次数、信息熵、PRPD图谱等特征量的变化趋势及规律,对比分析了高频和特高频在放电全过程中信号特征的一致性和差异性。研究发现:油楔放电在恒压下存在两种典型阶段:平稳发展阶段和加速劣化阶段;同时从放电机理的角度分析了两种放电阶段存在的合理性。在平稳发展阶段,单位时间内的放电次数呈缓慢递增趋势,放电幅值相关统计量具有一定波动性;放电进入加速劣化的危险发展区间时,单位时间内的放电次数出现了明显的拐点和剧烈震荡的特征,高频和特高频部分特征参数出现了明显的上升或下降走势,综合二者信息可实现对平稳发展阶段和加速劣化阶段的准确判别。研究成果对局放的状态检测和危险故障预警提供了试验依据。

Study on the State Transition Characteristics in Whole Development Process of Oil Wedge Discharge Under Constant Pressure

It is of significance to detect the insulation defect of electrical equipment accurately and warn of dangerous discharge. And it is an important target and key technical problem for the electric power department to carry out the state operation and maintenance. In this paper, the oil wedge discharge model is used to simulate the partial discharge defects between the winding turns and the intercake of the power transformer. It is used ultra high frequency (UHF) and high frequency current (HF) methods to detect the signals in real time under constant voltage. The trend and regularity of the amplitude, frequency, entropy of the signals and PRPD pattern are studied. The consistency and difference of signal characteristics of HF and UHF are analyzed. The results show that the oil wedge discharge has stable development stage and accelerated deterioration stage under constant voltage, and at the same time, the rationality of two discharge stages is analyzed from the angle of discharge mechanism. The frequency of the signals in the penod of stationary development is slowly increasing, and the statistical parameters of signals amplitude are certain fluetuation. In the accelerated deterioration stage, the frequency of the signals have obvious inflection point and the characteristic of violent concussion. The characteristic parameters of HF and UHF have obvious rise or decrease trend, and the information of the two can realize the accurate discrimination of stable development state and accelerated deterioration condition. The research results of this paper provide the test basis for the status detection and hazard warning.